MFJ-269 repair (I win)

[Jeff Liebermann]

I just repaired an old MFJ-269 antenna analyzer. This time, the 4
diodes around the RF connector were NOT blown. Instead, it was crappy
SMT soldering for the components surrounding the diodes. The solder
joints looked ok before I resoldered them, but were obviously a bad
connection because several resistors just fell off the board when I
touched one end with the soldering iron, indicating the other end was
not properly soldered. With the resistor removed, the PCB pad looked
like it had never been soldered. If you don't have good soldering
tools, a steady hand, and a good microscope, DON'T try this as you'll
probably make a mess, as I did before I realized what was happening.

Because the various parts on the RF board were not originally making
good contact to the PCB pads, the calibration is off. The display
reads about 12% too high for impedance and dead on for reactance. I'm
debating if it's worth calibrating.
<http://www.w8ji.com/mfj-259b_calibration.htm>

Now working on an MFJ-259A, which looks like the usual blown diode
problem:
<http://802.11junk.com/jeffl/MFJ-269-repair/>

[amdx]

Post by Jeff Liebermann
I just repaired an old MFJ-269 antenna analyzer. This time, the 4
diodes around the RF connector were NOT blown. Instead, it was crappy
SMT soldering for the components surrounding the diodes. The solder
joints looked ok before I resoldered them, but were obviously a bad
connection because several resistors just fell off the board when I
touched one end with the soldering iron, indicating the other end was
not properly soldered. With the resistor removed, the PCB pad looked
like it had never been soldered. If you don't have good soldering
tools, a steady hand, and a good microscope, DON'T try this as you'll
probably make a mess, as I did before I realized what was happening.
Because the various parts on the RF board were not originally making
good contact to the PCB pads, the calibration is off. The display
reads about 12% too high for impedance and dead on for reactance. I'm
debating if it's worth calibrating.
<http://www.w8ji.com/mfj-259b_calibration.htm>
Now working on an MFJ-259A, which looks like the usual blown diode
<http://802.11junk.com/jeffl/MFJ-269-repair/>

That's how I got my MFJ-259B, about 15 years ago, Someone at the local
ham club had a defective one, gave it to a fellow ham to fix, he
returned it saying that he couldn't fix it.
I told the owner, let me have a shot at it, if I can fix it I'll
buy it from you. It was "the usual blown diode problem:" I shocked the
owner when I gave him $60.00 for the repaired unit. I don't think he
expected me to contact him again.
Mikek

[Tom]

Post by amdx

Post by Jeff Liebermann
I just repaired an old MFJ-269 antenna analyzer. This time, the 4
diodes around the RF connector were NOT blown. Instead, it was crappy
SMT soldering for the components surrounding the diodes. The solder
joints looked ok before I resoldered them, but were obviously a bad
connection because several resistors just fell off the board when I
touched one end with the soldering iron, indicating the other end was
not properly soldered. With the resistor removed, the PCB pad looked
like it had never been soldered. If you don't have good soldering
tools, a steady hand, and a good microscope, DON'T try this as you'll
probably make a mess, as I did before I realized what was happening.
Because the various parts on the RF board were not originally making
good contact to the PCB pads, the calibration is off. The display
reads about 12% too high for impedance and dead on for reactance. I'm
debating if it's worth calibrating.
<http://www.w8ji.com/mfj-259b_calibration.htm>
Now working on an MFJ-259A, which looks like the usual blown diode
<http://802.11junk.com/jeffl/MFJ-269-repair/>

That's how I got my MFJ-259B, about 15 years ago, Someone at the local
ham club had a defective one, gave it to a fellow ham to fix, he
returned it saying that he couldn't fix it.
I told the owner, let me have a shot at it, if I can fix it I'll
buy it from you. It was "the usual blown diode problem:" I shocked the
owner when I gave him $60.00 for the repaired unit. I don't think he
expected me to contact him again.
Mikek

Good for you Mike,

I once came across an Ameritron ALS-600 with analogue power supply and a
couple of vhf-uhf transceivers in a junk box at a garage sale. I asked
how much for the whole box. I was told 60 bucks. I assumed the stuff was
probably defective. However, the person selling it was a woman who had
lost her ham husband.

I wrote her a check for $500. That is what I figured a defective ALS-600
might be worth. She was shocked. I did not do this to be generous. I did
it because I knew that if I really screwed her on that deal, I would
feel guilty every time I used that amplifier. It turned out that the
amplifier actually worked but introduced a bit of distortion. I sent it
to MFJ and they rebalanced the output transistors. It has very good
fidelity now. The trip to MFJ cost about 200 dollars. I had to buy one
of their shipping boxes. Those are not cheap. Still, 700 dollars for an
ALS-600 is a bargain.

I liked that design so well that I bought an ALS-1300 which is just two
ALS-600s in a box. So, I have the 600 as a backup amp. That 1300 has
been such a good work horse. Tom at MFJ and others who worked on that
amp design did a fine job. Originally there was a defect in the
switching supply that they bought for it. Mine has been updated to
protect the 12 volt supply.

[Jeff Liebermann]

Post by amdx
That's how I got my MFJ-259B, about 15 years ago, Someone at the local
ham club had a defective one, gave it to a fellow ham to fix, he
returned it saying that he couldn't fix it.
I told the owner, let me have a shot at it, if I can fix it I'll
buy it from you. It was "the usual blown diode problem:" I shocked the
owner when I gave him $60.00 for the repaired unit. I don't think he
expected me to contact him again.
Mikek

Yep. I'm working on an MFJ-259B which might have blown diodes. It's
very easy to do. I'm considering adding a 1M resistor from the center
pin to ground to bleed off any static buildup. Beware of ungrounded
antennas. BTW, I paid $100 for mine. Grumble...

I'm also working with another ham that has an old MFJ-269 with some
very strange problems. I can't conjur a theory except that his has
the same problem as mine with the crappy soldering on the RF PCB. I've
recommended reflowing all the SMT parts around the coax connector.
That should either fix it, or destroy it.

Drivel: I'm trying to find a replacement LCD 1602 display with
backlighting. Plenty on eBay, but all the wrong size. Argh.

[Dave Platt]

Post by Jeff Liebermann
Now working on an MFJ-259A, which looks like the usual blown diode
<http://802.11junk.com/jeffl/MFJ-269-repair/>
"Of course, when I got it back together (for the 2nd time), I found
the reading to be erratic and intermittent. It took a while to
discover that the owner had somehow spread the gold center contact
leafs in the type-N connector and my adapter wasn't making
contact."

My repeater cohort and I have seen quite a few N connectors which were
damaged in precisely this fashion.

One cause: some N-connector adapters floating around out there have
center pins which are either too large in diameter, improperly
tapered, or which protrude too far "forwards". I suspect that male N
connectors, if improperly installed, can have the same problem (the
pin is pushed too far into the connector).

In either case, (over)tightening such an N-male connector onto an
N-female will cause it to make excellent contact... once... as the pin
splays the female connector's contacts outwards. Subsequent
connection attempts with a properly-configured N male won't make good
contact.

In a pinch, you can try pinching the contact fingers back in, but it's
nigh-on impossible to restore them properly. Better to remove the
damaged female connector and replace it. Then, check all of your male
N connectors to make sure the center pin has the proper taper and is
in the proper position. A center pin with a rounded blunt end (rather
than a properly-tapered point) is Trouble.

This turned out to be all that was wrong with a defective TK-981 I
picked up at the De Anza ham flea market last year. Cut off the N
connector, solder-and-crimp a new one onto the pigtail, and it checks
out fine.

[Rob]

Post by Dave Platt
One cause: some N-connector adapters floating around out there have
center pins which are either too large in diameter, improperly
tapered, or which protrude too far "forwards". I suspect that male N
connectors, if improperly installed, can have the same problem (the
pin is pushed too far into the connector).

With some types of cable, there is a tendency for the inner conductor
to "lengthen" relative to the outer shield when the cable is repeatedly
wound and unwound in a small radius.

This can sometimes push out the connector pin a little.

[Jeff Liebermann]

Post by Dave Platt

Post by Jeff Liebermann
Now working on an MFJ-259A, which looks like the usual blown diode
<http://802.11junk.com/jeffl/MFJ-269-repair/>
"Of course, when I got it back together (for the 2nd time), I found
the reading to be erratic and intermittent. It took a while to
discover that the owner had somehow spread the gold center contact
leafs in the type-N connector and my adapter wasn't making
contact."

My repeater cohort and I have seen quite a few N connectors which were
damaged in precisely this fashion.

I can see that with N connectors that are assembled or crimped in
pieces, but not a 1 piece panel mount N receptacle. The PCB board
it's mounted upon would break before the connector.

Post by Dave Platt
One cause: some N-connector adapters floating around out there have
center pins which are either too large in diameter, improperly
tapered, or which protrude too far "forwards". I suspect that male N
connectors, if improperly installed, can have the same problem (the
pin is pushed too far into the connector).

Yep. However, I checked for that problem with some wire gauges.
Intermittent center pins, are a real problem, but not on this one.
Usually the center pin receptacle is ruined by a blob of solder on the
outside of the mating pin plug.

Post by Dave Platt
In either case, (over)tightening such an N-male connector onto an
N-female will cause it to make excellent contact... once... as the pin
splays the female connector's contacts outwards. Subsequent
connection attempts with a properly-configured N male won't make good
contact.

You should see the mess that problem produces when an unspecified
manufacturer of hard disk drives used power plugs that spread the
0.093 Molex connectors. Subsequent connections to "normal" size
0.093" connectors were very intermittent.

Post by Dave Platt
In a pinch, you can try pinching the contact fingers back in, but it's
nigh-on impossible to restore them properly. Better to remove the
damaged female connector and replace it. Then, check all of your male
N connectors to make sure the center pin has the proper taper and is
in the proper position. A center pin with a rounded blunt end (rather
than a properly-tapered point) is Trouble.
This turned out to be all that was wrong with a defective TK-981 I
picked up at the De Anza ham flea market last year. Cut off the N
connector, solder-and-crimp a new one onto the pigtail, and it checks
out fine.

Nicely done. I once saw a mobile (forgot the model) with the center
drilled out of the UHF SO-239, a pigtail inserted, and a BNC
receptacle at the end. I like it.

[gareth]

Post by Dave Platt

Post by Jeff Liebermann
Now working on an MFJ-259A, which looks like the usual blown diode
<http://802.11junk.com/jeffl/MFJ-269-repair/>
"Of course, when I got it back together (for the 2nd time), I found
the reading to be erratic and intermittent. It took a while to
discover that the owner had somehow spread the gold center contact
leafs in the type-N connector and my adapter wasn't making
contact."

My repeater cohort and I have seen quite a few N connectors which were
damaged in precisely this fashion.

The N connector is so-called because there are N different ways to assemble
it, and all of them wrong :-)

[Robert L Wilson Jr.]

Post by Jeff Liebermann
I just repaired an old MFJ-269 antenna analyzer. This time, the 4
diodes around the RF connector were NOT blown. Instead, it was crappy
SMT soldering for the components surrounding the diodes. The solder
joints looked ok before I resoldered them, but were obviously a bad
connection because several resistors just fell off the board when I
touched one end with the soldering iron, indicating the other end was
not properly soldered. With the resistor removed, the PCB pad looked
like it had never been soldered. If you don't have good soldering
tools, a steady hand, and a good microscope, DON'T try this as you'll
probably make a mess, as I did before I realized what was happening.
Because the various parts on the RF board were not originally making
good contact to the PCB pads, the calibration is off. The display
reads about 12% too high for impedance and dead on for reactance. I'm
debating if it's worth calibrating.
<http://www.w8ji.com/mfj-259b_calibration.htm>
Now working on an MFJ-259A, which looks like the usual blown diode
<http://802.11junk.com/jeffl/MFJ-269-repair/>

I've generally found MFJ stuff has decent design and rather good
components, but terrible wave soldering on the PC boards (and sometimes
hand soldering on components off the board like chassis mounted
connectors). On my 259B, it worked well for almost a year, and then
became erratic. When I saw how many soldered joints weren't, I decided
not to try to figure out which ones were bad: I just went around and
resoldered everything on the board. Since then it has worked perfectly.

Wave soldering is a marginal thing, I think it is amazing how many times
it does work. Think about how it goes: Basically the PC board is
suspended just above a vat of molten solder, and a wave is caused to run
across the vat. The wave, we hope, just reaches up to the connections on
the board and solders them. Too high and it makes solder bridges. Too
low and it either misses connections or at least does not stay on them
long enough. And it is not long on a connection at best, so does it get
it hot enough?

It is not just fairly inexpensive things like my MFJ analyzer that have
had problems. I did the "resolder the whole board" thing on my Phase
Linear preamp many years ago also, and that was by no means low end!

Bob Wilson

[Irv Finkleman]

I have a number of MFJ items that I picked up in non-working
conditions and fixed up. They include MFJ-259B, MFJ-931, MFJ-949E
and others. Other than the 259B which involved cleaning leaky battery
residue and replacing the input diodes. most of the work involved
resoldering and/or replacing blown meters, and in once case
a bandswitch. Once repaired, everything
has remained totally reliable and functional. I've never had
problems ordering parts from them to fix the stuff.
The 'Mighty Fine Junk' reputation is deserved only because of
the poor soldering, but once repaired it serves one well -- at
least in my books!

Irv VE6BP

[Brian Reay]

Post by Irv Finkleman
I have a number of MFJ items that I picked up in non-working
conditions and fixed up. They include MFJ-259B, MFJ-931, MFJ-949E
and others. Other than the 259B which involved cleaning leaky battery
residue and replacing the input diodes. most of the work involved
resoldering and/or replacing blown meters, and in once case
a bandswitch. Once repaired, everything
has remained totally reliable and functional. I've never had
problems ordering parts from them to fix the stuff.
The 'Mighty Fine Junk' reputation is deserved only because of
the poor soldering, but once repaired it serves one well -- at
least in my books!
Irv VE6BP

I think that is a pretty accurate assessment, based on my experience of
repairing a number of MFJ items.

In particular, I was asked to repair a 259 for someone which had some of
the worst soldering I've even seen in a commercial product. A bit of time
with a solder sucker and a soldering iron and all was well, save running
through a calibration procedure. Once that was done, it was fine.

[Jeff Liebermann]

On Thu, 12 Nov 2015 12:20:53 -0600, "Robert L Wilson Jr."
<***@math.wisc.edu> wrote:

I was afraid that my rant was going to turn into a discussion on MFJ
quality or lack thereof. I was more interested in giving owners of
the various MFJ antenna analyzers a clue as to what might be wrong
with theirs, than attempting to fix the problem at the source. I'm
sure MFJ knows that they have a problem by now.

Post by Robert L Wilson Jr.
Wave soldering is a marginal thing, I think it is amazing how many times
it does work. Think about how it goes: Basically the PC board is
suspended just above a vat of molten solder, and a wave is caused to run
across the vat. The wave, we hope, just reaches up to the connections on
the board and solders them.

Nope. PCB's with surface mount devices are not wave soldered. I
worked for several companies that had wave solder machinery during the
1970's, before SMT parts were common. Keeping the production line
machinery going was one my side projects. These daze, components are
attached with solder paste and soldered using infrared or vapor phase
reflow ovens.

Please note that the MFJ-269 PCB's have all the components on the
component side and have no leaded components on the board (except for
some flex wires to the meter and battery and several ribbon cables).

Post by Robert L Wilson Jr.
Too high and it makes solder bridges.

Nope. Too low a temperature and you get bridging. The wave has to
touch the pads on the bottom of the PCB or the pads don't get
soldered. Too low a wave is a bigger problem, where the pads don't
get any solder.

Post by Robert L Wilson Jr.
Too
low and it either misses connections or at least does not stay on them
long enough.

Soldering time is controlled by the speed of the chain drive moving
the PAB across the wave, not by the height of the wave. There might
be a tiny variation in timing with height, but with the nearly
vertical sides of the wave caused by the weight of the solder, the
soldering time is about the same for all wave heights.

Post by Robert L Wilson Jr.
And it is not long on a connection at best, so does it get
it hot enough?

We had thermocouples stuck into the wave to control the temperature.
At worst, were off a few degrees one way or the other.

Post by Robert L Wilson Jr.
It is not just fairly inexpensive things like my MFJ analyzer that have
had problems. I did the "resolder the whole board" thing on my Phase
Linear preamp many years ago also, and that was by no means low end!
Bob Wilson

I'm still slightly mystified how the components looked like they were
properly soldered, while the solder didn't stick to the PCB pad. The
best I can offer is some grease on the pads. Also, it was only in one
part of the PCB (around the RF connector). The other half of the RF
board was just fine.

[Sal M. O'Nella]

"Jeff Liebermann" wrote in message news:***@4ax.com...


I'm still slightly mystified how the components looked like they were
properly soldered, while the solder didn't stick to the PCB pad. The
best I can offer is some grease on the pads. Also, it was only in one
part of the PCB (around the RF connector). The other half of the RF
board was just fine.

===========================================================

Showing my age, I worked on a tube TV which had a red hum bar floating up
through an essentially normal color picture. The ground on the R-Y amp tube
heater needed to be resoldered. It was a quick fix after hours of fruitless
troubleshooting. (A high resistance joint caused the 60 Hz A/C voltage to
be coupled onto the cathode, modulating the R-Y signal. Oddly, the tube was
lit, keeping us from looking where the trouble lay.)

[highlandham]

Post by Robert L Wilson Jr.

Post by Jeff Liebermann
I just repaired an old MFJ-269 antenna analyzer. This time, the 4
diodes around the RF connector were NOT blown. Instead, it was crappy
SMT soldering for the components surrounding the diodes. The solder
joints looked ok before I resoldered them, but were obviously a bad
connection because several resistors just fell off the board when I
touched one end with the soldering iron, indicating the other end was
not properly soldered. With the resistor removed, the PCB pad looked
like it had never been soldered. If you don't have good soldering
tools, a steady hand, and a good microscope, DON'T try this as you'll
probably make a mess, as I did before I realized what was happening.
Because the various parts on the RF board were not originally making
good contact to the PCB pads, the calibration is off. The display
reads about 12% too high for impedance and dead on for reactance. I'm
debating if it's worth calibrating.
<http://www.w8ji.com/mfj-259b_calibration.htm>
Now working on an MFJ-259A, which looks like the usual blown diode
<http://802.11junk.com/jeffl/MFJ-269-repair/>

I've generally found MFJ stuff has decent design and rather good
components, but terrible wave soldering on the PC boards (and sometimes
hand soldering on components off the board like chassis mounted
connectors). On my 259B, it worked well for almost a year, and then
became erratic. When I saw how many soldered joints weren't, I decided
not to try to figure out which ones were bad: I just went around and
resoldered everything on the board. Since then it has worked perfectly.
Wave soldering is a marginal thing, I think it is amazing how many times
it does work. Think about how it goes: Basically the PC board is
suspended just above a vat of molten solder, and a wave is caused to run
across the vat. The wave, we hope, just reaches up to the connections on
the board and solders them. Too high and it makes solder bridges. Too
low and it either misses connections or at least does not stay on them
long enough. And it is not long on a connection at best, so does it get
it hot enough?
It is not just fairly inexpensive things like my MFJ analyzer that have
had problems. I did the "resolder the whole board" thing on my Phase
Linear preamp many years ago also, and that was by no means low end!
Bob Wilson

=======
What strikes me in this newsgroup thread , time and again, is that MFJ´s
quality control people (if they exist) pass badly soldered PCBs and
other imperfections which affect their products´ reliability . But for
some reason they get away with it. To me this seems to be an attitude
brought about by management.........Martin F. Jue ?

Frank , GM0CSZ / KN6WH

[Tom]

Post by highlandham

Post by Robert L Wilson Jr.

Post by Jeff Liebermann
I just repaired an old MFJ-269 antenna analyzer. This time, the 4
diodes around the RF connector were NOT blown. Instead, it was crappy
SMT soldering for the components surrounding the diodes. The solder
joints looked ok before I resoldered them, but were obviously a bad
connection because several resistors just fell off the board when I
touched one end with the soldering iron, indicating the other end was
not properly soldered. With the resistor removed, the PCB pad looked
like it had never been soldered. If you don't have good soldering
tools, a steady hand, and a good microscope, DON'T try this as you'll
probably make a mess, as I did before I realized what was happening.
Because the various parts on the RF board were not originally making
good contact to the PCB pads, the calibration is off. The display
reads about 12% too high for impedance and dead on for reactance. I'm
debating if it's worth calibrating.
<http://www.w8ji.com/mfj-259b_calibration.htm>
Now working on an MFJ-259A, which looks like the usual blown diode
<http://802.11junk.com/jeffl/MFJ-269-repair/>

I've generally found MFJ stuff has decent design and rather good
components, but terrible wave soldering on the PC boards (and sometimes
hand soldering on components off the board like chassis mounted
connectors). On my 259B, it worked well for almost a year, and then
became erratic. When I saw how many soldered joints weren't, I decided
not to try to figure out which ones were bad: I just went around and
resoldered everything on the board. Since then it has worked perfectly.
Wave soldering is a marginal thing, I think it is amazing how many times
it does work. Think about how it goes: Basically the PC board is
suspended just above a vat of molten solder, and a wave is caused to run
across the vat. The wave, we hope, just reaches up to the connections on
the board and solders them. Too high and it makes solder bridges. Too
low and it either misses connections or at least does not stay on them
long enough. And it is not long on a connection at best, so does it get
it hot enough?
It is not just fairly inexpensive things like my MFJ analyzer that have
had problems. I did the "resolder the whole board" thing on my Phase
Linear preamp many years ago also, and that was by no means low end!
Bob Wilson

=======
What strikes me in this newsgroup thread , time and again, is that MFJ´s
quality control people (if they exist) pass badly soldered PCBs and
other imperfections which affect their products´ reliability . But for
some reason they get away with it. To me this seems to be an attitude
brought about by management.........Martin F. Jue ?
Frank , GM0CSZ / KN6WH

It is too often that some of these things get past QC. The good news is
that some of their products, like their linear amplifiers have allowed
the ordinary ham to run power. Other amplifiers always cost more and
seem to be no more reliable than an Ameritron model. I have two, the
ALS-600 and the 1300. Both have been excellent products for me. I did
have an AL-80B, but sold it.

Most of us hams do not have the money to go out and buy an Alpha amp.
From my own experience, I can tell not difference in the signal from an
Alpha or Tokyo from an Ameritron.

I am guessing that Martin is pushing those products through QC very
quickly to keep margins up. It is a balance between QC and profit margin
that is probably hard to find. My own guess is that if he put more
emphasis on QC and charged a bit more for each product, that his
business would do better just from the reputation he would gain.

[Ralph Mowery]

Most of us hams do not have the money to go out and buy an Alpha amp. From
my own experience, I can tell not difference in the signal from an Alpha
or Tokyo from an Ameritron.
I am guessing that Martin is pushing those products through QC very
quickly to keep margins up. It is a balance between QC and profit margin
that is probably hard to find. My own guess is that if he put more
emphasis on QC and charged a bit more for each product, that his business
would do better just from the reputation he would gain.

I think Ameritron was bought by MFJ as they have bought a few other
companies.
I have only bought 2 items made by MFJ. One was a packet tnc years ago. It
was defective and I sent it back. They sent me a new one and I had it in
about 3 days. No problem on that as I know it is easy for a new item to be
defective out of the box and they did ship a new one just as fast as
possiable. About 5 years later I bought a new antenna tuner from a dealer at
a hamfest. It had loose screws and after I tightened them and recalibrated
the wattmeter that was way off with a Bird meter, it seemed to work fine.
The schematic in the manual did not match the tuner either. I try not to
even look at the MFJ items due to the poor reputation of the quality
control.

From what I am hearing, when MFJ buys a company, the quality goes down hill.

[Wayne]

Post by highlandham

Post by Robert L Wilson Jr.

Post by Jeff Liebermann
I just repaired an old MFJ-269 antenna analyzer. This time, the 4
diodes around the RF connector were NOT blown. Instead, it was crappy
SMT soldering for the components surrounding the diodes. The solder
joints looked ok before I resoldered them, but were obviously a bad
connection because several resistors just fell off the board when I
touched one end with the soldering iron, indicating the other end was
not properly soldered. With the resistor removed, the PCB pad looked
like it had never been soldered. If you don't have good soldering
tools, a steady hand, and a good microscope, DON'T try this as you'll
probably make a mess, as I did before I realized what was happening.
Because the various parts on the RF board were not originally making
good contact to the PCB pads, the calibration is off. The display
reads about 12% too high for impedance and dead on for reactance. I'm
debating if it's worth calibrating.
<http://www.w8ji.com/mfj-259b_calibration.htm>
Now working on an MFJ-259A, which looks like the usual blown diode
<http://802.11junk.com/jeffl/MFJ-269-repair/>

I've generally found MFJ stuff has decent design and rather good
components, but terrible wave soldering on the PC boards (and sometimes
hand soldering on components off the board like chassis mounted
connectors). On my 259B, it worked well for almost a year, and then
became erratic. When I saw how many soldered joints weren't, I decided
not to try to figure out which ones were bad: I just went around and
resoldered everything on the board. Since then it has worked perfectly.
Wave soldering is a marginal thing, I think it is amazing how many times
it does work. Think about how it goes: Basically the PC board is
suspended just above a vat of molten solder, and a wave is caused to run
across the vat. The wave, we hope, just reaches up to the connections on
the board and solders them. Too high and it makes solder bridges. Too
low and it either misses connections or at least does not stay on them
long enough. And it is not long on a connection at best, so does it get
it hot enough?
It is not just fairly inexpensive things like my MFJ analyzer that have
had problems. I did the "resolder the whole board" thing on my Phase
Linear preamp many years ago also, and that was by no means low end!
Bob Wilson

=======
What strikes me in this newsgroup thread , time and again, is that MFJ´s
quality control people (if they exist) pass badly soldered PCBs and
other imperfections which affect their products´ reliability . But for
some reason they get away with it. To me this seems to be an attitude
brought about by management.........Martin F. Jue ?
Frank , GM0CSZ / KN6WH

# It is too often that some of these things get past QC. The good news is
# that some of their products, like their linear amplifiers have allowed
# the ordinary ham to run power. .

MFJ seems to have gotten a bit better as the years go by.
Once I bought something (a cw filter perhaps) that had the PC board mounted
by wedging it at an angle and using a bead of epoxy to hold it in place.

I haven't seen that kind of sloppy work from them in a while.

[Sal M. O'Nella]

"highlandham" wrote in message news:n284cd$ais$***@dont-email.me...

<< snip >>

What strikes me in this newsgroup thread , time and again, is that MFJ´s
quality control people (if they exist) pass badly soldered PCBs and
other imperfections which affect their products´ reliability . But for
some reason they get away with it. To me this seems to be an attitude
brought about by management.........Martin F. Jue ?

Frank , GM0CSZ / KN6WH

=========================================================

I picked up an MFJ "Deluxe Versatuner" at a ham swap meet. I opened it at
home to give it some poking and prodding. I quickly discovered that most of
the hardware need to be tightened or retightened -- if it was ever tight.
This reminds me to open it again. It's been a few years. :-)

"Sal" (really KD6VKW)

[Bob Wilson]

Post by Sal M. O'Nella
<< snip >>
What strikes me in this newsgroup thread , time and again, is that MFJ´s
quality control people (if they exist) pass badly soldered PCBs and
other imperfections which affect their products´ reliability . But for
some reason they get away with it. To me this seems to be an attitude
brought about by management.........Martin F. Jue ?
Frank , GM0CSZ / KN6WH
=========================================================
I picked up an MFJ "Deluxe Versatuner" at a ham swap meet. I opened it
at home to give it some poking and prodding. I quickly discovered that
most of the hardware need to be tightened or retightened -- if it was
ever tight. This reminds me to open it again. It's been a few years. :-)
"Sal" (really KD6VKW)

It's not just what we first think of as electronics: I have a Chevrolet
pickup truck, and the windshield wipers quit working. (Of course it
happened during an intense storm while I was far from home.)

Online I found that (a) it was a common problem among many models from
General Motors (not just Chevy) for quite a few years, and (b) if you
went to the dealer they would install a new wiper motor for about $200.

I took the motor out and disassembled it. There was a surprisingly
complicated PC board governing the several different speeds of
operation. And, of course, at least half the soldered connections needed
to be redone.

It has now worked fine for another decade, but I feel badly about the
(hundreds of?) thousands of people who wasted all that money, and all
the wasted (probably trashed rather than recycled) motors and gear
trains and electronics, etc.

Maybe I should be amazed at how well so much of our electronics does
work, if it is this hard (read expensive to the manufacturer, not really
difficult!) to do mass production PC board soldering right!
Bob Wilson

[Sal M. O'Nella]

"Robert L Wilson Jr." wrote in message news:n22l9o$5k6$***@speranza.aioe.org...

<< snip >>

It is not just fairly inexpensive things like my MFJ analyzer that have
had problems. I did the "resolder the whole board" thing on my Phase
Linear preamp many years ago also, and that was by no means low end!

Bob Wilson

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

In 1970, I bought a new Chevy Impala, drove it for a couple of years,
including cross-country. One day the radio quit. One dashboard-thump
later, the radio was back.

After another YEAR, the radio quit again and no amount of thumping had any
effect. On the weekend, I pulled it and opened it. Inside, a single wire
ran from the DC plug on the back to the ON/OFF switch. The front end of
that wire was looped through a lug on the switch but it had never been
soldered. Not a trace of solder on the lug or the wire. After a minute's
work and a centimeter of solder, I had my radio back. No more problems.

How/why did it work all those years ... then abruptly quit, work again, then
quit again? Unexplained.

[Robin Midgett]

Post by Jeff Liebermann
I just repaired an old MFJ-269 antenna analyzer. This time, the 4
diodes around the RF connector were NOT blown. Instead, it was crappy
SMT soldering for the components surrounding the diodes. The solder
joints looked ok before I resoldered them, but were obviously a bad
connection because several resistors just fell off the board when I
touched one end with the soldering iron, indicating the other end was
not properly soldered. With the resistor removed, the PCB pad looked
like it had never been soldered. If you don't have good soldering
tools, a steady hand, and a good microscope, DON'T try this as you'll
probably make a mess, as I did before I realized what was happening.
Because the various parts on the RF board were not originally making
good contact to the PCB pads, the calibration is off. The display
reads about 12% too high for impedance and dead on for reactance. I'm
debating if it's worth calibrating.
<http://www.w8ji.com/mfj-259b_calibration.htm>
Now working on an MFJ-259A, which looks like the usual blown diode
<http://802.11junk.com/jeffl/MFJ-269-repair/>
--

snip..

Hi Jeff & the list,
I found your post while looking for potential solutions to the problem I'm having with my MFJ-269. It seems to work fine below UHF. Activating the UHF portion, I see "Increase Frequency" in the display, which is usually followed by "Voltage Low .2Volts". I wonder if you've seen this problem before and if you might share any insight as to the usual cause of it.

Thank you,
Robin K4IDC

[Jeff Liebermann]

On Fri, 26 Aug 2016 14:40:41 -0700 (PDT), Robin Midgett

Post by Robin Midgett

Post by Jeff Liebermann
I just repaired an old MFJ-269 antenna analyzer. This time, the 4
diodes around the RF connector were NOT blown. Instead, it was crappy
SMT soldering for the components surrounding the diodes. The solder
joints looked ok before I resoldered them, but were obviously a bad
connection because several resistors just fell off the board when I
touched one end with the soldering iron, indicating the other end was
not properly soldered. With the resistor removed, the PCB pad looked
like it had never been soldered. If you don't have good soldering
tools, a steady hand, and a good microscope, DON'T try this as you'll
probably make a mess, as I did before I realized what was happening.
Because the various parts on the RF board were not originally making
good contact to the PCB pads, the calibration is off. The display
reads about 12% too high for impedance and dead on for reactance. I'm
debating if it's worth calibrating.
<http://www.w8ji.com/mfj-259b_calibration.htm>
Now working on an MFJ-259A, which looks like the usual blown diode
<http://802.11junk.com/jeffl/MFJ-269-repair/>
--

snip..
Hi Jeff & the list,
I found your post while looking for potential solutions to the problem
I'm having with my MFJ-269. It seems to work fine below UHF. Activating
the UHF portion, I see "Increase Frequency" in the display, which is
usually followed by "Voltage Low .2Volts". I wonder if you've seen this
problem before and if you might share any insight as to the usual cause
of it.
Thank you,
Robin K4IDC

Is this an MFJ-269a, b, or c?

I haven't seen that problem, but I do have a bad guess(tm). If it
works on HF/VHF, but not on UHF, it's most likely something in the UHF
section. The UHF band edges are hard coded in firmware:
<http://www.vk2zay.net/article/197>
"There is also a "UHF" switch that triples the oscillator
in the 114-170 band giving 415-470 MHz coverage the edges
of which are enforced in software, the display telling
you to increase or decrease frequency until within that band."

An error message of "Increase Frequency" might mean that the UHF
oscillator is operating too low in frequency, which methinks is
unlikely, or too low an output, which is more likely. Look around
Q25, U11, and U12. My guess(tm) is that Q25 is fried due to someone
transmitting into the MFJ-269 while it was in UHF mode. It's the same
problem as with the blown PIN diodes, but with a different
(switchable) RF section.

See schematic at:
<http://802.11junk.com/jeffl/MFJ-269-repair/mfj-269-schematic.pdf>

Also, the two I repaired had bad and intermittent solder connections
on the ribbon cables. You might want to check or just premptively
resolder the connections while you have it open.

Incidentally, I've been looking for a backlighted replacement display,
but so far, no luck.

More:
<http://vr2xmt.blogspot.com/2010/09/mfj-269-anatenna-analyzer-repairing.html>

[c***@gmail.com]

I need my mfj analyser 259 repaired

[Allodoxaphobia]

Post by c***@gmail.com
I need my mfj analyser 259 repaired

Thanks for letting us know.

Next time start your own thread -- instead of
replying to a nearly FIVE YEAR OLD thread.

Sheesh! google groopers!

[Petr OK1RP]

Hi all,

anybody here experienced with polarity reversal damage of MFJ-259B please?
My father damaged it by his mistake and he is totally frustrated so I would like to repair it for him.
Just want to ask what should be burned and where to start...?

Thanks, 73 - Petr, OK1RP

[Robert Wilson]

Post by Petr OK1RP
Hi all,
anybody here experienced with polarity reversal damage of MFJ-259B please?
My father damaged it by his mistake and he is totally frustrated so I would like to repair it for him.
Just want to ask what should be burned and where to start...?
Thanks, 73 - Petr, OK1RP

Petr,

There is a schematic at >
https://qrzcq.com/pub/RADIO_MANUALS/MFJ/MFJ--259-Ant_Analyser-sch.pdf

I can see lots of things (e.g. many of the transistors) that could be
damaged, far too many for me to have any confidence picking them out
just from that.

But you could start there for testing components.
WA9D

[wicklowham]

Post by Robert Wilson

Post by Petr OK1RP
Hi all,
anybody here experienced with polarity reversal damage of MFJ-259B please?
My father damaged it by his mistake and he is totally frustrated so I
would like to repair it for him.
Just want to ask what should be burned and where to start...?
Thanks, 73 - Petr, OK1RP

Petr,
There is a schematic at >
https://qrzcq.com/pub/RADIO_MANUALS/MFJ/MFJ--259-Ant_Analyser-sch.pdf
I can see lots of things (e.g. many of the transistors) that could be
damaged, far too many for me to have any confidence picking them out
just from that.
But you could start there for testing components.
WA9D

==============================
Had a look at the schematic as per the above pdf
Power input is via J1 or from internal batteries
Reverse polarity protection is by D9, a 4001 SMD diode
It could well be that this diode is shorting

Was the unit powered by batteries or from an external supply
If so , a shorted D9 could have blown the fuse (if any) in the external
power supply.

Good Luck with the fault finding

Frank , EI7KS

[Jeff Liebermann]

On Thu, 1 Sep 2022 14:03:37 -0500, Robert Wilson

Post by Robert Wilson

Post by Petr OK1RP
Hi all,
anybody here experienced with polarity reversal damage of MFJ-259B please?
My father damaged it by his mistake and he is totally frustrated so I would like to repair it for him.
Just want to ask what should be burned and where to start...?
Thanks, 73 - Petr, OK1RP

Petr,
There is a schematic at >
https://qrzcq.com/pub/RADIO_MANUALS/MFJ/MFJ--259-Ant_Analyser-sch.pdf
I can see lots of things (e.g. many of the transistors) that could be
damaged, far too many for me to have any confidence picking them out
just from that.
But you could start there for testing components.
WA9D

Did he plug the batteries in backwards or apply reverse polarity power
from an external source into J1 on the above schematic? I don't see
how it could have damaged much since diode D9 (lower left of
schematic) should protect the unit from reverse polarity from both
sources.

My guess(tm) is that all that happened is that diode D9 did its job
and shorted out which protected the rest of the circuitry. D9 seems
to be an SMD component (not sure). Try unsoldering one lead and check
for a shorted diode with an ohmmeter. Look around for fused traces
around the power connector and D9.

I don't know if this will help, but here is some info and experience I
accumulated on the MFJ-269. The MFJ-259 and MFJ-269 have similar main
boards:
<http://www.learnbydestroying.com/jeffl/MFJ-269-repair/>
Annotated schematic:
<http://www.learnbydestroying.com/jeffl/MFJ-269-repair/mfj-269-schematic.pdf>

Good luck.

[David Wade]

Post by Robert Wilson

Post by Petr OK1RP
Hi all,
anybody here experienced with polarity reversal damage of MFJ-259B please?
My father damaged it by his mistake and he is totally frustrated so I
would like to repair it for him.
Just want to ask what should be burned and where to start...?
Thanks, 73 - Petr, OK1RP

Petr,
There is a schematic at >
https://qrzcq.com/pub/RADIO_MANUALS/MFJ/MFJ--259-Ant_Analyser-sch.pdf
I can see lots of things (e.g. many of the transistors) that could be
damaged, far too many for me to have any confidence picking them out
just from that.
But you could start there for testing components.
WA9D

The issue you will have is that if the CPU which is a PIC chip is dead
the code to re-program it isn't available anywhere, so hopefully it is
just the protection diode

Dave
G4UGM