Diode soldering tutorial

[V-bro]

I just posted this somewhere else and realised this really belongs here (to test the soldering of the diodes after you're done):

"Measuring diodes is best done by measuring the board, not on the diodes otherwise you're not really judging the soldering. First measure a bare diode in both directions to give you an idea of what your meter does, how it responds. This should be done on either a specific diode setting or simply on resistance(ohms)/conductvity(beep) setting on your multimeter.

Then place on probe in the holes next to the diodes that are for the big electrolytic caps (these are parallel to the railvoltage and the diodes are clamped between pos and neg rail in pairs meeting on the speaker traces in the middle) Start with the positive capacitor hole. Measure with the other probe on the dots of solder on the opposite side of the board than where the diodes are (the points where the diode pairs meet in the middle) and do the whole row one by one to see if they measure alike. Then place the other probe in the same capacitor hole and do the row of middlepoint dots again, this time the meter responds like measuring a diode in opposite direction.

Then do the same measurements with the probe in the other capacitor hole (the negative). The measurements should again all be alike, but when probes are swapped they all again measure like the diode is measured in the other direction.

Most meters measure best in conductivity setting (or "beep" setting) In one direction you get a short beep, in the other mostly it doesn't, but gives an ohmic value like say 400 ohms (this can be different, but they should be more or less alike)

That's all to it! "

------X-max. can be several meters on any driver, too bad it can be done only once...------

[Scratchy]

I believe I posted pictures on the first page of this thread showing where to place the probes, and which solder joints will be tested......
Let me know if this is not correct V-bro, and I will delete the pictures and the post.

***It's so easy, everyone should be doing it***

[V-bro]

Your photo's a good Scratchy, But to check the soldering it's enough to actually keep the board wtih the diodes down and measure it all from the back side. The top photo's where you point out to hold the probes literally on the solders will actually only allow you to measure the diodes themselves, not the solders.

But when you write down what you measure straight on the solders the results must exactly match what you measure on the board points. Only then you can be sure the solders are good, and still not 100%, a diode can still only "touch" the board without the solder actually having flowed in between. Then it's still possible that due to the lack of current that can pass through the DC offsets will drift...

------X-max. can be several meters on any driver, too bad it can be done only once...------

[Scratchy]

quote:Originally posted by V-bro

The top photo's where you point out to hold the probes literally on the solders will actually only allow you to measure the diodes themselves, not the solders.

------X-max. can be several meters on any driver, too bad it can be done only once...------

I am actually measuring the solder joints circled in green (through the diodes and PCB path), not the solder joints where I'm holding the multi-meter probe.
That's why I've drawn 4 different paths to test.
As you say, this does not ensure the solder joint will hold up with higher currents, but it is a starting point.

***Patience is a PCB's best friend***

[Mayday]

Thank you guys for this and all the help you give so generously!

[Mayday]

Thank you guys for this and all the help you give so generously!

[V-bro]

Welcome Mayday [^]

I just noticed the pictures we're gone here too! [:0](but I fixed it now...)

If anyone sees my pics aren't working in any thread please be so kind to let me know so I can fix it, big thanks!

------X-max. can be several meters on any driver, too bad it can be done only once...------

[Havoc]

quote:Originally posted by V-bro

I wanted to add another on topic remark.

BE CAREFUL NOT TO LEAK SOLDER IN TO THE CHIP HOLES!!!

------X-max. can be several meters on any driver, too bad it can be done only once...------

Which chip holes are you referring to v-bro?

[V-bro]

The holes of the TAA4100A are right next to the diode solders. Holding the iron too flat will make it seep in there before you know. It can be very hard to get the solder out of the holes again when you want to install the chip...and have no experience on how to solve this...

If this happens don't go applying big force on them as they are VERY vulnerable!!!

I find it works best to just gently heat up the solder and blow it out with some compressed air. (either from a compressor or from an "airduster" spraycan) It works much like blowing your nose

------X-max. can be several meters on any driver, too bad it can be done only once...------

[krilli]

quote:Originally posted by V-bro

The holes of the TAA4100A are right next to the diode solders. Holding the iron too flat will make it seep in there before you know. It can be very hard to get the solder out of the holes again when you want to install the chip...and have no experience on how to solve this...

This is the one perfect place for a solder sucker. Iron goes in one end, place sucker at other end, heat, suck, presto!

(Unless I'm mistaken about the type of hole ... generally if you have access to both sides of the hole, a sucker is useful.)