[BUILD] CAPI FC526~500 Series~FET Limiter Kit~Official Support Thread

Hi jeff,

My iron is set at 752°F (400°C), I put it at 800°F(426°C) and reflow all the solder joints; no changes come...

I look at the zener diodes and the 3904 transistor, they are in place and the soldiers arround the corner are clean for me.... can I tchek or do something else?

Check these points for ACV with the unit in ACTive mode and some signal applied to the input. This is essentially immediately after the input relay.

I find 0.042V

(thanks for not let me alone )

You should have the same AC voltage when measuring between those 2 points as you do measuring the source signal you are injecting into the card.

Are your opamps fully seated? http://capi-gear.com/catalog/DOA_Install.php

???

I inject 1kHz sine wave at -30dbU, about 0.02Volts

so I must find between the 2 points you show me the same voltage, 0.02Volts, but I was founding 0.042, and now that I have done again this 2 solders you show me, I find 0.003Volts or 0.004????

Yes my opamps are fully seated!

but what's happening? I'm a litle lost....

It sounds to me like the relays are not working. Can you hear them "click" when you flip the bypass/active switch back and forth?

yes I can hear them, back and forth

OK well its hard to tell if both are flipping or not. At least you know something is happening. You will have to check the relay pins for continuity.

The pic attached shows what should have continuity in ACT mode. It will be the other contacts when in BYP. Make sure both poles of the relay are functioning correctly. K1 is the input relay and K2 is for the output.

Hi again

I make the continuity check between all the poles you show me and the continuity between them are fine in the  picture attached it mean's there is a continuity between B and C ; and between B' and C' in "BYP" mode ; and there is continuity between C and D ; and between C' and D' in "ACT" mode

I make the test continuity on K2 to, and it's ok on K2 to...

the new frenchy said:

Hi again

I make the continuity check between all the poles you show me and the continuity between them are fine in the  picture attached it mean's there is a continuity between B and C ; and between B' and C' in "BYP" mode ; and there is continuity between C and D ; and between C' and D' in "ACT" mode

Click to expand...

OK good. Well, there is nothing between the ends of R78 & R82 but PCB traces and C36 & C38. Maybe the solder job on those caps is the problem?

I just clean the solders of C36&38, and do them again, and redo the mesure..... they aren't stable... when I touch C36&38 I can ear some "mouse scream" like a charge and discharge of condensator....
I have a second pair of FC526 not build yet, so I think I can change C36&38 are you agree?

the new frenchy said:

I just clean the solders of C36&38, and do them again, and redo the mesure..... they aren't stable... when I touch C36&38 I can ear some "mouse scream" like a charge and discharge of condensator....
I have a second pair of FC526 not build yet, so I think I can change C36&38 are you agree?

Click to expand...

The chance of both of those caps being bad would be incredibly high. If they are making noise when touching them, its solder joints somewhere.

You mean solders only before this caps, or every where?

the new frenchy said:

You mean solders only before this caps, or every where?

Click to expand...

Its hard to say. I would start with the caps. I run my iron just under 800˚F.

Ok Jeff!

Sorry for not answering you before! But you are the Boss!!!! for sure!!!!

I decide to reflow some solders which could look better and now I have the good value everywhere

But I want to calibrate RV7 and doesn't understand which punkt I must put my oscilloscope?

You can monitor the final output or TP3 for the RV7 THD trimmer.

Yes Ok Jeff!
but now I see any changes in the monitor, and doesn't understand why...  :'(

the new frenchy said:

Yes Ok Jeff!
but now I see any changes in the monitor, and doesn't understand why...  :'(

Click to expand...

Maybe you are not zoomed in enough with your scope? The trimmer will go from about 1% down to around 0.3 something % back up to 1%. You should see it if you zoom into the top of your waveform close enough.

First sorry for my english  ...

but if I understand, the "movement" of the sinusoid is very very little?

my scope is tektronix 2465, an old one.... can I see that little movement with it?

because I zoom a lot, almost the max I can.... and I just see a sort of vibration but is it what I must observe?