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SansAmp GT2 from Tonepad Issue

Started by lezerec, June 05, 2018, 05:04:31 PM

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lezerec

#20
June 09, 2018, 03:13:35 AM Last Edit: June 09, 2018, 04:01:03 AM by lezerec
Ok, I will have a look during the weekend.

- I have changed IC1 a few days ago (I will try with another one)
- I haven't cleaned the wire yet, as you said before

Thanks for your help

Govmnt_Lacky

#21
June 09, 2018, 02:51:51 PM
One thing I also noticed is your opamps are different from the SansAmp GT2.

The original used TLC2272. A lot of the "sound" attributed to this build is due to the op amps. Might want to consider swapping them out with the 2272s.
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

duck_arse

#22
June 10, 2018, 10:50:42 AM
in your build photo, I see two green "Ero" caps, looks like they are marked ".22", as in 220nF, in the feedback loops for IC2.  the circuit shows 220pF. please check/replace/report.
" I will say no more "

lezerec

#23
June 10, 2018, 11:21:04 AM
Oh man, I thought .22 meant .22 nf (=220pf), as MKT capacitors !! Actually, I am having some fun with my children now, and will have a look tonight (it's 5 pm here).
I really hope you found the solution ! Are you sure about that ?

duck_arse

#24
June 10, 2018, 11:27:29 AM
I'm sure that if the cap marking is ".22" that it means 220nF, yes. I'm can't say 100% that it says .22, tho, only you can do that ...... and 220nF will KILL your gain in each place, which won't help.
" I will say no more "

lezerec

#25
June 10, 2018, 11:38:39 AM
It' written .22, I can confirm :)

lezerec

#26
June 10, 2018, 12:56:53 PM
Ok, so I replaced them by MKT .22j63 (=0.22 nf = 220pf, right ?), and.... still doesn't work... I suppose last caps were at the same value, at last.
I will try the other tips in the next hours. Please let me know, if you find anything else !

Govmnt_Lacky

#27
June 10, 2018, 03:47:45 PM
Quote from: lezerec on June 10, 2018, 12:56:53 PM
Ok, so I replaced them by MKT .22j63 (=0.22 nf = 220pf, right ?)

Actually, those are 0.22uF or 220nF

Typically, pF caps do not come as those types of caps (not ALL of the time, most of the time)

Those still look like the wrong caps. You need 220pF caps.
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

lezerec

#28
June 10, 2018, 03:57:04 PM
Ok, ok, I'm happy to tell you that it works now !!!
You were right about the caps. Actually, I made a cold joint when swapping them, and fixed that immediatly after posting here.
I didn't know this particularity about that type of caps until you noticed the mistake.
Well, I would like to thank you so very much, guys.  Good experience for me, because I learn many things : voltages, probing...

You're the best

Govmnt_Lacky

#29
June 10, 2018, 04:00:19 PM
Quote from: lezerec on June 10, 2018, 03:57:04 PM
Ok, ok, I'm happy to tell you that it works now !!!
You were right about the caps. Actually, I made a cold joint when swapping them, and fixed that immediatly after posting here.
I didn't know this particularity about that type of caps until you noticed the mistake.
Well, I would like to thank you so very much, guys.  Good experience for me, because I learn many things : voltages, probing...

You're the best

Good to hear! :)
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

lezerec

#30
June 10, 2018, 04:55:39 PM Last Edit: June 11, 2018, 06:57:46 AM by lezerec
Well, it worked for 20 Minutes (awesome sound), and then the sound came fuzzy and next PIOOOOW, it finally died in my hands. Now, I am back to step 1 : only clean sound and tweed very very low..:). Actually, a solder broke : the little wire between C220pf and pin 1 of IC2 maybe touched the V trace. I fixed that, changed IC1 and IC2, but still no distortion . This morning, I noticed I gave it 12 V ! I was too excited and made a mistake by choosing the wrong adaptator :).  I think I must audioprobe tomorrow (I think about the tranny or other IC's. ..
I have thrown my soldering station in the garden..

lezerec

#31
June 11, 2018, 08:50:52 AM Last Edit: June 11, 2018, 08:59:59 AM by lezerec
Ok, voltages are fine. I changed the four ICs.

Audio probe reveals one thing :

-IC4 : no signal on pins 2 and 6
- no signal on resistors 3k3, 10k, 100k, 330k (for their leads down to IC4)

My theory is :

- I swapped .22 caps (Ero) with .22 caps (MKT), believing they were 220 pf but I was wrong
- I plugged a 12 v adaptator
- the pedal worked for a while and then died

No ?

Heeeelllp !!

lezerec

#32
June 11, 2018, 09:41:01 AM
It wooorks ! My theory was right. I definitely swapped those .22 by 221 caps.
The sound is aaaaaawesooome :)

vigilante397

#33
June 11, 2018, 10:38:47 AM Last Edit: June 11, 2018, 10:52:14 AM by vigilante397
As a general rule of thumb cacpacitor values are going to be written in picofarads or microfarads, seldom in nanofarads (though several of the caps I see in your build are labelled in nano). If it says something like "0.1" or "0.47" that would be 0.1uF = 100nF and 0.47uF = 470nF. The caps I usually use have a code more like "104," which is 10 x 10^4 pF or 100nF, and smaller caps like ceramic are almost always labelled this way, i.e. 221 = 22 x 10^1 pF, or 220pF. It's just one of those things everyone messes up at least once then gets the hang of, glad to hear you've got yours figured out ;D
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lezerec

#34
June 11, 2018, 10:48:17 AM
Yeah, I could be in the Guinness Book with this effect : about 50 hours spent debugging !!
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