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cctsim
Silver Member

United Kingdom
418 Posts
Posted - 10/27/2008 :  02:44:08  Show Profile  Reply with Quote
I have since 1989 a CS3 (ACA, MIT) that pops when you switch it off.

I didn't notice that over the years because I operated it with a noise gate but it is really annoying.

Anyone with similar experience or a even a remedy.

Best Regards
CT

Laurie
Double Platinum Member

Canada
4854 Posts
Posted - 10/27/2008 :  03:43:55  Show Profile  Visit Laurie's Homepage  Reply with Quote
Only one I've found a definitive solution for is here:
http://www.bossarea.com/forum/topic.asp?TOPIC_ID=4917
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Dr. Bob
Moderator

Australia
6593 Posts
Posted - 10/27/2008 :  08:59:04  Show Profile  Visit Dr. Bob's Homepage  Reply with Quote
Hi cctsim

Please upload some pics, so we might be able to help you out.

What type-brand of power supply are you using?

And does it still do that, when you fit good battery?

Regards Dr. Bob
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cctsim
Silver Member

United Kingdom
418 Posts
Posted - 10/27/2008 :  16:04:03  Show Profile  Reply with Quote
I don't think it is power-supply related as it "pops" with battery too.

I have also checked all the diodes on the board and they point to the right direction.
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cctsim
Silver Member

United Kingdom
418 Posts
Posted - 10/27/2008 :  23:19:16  Show Profile  Reply with Quote
I think I am a bit closer to the root of the problem. I measured with the scope the voltage at the node connecting C15 and the drain of Q4. It seems that the dc control voltage from pin 2 of the THAT2159 chip (dbx in my case) is leaking via R10 and R26 to the drain of Q4.

When switching between on/off I could clearly see a spike followed by a short oscillation between 4.4 and 4.6 V. The dc control voltage is around 100 mV.

Tomorow, I will try to put a small capacitor across either R10 or R13 to smooth out the spike.

Man, I've waisted so much time on this I could have bought a new CS-3. I don't like giving up easily though.
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Laurie
Double Platinum Member

Canada
4854 Posts
Posted - 10/28/2008 :  02:21:31  Show Profile  Visit Laurie's Homepage  Reply with Quote
quote:
Originally posted by cctsim

I think I am a bit closer to the root of the problem. I measured with the scope the voltage at the node connecting C15 and the drain of Q4. It seems that the dc control voltage from pin 2 of the THAT2159 chip (dbx in my case) is leaking via R10 and R26 to the drain of Q4.

When switching between on/off I could clearly see a spike followed by a short oscillation between 4.4 and 4.6 V. The dc control voltage is around 100 mV.

Tomorow, I will try to put a small capacitor across either R10 or R13 to smooth out the spike.

Man, I've waisted so much time on this I could have bought a new CS-3. I don't like giving up easily though.


Kudos to you! Please accept my moral support from afar...
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cctsim
Silver Member

United Kingdom
418 Posts
Posted - 10/28/2008 :  02:46:43  Show Profile  Reply with Quote
Thanks for the moral support Laurie!

Sometimes I am wondering what my guitar technique will be if I wasn't nuts about electronics, although that's serious fun too.
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Laurie
Double Platinum Member

Canada
4854 Posts
Posted - 10/28/2008 :  02:53:14  Show Profile  Visit Laurie's Homepage  Reply with Quote
quote:
Originally posted by cctsim

Thanks for the moral support Laurie!

Sometimes I am wondering what my guitar technique will be if I wasn't nuts about electronics

I know for sure that my (poor) guitar playing is simply the catalyst for my pedal collecting and modding
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starr36
Platinum Member

Canada
1172 Posts
Posted - 10/28/2008 :  05:53:29  Show Profile  Visit starr36's Homepage  Reply with Quote
quote:
Originally posted by Laurie

quote:
Originally posted by cctsim

Thanks for the moral support Laurie!

Sometimes I am wondering what my guitar technique will be if I wasn't nuts about electronics

I know for sure that my (poor) guitar playing is simply the catalyst for my pedal collecting and modding


LOL so many like minds here at bossarea.com
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