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Pas tone control removal question

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Posted on May 31, 2003 at 18:00:14
Miser lee
Audiophile

Posts: 6
Joined: May 3, 2003
 I have a question about the directions listed in Dynaco Doctor. For the right channel, the text says to connect a jumper from terminal 12 to 13. But the location of terminal 12 in the accompanying photo corresponds to terminal # 14, which seems to make sense as this would be symetrical with the left channel.

That was my rationale, but when I attempted this, I got a low frequency heartbeat in my right channel, causing full extension of the woofer. I put the tones back to original, and the pas is working normally.

Did I do this wrong, or is something else wrong?

 

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Looks like..., posted on June 1, 2003 at 06:01:48
airtime
Audiophile

Posts: 11287
Location: Arizona
Joined: February 4, 2003
 from the schematic on the right jumpers between 11/13 and 13/14, cut terminal 10. I think I did the same thing once before.
charles

 

Re: Pas tone control removal question, posted on June 1, 2003 at 07:47:06
Joe Curcio
Manufacturer

Posts: 1261
Location: Northern CA
Joined: October 10, 2001
 Terminals 12 & 14 are electrically the same (12 is the terminal connected to the bass pot while 14 is the terminal connected to the audio output) so in step # 8 it doesn't matter if you jump 13 to 12 OR 13 to 14.

Did you complete the previous step (step #7) - connecting terminal 11 to 13 ?

 

Re: Pas tone control removal question, posted on June 1, 2003 at 14:57:59
Miser lee
Audiophile

Posts: 6
Joined: May 3, 2003
 I completed all the steps. Then it should have been ok. It was the left channel that acted up anyway. (left handed, always mix these up)

But I'm pretty sure I had everything right. What is the possibility of the tone circuit hiding a faulty component, resulting in said symptom?

 

Re: Pas tone control removal question, posted on June 1, 2003 at 16:38:24
Joe Curcio
Manufacturer

Posts: 1261
Location: Northern CA
Joined: October 10, 2001
 I don't think it's likely that the tone control could be providing a complimentary mask to another problem - but stranger things have happened.

I would double check the TC removal wiring. If this still fails to work, feel free to call me to discuss.

 

Re: Pas tone control removal question, posted on September 8, 2003 at 00:30:22
dave osborne


 
Joe:

I have downloaded your instructions for defeating the tone controls in my PAS. I would like to perform that operation in a couple of SCA-35 integrated amps, too. I'd like to keep one and give the other to a friend's kid going off to college. I've read descriptions of the SCA-35 preamp circuitry ranging from "a PAS grafted onto a SC35" to "a completely different cicuit), though the latter seem to primarily refer to the dual vs. seperate pots. I dunno. I've read Roger Stevens instructions, which 1)much more complicated, and 2)resultant of weird side effects.

Can I use your method with the SCA-35s? (I realize that it wont transfer literally, i.e., I'll need to identify anaolgous leads and board terminals) Maybe something similar?

Any guidance you can lend will be greatly appreciated. I do have schematics to all the Dynaco amps.

Very truely yours,
Dave Osborne

PS: Thank you for unusually clear written instructions.

 

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