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Old 6th November 2006, 11:58 AM   #1
Peppe is offline Peppe  Italy
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Unhappy Conrad Johnson PV 7 problem

Hi,

I have a problem in my C-J PV7, it sometimes turn off and restart automatically. It means that I must wait 45 seconds about (warmap time) before the music restarts.

It is possible that the SPRAGUE capacitors (TVLU 1095) in the PSU are exhaust?

Someone got the schematics?

Thanks in advance
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Old 6th November 2006, 01:52 PM   #2
Peppe is offline Peppe  Italy
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The cap on the left is Spraugue TVLU 2925, are they still in production?
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Old 6th November 2006, 03:24 PM   #3
SY is offline SY  United States
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You can certainly still find equivalent Twist-Lok electrolytics, but at the cost of not being "vintage," one can replace them with more modern caps of the same capacitance and voltage. Look for 105C rated capacitors. You'll be surprised at how much smaller we make them today.
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Old 6th November 2006, 03:44 PM   #4
Peppe is offline Peppe  Italy
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Thanks SY,

do you think my problem are the caps?

Do you have a favorite Twist-Lok capacitor producer?

Cheers
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Old 7th November 2006, 09:32 PM   #5
dhaen is offline dhaen  Europe
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In my experience, Conrad Johnson will email you a scan of the schematic if you ask them nicely.
When asking for schematics it normally it helps to give the serial number as proof of ownership.
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Old 7th November 2006, 09:43 PM   #6
SY is offline SY  United States
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Quote:
Originally posted by Peppe
Thanks SY,

do you think my problem are the caps?

Do you have a favorite Twist-Lok capacitor producer?

Cheers
Possible, and I'd replace them anyway, but it's more likely in the soft-start/mute circuit or the regulator. But bad caps can still be the root cause.

I don't like Twist-Loks in general, so that's like asking me about my favorite rap artist.

Dhaen's point is well-taken: get a schematic, and troubleshooting will be much easier.
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Old 7th November 2006, 10:41 PM   #7
moamps is offline moamps  Croatia
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Hi Peppe:

You can find the schematics of the PV6 and PV10 versions here
http://www.drtube.com/audioamp.htm . The schematics should give you a pretty good clue as to your preamp.. From what I can tell, mulfunction may be somewere on the primary side of the transformer (if the "pilot" lamp turns off at the reset moment) or inside the "delay output on" circuitry.

Regards,
Milan
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Old 7th November 2006, 10:45 PM   #8
anatech is offline anatech  Canada
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As I recall, they were using film caps for the B+ filter. Lower value of course. Also, every CJ I've looked at had the heater filter cap opening up. Check that first.

-Chris
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Old 8th November 2006, 08:37 AM   #9
Peppe is offline Peppe  Italy
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Quote:
Originally posted by dhaen
In my experience, Conrad Johnson will email you a scan of the schematic if you ask them nicely.
When asking for schematics it normally it helps to give the serial number as proof of ownership.
Ok, I'll try and will report the result...


Quote:
Originally posted by SY


Possible, and I'd replace them anyway, but it's more likely in the soft-start/mute circuit or the regulator. But bad caps can still be the root cause.
Sure, I will try to find the caps anyway


Quote:
Originally posted by moamps

From what I can tell, mulfunction may be somewere on the primary side of the transformer (if the "pilot" lamp turns off at the reset moment) or inside the "delay output on" circuitry.
Yes, the led turns off at the reset moment.....


Quote:
Originally posted by anatech
As I recall, they were using film caps for the B+ filter. Lower value of course. Also, every CJ I've looked at had the heater filter cap opening up. Check that first.
All suggestion are very important for me. It's my first time I decide to repair a my object, I just finished my first DIY-job (Aleph30) and now the pre decided to stops working......ARGH!

Maybe I will ask a friend of mine to help me in this job....

I want to thanks very much all you guys for suggestion

Regards

Peppe
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