Drawmer 1960 repair

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CCorcoran

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Aug 30, 2021
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Cambridge, UK
I hope someone can clear up a few problems I'm having repairing a Drawmer 1960.

In Bypass seems to work (using Aux input) CH2 meter ok, CH1 doesn't move, it is getting signal to the meter

Valve heater cct (7812 - gets hot and noticeable heat damage around the 56ohm resistor / Diodes and 2200microF Capacitator (But giving 11.3V)

when in Normal CH2 Attenuates considerably, you have to turn the gain (pot next to VU meters) upto to maximum, and then only get half the output of channel1 with no gain

1) is channel one behaving as it should, ie in Normal mode should the amplitude going through be the same as the bypass (Not well skilled in using these)
2) if so, any ideas what to look for. This is a later 1960 than the VCA potted variety. and the schematics I can download from here don't seem to match
3) Do the meters fail -
 

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CCorcoran

New member
Joined
Aug 30, 2021
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Location
Cambridge, UK
ok, turned out to be a shortened +15V rail onto the CH2 CV test point, 7/23 and 7/24 pins on the connector has 80ohms between them. Unsoldered and recleaned and all working again. Just VU meter for CH1 not working. A possible solution to the overheating of the Valve heater cct is proposed here. Real shame Drawmer cct diagrams not available, almost impossible to track with them :-(
Drawmer 12V Valve heater circuit - diyAudio
 

gyraf

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Aah, need to take note of that and find an update then..

/Jakob E.
 
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jensenmann

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Oct 10, 2004
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Karlsruhe, Germany
While Drawmer doesn´t give away the complete schematics for the obvious reason, they usually help with parts of the schematic. Send them a mail and describe the problem. If you add a picture of the serial number then they know exactly which version you have and will help for sure. I have a boatload of their gear in my dayjob and they always helped me when I had problems.
 
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