Carver amp, needs doc

[unclejed613]

in storage (sorry, i don't have it in front of me) i have the service manual for an M400. probably wouldn't be a lot of help for the amp section or any of the low level sections, but it has about 10 pages or more devoted to explaining the operation of the power supply. a very interesting design. if the power supply is operating normally (and it sounds like yours is...) don't try to hotrod it. the amp circuits are made to run normally at a certain rail voltage, and only higher voltages for very short periods, and that's when the power supply decreases the firing angle of the SCR's

[techgadget]

Hello to all. Sorry for hijacking this old thread. I have recently acquired a non-working Carver M-400 and I am wonder if I can get some advice. I noticed that Unclejed613 mentioned he has a service manual although he is not set to accept emails from board members. If there is a chance that someone has this manual available that would be great. I have not serviced this type of amp yet although years ago I did work on M-1.0t, 1.5 and others. This amp is in good physical condition with no apparent damaged components. When it is plugged in you can hear a faint clicking sound and I can measure a small voltage pulsating on the speaker output terminals (about 2 volts) every couple of seconds. Seem to measure this small voltage on both AC and DC scale. Could this be a case of bad diode or triac? Any advise would be welcome. I think the service manual would be a good starting point! Thanks for any help. I will continue to search for old posts in the interim.

[anatech]

Hi techgadget,
This Carver amplifier is the starting point for the design of the amps you have worked on. Conceptually it is very close.

I think you either have a shorted output or something causing a DC offset. The trick with this little beasty is that you must be very careful with disassembly and reassembly. The transistor sockets are easy to break if you don't pay attention. Do not over tighten the transistors.

This unit is very difficult to work on because you must take it right apart in order to test any component. You will need to install test points on wires that come out of the chassis in order to do any effective troubleshooting. What you do not want to do is continually have to take this thing apart.

There were some Engineering Change Orders (ECO) on this model. The triac was upgraded, so was the triac firing circuit. They did have trouble with the supply misfiring at idle, that would cause an uneven tick-tick - - - tick tick - tick type sound. Your supply does appear to be working correctly as unclejed613 stated. It does sound like you are in protect mode though.

-Chris

[unclejed613]

unfortunately, my carver manual is in storage right now..... along with my Apt-1 service manual, which i also want to scan into PDF format....

[anatech]

Hi unclejed613,
Could I request a copy of those once you scan them? I know exactly how much work that is, especially if you clean up the scans afterwards.

-Chris

[unclejed613]

i'll try, but it's going to be a while. the storage is an hour from here, and i'm currently without a vehicle.....