|
Re: identification and schematics [message #13071 is a reply to message #13069] |
Tue, 02 March 2010 12:54 |
chicagobill
Messages: 2005 Registered: April 2003
|
Senior Member |
|
|
Welcome to the place.
Almost all Kustom amps have a pc board number etched into the foil side. If you let us know what boards you need, we can try and supply the schematics to you.
As for the gain characteristics of the output transistors, I wouldn't worry too much about it. I've only seen one case where the gain was too low to work in a Kustom power amp.
I'd suggest starting with the power supplies in the PA head.
|
|
|
|
Re: identification and schematics [message #13074 is a reply to message #13069] |
Tue, 02 March 2010 13:36 |
ElectricRoomAmps
Messages: 8 Registered: March 2010 Location: oakland ca
|
Junior Member |
|
|
I tested power supply. I got 57.4 VAC off transformer and 76.4vdc off of the caps without powertsansisters in circuit. I believe these are proper voltages based on all the other posts I read.
I also tested two rca 36892s in the k150sc series guitar amp which i know were good and got comparable results so I believe they are all good.
Will begin to identify boards in amp for futher classification.
Thanks to chicagobill for info and assist.
brian@electricroomamps
brian@electricroomamps.com
|
|
|
Re: identification and schematics [message #13075 is a reply to message #13069] |
Tue, 02 March 2010 14:22 |
ElectricRoomAmps
Messages: 8 Registered: March 2010 Location: oakland ca
|
Junior Member |
|
|
I got board numbers off of pc's. The first channel is labeled "ROSS PC 102" I didn't pull channels 2-3 they are all identical.
Preamp board is labeled "ROSS PC 802"
Two small boards off of preamp board are labeled "ROSS PC 602" and "ROSS PC 502"
Poweramp board is labeled "ROSS PC 702"
Any help with schematics would be greatly appreciated.
Thanks
brian@electricroomamps.com
|
|
|
|
Re: identification and schematics [message #13082 is a reply to message #13069] |
Wed, 03 March 2010 17:39 |
chicagobill
Messages: 2005 Registered: April 2003
|
Senior Member |
|
|
I have sent you the schematics that I have.
As I recall the PC802 is the reverb/mixer board. It shouldn't be too hard to figure out.
There should be + and - 34vdc at the filter caps.
The two regulator boards will supply + and - 23vdc for the preamp and mixer boards.
Start by testing the PC702 power amp board. Is the speaker fuse ok? Is there any voltage on the output?
|
|
|
|
Re: identification and schematics [message #13086 is a reply to message #13082] |
Wed, 03 March 2010 20:04 |
ElectricRoomAmps
Messages: 8 Registered: March 2010 Location: oakland ca
|
Junior Member |
|
|
Update on mixer! After testing out power transistors, checking power supply voltages and a thorough cleaning of fiftysome years of dust, I tested it out for the first time since picking it up.
Channel 1 and 3 are fine. Channel 2 and 4 are blown out! 2 more than 4 because a little of the signal gets through at full volume. My pal didnt even know it was a mixer, was using it as aguitar amp and didnt know how to operate all channels. But they did kill at least 1 channel or possibly both, who knows. Temporarilly returned it so he could use it till I get schemos, which i think I might have now and need to print.
Thanks all for replying and sending schemos.
brian@electricroomamps.com
|
|
|
Re: identification and schematics [message #13088 is a reply to message #13069] |
Thu, 04 March 2010 03:24 |
ElectricRoomAmps
Messages: 8 Registered: March 2010 Location: oakland ca
|
Junior Member |
|
|
I fixed the k150 sc series guitar amp! The first transistor was fried (had an hfe of 11 when shouldve been between 1 and 3hundred) just as suspected after reding earlier posts. It had already been replaced once with a 2n3904 and I had 1 in my shop, didnt even have to go by parts. I would like to thank everybody who helped out with schemos and info and troubleshooting tips.
Anyone near Oakland, CA need amps repaired look me up....
brian@electricroomamps.com
|
|
|