• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Kenwood KR-9600 - Preamp problems?

d3solute

New Member
I recently bought a KR-9600. When I bought it, I was having a problem with the pre-amp. It would only work partially when you move the selector switch from one input to another. It would then play for a second then stop. It was not just a dirty connector as it was very systematic meaning that it did the same thing every time. I opened it up and chased the loss in the RLP1 relay on the mic board. It was not getting the 10v from the power supply board A. In board A, I found that transistor Q9 was not engaging and letting the 34v to a resistor that steps it down to 10v. (Also, when used as an amp with another receiver as a preamp through the jumpers, the amp stage works correctly)

One morning, I got up and it just started working. Odd...too good to be true. While it is fully working, I was not satisfied. I checked DC voltages on the entire power supply A board and almost all of them were off. They were as follows, I apologize for the long list:
Terminal 1: .6v, 2: 68.8, 3: 68.8, 8: .07, 9: -8.5, 10: -31.3, 11: 9.6, 12: 0, 13: .73, 14: 36.1, 15: 68.8, 16: 0, 17: 13.5, 18: 12.9, 19: 13.5, 20: 0, 21: -15.3, 22: -35.2, 23: -69.9, 24: .2, 25: 68.7, 26: 0, 27: 0, 38: 36.9, 29: -35.7, 30: 69.2, 31: .23

Comparing to the FSM, almost every voltage is incorrect by 1-2 volts. Is this within spec or is it something to be concerned about? If so, what could cause this issue?

Additionally, the receiver, when power off, still plays for about 2-3 seconds. Initially, I read that this is caused by bad input lights or LEDs, but the issue remains in an input with a working light, and all are original bulbs. Could this be connected?

When powered off, the transistor Q9 mentioned earlier does not disengage. I will look further to see if it is because of an issue upstream.

Any help/input is very appreciated.
 
Register to hide this ad
Back
Top Bottom