So, trying my hand at this again. This time I think I have an advantage to having a pretty comprehensive service manual. Been trying to get this amp to work for some months now. When I got it, both LEDs were orange upon powering up. I took it apart and found it needed caps as expected. I replaced all the obvious leakers and the surrounding ones. Basically all new caps except for the ones on the RCA input board. Scrubbed the affected areas wtih alcohol and all that. Result now is I get a green status, but yellow mute LED. No speaker relays are clicking. I adjusted the rail voltage per the beginning of the service manual to within spec. I am throwing in the towel and asking for some help on what to look at next. From what I can see, the relays are not getting a ground to trigger them. Thanks for any and all help and I promised not to be like that other guy asking that never followed up with what he found wrong after being asked to check pins 1 and 2 at IC 502, lol
maybe I can learn enough to get back to the ADS units after this one.
maybe I can learn enough to get back to the ADS units after this one.
According to the diagram, the relay is directly connected to ground.
What's the DC voltage on all 3 terminals of Q531?
What's the DC voltage on the RCA shields?
What's the DC voltage on all 3 terminals of Q531?
What's the DC voltage on the RCA shields?
rca shield voltage with chassis gnd reference is right about 1.5mV
q531= Base+13v Emitter+13v Collector+5v
q531= Base+13v Emitter+13v Collector+5v
What's the DC voltage across the relay coil?
What's the coil voltage rating printed on the relay?
DCV on all 3 terminals of Q504?
What's the coil voltage rating printed on the relay?
DCV on all 3 terminals of Q504?
relay coil looks like 10mV. voltage on relay says 9vdc
q504 looks like:
base +5v.
collector +13v.
emitter +5v
q504 looks like:
base +5v.
collector +13v.
emitter +5v
Double checked RCA shields with chassis gnd reference and yes, right around 1.5mV
.5mV as tested on the inner non bridged speaker terminals. I was just testing one lead on one terminal and the other on the other terminal in this test. no chassis ground reference.
.5mV as tested on the inner non bridged speaker terminals. I was just testing one lead on one terminal and the other on the other terminal in this test. no chassis ground reference.
Do you see any open traces on the amp?
Do you read 0 ohms between all of the non-bridging speaker terminals?
Do you read 0 ohms between all of the non-bridging speaker terminals?
I dont see any open traces. however, the side we are talking about had some hot/ugly resistors. I had replaced them with 5% tolerance units. Ive probably spent hours looking at this board with the magnifying glass, lol
Continuity between the inner non bridgeable speaker terminals with no power applied to the amp reads about 1 ohm
Continuity between the inner non bridgeable speaker terminals with no power applied to the amp reads about 1 ohm
Im not sure what you mean by brown fixative? There was some nasty corrosion stuff that took a good amount of scrubbing to get rid of. From what I can see, its no longer present.
yeah, there was some of that. cleaned it all as best I could. Dont see any residual. I have continuity from the emitter at q504 to e502 and q507 per the trace on the board. at least on that side of the board.
What's the resistance between Q504 emitter and the non-bridging speaker terminals?
Emitter and primary ground?
Emitter and primary ground?
open circuit between q504 and inner non bridging speaker terminal connections.
2ohm between primary gnd input from power supply to emitter at q504
2ohm between primary gnd input from power supply to emitter at q504