Nakamichi Receiver 1 PA

[456jss456]

Recently my Nakamichi Receiver 1 was idling along happily when the smoke came out of R322R, a resistor on Q310R, one of the SA1492's in the PA section. Now the power supply comes up (relays click in the power supply, green LED comes on) but nothing on the display and nothing else works.

I replaced the blown resistor but it did not fix the problem. Perhaps the transistor has failed. But I find it odd that a right-channel PA transistor would bring the whole system down? I've checked that it's not something simple like fuses.

I can't take it much beyond this because I don't have a schematic.

Does anyone have experience with the Nak Receiver 1? Does this fault ring a bell?

I'd also appreciate any links to where I might find a service manual or schematic.

Thanks to all,
jss

 

[Chrisr3521]

try replacing all trannys on that side including the drivers(+/-) then trace back on the board where the burned resistor connects to this too is likley to be a transistor and will now be faulty and possibly the next component down the line. Also just an idea but if the green power led isnt flashing this means that the circuit is not in protect mode which means you can get voltage readings off the left side which would be extremely helpful.

if above doesnt work i do have an amplifier 1 service manual i can e-mail you if you wish, but be aware that original parts are very hard to come by, and if you go down the equivelent part route i would personly recommend replacing on the left channel any that you do on the right.

 

[Chrisr3521]

sorry tired and didnt pay enough attention to you post.
the circuit is in protect. the reciver/amplifier 1 only has one protection circuit for both channels this is why noting will work