The 371s are matching up with the voltage supplied on the schematicIf thats the case then both channels are f#k up. And you would have rail voltage( -38.1v)on both L701 and 702.
The 371s are matching up with the voltage supplied on the schematicIf thats the case then both channels are f#k up. And you would have rail voltage( -38.1v)on both L701 and 702.
If the problem was the PS it would effect both channels..
So this resistor (I think) (the one covered in the tube) Just popped and made a nice little fire for a bit.Post a photo of the heatsink so I can see the output transistors labels.
Also here's the transistor picPost a photo of the heatsink so I can see the output transistors labels.
You got it.
I can't read the transistors.. Are the from left to right 2SD 2SB 2SD 2SB ?
If so measure the voltages around(E,B&C) all four and post results.
However before it popped the E B & C on the 2SD371s we're within tolerance. It was the 2SBs that we're showing 38v on the EB and CIf so measure the voltages around(E,B&C) all four and post results.
Looks like a 4.7Ω 1/4 watt. What were you doing when this burnt up?So this resistor (I think) (the one covered in the tube) Just popped and made a nice little fire for a bit
Nothing actually, it was between measuring voltages.Looks like a 4.7Ω 1/4 watt. What were you doing when this burnt up?
Because....But not sure why only L701 would be showing rail voltage in that case
Because....
both of the of the 2SB531 are showing C- -37.2 B- -37.2 E- -38.1v
Remove the 2SB's and test them out of the circuit.
That will solve one problem.So just an update, pulled both the 2SBs and tested them (just using continuity/diode mode on my multimeter). One of them tested fine. The other showed a dead short between the Collector and Emitter. Going to guess that was our problem.
Okay so, we removed the two bad transistors, and powering the amp on with the good ones in yields a click (In the TR-723 and TR-725 spots). However, doing so in the TR-726 and TR-724 side yields wildly varying negative voltages. And using a known good set of transistors to replace the bad ones puts us back to the beginning with there being rail voltage at L701 again, and caused our replacement resistor to pop.That will solve one problem.
TR723 ---- 2S ?In the TR-723 and TR-725 spots).
One 2SB and one 2SD?Okay so, we removed the two bad transistors
Yup, blown pair.TR723 ---- 2S ?
TR725 ---- 2S ?
One 2SB and one 2SD?