Working on a nice old Yammy receiver. Relay won't click - it's in protect. Measured normal DC offset on Left channel (10mV). Right channel is showing +20vDC which is obviously why it's in protect. Pulled the two output trannys on the R channel (2SC2579 & 2SA1104) and it now comes out of protect. But, both test fine out of the unit - no shorts. The drivers also test fine.
I have worked backwards measuring the various transistors on the right channel and the incorrect voltage tracks back quite a ways. But I'll be damned if I can find the culprit. These are the voltages as per the service manual and what I'm measuring:
Manual: B / C / E // Measured: B / C / E
C202: -11 / 0 / 0 // -11 / 0 / 0
C204: 44 / 43 / 44 // 45 / 45 / 45
C206: 0 / 43 / 0.5 // 0 / 45 / 6.0
C208: 0 / 45 / 0.5 // 6.0 / 45 / 6.0
C210: 44 / 18 / 44 // 45 / 0 / 45
C212: 44 / 1.1 / 44 // 45 / 21 / 45
C214: 0.5 / 1.1 / -1.1 // 19 / 21 / 19
C216: 1.1 / 45 / 0.5 // 22 / 45 / 22
C218: -1.1 / -45 / -0.6 // 19 / -45 / 20
C220: 0.5 / 45 / 0 // 21 / 45 / 21
C222: 0.6 / -45 / 0 // 21 / -46 / 21
As you can see, things start to go off at the emitter of C206. Any help would be appreciated. Thanks.
I have worked backwards measuring the various transistors on the right channel and the incorrect voltage tracks back quite a ways. But I'll be damned if I can find the culprit. These are the voltages as per the service manual and what I'm measuring:
Manual: B / C / E // Measured: B / C / E
C202: -11 / 0 / 0 // -11 / 0 / 0
C204: 44 / 43 / 44 // 45 / 45 / 45
C206: 0 / 43 / 0.5 // 0 / 45 / 6.0
C208: 0 / 45 / 0.5 // 6.0 / 45 / 6.0
C210: 44 / 18 / 44 // 45 / 0 / 45
C212: 44 / 1.1 / 44 // 45 / 21 / 45
C214: 0.5 / 1.1 / -1.1 // 19 / 21 / 19
C216: 1.1 / 45 / 0.5 // 22 / 45 / 22
C218: -1.1 / -45 / -0.6 // 19 / -45 / 20
C220: 0.5 / 45 / 0 // 21 / 45 / 21
C222: 0.6 / -45 / 0 // 21 / -46 / 21
As you can see, things start to go off at the emitter of C206. Any help would be appreciated. Thanks.
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