Crest Audio V1500

[razirafi]

Hello to all. I am currently in the process of repairing a Crest V1500 with the following symptoms. There is a distorted output for the left channel and no output for the right channel. Upon power on, the two clipping LEDs light up with the meter bridge bars lit up about half-way, then they slowly settle back down until they completely turn off. The clipping LEDs also turn off and only the active LED is lit. Checked out the power supply section and it seems to be OK. I traced out the schematic and found IC1 (a hybrid). I am suspecting that this is the damaged part but I would like to check further. I need to inject a signal into the next stage after this hybrid. I am thinking of injecting this signal into the bases of Q103 (positive lead of signal gen) and Q105 (ground lead of signal gen). Am I on the correct route here?

Other Crest amps in the V/Vs series use the STK3152-III for this IC. Is there any replacement for this hybrid in the V1500? Does anyone have and is willing to share the service manual for this model as I only have the schematics?

[razirafi]

Update: I first thought that the hybrid module is a sealed unit encased in epoxy but after disassembling the whole unit I found out that it is just a circuit board with SMD components. Did a visual and found nothing unusual. I then started probing and found a short across Z1. I took the part off the board and checked it again but it was OK. I probed the board again without Z1 and found the short still present. I then traced it to capacitor C1. I replaced C1 and now the amp is kicking again.

[mrfeedback]

Good work sorting that fault.
Tantalum bead capacitors are prone to failing short circuit condition....you found one.

Eric.