Repairing Cinema Grand - half waveform

s800 · 13th January 2009, 02:14 AM

Hi all,

Trying to repair a bad channel on a Sunfire Cinema Grand. Before I start desoldering the boards to really get at them, I thought I'd ask the gurus here if they've seen something like this before.

Basically all but one of the channels are fine, but the bad channel is only showing a half waveform; anything above ground is dead. I've posted some pics here:

Link

As much tracing as I can do shows the full waveform through the opamps and on filter caps, so it must be near the output. Any thoughts?

Thanks!

acid_k2 · 13th January 2009, 11:13 AM

s800,
probably you have posted a thread in the wrong section of the forum.

About your problem: try to check output transistors and relative driver transistors.

13th January 2009, 02:14 AM	#1
s800 diyAudio Member Join Date: Jan 2009	Repairing Cinema Grand - half waveform Hi all, Trying to repair a bad channel on a Sunfire Cinema Grand. Before I start desoldering the boards to really get at them, I thought I'd ask the gurus here if they've seen something like this before. Basically all but one of the channels are fine, but the bad channel is only showing a half waveform; anything above ground is dead. I've posted some pics here: Link As much tracing as I can do shows the full waveform through the opamps and on filter caps, so it must be near the output. Any thoughts? Thanks!

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13th January 2009, 11:13 AM	#2
acid_k2 diyAudio Member Join Date: Oct 2006	s800, probably you have posted a thread in the wrong section of the forum. About your problem: try to check output transistors and relative driver transistors.

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