EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: superchode on December 31, 2019, 07:34:53 pm
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Good day,
New to the forum, this old receiver has me at the limits of my limited electronics troubleshooting skills.
Receiver powers off automatically (relay clicks, turns on, then shuts itself off).
I've narrowed it down to the I/O board - specifically when the cable that connects to the analog inputs is plugged in, the receiver shuts itself off when you select any analog input.
It seems Outlaw doesn't release any service information/schematics for their gear - so i'm not sure where to start.
Can anyone with more knowledge/experience at least lay out a general strategy to pursue? I've really only gone as far as to check fuses (there are virtually none on the input board section) and resistances between inputs, to see if one doesn't match.
Not sure how to actually do this effectively. No visible damage anywhere, that i can see.
Photos attached for general reference. Not sure what one would really need/want to see.
Thanks for any direction you can give.
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That's an aweful lot of electrolytic capacitors. I would probably start by looking for swollen or leaking caps. Especially near heat sources like regulators, bridge rectifiers and output transistors.
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i don't see any bulging, leaking or any other evidence of damaged caps. the layout actually does a good job of keeping the I/O boards away from the major heat sources.
i was hoping to be able to do enough diagnostics to at least identify which input is causing the trouble (if it's not something common to all) - and do something about it.
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looks like someone did a bodged repair job on the board near IC 282
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OK did a quick google, looks like outlaw had a relationship with Marantz, see if you can find amarantz service manual that looks like your outlaw unit
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ok, i'll give that a try.
i did get in touch with Outlaw. they're only willing to sell me a replacement DSP board, without knowing if that will resolve the issue.
if i can find a marantz manual that gives some direction, i'll see where that goes.
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also, i've had the unit from new - so that wire near IC 282 would have been installed at the factory.
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Unit failed production QA probably and went through repair. Your photos show multiple ribbon connectors emanating from the board. Which one when connected induces the shut down? Have you tried tracing back from the pins of that connector to see if there are multiple similar components associated with each specific input.
any luck with a manual?
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1. Check for any shorted output transistors.
2. During the interval before the unit shuts down check the DC voltage at each amplifier channel output.
Any DC offset more than a volt or so will trigger the protect.
3.Next check the output from any voltage regulator you can find.
There's also the possibility of thermal detection issues.