[TechAssist] Re: Yamaha HTR 5250 RCVR Powers up then protect mode

I don't have the schem for that unit but, I can offer my own experience as a 
starting point.

Since you've already taken out the finals, I would look next in the preamp 
circuitry.  It sounds like the Yamaha, and a few others I've worked on, I own 
when it's Protect circuitry for the output to speakers used to shut off the 
audio output soon after Power On.  I had one set of match-pair outputs that 
caused the complete shutdown.  Replaced them, and then only the audio 
section got shut off.  I ended up replacing a set of preamps as well.

I've also noticed that many of the Yamahas are critical in having the outputs 
replaced as "pairs" (NPN/PNP compliments) at the same time.  Replace one 
with a new and leave the other (still good) in place has brought me "repeat 
repairs" in the past.

On the other hand, if the "protect" circuit in that unit is for over-voltage 
protection - then, again, since the outputs are out, I'd confim that there 
aren't 
any faulty electrocaps between the supply's bridge and the protect circuit.

Chaz



Date sent:              Sat, 17 Nov 2001 02:01:53 -0800 (PST)
From:                   Timothy Williamson <timvcr@xxxxxxxxx>
Subject:                [TechAssist] Yamaha HTR 5250 RCVR Powers up then 
protect mode
To:                     techassist@xxxxxxxxxxxxx
Send reply to:          techassist@xxxxxxxxxxxxx

> 
> Hi:Guys I'm working on a Yamaha HTR 5250 similar to
> the 5240 and 5280.  The unit powers up when the power
> sw is push, display in all,the AC relay clicks.the
> RCVR stays on about 3 seconds,then the relay clicks
> off and the unit goes dead. I Took all off the out put
> out off circuit, it still did the same thing. Any one
> have I clue.
> 
> Thanks:
> Tim Williamson
> BCT Electronics
> 410-256-0344
> 410-529-1188 Fax
> Timvcr@xxxxxxxxx 
> 
> 
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