[TechAssist] Re: Yamaha R700 receiver parts
- From: Larry <schntv@xxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Thu, 28 Jul 2005 18:22:18 -0400
I have 49 volts + and - on the output IC s vcc.
but the audio output pin has 49+ on the one chip,
obviously the problem. it is a new stk and all resistors and
diodes are ok.
again i have no schematic, is it possible the C is wok and the
voltage amp C SK3056, which i cant find a supplier, can
cause this?
Larry
Leonard Caillouet wrote:
> Yes, IIRC, a failure in the voltage amp could take out the outputs. Seem to
> remember that there was a cap that would fail when that happened.
>
> Hope you did not blow the outputs. Is there any dc on the lines to the
> finals?
>
>
>
> ----- Original Message -----
> From: "Larry" <schntv@xxxxxxxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Thursday, July 28, 2005 11:05 AM
> Subject: [TechAssist] Re: Yamaha R700 receiver parts
>
>
> thank you Leonard.
> well one IC had 2 burnt resistors, but i replaced both output
> ICs. and the 2 resistors.
> the tuner shows signal but just no audio or relay click.
> the tech at yamaha recommended replacing the voltage amp
> stk3156 with a stk3076, and said it is common for this chip to
> blow the 2 outputs. does this sound correct.
> i can find no documentation on either chip.
> i know this is old but the customer is willing to invest 200
> bucks to have it work again.
> so that is my incentive.
> lol
> Larry
>
>
>
>
> Leonard Caillouet wrote:
>
>>Have you tried checking with Steve Coy at Consolidated? 800-543-3568. He
>>often has hard to find audio semiconductors.
>>
>>This receiver was one of the worst that Yamaha ever made, BTW. I would
>>not
>>put too much effort into it. It dates back to the early 80s and was
>>notoriously inept at driving any kind of complex load or anything below 8
>>ohms. Overall reliability was not bad if you did not push it and drove an
>>easy load. When they did break it was usually the output and a resistor.
>>Check the related electrolytics.
>>
>>Sorry, this is one schematic that I don't have. Haven't seen one of these
>>units in 10 years.
>>
>>Leonard Caillouet
>>Electronics World
>>1261 NW 76 Blvd
>>Gainesville, FL 32606
>>352-332-5608
>>352-332-5668 fax
>>
>>----- Original Message -----
>>From: "Larry" <schntv@xxxxxxxxxxxx>
>>To: <techassist@xxxxxxxxxxxxx>
>>Sent: Wednesday, July 27, 2005 6:56 PM
>>Subject: [TechAssist] Yamaha R700 receiver parts
>>
>>
>>im still working on this old receiver.
>>i ordered a schematic but it is a photocopy and un usable.
>>they say they have nothing better to distribute.
>>so, now after replacing stk1050 II and a few resistors, it
>>still has no audio.
>>I now suspect a voltage amplifier STK3156, but no one i tried
>>has it.
>>any help on this thing would be appreciated.
>>Larry
>>
>>
>>
>
>
--
Schneider TV & Electronic Inc.
5415 N. Wooster ave.
Dover, Ohio 44622 www.geocities.com/schntv2000/
330-343-0768 FCC. first class & Extra class K8WLY
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