[TechAssist] Re: Aiwa ADV58u amplifier-tuner , no sound

Well, larry...
Still no sig file???? why don't you just type it in until you get the 
thing to do it automatically,...or ...well...you know the rules...;-)

Sincerely,
See sig file below!

Jim McVey
McVey Alltronix   
327 Broadway
Newburgh N.Y. 12550

Factory authorized
service for over 20
major brands.
845 561 8383



larry wrote:

>thank you again, jim.
>good question, why isnt my name and address at the bottom.
>i dont know
>it was on the original i sent.
>i checked and my signature file is supposed to be at the very 
>bottom.
>so i hope it works this time.
>Now on the stereo.
>i am slowly learning, i think.
>i was confused on which ground to use for the voltage 
>measurements, but now think i got it.
>on all 5 push/pull 2 transistor output circuits, i read the 
>same voltages, -22 on one collector and +23 on the other 
>collector and zero volts on the junction of the 2 emitter 
>resistors for each of the 5 sets of outputs.
>so , in my opinion i see nothing wrong there.
>also no ohm meter shorts between the output transistor pins of 
>any of the 10 output transistors.
>the tuning meter shows signal, but no audio on any of the 5 
>output channels.
>what do i check next??
>Larry
>
>
>
>becyn wrote:
>  
>
>>the relay has nothing to do with the voltages seen  on the amp board. it 
>>only disconnects/connects  the  the amp output to the speaker terminals. 
>>( By the way you dont need any loads hooked up to start the process) DO 
>>NOT UNDER ANY CIRCUMSTANCES  ENGAGE THE PROTECT RELAY IF LOADS ARE 
>>ATTACTCHED!!!!! This will damgage the loads and do furher damage (ie; 
>>smoke, flame) to the amp
>>
>>I dont understand what you mean by "no voltage on the junctions". You 
>>mean that literally? As in  no Vcc or Vee or just no offset at the 
>>emitter swamping resistors? (low ohm ceramics)?
>>Perhaps it's as simple as open fuses in the power supply?
>>You need to be very precise in describing the voltages otherwise I can't 
>>make head nor tails of it.
>>A normal fail mode is : 1) unit powers up, but no audio out
>>                                   2) all voltages present at amp and 
>>everywhere else, but  a DC offset of 1volt or more can be measured at 
>>the power amp's output  connection. (you must measure it at the pcb)
>>You might have something else, especially if you really don't see ANY 
>>voltages at the amp, but you're gonna have to do some 
>>troubleshooting...or send it to ME for repair!! ;-)
>>By the way, whats your company name and address?  I'm surprised that 
>>Jeff didn't get on you about this!
>>
>>Jim McVey
>>McVey Alltronix   
>>327 Broadway
>>Newburgh N.Y. 12550
>>
>>Factory authorized
>>service for over 20
>>major brands.
>>845 561 8383
>>
>>larry wrote:
>>
>>
>>    
>>
>>>thank you for the advice.
>>>I do mostly tv repair but fix a few audio, now and then.
>>>most the time i can check the collectors and find a short or 
>>>see burnt resistors.
>>>but this time none of the 5 output transistors have a short 
>>>and no burnt resistors.
>>>i have no voltage on the junctions of the transistors, where 
>>>the outputs are connected.
>>>but i doubt i would, because the relay never closes.
>>>the power supply has normal voltage to the relay.
>>>i am afraid to manually close the relay.
>>>what is my next step?
>>>Thank you,
>>>Larry
>>>
>>>
>>>
>>>
>>>becyn wrote:
>>>
>>>
>>>
>>>      
>>>
>>>>Are amps new to you?
>>>>IF you have voltages and no output, the thing is in protect mode which 
>>>>kicks in if a dc voltage is dectected on the amp out node. Otherwise, 
>>>>the speaker would burst into flames-(not good ;-)
>>>>
>>>>No doubt one (or more)  of the amps have a dc offset caused by shorted 
>>>>output transistor, drivers or problem with the differential amp. happy 
>>>>hunting...
>>>>
>>>>Jim McVey
>>>>McVey Alltronix   
>>>>327 Broadway
>>>>Newburgh N.Y. 12550
>>>>
>>>>Factory authorized
>>>>service for over 20
>>>>major brands.
>>>>845 561 8383
>>>>
>>>>larry wrote:
>>>>
>>>>
>>>>  
>>>>
>>>>
>>>>        
>>>>
>>>>>the readout lites, tunes stations, but no sound.
>>>>>please , any clues where to start?
>>>>>I have plus and minus 45 volts and also 23 volt + and -.
>>>>>Larry
>>>>>
>>>>>
>>>>>
>>>>>    
>>>>>
>>>>>          
>>>>>
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>>>>  
>>>>
>>>>        
>>>>
>>>
>>>      
>>>
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>>    
>>
>
>  
>

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