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

  • From: becyn <becyn@xxxxxxxxxx>
  • To: techassist@xxxxxxxxxxxxx
  • Date: Tue, 30 Nov 2004 18:43:36 -0500

OK, thanks for the effort.
I now use mozilla also, but always kept my sig file in a text file on my 
"desktop".
i open it, select it, do a ctrl-c, then ctrl -v  it to the e-mail. Once 
it's on the "clipboard" it stays there until you ctrl-c something else.  
I never did like letting the program doing it automatically...

Anyway, back to Amp 101.
Next step (no loads required). input a sine wave into the aux or cd  
jacks. Select the input on the front panel, turn up the vol to about 25% 
, center balance,and also check that you're not in some weird monitor or 
mute mode. Take your scope probe and look at  the  amp out  node at the 
pcb-in your case, the emitter resistors are a good bet. See if there is 
signal at that point on EACH AMP using DC mode
That way you can check for DC offset and siganal at the same time.

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

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

>this is weird,
>the message i posted has a sign file on it, but it is gray 
>instead of black print.
>but when you reply it is gone completely.
>can anyone explain this?
>i am using Mozilla.
>well any way, We are Schneider tv
>dover ohio.
>
>i just cut and pasted this from my earlier sign file.
>
>Schneider TV & Electronic Inc.
>5415 N. Wooster ave.
>Dover, Ohio 44622       www.geocities.com/schntv2000/
>330-343-0768         FCC. first class & Extra class K8WLY
>  maybe it will show up now.
>Larry
>
>
>becyn wrote:
>  
>
>>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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