[NJARC] Re. Sears guitar amp

[Bill Zukowski]

Chuck,

Just talking to a friend (previous NJARC member), and mentioned your amp 
issue.  He remembered *Danelectro* was making amps for Sears.  You may 
want to pursue that path.

Bill

On 1/12/2017 12:02 AM, Chuck wrote:
> Hi William,
> Thanks for you help...
> I removed the PNP and NPN power output transistors (one each) and 
> tested them with a transistor tester and they both read good.
> In fact, I have tested every transistor, all the Ecaps and most of the 
> resistors, and replaced all that were too far off, plus took a few 
> voltage readings that looked okay. But I couldn't really know because 
> I don't have the tech data - ugh...
>
> Thanks,
> Chuck
> AC2DP
>
> -----Original Message----- From: William S Zukowski
> Sent: Wednesday, January 11, 2017 4:37 PM
> To: njarc at mailman.qth.net
> Subject: Re: [NJARC] Re. Sears guitar amp
>
> Just remember
> Reply = Poster
> Reply All = Everyone
>
> _________________________________________________________
> That's "....analog VOM using the diode test range."
>
> Bill
> Sent from my iPad
>
>> On Jan 11, 2017, at 16:23, William S Zukowski <n2yeg at optonline.net> 
>> wrote:
>>
>> Just remember
>> Reply = Poster
>> Reply All = Everyone
>>
>> _________________________________________________________
>> Sounds like a shorted output transistor.
>>
>> Is the hum still there with the volume control at minimum?
>>
>> If you can determine the output transistors' leads, measure the 
>> voltage across the emitter - collector leads of each transistor.  The 
>> output transistors act like a voltage divider, so you should measure 
>> 1/2 the supply voltage across each transistor.  A shorted 
>> emitter-collector will have 0 voltage across it, and the other 
>> transistor will have full voltage. However, if it's a base-emitter or 
>> base-collector short this method may not be conclusive.  The best way 
>> is to remove at least 2 of the connections and measure the resistance 
>> between each junction.  Do this with either an older analog VOM or 
>> using the dio
>>
>> Hope this helps.
>>
>> Bill
>>
>> Sent from my iPad
>>
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