Re: Adcom GFT-555 front end MOSFET


Herb Ward
 

Mike,

As is often the case with vintage audio,
oxidation on contacts is frequently the cause of open circuits on tuning caps, trimmer caps , speaker relays and potentiometers. If the original trimmer caps continue to be tap sensitive after adjustment,  replace them. Normally we would just replace all the trimmer caps in the Adcom tuners, and tuner preamps as intermittents in the trimmers would disrupt proper operation in all of the front end stages. ( and we did not want the customer to return the unit for another trimmer cap replacement )  If you can receive weak stations at 90mhz and 106 mhz ( or there abouts ) chances are good that the front end alignment is fine. 

HRW

On Fri, Nov 26, 2021, 1:38 AM MikeM via groups.io <mmaghakian=yahoo.com@groups.io> wrote:
the tuner is repaired and working great
I adjusted CT104 and L107 which were off
now receiving with strong signals

I have learned some lessons today that is for sure

thanks to all for making me think harder and to go do something

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