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Fender Concert amp

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N_Cook

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Jul 26, 2010, 11:39:29 AM7/26/10
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Bad splitter-driver plate/anode 100K resistor, what goes bad with them?
Causing rustle noise in output. Partial crack? or something chemical. I may
as well replace the 82K while I'm at it , but is there any point to
pre-emptively replacing all the HV droppers ?
Anyone happen to know the datecode structure for Mallory electrolytics of
the 1980s?
say 4uF, 450VDC
marked
012022
235
8346B

1982 and 35/52 from 235 or 1983 and 46/52 from the last number?


Ron

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Jul 26, 2010, 12:17:19 PM7/26/10
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Noisy 100k resistors is a common and well known problem with Fender
amps, change em all.

Ron

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Arfa Daily

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Jul 26, 2010, 12:54:00 PM7/26/10
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"Ron" <r...@lunevalleyaudio.com> wrote in message
news:uoydnVAX4qqSKNDR...@bt.com...


> On 26/07/2010 16:39, N_Cook wrote:
>> Bad splitter-driver plate/anode 100K resistor, what goes bad with them?
>> Causing rustle noise in output. Partial crack? or something chemical. I
>> may
>> as well replace the 82K while I'm at it , but is there any point to
>> pre-emptively replacing all the HV droppers ?
>> Anyone happen to know the datecode structure for Mallory electrolytics of
>> the 1980s?
>> say 4uF, 450VDC
>> marked
>> 012022
>> 235
>> 8346B
>>
>> 1982 and 35/52 from 235 or 1983 and 46/52 from the last number?
>>
>>
>
> Noisy 100k resistors is a common and well known problem with Fender amps,
> change em all.
>
> Ron
>


I reckon that goes for all amps with 12AX7 stages, doesn't it Ron ?

Arfa

Meat Plow

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Jul 26, 2010, 1:36:37 PM7/26/10
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I repaired an old 50 watt Silvertone a few months ago and found two 100k
plate resistors one in the splitter and one in the reverb driver that had
increased in value by nearly double. The splitter was a 12a-something but
the reverb driver was a 6-something.

Ron

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Jul 26, 2010, 2:36:02 PM7/26/10
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Not sure, I know I`ve changed a lot in Fenders. on the newer models it's
such a lot of parping about getting the board out, it`s easiest to
change the lot.
Modern valve amps are so very noisy anyway, specially fenders - the
don't make em like they used to you know!

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