MkIIC Lead CH fades in volume after a while

[okgb]

Afriend has this , changed the tubes for the lead ch and it helped
but still fades in overall level after a period of time .

any common fixes for this ? tia

 

[zodiac272]

Maybe the LDR's or in need of a cap job. any idea when it was last serviced by a tech?

scott

 

[okgb]

From Canada , post to boogie would be Horrendous in cost
likely hasn't been " serviced " for a while , no one around here
that i trust or who has the time . SAR custom power amps
here , don't bother much M.I. things .

I'll check electrolytic caps around the circuit , suppose if they
let go or don't hold the charge , could be .
How likely is it for LDR's to have a problem ?

tia , again , regards Greg

 

[zodiac272]

the LDR'S change the channels, like switches, and when they go bad, I believe they bleed noise, and may have vol fade or something like that. Boogiebabies? you there?

 

[okgb]

The led part of it should either work or not
suppose the photo resister could become
less sensitive and change resistence

I haven't seen the amp yet , I'm smart enough
to build electronics just not quite enough to design them

 

[okgb]

No help or idea's so far But
my friend did bring it over which
out of the cabinet and without the reverb plugged in
the amp didn't exhibit the problem he had experienced
[ those were the 2 main differences ]
so maybe heat or verb releated , considering it uses
part of the tube for the ver circuit as well as the lead
drive , there is some relationship .

Have to say it was a good sounding amp ,
a thicker almost compressed midrange with a slightly
more saturated drive , compared to my no stripe
[ although my .# suggests it's newer ] mkIII
which was thinner and more " hifi " like sounding

I'd still dump my mkIII if the value wasn't so low

 

[zodiac272]

So does the problem exist if you turn the reverb to zero? is the reverb cord grounded? check out the reverb mod.

scott

 

[zodiac272]

shhhh... bartchamdoh will chime in

but yes a ringing endorsement of the IIC

 

[okgb]

Next step , see if problem occurs again
with old conditions if it does , try with verb
unplugged . if still ocurring , take out of chasis again
Got a link to the particular verb mod ? is there
more than one ?
Diff between II and IIC ?

 

[zodiac272]

I'm sure there are a few mods, this one is about grounding

http://forum.grailtone.com/viewtopic.php?f=27&t=50252

scott