Up date # 1 (yes I'm keeping count)
So far no filament voltage..Hope it's just a pinched wire and not the
transformer.
Schematic doesn't show any thing between the tranny and the filaments like a
fuse or other component that could open.
As Alex suggested I'm pulling tubes (good idea !). I will be checking them
for shorts. Please don't be the tubes.
Digging deeper, hope it's just the ole pinched wire during construction
routine.
$%@#@& !!!
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Up date # 2 (yes I'm still keeping count)
What do you get when you try to measure an AC voltage with your meter set to
DC? NOTHING!
No condemning comments please.ALL of you have done the same thing..LOL.
Well I've got 6.3.."VAC" on the filaments. With that known it was time to
find out why the delay relay didn't cause the ready light to come on.
Guys it's been almost 30 years back when I went to an electronics class and
it's been at least 15 since I've really dug deep into circuits. I have
worked with HV recently and know how to keep one hand in my pocket with my
fingers crossed. So please bear with me.
After looking closely at the foil side of the delay relay board I found that
the 12v trace that goes from the bottom of the board to the top has been
fused open due to an over current condition. This trace also has a diode
branching off that goes to one side of the 12v control voltage to the relays
via the delay tube. According to the schematic this side of the diode also
goes through an electrolytic cap to ground. Looking at the actual board
layout this ground circuit also eventually connects to B-.(B+ of B-?)
My theory on this is the cap is shorted; diode is going to be suspect also.
(Chicken or the egg?)
Has any one had this problem with this type of amp? Am I looking at symptoms
and not the root of the problem?
The last amp I built was about the 25 year ago time frame and it was a sweep
tube amp.
This is my first legal limit amp and I don't want to screw it up !!
Ken
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