I might add that Dentrons are notorious for bad caps blowing transformers.
Part of it is due to using only a 500pf plate choke bypass and operating a
lot on 80/160. Electrolytics do not like RF.
That meter indication is a classic for both diodes starting to break down
and caps ready to short.
Be very quick with the retest.
The comment about meter multiplier resistors are valid BUT in that amp they
used 1% precision HV resistors. OTOH the equalizing caps across each cap are
garden variety carbon composition and one breaking down or way high in value
could hasten a cap failure.
Removing the lead from the HV board to plate choke will eliminate that path.
Carl
KM1H
----- Original Message -----
From: "Carl" <km1h@jeremy.mv.com>
To: "Ken Durand" <N4zed@comcast.net>; <amps@contesting.com>
Sent: Saturday, February 15, 2014 6:19 PM
Subject: Re: [Amps] Plate Voltage Not Stable
If they are the originals they are long overdue. Pull the tubes first and
retest BUT still replace the caps in any case.
I believe FAR Circuits has a new PC board that is for the modern Snap-In
caps.
Carl
KM1H
----- Original Message -----
From: "Ken Durand" <N4zed@comcast.net>
To: <amps@contesting.com>
Sent: Saturday, February 15, 2014 5:45 PM
Subject: [Amps] Plate Voltage Not Stable
The plate voltage on my MLA-2500 amp has always been rock steady. It has
a
dedicated 220v line ran to it. The plate voltage has always been 2400v as
read on the panel meter....
After powering on the amp the other day this is what I get...Time to
replace
the caps and rectifier diodes? They are original.
https://www.dropbox.com/sc/uvd3jcwbrk86226/lDmNszwxYP
Ken
N4zed
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