[Amps] ok ONE more time <g> Ameritron 811H
Will Matney
craxd1 at ezwv.com
Sun Jan 2 21:21:35 EST 2005
Dan,
There grid resistors are there to actually work as a fuse which will
open if an internal arc in the tube occurs (anode to grid). Most likely
the resistor had failed some time back and was probably broke or
cracked. This was making the arc that you seen. Finally the resistor
gave way and failed completely. I would just change them out with new
ones on each tube. There's squirlley reasons for this internal arc but I
wouldn't worry too much about that. The main thing is just replacing the
resistors with the same size. You will want non-inductive resistors here
of course. I'd say that this will cure your problem.
Will
Dan wrote:
> You guys have had the answer everytime so far. I bought a 2nd hand
Ameritron 811H amp. It has worked very well exept .. at first start up
serveral weeks ago.. after it had been stored when i first turned it on
it arec at the vents 9right side) switched it off.. long story short
after a few turn ons and off it work great.. I get good ooutpit and
great reports. Well over the past few weeks once in a while (only when I
turn it on) I woud get an arc same place. after it has been on and after
serveral times on and off during the day it would be fine great output
and no arc even when switched back on .. seemed like only would do it
after it had been off all night and then only sometimes.. I have remoed
and check for any signs of arc etc never found anythign.. Well until
today.. I switched it on.. and again a little arc that was visable at
the vents.. and quickly this time a loud pop.
>
> Well obviously not a good thing. I remove the cover again and this
time found that one of the 53 ohm 2 watt resistors had actuall blew
apart. onone end. I shoudl mention that this time I had very little
power out after the arc/bang..
>
> In reviewing the circuit I can ot tell what these four resistors are
but I assume it has to do with some type of bleeder circuit to grd as
all four have one log to grd the other to a small wire maybe 18 ga.
(light wires.. one is yellow one is blue and the other two are red..
> the yellow one is the one that blew the resistor...
> The diagram they provide in the book and the parts list has to be
incomplete as the 53 ohn resitors are nto even liosted. there are two
physically near the rear of the tube cage (just to the rear to the
torrid) the other two are near the front edge of the same are... the
yellow wired resistor that blew is one of the two at the rear side of
the tube cage..
>
> Any ideas? Are these bleeder circuits ? part of the neutralization
circuit? .. Any ideas what might of caused this .. this amp sat for
about 3 yrs in a closet not used.. before I got it..
> any ideas woud be of help. Could a tube of caused it? what else
shoudl I check thanks
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