Re: TECH: Amplifone Q's

On 06 Oct 1997 12:00 EDT, you wrote:

>In message "TECH: Amplifone Q's", you write:
>> The wierd part of it all is that the tube NEVER sparks,
>>crackles, etc when I discharge it to disconnect the HV connection.
>>It never sparks when I discharge it to re-connect the HV connection.
>>In every monitor I've worked on, I've always been able to get some
>>kind of spark/snap/whatever when I went to discharge it (even when it
>>had just been sitting there, with the HV connection disconnected for
>>a while....There also NO glow from the back of the neck (I even looked for
>>thse sparks and glow at night.) Does this sound like a bad tube? There
>>is no high-pitched whine from the HV transformer but there isn't from the
>>WG HV transformers either, so I don't know if that is normal or not.
>
>Well the HV is totally unrelated to the heater as far as charges go.
>If you aren't getting heater then I believe there is a separate
>fuse just for taht 6.3VAC which you should be able to check. Fix that
>first since it should be simple.

Well on an Amplifone the HV and heater are very related. The Amplifone is
like the Sega X/Y montitor in that they drive the heater filament from a
winding on the HV transformer. So if your HV section is not working, your
your CRT heater won't glow.

It seems to me that running the heater off the HV transformer is just more
loading on the transformer. I guess the new Wintrons are pretty bullet
proof, but for the old (still working) RED transformers it might be a good
idea to run the filament directly off one tap of the 25v transformer,
through a diode and a couple of resistors (for details follow the schematic
of the WG X/Y monitor which does exactly this) instead of the HV
transformer.

Does your HV section still have one of the red HV transformers? If so,
it's probably bad.

If it's the new Wintron it's probably something else, make sure you follow
the wiring diagram very carefully, and that your using the newest wiring
diagram (I guess when Wintron first came out with a replacement HV they had
the wiring diagram wrong, but that was a few years ago.)

Don't know if I help much except to let you know that on an Amplifone, no
heater glow usually means bad HV.

-Zonn
Received on Mon Oct 6 10:07:38 1997