Atari B&W: no HV

Last night I discovered that my monitor's problems have a very simple
explanation: blown fuses. F101 and F102 looked fine, but tested bad.

I replaced them, disconnected the HV cage connector from the deflection
board and fired it up. All voltages on the connector pins present and
accounted for.

I reconnected the HV cage, held my breath, and fired it up again....picture!
Yes! The old whistling/hissing sound is gone, but I can hear and feel charge
on the tube.

HOWEVER, I have new symptoms to deal with:

1. All lines have pretty heavy sinus distortion. Adjusting brightness or
contrast changes the frequency of the distortion (racing vs. crawling).

2. The picture occasionally alternates between being small and filling the
screen. Sometimes it goes blank and fades up when it switches.

3. The big square resistor in the HV cage is running a lot hotter than
before, and giving off a burning odor. I stopped running the monitor when I
discovered this.

Before I discovered the blown fuses, I had removed and visually inspected
the HV diode. I have not discharged the tube by any method since then.

What do these symptoms point to?

-Anthony R.

on 06 12 01 10.20, John Robertson at jrr@flippers.com wrote:

> Easy test. Check the other voltages for the HV transformer circuit. If you
> get the other HV's but no 12KV, then your HV diode is shot. If you do NOT
> get the 90VDC and 400VDC (? I can't remember, something like that...), then
> you have a problem somewhere else.
>
> ---->>>Remember: NEVER, EVER EVER SHORT A B&W HV ANODE TO THE
> CHASSIS!!!!!!!!!!!<<<----
>
> You must use a HV meter or a series of 1 meg resistors (total 10Meg
> insulate the suckers!) to discharge the HV anode on the side of the tube.
> This is what is killing the HV diodes, getting the anode shorted by a
> jumper wire to the chassis common...
>
> John :-#)#
>
> At 10:41 PM 12/05/01, you wrote:
>> Hi again everyone,
>>
>> Awhile back I asked for help diagnosing my Battlezone cabaret's monitor. It
>> has yoke chatter and neck glow, but gone no picture, charge on the tube
>> face, or hissing/whistling sound that used to come from the HV cage.
>>
>> A couple of people suspected the HV diode. I'd order a replacement, but at
>> $15 each, I'd like make sure I need one.
>>
>> Is there any way for me to test this diode? I don't have any known-good HV
>> cages to put it in.
>>
>> Besides, I thought that a bad diode caused screen *bloom*, not total picture
>> loss. Shouldn't the transformer still be hissing/whistling?
>>
>> I'd appreciate any suggestions. Thank you...
>>
>> -Anthony R.
>>
>> --
>> Anthony Ramos________
>> 600 SE 39th Ave., # 3 \__ aramos@ele-mental.org .. aramos@hyperreal.org
>> Portland, OR 97214 \___ information design .. multimedia production
>> (503) 236-6303 \____________interactive art .. image synthesis
>>
>>
>> ---------------------------------------------------------------------------
>> ** To UNSUBSCRIBE from vectorlist, send a message with "UNSUBSCRIBE" in the
>> ** message body to vectorlist-request@synthcom.com. Please direct other
>> ** questions, comments, or problems to neil@synthcom.com.
>

-- 
Anthony Ramos________
600 SE 39th Ave., # 3  \__ aramos@ele-mental.org .. aramos@hyperreal.org
Portland, OR 97214      \___ information design .. multimedia production
(503) 236-6303           \____________interactive art .. image synthesis
---------------------------------------------------------------------------
** To UNSUBSCRIBE from vectorlist, send a message with "UNSUBSCRIBE" in the
** message body to vectorlist-request@synthcom.com. Please direct other
** questions, comments, or problems to neil@synthcom.com.