Re: G05-801 Tech

What were your voltage readings?

On Fri, May 1, 2009 at 10:34 PM, utahtaper <utahtaper@comcast.net> wrote:

> Thanks for answering my post guys. I really appreciate the lengthy write
> up Mark! I checked all of the stuff you suggested and everything looked
> within range. So in the agony of defeat I grabbed a G05-802 HV cage and
> threw it in the 801 and it's running perfect. So I can assume the problem
> lies within the HV cage. Any ideas what in the HV cage might cause the
> things I described?
>
> ----- Original Message -----
> *From:* Cinelabs Info <cinelabs.info@gmail.com>
> *To:* vectorlist@vectorlist.org
> *Sent:* Friday, May 01, 2009 12:30 AM
> *Subject:* Re: VECTOR: G05-801 Tech
>
> Jason,
>
> Your complaint about retrace that can't be adjusted out indicates you have
> a voltage wrong (somewhere). Since you didn't mention a focus problem, it's
> most likely on G1 and/or the cathode. Both of these are derived from your
> +90V supply, so that's a prime candidate. Regardless, check all of your
> voltage supplies.
>
> Your complaint about a spot after power down indicates the grid and cathode
> are losing potential too quickly (relative to the crt cooling down). This
> also supports the low +90V supply theory.
>
> D509 and C506 are intended to suppress "the spot" after power down. If you
> replaced C506 when you capped the monitor, you may have installed a
> defective part, an incorrect part, or the part may have been installed
> incorrectly. You didn't mention if the symptom was present before you capped
> it, but that would be a good indicator.
>
> If your +90V supply is good, check the voltage across C506. It should be
> very close to whatever voltage you measured on the 90V rail. If it's not,
> C506 or D509 may be defective.
>
> One other note. The spot on the screen remains until the heater in the CRT
> cools down, which is around a minute. The "voltage in the tube" can remain
> for a much longer period of hours or even days or more. C506 is used to
> ensure sufficient voltage to pinch off the beam, is present for at least as
> long as it takes the heater to cool.
>
> HTH. Let us know what you find.
>
> Thanks,
> -Mark
> On Thu, Apr 30, 2009 at 9:50 PM, utahtaper <utahtaper@comcast.net> wrote:
>
>> I'm debugging an 801. Monitor has been capped and bottlecaps replaced.
>> The monitor fully works however there is always a dot right in the middle of
>> the screen(Like a spot killer dot) not a bright dot, but a dot none the
>> less. The dot is even still there when the brightness and contrast are
>> turned all the way down. Never ran across this one before. Anyone seen this
>> before and have some suggestions?
>> The dot is also there when the game turns off and slowly disappears as the
>> voltage in the tube drops. Or if I bleed it off myself with my probe.
>> Thanks in advance!
>> Jason
>>
>
>

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Received on Sat May 2 04:25:41 2009