Re: Tempest K6100 - intermittent HV problem

John Huie wrote:
> Ok, thanks again guys. This is helpful and I'm beginning to
> understand a bit more about this. You are dealing with a relative
> novice here. Ok, I've looked up the HV over voltage protection
> adjustment procedures and...well....I don't have an HV Trim pot on
> mine. Nor do I see an LED. So, does this mean that I have an older
> version that does not have over voltage protection? I read that this
> was a feature of the later version monitors.
>
> I'm not sure where to check for the +13 that you mentioned. I will
> see if I can figure that out unless someone hear can tell me off the
> top of your head where to check that. And also I'm not sure where to
> check to see if the oscillator is running. I have a logic probe and
> know kinda how to use it. A little..... :)
>
> Any pointers would be greatly appreciated! This is my favorite game!
>

If you can identify the LM555 timer/oscillator and know which pin is #3
then you can check if it is working with a logic probe, 'scope, or
even an AC voltmeter (the AC voltage should be about 1/2 of the DC
supply voltage to the 555 - or a bit less). Take care not to touch any
higher voltage points on the chassis - hard on logic probes, etc.!

If you have any way to power the HV cage on your workbench, put the HV
Anode cap in a very clean ceramic mug to avoid getting a shock, then you
can happily probe the underside of the cage - once you know which test
points to use - for correct voltages, etc.

Don't leave the HV cage running without being attached to a monitor for
too long, but it does work for short periods of time safely - under 1/2
hour say.

Technical aside only for B&W Vector monitors:

I do find the ceramic mug is a good test of B&W HV diodes in the cage -
monitoring with an IR temperature detector will let you know if the HV
diode is failing. Failing HV diodes heat up in this situation, good ones
stay at room temperature. Of course a clue at this point (failing B&W HV
Diodes) is the rubber end caps look a bit cooked, but that can be an
artifact from a previous bad diode...

Should write all this up...someday...

John :-#)#
 
>
> --- On *Wed, 5/12/10, Cinelabs Info /<cinelabs.info@gmail.com>/* wrote:
>
>
> From: Cinelabs Info <cinelabs.info@gmail.com>
> Subject: Re: VECTOR: Tempest K6100 - intermittent HV problem
> To: vectorlist@vectorlist.org
> Date: Wednesday, May 12, 2010, 9:02 PM
>
> John,
>
> The install manual details the HV shutdown adjustment and how to
> determine if it's applicable (not hard to tell, once you see the
> difference).
>
> It also explains why you shouldn't depend on the B+ to adjust the
> anode voltage.
> When it fails, check that you have your low voltage supply (the
> +13v one in the HV cage, not the LV-2000 one).
>
> Also check that the oscillator is running (at the first stage). Be
> careful going farther towards the flyback, as there are obviously
> dangerous voltages there (we hope).
>
> The ~24V is just the DC input going through the primary of the
> FBT. The B+ circuit is kind of in an auto-transformer
> configuration. If the oscillator isn't running, you'll see the 24V
> output.
>
> -Mark
> On Wed, May 12, 2010 at 10:06 PM, John Huie <jehuie@sbcglobal.net
> </mc/compose?to=jehuie@sbcglobal.net>> wrote:
>
> Wow, I didn't know that. Yes I did adjust it. Well, I don't
> have a HV probe but I adjusted the B+ to be 180 volts. And
> interestingly, if I monitor the voltage it slowly
> climbs...very slowly. But if I leave it on for a long time it
> will climb to around 184 volts and stay there. But it still
> plays fine when that happens.
>
> The times when it doesn't work, the voltage just comes on way
> low and stays there (24 volts or something like that). So it
> doesn't really sound like over-voltage protection to me. But
> that's an interesting fact to tuck away for future reference!
>
> --- On *Wed, 5/12/10, Christopher X. Candreva
> /<chris@westnet.com </mc/compose?to=chris@westnet.com>>/* wrote:
>
>
> From: Christopher X. Candreva <chris@westnet.com
> </mc/compose?to=chris@westnet.com>>
> Subject: Re: VECTOR: Tempest K6100 - intermittent HV problem
> To: vectorlist@vectorlist.org
> </mc/compose?to=vectorlist@vectorlist.org>
> Date: Wednesday, May 12, 2010, 7:59 PM
>
>
> On Wed, 12 May 2010, John Huie wrote:
>
> > When it's playing blind I have deflection chatter. Spot
> killer is off. But...my B+ has dropped from 180
> > back down to 24 volts. Which is right where it was
> before I "fixed" it by replacing the zeners. I can
> > replace them again. They are about 25 cents each so no
> big deal. But....not sure if that would help and
> > even if it does something else seems to be wrong since
> these are brand new.
>
> You may be running borderline on the HV. I believe the
> K6100 has an
> over-voltage proteciton circuit that chuts down the
> monitor if the HV is too
> high.
>
> Did you adjust the high voltage after the rebuild ?
>
> ==========================================================
> Chris Candreva -- chris@westnet.com
> <http://mc/compose?to=chris@westnet.com> -- (914) 948-3162
> WestNet Internet Services of Westchester
> http://www.westnet.com/
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