RE: Adjusting K6100 (tempest) HV / b+

A circled 2 means the manufacturer was Sprague. The rest suggests a house
part.
On Oct 8, 2011 8:52 PM, "David Shoemaker" <davids@oz.net> wrote:

> Got it, Q902 (another MPSA06) was bad. Replaced it I can now get B+ up to
> where it belongs. The voltages going into Q903 were all wrong so this was
> next up the chain. ****
>
> ** **
>
> As for possible improper parts / values the part I took out was marked
> oddly. I suspect a house part but can’t be sure.****
>
> ** **
>
> It has a 2 in a circle then 71. Next line is -1****
>
> ** **
>
> Thanks for the pointers.****
>
> ** **
>
> David****
>
> ** **
>
> ** **
>
> ** **
>
> *From:* owner-vectorlist@vectorlist.org [mailto:
> owner-vectorlist@vectorlist.org] *On Behalf Of *Mark Shostak
> *Sent:* Saturday, October 08, 2011 6:24 PM
> *To:* vectorlist@vectorlist.org
> *Subject:* Re: VECTOR: Adjusting K6100 (tempest) HV / b+****
>
> ** **
>
> The pass transistor is the power trani regulating the supply to the fbt.**
> **
>
> ** **
>
> Most of that is easier to troubleshoot in-circuit, so you can measure the
> actual voltages, rather than pulling out something like a zener trying to
> figure out if it's avalanching at the right voltage.****
>
> ** **
>
> Make sure the reference voltage is correct on the zener. Going by
> appearances makes the process a lot longer than it need be.****
>
> ** **
>
> Be advised that many incorrect / can't adjust, symptoms on the HV cage are
> caused by installation of improper parts / values during previous repairs.
> ****
>
> ** **
>
> -M****
>
> ** **
>
> On Sat, Oct 8, 2011 at 8:11 PM, David Shoemaker <davids@oz.net> wrote:****
>
> Sounds reasonable. ****
>
> ****
>
> But I don’t follow “Pass transistor”.****
>
> ****
>
> I pulled ZD901 and diode checked it, and it appears ok. I decided to pull
> the adjustable resistor and if literally fell apart when it hit the bench
> J****
>
> ****
>
> Replaced it though and no change.****
>
> ****
>
> *From:* owner-vectorlist@vectorlist.org [mailto:
> owner-vectorlist@vectorlist.org] *On Behalf Of *Mark Shostak
> *Sent:* Saturday, October 08, 2011 5:23 PM
> *To:* vectorlist@vectorlist.org
> *Subject:* Re: VECTOR: Adjusting K6100 (tempest) HV / b+****
>
> ****
>
> Check both sides of the pass transistor (make sure the rail is nominal)***
> *
>
> ****
>
> Check the Zener****
>
> ****
>
> Check the parts between the Zener and the pass trani****
>
> ****
>
> On Sat, Oct 8, 2011 at 7:11 PM, David Shoemaker <davids@oz.net> wrote:****
>
> I just recapped a HV unit on a tempest. In the process I replaced Q901
> (MSPA06) and R904 (470 1/2w).****
>
> ****
>
> The monitor turns on and has a reasonable display.****
>
> ****
>
> BUT: My B+ voltage is 56v (checked at Pin 5 of the J900). I can’t find my
> HV probe to check what the HV is at right now.****
>
> ****
>
> The pot on the HV board doesn’t make any difference to the b+ voltage.****
>
> ****
>
> Before I start to just shotgun parts (R918 the adjustment pot, Q902, Q903)
> anyone have any suggestions?****
>
> ****
>
> Thanks,****
>
> David****
>
> ****
>
> ****
>
> ** **
>

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Received on Sun Oct 9 01:53:46 2011