Re: WG 6199 HV section help

Well, that was interesting. It turned out to be the 555 timer. After
rechecking everything in the HV cage (and out of desperation), I
replaced the timer with one from a pull from another cage I had. It
worked. Then I still had low High Voltage at about 136v. Traced it
back to ZD901. Replaced it and all is good now. The 555 I used as a
replacement was of the CMOS variety the first time. Don't know if that
would cause an issue or not. May have to get some regular 555's for
next time. Thanks for all of the assistance. Sometimes you need
another brain to make sure that yours is still working.

Pat

On 2/10/2013 6:15 PM, John Robertson wrote:
> Pat Danis wrote:
>> Like Ian, I have the same issue with my HV cage. P316 model. R903
>> gets fried and I keep frying q901 and q902. I have been thru the
>> entire cage and can't find anything bad. Read the FAQ and checked or
>> replaced everything suggested. I'm not a smart enough guy to figure
>> out what is drawing so much current.
>>
>> I can only power up the monitor for a few seconds. (about 5-10) When
>> I power up the monitor, it is very dim and then I get a high voltage
>> crackle and R903 starts to smoke, then the transistors let go. The
>> issue I was having before was the image was blooming. I replaced
>> ZD902 and I think that stopped the blooming. Now I need to know why
>> I keep frying these parts.
>>
>> Can anyone offer some suggestions? I've been thru this cage so many
>> times, I'm starting to forget what circumstance leads to what condition.
>>
>> Pat
>
> Do you have a ring tester for the flyback? One shorted winding can
> take out the parts you are speaking about...
>
> A cheap and easy alternate tester is to use an multi-function audio
> signal generator (all of us have these, right? - eBay, "audio signal
> generator" look for Sine/Square wave within those) - hook up the
> output to the transformer and fire up the generator (square-wave)
> around 15KHz @ 10 to 20V. You should see on your 'scope (you have
> these too, eh?) a nice signal with a ring that rolls down after about
> five to more cycles after each pulse.
>
> There is no reason you have to run the HV cage at the rated DC input,
> use a variable power supply and dial it up slowly while you watch the
> screen/focus outputs (not the HV lead!) on your 'scope. You may see
> something interesting...
>
> John :-#)#
> PS, I sell the ring testers as a kit, cheap @ $49.95, I'll knock $5
> off the shipping if you mention you post on Vectorlist.
>

---------------------------------------------------------------------------
** Unsubscribe, subscribe, or view the archives at http://www.vectorlist.org
** Please direct other questions, comments, or problems to chris@westnet.com
Received on Mon Feb 11 09:18:05 2013