Re: Tech: WG6100 Help:(

Either Q101 is open (emitter to base) OR Q103 on the chassis is open, OR Q103
isn't a 2N3792 OR there is a bad connection at J100. You should have
approximately -27.7 at Q103 emitter (J100 pin 5), -28.4 at Q103 base (J100 pin
6), and -33.3 at Q103 collector (case) (J100 pin 7). If the emitter and base
are within a volt of each other the transistor is probably OK and Q101 (or the
connector) is the problem. If you have more than a volt difference between the
emitter and base of Q103 then it is either bad or the wrong part. If you don't
have at least -28 volts or so at Q103 case (collector) the transistor may have a
loose mounting screw, an insulator on the screws, or J100 problems at pin 7. If
ANY of that happened Q101 would probably instantly blow.

Justin Monast wrote:

> Hey Tek,
> I have checked the voltage at D105, so before the voltage passes through its
> at -27.7 and on the other end its at +11, I hope that makes sense..
>
> -----Original Message-----
> From: owner-vectorlist@synthcom.com
> [mailto:owner-vectorlist@synthcom.com]On Behalf Of Tek
> Sent: Saturday, May 20, 2000 11:45 AM
> To: vectorlist@synthcom.com
> Subject: Re: VECTOR: Tech: WG6100 Help:(
>
> Justin Monast wrote:
> >
> > Hey Guys,
> >
> > I have a quick question, on my defection board I'm getting the correct
> > reading on the low voltage power supply +27.7 -27.7 but on the other end
> of
> > diode 105 (which goes to P100 and others) reads +11.3 it should be -27.7.
>
> Where did you actually check for the -27.7 volts? It seems the transistor
> Q101,
> Q103 or ZD101 is defective.
> Can you find out what the voltages are at the B, C and E of Q101 and 103?
> If you get the right voltage (about -28.4V) at the E of Q101 (and thus the B
> of
> Q103) Q101 should be ok. Then check Q103 to see it is actually receiving the
> main 33V at it's Collector. If these two requirements are met then Q103 is
> probably failing (because at the Emittor of this baby originates the
> main -27.5
> V, which is +12 V according you. Then the 12V you are reading there is
> probably
> the +27V minus a voltage drop from the 'positive half' of the XY amplifiers
> ect.
> since they are not negatively fed anymore.
>
> Normally a defective transistor/diode is short-circuiting, but in you case
> is
> prbably gone high-ohmic or a bad connection.
>
> I
> > also replaced, checked and capped every component from the high voltage to
> > the chasse transistors. I know it's not the high voltage section because
> I
> > swapped a know good one and still have the same problem. At this point I
> 'm
> > stuck I've been working on this for two months and have looked at every
> > place on the net that has dealt with vector monitors, but to not avail...
> >
> > p.s. Also since I'm not getting the corect -27, the high voltage does not
> > come up and the spot killer light stays on...
>
> You're roght, the HV cannot cause this I think...
>
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