[TechAssist] Re: Update on the Magnavox FP5230 chassis PTv620 continuos blowing ofQ802
- From: wpt19@xxxxxxxxx (Pete)
- To: techassist@xxxxxxxxxxxxx
- Date: Sun, 9 Oct 2005 23:25:44 -0400
John I found the problem by accident, switching the main board from
other similar chassis set, I forgot to connect plug J431 coming from
convergence bd, that lead me to suspect of that component, replaced it
and no more problem. Remember before I removed the 3 crt boards with no
success. I have the Force32 CD with the schematic, and those -H +H scan
pulses derived from T801, the sweep transformer, are maybe overloaded,
The fuse resistors in series are R2802 and R2803 750 ohms off pins 12/14
on T801, and R700 / R705 1.5k in the convergence bd, I think those
pulses are pretty hi in value and needs to be reduced with those hi
value resistors.
Tomorrow I'm going to check carefully those resistors and the
components related with the 11 to 20 volts enhance circuit on
convergence bd.
pete
Perdomo TV Inc. Since 1972
Miami, Fl
Sender: techassist-bounce@xxxxxxxxxxxxx From:
contitv@xxxxxxxxxxx(John=A0Conti) Date: Sun, Oct 9, 2005, 10:31am
(EDT-1) To: techassist@xxxxxxxxxxxxx
Subject: [TechAssist] Re: Udate on the Magnavox FP5230 chassis PTv620
continuos blowing ofQ802 Reply=A0to: techassist@xxxxxxxxxxxxx
Pete, I never heard of a manual convergence board blowing a HOT ...
There is
no real direct link between the circuits....????
1. Convergence board runs off 11-15 volts...not 130v.
2. If the matched outputs for each color would short, there would be
massive pix distortion with convergence, not a blowing of the HOT , even
though we have 'dual' yokes. )defl. and conv. built together.)
3. The only direct link would be the + and - scan derived horz. pulses
from T801, but if there buffers on the convergence board wew to short,
those lines coming from T801 are fuseable resitors protected. These
would go first, only .27 ohms, less than half an ohm. I believe that
there is another force at work here causing this part to fail. ther is
not anything I can think of on that board, even if you had a chorted
yoke, that would do this.
Only things I know that will knock out this HOT and nothing else is:
1. c811, off the collector of Q802.
2. T801 if it has a load breakdown internal short.
3. arcing of high voltage from any on the anode cups to one of the
yokes. Only about 3/8" gap thereto jump, that directly is linked to the
collector of Q802.
4.Checking of all higher voltage carring wires proper lead dress
positioning..this has caused some problems also.
Good Luck
John
Conti,sTV
Texas
From: wpt19@xxxxxxxxx (Pete)
Reply-To: techassist@xxxxxxxxxxxxx
To: techassist@xxxxxxxxxxxxx
Subject: [TechAssist] Udate on the Magnavox FP5230 chassis PTv620
continuos blowing ofQ802
Date: Sat, 8 Oct 2005 18:25:23 -0400
, The problem was in the convergence module, I put one from another set
and bingo, no more horizontal sweep transistor Q802 shorted Thanks to
all the colleagues that help with theirs tips, now I need to repair the
convergence module. If somebody faced this problem before, I'll
appreciated your help.
pete
Perdomo TV Inc. Since1972
Miami, Fl.
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