[TechAssist] Re: PTK178L2
- From: Gary McCartney <gary@xxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Thu, 07 Nov 2002 10:06:07 -0500
Mark, checking the schematic,
on screen display output comes from U3101 system control IC. Pin 19 is
red out, pin 18 is green out, pin 17 is blue out. these 3 pins show 0V
dc on each, and waveforms 4.8V p-p on pins 17 and 18. Pin 19 doesn't
show waveform.
These RGB outputs go through transistors Q3303, Q3302, Q3301, collectors
out at 0.7V dc (fed from +7.6V source through R3312, R3308, R3304 1500
ohm each ) then into U2001 T chip, on pins 39 for red, pin 41 for green,
and pin 42 for blue. Each of these pins is labeled 1.9 or 2.0 V dc with
waveforms at 680mV p-p. The on-screen blanking line comes from U3101
pin22, with dc measurements of 0V or 4.6V in standby mode, then goes
into pin 39 of U2001 where it shows 1.0V dc either standby or run mode.
From pin 22 of U3101, OSD blanking line also goes to Q2503 buffer where
collector connects to +9V B+ and emitter goes to U2501 luma processor
pin 20 labelled VM switch and shows 0.3V dc.
U2001 has a matrix inside which processes the OSD and the video and
outputs them together on pins 36 (red), 37 (grn), 38 (blue), with dc
reading of 2.8V on each and waveforms 2.7 V p-p (red), and 2.3 V p-p
(grn, blue).
Hope this helps for now. If need be later I can send you partial print
of the area.
******* ATTENTION, PLEASE ********
I have a new email address. Please
send all email in the future to:
"Gary McCartney" <gary@xxxxxxxxxxx>
Thanks.
Gary McCartney
McCartney Electronics
7134 Fife Rd, RR 7
Guelph Ontario Canada N1H 6J4
Fax: (519)821-1530
mark brock wrote:
>
> brought it in dead, replaced splitter, came up, did a routine
> maintenance upgrade including changing diodes, and resoldering, let it run
> for 2 hours on test bench with a mirror, all looked good, took it back and
> I have no menu, probably never did as not needed. checked the plugs,
> cleaned, scraped etc still no menu. I did find some corrosion on the cpu
> pins, cleaned but dont' think its from tube leak, odd place for it and not
> enough visible. any ideas why I've lost a menu ?
> much appreciated
> brock
> Brock Electronics
> R.R.4 box 237
> 5208 cr.3385
> Independence Ks. 67301
> 620-331-0235
> fax 331-7191
>
> brock@xxxxxxx
> mailto:brock@xxxxxxx
>
> ----- Original Message -----
> From: "Bruce Youmans" <youmans@xxxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Tuesday, November 05, 2002 6:15 AM
> Subject: [TechAssist] CTC167R pincushin
>
> >
> > Back on February 12th of this year this FIX was posted for a RCA CTC167R
> on
> > for a pincushion problem. The fix was; Solution: SMD R4802, an 1800ohm
> > chip, had a cracked end cap.
> >
> > I have a CTC167R with pincushion problems. I have not been able to find
> what
> > is bad. I have tried to find the SMD R4802 mentioned with no success. I do
> > not have a schematic. Does anyone happen to have one and could you tell me
> > what R4802 connects to. Thanks in advance.
> >
> > Bruce
> > Bruce's TV Service
> > Sierra Vista, Arizona
> >
> > ----- Original Message -----
> > From: Wayne Vanaman <Wayne@xxxxxxxxxxxxxxxxxxxxx>
> > To: <techassist@xxxxxxxxxxxxx>
> > Sent: Tuesday, February 19, 2002 2:40 PM
> > Subject: [TechAssist] fix CTC167R pincushin
> >
> >
> > >
> > > Greetings all:
> > >
> > > An RCA ctc167R chassis, pincushin problem.
> > > Solution: SMD R4802, an 1800ohm chip, had a cracked end cap.
> > >
> > > Wayne Vanaman
> > > Omega Electronics
> > > 6904 W Fairfield Dr
> > > Pensacola, Fl. 32506-3310
> > >
> > > 850-456-5995 voice
> > > 850-458-6369 fax
> > >
> > > Mailto:Wayne@xxxxxxxxxxxxxxxxxxxxx
> > > WWW.PensacolaTVRepair.Com
> > >
> > > >
> > >
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--
******* ATTENTION, PLEASE ********
I have a new email address. Please
send all email in the future to:
"Gary McCartney" <gary@xxxxxxxxxxx>
Thanks.
Gary McCartney
McCartney Electronics
7134 Fife Rd, RR 7
Guelph Ontario Canada N1H 6J4
Fax: (519)821-1530
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