[TechAssist] update:Toshiba CE32H15 IC Q501 info (no DPC adjust.)]
- From: Phil Bader <philbad@xxxxxxxxxx>
- To: "techassist@xxxxxxxxxxxxx" <techassist@xxxxxxxxxxxxx>
- Date: Thu, 03 Oct 2002 12:16:41 -0400
On going battle with this:
Toshiba CE32H15/TAC9805.
Need any input avail.
Phil Bader, Jan Phyl TV
Thought I would forward this to the group for information sake.This
brings us up to date:
Set was dead.storm.Repl. fuse,fixed open trace, shuts down instant:repl.
Q471.Cured.Plays but has severe side pincushion distortion,worse on
right.Entered service mode.Selected DPC.Changed the adjustment values
and absolutely no change.Checked all the DPC circuitry,all seems
OK.Suspect the DPC circuit is not getting a good control voltage, even
tho the service menu OSD values are changing with the vol up/down
adjust.This signal/voltage originates fron IC Q501 pins 15,17. (Q501 was
changed).Joe (Pro-Electronics)has "adopted me" on this one! ;-) So:
I entered service mode,got to the DPC, selected a crosshatch pattern.
My plan is to measure these pins (Q501:15 and 17) while pushing vol up
and down, changing the values on the DPC correction values and look for
a change in the DCV or scope P/PV on those pins.
Then, I put my DVM probe on IC Q501 pin 15. A constant DCV of about
+2.3V.Same on pin 17.No changing thru a range of values.
Scope probe on 15, see a composite squarewave about 4VPP, pin 17 a
flattened ramp wave about 1VPP.
Neither the DC or scope signals on either pins change while I change
the values of DPC in service menu.So, correction voltages are
unchanging.
I think the problem is the PC ckt is getting a constant correction
voltage from Q501. I changed Q501 so that's not the culprit.
Wondering now if I'm dealing with a micro or eeprom chip.
The OSD shows the parameters are increasing and decreasing,but no
voltage change,Q501 OK, that leaves only other thing: micro or eeprom.
Is my thinking flawed?
Phil
PRO-ELECTRONICS wrote:
>
> Phil,
> Its good to take a break.
> I did notice an error (surprise) on the drawing. The collector does go to
> ground-not sure how they get the -10 volts on the drawing.
> The EW out signal comes from IC Q501 pin 18 0.6V
> pin 17 is EW FB 4.7V Looks like the signal goes to Q461 (B) then from the
> collector to Q460-
> Phil-you should check that for signal.
> Also it shows D461 going to ground thru L463-check for good connection.
> I bet you'll never forget this DOG!
> Keep the faith.
> Joe
> PRO-ELECTRONICS
> pro501@xxxxxxxxxxxxx
> ----- Original Message -----
> From: "Phil Bader" <philbad@xxxxxxxxxx>
> To: "PRO-ELECTRONICS" <pro501@xxxxxxxxxxxxx>
> Sent: Wednesday, October 02, 2002 10:02 AM
> Subject: Re: CE32H15
>
> > I dont know, my friend...
> > I have swapped and tested everywhere in this circuit to no avail.
> > Pulled Q460, tested OK.Noticed the collector is at DC ground
> > potential.This explains the zero volts there.Collector has a trace that
> > goes to a small less-than-1-ohm coil that goes to ground.I've pulled ALL
> > the scan caps,all OK.All the small transistors,seems all OK.Changed the
> > diode D467 tho it was good.There is no good reason why the right side
> > DPC is worse.At the least there should be a uniform distortion on both
> > sides equally.
> > I do thank you for all the assistance.God knows Toshiba would not turn
> > their hand.
> > I'm sick,and going home!
> > Phil
> >
> > PRO-ELECTRONICS wrote:
> > >
> > > Hi Phil
> > > Sorry the scan did not come out.
> > > I think you've found the problem with Q460 it should have -10VDC on the
> > > collector.that feeds to D467 and C464 (100V 10MFD) likely suspect.
> > > the base is -0.6 and the emitter is 0V.
> > > That might be another problem is the ground reference for the readings.
> > > The capacitor values for C439(.43MFD 400V)
> > > C442 (.33MFD 315V)
> > > C467 (0.018MFD +/- 3% 630V)
> > > That's out of the service manual.
> > > One more item is R463 4.7 1W
> > > that ties to the emitter of Q460
> > > also D464= Zener MTZJ2.2A
> > > that ties to Q461 Collector.
> > > I do know that your right about Q460 being cold-you can also check the
> > > waveforms there-but my drawing doesn't show any.
> > > Your in the right area-don't give up!
> > > Joe
> > > PRO-ELECTRONICS
> > > pro501@xxxxxxxxxxxxx
> > > ----- Original Message -----
> > > From: "Phil Bader" <philbad@xxxxxxxxxx>
> > > To: "PRO-ELECTRONICS" <pro501@xxxxxxxxxxxxx>
> > > Sent: Wednesday, October 02, 2002 05:23 AM
> > > Subject: Re: CE32H15
> > >
> > > > Yes, the B+ is at 125.5VDC.In the mean time I pulled those scan caps
> > > > mentioned and measured them on my cap checker.
> > > > C439, "443J" measurs 43.4nF
> > > > C442 "334J" meas .333uF
> > > > C467 "183H" meas 17.9nF (is this in range?)
> > > > I replaced all the coils: L441,442,461 from a known good tosh TAC9609
> > > > chassis.
> > > > R441(1K) was OK meas. out of ckt.
> > > > D461 good out of ckt. (diode ck and ohms ck front and back)has about
> > > > neg-34 volts on it runnung.
> > > > D442? can't find.
> > > > BTW the large Q460 transistor runs absolutely cold.strange,a power
> > > > transistor on a heat sink should be warm.( E -35.7vdc, B -35.8vdc , C
> > > > zero vdc)
> > > > When I am running this DPC value up and down in service mode, is there
> a
> > > > test location I can monitor to see if I do get a change? (like a
> volume
> > > > control pin on an audio IC where min. volume is zero volts, max vol is
> 5
> > > > volts.)to see if I really get a change corresponding with the number
> > > > values change on the osd.
> > > > still, the right side is severe pin, left side slight. Not equal.
> > > > I'll check the other scan caps and see.
> > > > Whew.
> > > > I want to thank you for all the help. I can't read the scans sent but
> > > > will make do.
> > > > Regards, Phil
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