Old Quintrix fix or throw


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Old Quintrix fix or throw

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No-Box
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Jul 9, 2015, 3:16 PM

Post #1 of 30 (3491 views)
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Old Quintrix fix or throw	Can't Post

Hi everyone
Hoping to repair an analogue Panasonic TV Quintrix which belongs to a friend and recently died. Yes it would make a good boat anchor!
First off I'm an inexperienced amateur but I tread carefully.TV switched on ok according to the red light but then shut down repeating this shutdown cycle every 10 seconds following repeated switching.
Back off, board out, no apparent dry joints ,cleaned however noticed a jump wire touching a capacitor with some insulation melting?.
reassembled to find set works without cycling now however picture reduced to thin horizontal line.....any idea's or comments...landfill!!!..seems to good to throw.

Ron.M
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Jul 9, 2015, 4:57 PM

Post #2 of 30 (3469 views)
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Re: [No-Box] Old Quintrix fix or throw [In reply to]	Can't Post

No-Box;....

I'm guessing that we're at opposite ends of the great pond since I've never heard of that model Panasonic TV...
I should still be able to help you...
I've been fixing analog TVs for 50+ years till the LED/LCD & Plasma revolution hit...

Keep your TV as long as you can..
A thin horizontal line means that you have no vertical sweep...(Top to bottom deflection)..
IF your TV still has the model number label on it after all these years , PLEASE post the number so I have a shot at getting a Service Manual online...(FREE , of course)..
IF needed , can you take & post pix of requested areas of your TV ???

THANKS,,,

Later...Ron.M... Cool

..
Veteran & Retired TV technician

jts1957
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Jul 9, 2015, 4:59 PM

Post #3 of 30 (3467 views)
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Re: [No-Box] Old Quintrix fix or throw [In reply to]	Can't Post

NO enough info.
NO model.
NO location number(s).
NO picture(s).
NO chance.

Quintrix is a name given to a flat and wide television tube made by Panasonic.

-------------------------
Location: Far, Far Away

(This post was edited by jts1957 on Jul 9, 2015, 5:02 PM)

t0nito
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Jul 9, 2015, 6:09 PM

Post #4 of 30 (3460 views)
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Re: [jts1957] Old Quintrix fix or throw [In reply to]	Can't Post

Not only flat and wide, Panasonic named virtualy all their tubes Quintrix back when I was in Canada we had a late 70's/early 80's TV and it also had Quintrix written on it.

It was this same TV, I wish I knew the model number though:

No-Box
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Jul 11, 2015, 9:49 AM

Post #5 of 30 (3434 views)
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Re: [No-Box] Old Quintrix fix or throw [In reply to]	Can't Post

Hi Ron and everyone and thanks for responding.
Yes you guessed right I'm from Blackpool in NWest England.
The Panasonic Quintrix model is TX21-AP1 made by Matsushita Television(Central Europe)in Czechoslovakia. The serial no. is ND-2242571 on a ZBT chassis. Sorry about the information overload but it might help.

jts1957
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Jul 11, 2015, 6:41 PM

Post #6 of 30 (3424 views)
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Re: [No-Box] Old Quintrix fix or throw [In reply to]	Can't Post

Colour Television
TX-21AP1
Z8T Chassis

Check IC451 for bad solder joints.

Do you have a DVM to take ohm/voltage readings?

-------------------------
Location: Far, Far Away

Ron.M
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Jul 11, 2015, 7:05 PM

Post #7 of 30 (3419 views)
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Re: [No-Box] Old Quintrix fix or throw [In reply to]	Can't Post

No-Box;...

Quote

Back off, board out, no apparent dry joints ,cleaned however noticed a jump wire touching a capacitor with some insulation melting?.

Need some idea as to where & what the wire was & the cap it was touching...
Look on the circuit board at the base of the cap for a number begining with "C"...
Please post that number so I can see what may have happened that caused the wire's insulation to melt..

Quote

IF needed , can you take & post pix of requested areas of your TV ???

Yes or No ???

Thanks...
Later..Ron.M... Cool

...
Veteran & Retired TV technician

(This post was edited by Ron.M on Jul 11, 2015, 7:14 PM)

No-Box
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Jul 12, 2015, 9:33 AM

Post #8 of 30 (3390 views)
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Re: [jts1957] Old Quintrix fix or throw [In reply to]	Can't Post

thanks for your suggestion yes there seems to be a continuity problem at IC451 as you suggested and it returned a resistance value of 0.6 ohm.Shall resolder but I have limited Knoledge here.

jts1957
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Jul 12, 2015, 10:11 AM

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Re: [No-Box] Old Quintrix fix or throw [In reply to]	Can't Post

Huh?

A visual inspection of the seven pins of the LA7840 IC and resoldering of same if needed was suggested.
That IC may have already croaked, (sometimes with obvious visual evidence, sometimes not) which is why I asked about your ability to take readings.

Quote

it returned a resistance value of 0.6 ohm.

You give NO frame of reference, so means nothing. Unimpressed

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Location: Far, Far Away

No-Box
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Jul 12, 2015, 10:42 AM

Post #10 of 30 (3386 views)
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Re: [jts1957] Old Quintrix fix or throw [In reply to]	Can't Post

Oh by continuity I meant checking for a circuit between the IC 451 conductor legs and nearest solder joint on the board. Completed this now checking upstairs for a fire extinguisher.
Am I right in thinking LA7840 is the ID of the IC I am soldering. Please assume I have limited ability with measurement. Good for self improvement but potentially dangerous. No visual evidence of IC damage. Any recommendation before reassembly and testing?

jts1957
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Jul 12, 2015, 11:30 AM

Post #11 of 30 (3381 views)
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Re: [No-Box] Old Quintrix fix or throw [In reply to]	Can't Post

LA7840 should be the part number of the IC that should have the seven pins resoldered.

IF that doesn't cure your No Vertical Sweep problem, then sharpen the tips of your meters' probes (so the are unlikely to slip off and short out any adjacent points) because measuring for VCCs will be the next step.

-------------------------
Location: Far, Far Away

No-Box
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Jul 13, 2015, 8:26 AM

Post #12 of 30 (3369 views)
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Re: [jts1957] Old Quintrix fix or throw [In reply to]	Can't Post

thanks jts. sharpening my probes for VCCs measurement. TV now exhibits original fault 'cycling red light'.Can you expand on 'VCCs '

jts1957
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Jul 13, 2015, 9:55 AM

Post #13 of 30 (3367 views)
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Re: [No-Box] Old Quintrix fix or throw [In reply to]	Can't Post

I assume you have reflowed IC451 joints? Since the set is back to the shutdown problem, there is no point in going further into vertical deflection area at this time.

I'd also like to find out answer to wire with melting insulation as was mentioned in your original post. I assumed it was just up against a hot power resistor or something and would just need to be taped with electrical tape and routed away from hot part(s).

Quote

TV switched on ok according to the red light but then shut down repeating this shutdown cycle every 10 seconds following repeated switching.

Quote

TV now exhibits original fault 'cycling red light'.

IF the red light is cycling along with the set turning on and then shutting down, the sets standby circuit may have a problem. D1104 LED is located in the 5 volt standby circuit and should remain lit as long as the set is plugged in.

VCCs are power supply DC voltages that the TV needs to operate properly.

This set uses both HOT & COLD Ground points as references for voltage measurements. For some of the power supply and some horizontal deflection circuitry, HOT ground is reference. We will cover that if/when the time comes. The rest of the set uses COLD ground.
You may connect your meter's Negative test lead to the tuner's metal frame for Cold ground measurements or I will just indicate that you measure 'across' a certain electrolytic capacitor. Electrolytic capacitors are polarity conscious like batteries. They have positive and negative terminals - negative is usually marked on the cap itself and the printed circuit board usually has some mark to identify one lead or the other (for example: a '+' for positive or a partial circle for negative).

Let's start with you measuring (Be sure to inspect solder joints in the area along the way):
1) the (more than 5 but less than 16 volts) raw Standby voltage across C1201?
2) the (5 volt) standby across C1203 (TP8)?
3) the (3.3 volt) standby across C1204 (TP1)?
Are one or more of these voltages fluctuating with the set cycling on/off?

-------------------------
Location: Far, Far Away

No-Box
New User

Jul 13, 2015, 12:54 PM

Post #14 of 30 (3363 views)
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Re: [jts1957] Old Quintrix fix or throw [In reply to]	Can't Post

Hi jts
yes reflowed joints on IC451 seems ok
re: melting insulation issue- that turned out to be glue(for support) and not an issue.
The D1104 LED you mentioned does not remain ' lit ' but cycles on and off like it was being controlled by a self resetting circuit breaker.
Testing results so far are 1/ C1201 5VDC at terminal 1;C1201 1.6mV at 2,and C1201 3.28V at 3.So Yes

2/ C1203 Returns 5.04V
and
3/ C1204 Returns 3.28V so I assume Yes to the range required? Happy with joints too.

jts1957
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Jul 13, 2015, 7:27 PM

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Re: [Ron.M] Old Quintrix fix or throw [In reply to]	Can't Post

In Reply To

Ron.M ...
This was BEFORE he even touched the set with a iron.

-------------------------
Location: Far, Far Away

jts1957
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Jul 13, 2015, 7:47 PM

Post #16 of 30 (3346 views)
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Re: [No-Box] Old Quintrix fix or throw [In reply to]	Can't Post

We'll take this one reading at a time then ... Give only YES or NO answers.
Black meter lead on tuner - Red meter lead anywhere you choose as long as that point is on the FOIL that connects to C1201's positive terminal.

For C1201 (and ONLY C1201)
Is there a DC voltage there? Y/N
Is whatever voltage is there steady? Y/N

-------------------------
Location: Far, Far Away

No-Box
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Jul 14, 2015, 8:55 AM

Post #17 of 30 (3341 views)
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Re: [jts1957] Old Quintrix fix or throw [In reply to]	Can't Post

Hi Jts
In reply to your questions:-
Is there any voltage there? -YES
is whatever voltage steady? -YES

jts1957
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Jul 14, 2015, 9:29 AM

Post #18 of 30 (3335 views)
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Re: [No-Box] Old Quintrix fix or throw [In reply to]	Can't Post

We ARE STILL dealing with:

Quote

TV switched on ok according to the red light but then shut down repeating this shutdown cycle every 10 seconds following repeated switching.

RIGHT?

I'm sort of afraid to ask ... What was that voltage?

NEXT:
Black meter lead on tuner - Red meter lead anywhere you choose as long as that point is on the FOIL that connects to C1203's positive terminal.

For C1203 (and ONLY C1203)
Is there a DC voltage there? Y/N
Is whatever voltage is there steady? Y/N

-------------------------
Location: Far, Far Away

No-Box
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Jul 14, 2015, 11:44 AM

Post #19 of 30 (3333 views)
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Re: [jts1957] Old Quintrix fix or throw [In reply to]	Can't Post

Hi Jts
Yes red light still cycles but this has now changed. Now it flashes every 10 seconds with a clicking noise(circuit breaker?) then after 30 seconds the clicking stops and the LED flashes rapidly.
The voltage at C1201 is 3.28V
Voltage at C1203? NO
Would a pic help the diagnostics?

jts1957
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Jul 14, 2015, 7:04 PM

Post #20 of 30 (3315 views)
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Re: [No-Box] Old Quintrix fix or throw [In reply to]	Can't Post

BOTH questions please.
For C1203 (and ONLY C1203)
Is there a DC voltage there? Y/N
Is whatever voltage is there steady? Y/N

Is IC1202 getting hot?

RL801 (degaussing/main power relay) should be the source of your clicking.

A Short video showing red light cycling with audio for say 45 seconds.

-------------------------
Location: Far, Far Away

(This post was edited by jts1957 on Jul 14, 2015, 7:31 PM)

No-Box
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Jul 15, 2015, 2:54 PM

Post #21 of 30 (3295 views)
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Re: [jts1957] Old Quintrix fix or throw [In reply to]	Can't Post

Hi Jts
Is there a DC Voltage at C1203? NO
steady No Voltage present!

Is IC1202 GETTING HOT? NO

Video to follow but length about 3 mins via imageshack.

jts1957
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Jul 15, 2015, 3:09 PM

Post #22 of 30 (3296 views)
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Re: [No-Box] Old Quintrix fix or throw [In reply to]	Can't Post

Next I need to have you 'float' IC1202 pin #1 (remove solder to isolate the pin from the foil) and remeasure the voltage across C1201.

Was 3.28V. Now=?

-------------------------
Location: Far, Far Away

No-Box
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Jul 17, 2015, 1:52 PM

Post #23 of 30 (3277 views)
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Re: [jts1957] Old Quintrix fix or throw [In reply to]	Can't Post

Hi jts
removed IC1202 Pin 1 from foil to isolate
voltage across C1201 Now= NO

jts1957
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Jul 17, 2015, 2:23 PM

Post #24 of 30 (3276 views)
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Re: [No-Box] Old Quintrix fix or throw [In reply to]	Can't Post

Power switch IS 'on,' right?

AC voltage across D1201 bridge rectifier '~' pins?

-------------------------
Location: Far, Far Away

No-Box
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Jul 17, 2015, 2:41 PM

Post #25 of 30 (3273 views)
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Re: [jts1957] Old Quintrix fix or throw [In reply to]	Can't Post

Hi jts
Yes power is on
AC Voltage across D1201? NO

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