# [SOLVED] Need help Sony Trinitron schematic diagram



## mahathev (Dec 21, 2009)

SONY Trinitron Model KV-XF21M65 LED blinks twice and TV has no sound and picture. I know the fault is due to a high currant leakage in one of the power supply circuits, causing the overload protection circuit to shut-down the TV.

The Horizontal o/p transistor C4927 is OK and no other components is faulty in that area. I did a thorough clean and resolder job.

But without a schematic diagram, the fault finding will be an uphill task looking for a pin in a haystack.

This TV belongs to an Old Folks home and I want to bring in some cheer to their faces by repairing it free.

Agoraquest has it but my country Malaysia does not allow purchase through paypal. Can someone out there either help me to solve this problem or obtain a schematic diagram free of charge and send it through email. ( [email protected])

I will report repair follow up for everyone's benefit.

Your help is greatly appreciated. 

Warm regards

MahathevKrishna

Malaysia


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## octaneman (May 13, 2009)

*Re: Need help Sony Trinitron schematic diagram*

Hi Mahathev


You can find your schematic here: Service Manuals - Service Manuals


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## mahathev (Dec 21, 2009)

*Re: Need help Sony Trinitron schematic diagram*

Thankyou for yr quick response and willingness to help me, Octaneman.
But what I am looking for is a free complimentary e-copy of the schematic diagram from TSF members.
My previous unpleasant encounter with pay centres for service manuals resulted in wrong schematics, incomplete and vague diagrams, very late response, lost mail etc. 
The manuals are expensive in my currency and in all cases it ends without any refund.
Can someone who has experience in repairing a similar fault throw some light as to the most likely component malfunction.

Thanks


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## mahathev (Dec 21, 2009)

*Re: Need help Sony Trinitron schematic diagram*

Thanks for the quick response, Octaneman.

But what I am looking for is a free complimentary ecopy of the schematic diagram from TSF members.
My past unpleasant encounter with pay centres for service manuals are receiving wrong schematics, vague and incomplete diagrams, very late response, lost mail etc. In all cases the money is not refunded. 
The payment however is quite high in my currency.

I will be most grateful if someone, who has the experience, can shed some light in pinpointing the probable component malfunction.

Thanks

Note: This morning I isolated the rectifier D627 which is supplying voltage to AF Chip TA8248K and other circuits. Now there is no LED blink and the push buttons are responding. No pix yet as it may also provide power to the the jungle IC etc. I will remove voltage to the AF chip pin to narrow down my troubleshooting. A diagram would really help here. Will keep posted.


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## octaneman (May 13, 2009)

*Re: Need help Sony Trinitron schematic diagram*

I'll help you troubleshoot the board but you will need to post voltages from the flyback transformer. 
Can you post pictures of the PCB's component side and solder side. 

Have you tested the horizontal output transistor ?


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## mahathev (Dec 21, 2009)

*Re: Need help Sony Trinitron schematic diagram*

Thank-you for your kindness to help me out, Octaneman.

I will post you the pix and flyover x-formr voltages later. Yes, I tested the HOT 2SC4927 and it is OK. In the meantime, this is my follow-up so far.

Just by chance I removed one side of D627 - it is a large rectifier with a copper heat sink on it. This diode is supplying a small DC voltage from the main switching xformer to pin 4 of AF IC TA8248K and also to other circuits that I hv not traced yet.

When I switched on the TV there was no LED blink. The channel select and sound volume buttons worked normally (LED flickers when buttons pressed).
Still no pix. The Vcc at HOT collector now showed 125V and since there is no power shutdown all other voltages seem to be normal.

Thinking the AF IC is the culprit, I removed the voltage jumper wire to the IC pin 4 and reconnected D627. The LED again blinked twice showing the fault is on some other circuit along the D627 line. Now I have to isolate the voltage connectors to the other circuits to narrow down the fault.

Do you think there is a problem with the flyover xformer or some other circuits? Thanks


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## octaneman (May 13, 2009)

*Re: Need help Sony Trinitron schematic diagram*



mahathev said:


> Just by chance I removed one side of D627 - it is a large rectifier with a copper heat sink on it. This diode is supplying a small DC voltage from the main switching xformer to pin 4 of AF IC TA8248K and also to other circuits that I hv not traced yet.


 Does the D627 check out ok ? 




mahathev said:


> Do you think there is a problem with the flyover xformer or some other circuits? Thanks


I'm thinking more on the lines of a transistor that may have gone bad on the B+ of the flyback.


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## mahathev (Dec 21, 2009)

*Re: Need help Sony Trinitron schematic diagram*

Hi Octaneman,

The problem is solved, the TV came alive. Yes, you have got a point there - the fault was most likely in the horizontal HT area. This is my full report:-

The 12v rectified o/p from D627 other than feeding the Audio IC also supplies (thru regulator IC) 5v to tuner and 9v to AV processor IC. 

When I removed the jumper of the 9v supply, there was no 2 blinks of the LED indicating a problem in that area. I noticed some dull solder points - cleaned and resoldered. Checked all components OK.

When I reinserted the jumper and switched on, there was heavy arcing on the top of the flyback Xformer. The TV then goes into 2-LED blink in about two seconds. Off and switched on a couple times the arc still there. Thanks to Sony self-diagnosis.

Removing the plastic cover on the Flyback top, I noticed a 1-inch crack just below the HT cable o/p to the CRT, where the arcing was taking place. After refering to the web help, I throughly cleaned the carbonized crack with a wire brush. I did not apply any adhesive as it may be conductive.

The TV was left on for about 8 hours and it is fine so far. Still trying to figure out what was the cause of the initial problem. Got a feeling the arcing may come back after further carbonization. There are no more parts for CRT TVs nowadays.

Still managed to repair the set w/o service manual and guidance from you, Octaneman. Thanks to you and TSF for bringing happiness back to the Old Folks. I am still open to any tips and advice from you, Sir.

Note: I feel older TV's need to be opened up cleaned and decarbonized esp. on the flyback and CRT. Hope this forum thread would be of help to others. 

Warm Regards,

Mahathev


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## mahathev (Dec 21, 2009)

*Re: Need help Sony Trinitron schematic diagram*

Please view these pictures of SONY TRINITRON KV-XF21M65. Thanks,
Mahathev


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## mahathev (Dec 21, 2009)

OK no reply or response from anyone after my previous post. Anyway my Sony Trinitron 21 inch is still going good. Presume this thread closed. 

Still , if anyone can provide me the schematic, just email me. Thanks


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