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Crumbtrail TV Forums: TV Equipment: TV Repair Forum:
No Picture on Sony Trinitron KV-32TW75

 
 


SuperB
New User

Apr 15, 2005, 3:47 PM

Post #1 of 7 (15773 views)
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No Picture on Sony Trinitron KV-32TW75 Can't Post
First off, thank you to everyone for contributing to this forum. It gives me a glimmer of hope. Cool

My 1991 Sony Trinitron KV-32TW75 has no picture. The sound and tuner are still fine (at least I can still listen to TV). The picture is completely blank. When I power it on, it still makes the same buzz that it has always made on startup.

I have no experience in servicing or reparing TVs, but it would sure be nice to take a stab at it. This TV is massive but my friends and I managed to move it up to my 3rd floor apartment. Maybe its time to let it go, but I'm not ready to invest in a new nice one and even if I had another large TV, those 32 stairs pose a major roadblock for me. I'll probably be using a ~20 year old 19" TV set on top of the Trinitron until I move out or fix it. Frown

Thanks for any help you can provide. Smile

-Brendan



mel
Veteran

Apr 15, 2005, 10:38 PM

Post #2 of 7 (15754 views)
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Re: [SuperB] No Picture on Sony Trinitron KV-32TW75 [In reply to] Can't Post
First, check to see if the filaments are lit in the picture tube. If not, the filaments are open or you have lost filament voltage. More than likely, the set is in IK shutdown due to an aging picture tube. Try turning up the screen voltage. If not, post back with your findings and we can go from there. You might also want to check out www.FreeFlatScreens.com/?r=10948674 for an opportunity to earn a free replacement for this set with a little effort on your part. A 27" set may not be as big as your current set but it will be a heck of a lot easier getting up the stairs.


SuperB
New User

Apr 16, 2005, 1:14 AM

Post #3 of 7 (15752 views)
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Re: [mel] No Picture on Sony Trinitron KV-32TW75 [In reply to] Can't Post
Hi Mel,

Thank you very much for the advice! I read another one of your posts and found how to turn up the screen voltage. I'll paste that here in case anyone else reads this and wonders how to do it:

"the screen adjust pot on Sonys is usually either the bottom knob on the back of the flyback transfomer (the black transfomer with the red wire going to the back of the CRT) or a potentiometer on the CRT board which is labeled as screen. Just turn the knob clockwise until you see retrace lines on the screen and then back it off until they disappear."

I'll give it a try over the weekend and post back on Monday. Thanks again!

-Brendan


SuperB
New User

Apr 18, 2005, 7:21 PM

Post #4 of 7 (15739 views)
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Re: [mel] No Picture on Sony Trinitron KV-32TW75 [In reply to] Can't Post
I don't think the filaments are lit. At least, there was no light that I could see inside the back of the set when it was turned on. I tried turning the screw marked 'screen' clockwise. However, it was already turned all the way up, as it would only turn counter-clockwise. Am I out of luck, or is there anything else I can try? Thank you for your help,

Brendan


mel
Veteran

Apr 18, 2005, 9:46 PM

Post #5 of 7 (15736 views)
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Re: [SuperB] No Picture on Sony Trinitron KV-32TW75 [In reply to] Can't Post
If you have an ohmeter, check for resistance between pins 7 and 8 on the CRT with the CRT board disconnected from the CRT. If you have no reading, the filament is open and the CRT is shot. If there is a reading, check the resistance between pins 9 and 10 on the CRT board still unplugged. If you have no reading, check the resistance of the filament current limiting resistor (probably R704 which is either on the CRT board or the main board near the flyback). If that is good, check the solder joints on the flyback. If you ultimately find that the filaments are lit, and since the screen is already turned up all the way, there is one final trick that you can try. Try jumpering a piece of fine wire (I use a single strand from a braided power cord) across R704. This will have the affect of boosting the filament voltage and perhaps giving you a little more useful life from the weak CRT.


SuperB
New User

Apr 18, 2005, 11:14 PM

Post #6 of 7 (15734 views)
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Re: [mel] No Picture on Sony Trinitron KV-32TW75 [In reply to] Can't Post
Thanks, Mel! Cool Do you know of a way to get a service manual or schematic diagram for the KV-32TW75? I don't know which one is the CRT board. Unsure This may take me a few days as I review my notes and try to understand which subsystem is which. I also don't really know how to disconnect any of this stuff safely. I'm assuming that unpugging the TV won't be enough due to long decay times of some of the huge caps. Pirate Is this true for any these steps? Should I look for the large caps and then discharge them? Thanks again for your wisdom.

Brendan


mel
Veteran

Apr 19, 2005, 1:06 AM

Post #7 of 7 (15730 views)
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Re: [SuperB] No Picture on Sony Trinitron KV-32TW75 [In reply to] Can't Post
You can go to www.samswebsite.com and download the E:fact for this model for $20 and it will give you the schematic as well as the component layout and most also include troubleshooting tips. The CRT board is the one that plugs onto the picture tube (CRT). The only residual voltage that I worry about is that stored in the anode of the CRT and you should not be worling in that area anyway. In more than 40 years in this business, I've been bit more than once by that 30KV and I ain't dade yet but it will give you a thrill if you get into it.

 
 
 


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