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#17
12-14-2022, 09:54 AM
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I did look at chassis on bench but nothing looks bad on ether the top or bottom of the board nore dose any component look bad physically bad. I also resolder ever solder connection on the board as to element any chances for bad soldier joints. Since nothing changed it most be a bad part.
Last edited by liammc00; 01-17-2023 at 04:05 PM. 
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#18
12-15-2022, 02:12 PM
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I did some looking through the same I have and thing I have made some progress.
This info comes right out service manual Shutdown from an overvoltage or over current condition is preformed in the SMPS. When there is an overvoltage condition in the chassis, a High singal is applied to the base Error Latch transistor, Q494, from the overvoltage sensing circuit. When Q494 is turned On, grounding the 7.1Vdc bus, which removes the source voltage for Q470. an overcurrent condition will will create a negative singal at pin8 of T48, which will forward bias, the overcurrent Sensing Diod D465. This negative signal will be applied to emitter of Q494, turning it on, shutting the chassis down. The chassis will try to start and run again as as error causing the condition goes away. This can produce a sound of "ticking" from the chassis. That is exactly what my seat is doing when the seat is first powered on after that seat runs fine with no trouble. Know I got find what could be causing the porblem it's eather overcurrent, overvoltage, or the SMPS has a part that is failing. At this time I can't test for high voltage as a currently don't have a high voltage porb. Here is link to service manual. I will remove it if any has porblem with being posted here https://drive.google.com/file/d/14kw...w?usp=drivesdk Last edited by liammc00; 01-17-2023 at 04:06 PM.
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#19
12-16-2022, 09:10 AM
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OK this is probably one of the nastiest power supplies ever used
in a TV. Only the Sony double SG613 may be worse. You need to find if the SD is from a fail in either the TV or SD. Looking at the pix its near perfect so odds are its a SD problem. I assume the arcing is the SMPS making the TIC TIC. BE AWARE this set has 2 major grounds !! You want to use the HOT ground ( blank triangles ) for voltage measurements. Anyhows you may want to use freeze mist on it & see if you can knock it out. Start at Q492 v& 494. Also Z402. Also any 'litics in the area. Just a few parts at a time. If you hit it put freeze on a Q-tip & touch the suspect. 73 Zeno  LFOD !
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#20
01-17-2023, 12:09 PM
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Would this transistor be a good substitute for a NTE159 as dummy here broke a lead off one of the originals when removing to put it in a component tester. Once I get my freeze spray and put a new transistor in I will trune seat on use freeze spray and see if that helps me find the bad part. I have substitute a transistor before and just wanted known if the one I found would work.
KSA916YTA https://www.mouser.com/datasheet/2/3..._D-1810346.pdf NTE159 https://www.nteinc.com/specs/100to199/pdf/nte159.pdf Last edited by liammc00; 01-17-2023 at 04:20 PM.
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#21
03-04-2023, 09:38 AM
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I put in the new transistor to replace the one I broke the lead off of. Truned on the set and it powerd on. I could hear arching and in the past I just thought it was static electricity from first turning on the TV as arching quites after little bit of time. Now I know that is not the case as I paid closer attention. Noticed with volume truned all the way down to element that static as it will over shadow the pops and snaps coming from the speaker. After about a minute it stopped like it normally dose. Still thinking it might be temperature related I tired using freeze spray and that did nothing set still worked as intended.
So I believe now that the protection circuitry is working as intended. Something is arcing and sometimes it arcs bad enough to trigger the protection circuitry to shutdown the set. After a while the arcing gets less server so the set stays on but still arcs a little bit. After a while it quits arching completely and the set will run fine. You can turn the set off and come back to set with in hour and trun the TV on. It will come on and not arc at all. I do know that arcing is coming from something internally as I have tried looking at the set in pich dark and could not see it arching at all nor do I see any carbon or burn marks were something has been arching. I do know it's coming from the right side of the main board. It could be the flyback but I thought if that was the case the set would have failed in very short order. I have worked on this set off and on for hours apon hours over many months. So before I button up the set and move on to other projects. I will take a better video of the porblem for you tube I doubt it will so anything new. If I come up with anything new I will return to this set. Last edited by liammc00; 03-05-2023 at 10:18 AM.
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#22
03-05-2023, 10:35 AM
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Well all that work I did trying to porve it wasn't the flyback transformer was a wast of time. I took an old paper tow spol and put it up to my ear and listened and I could here little bit fant arcing and sometimes a big snapp coming from the flyback it is arching internally and yet some how it was able to run the set for many hours and it has not yet completely failed. So I'm going to try and find a flyback or another main board and if I can't the tv will run until set dies completely. Then I will part the set out.
Last edited by liammc00; 03-05-2023 at 11:20 AM.
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#23
03-05-2023, 11:48 AM
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I managed to aptan a new old stock flyback I hop it fixes it and when I get I will have to ask on how to install it as it looks like you have to plug in the anode lead into it. Flyback mad by HR Diemen
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#25
03-22-2023, 11:14 AM
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An update. Good news I made some progress. the new flyback fixed the main porblem and the TV has a very sharp and nice picture still however only in black and white
 . I do have the Sam's photo fact which dose have troubleshooting guide but it requires an oscilloscope and for time being that's a porblem. The jungle IC150 (303-1) or (NTE1416) is responsible for color processing also is responsible for the adjustment of brightness and more. The brightness is adjustable along with contrast only porblem is no color.
Last edited by liammc00; 03-22-2023 at 04:20 PM.
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#26
03-22-2023, 01:35 PM
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If you are running RF input be sure the band switches are set
to OTA TV & normal AFT. If you are running video in check the voltages on the IC & compare them to Sams. Look for something way off. One of the pins will go to the color level control. That varies with the control setting....... Be sure the IC is running cool. Should only get warm while running not HOT. Zeno
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#27
03-22-2023, 02:43 PM
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The TV is RF only and I had it set to normal ( not Cable). The AFT has no user control adjustment. However it does have a control on the board labeled AFT
Last edited by liammc00; 03-29-2023 at 02:29 PM.
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#28
03-23-2023, 10:00 AM
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Still trying to figure out the color porblem. In the Sam's it has this information about troubleshooting the video buffer/Comb filter which this set doesn't have so I skipped that part. Also I did test Q153 and it was good. The AFT is done between the first video and the microprocessor on the MCU tuning system and there is no adjustments for AFT. Before I continue I have been using a Sega Genesis with the OEM RF adapter. The game system with the adapter works on all of my other TVs with RF adapter perfectly fine. There is now way to turne of the AFT but I think there might be adjustment I will need to look in the Sam's. However I don't think tunner and the video If are bad as I get nice picture with no snow or interference and clear sound just no color at all purlye monochrome as if the color killer is always on. There is no adjustment for the color killer so can't tell if that's giving a porblem. I'm afraid when it comes to color TV circuitry I'm pretty losed. I have included parts of the schematic that center around the IF and the NEC 303-1 IC. I like figuring things out on my own but I have spent hours looking at schematic and testing some parts I thought might be bad. Maybe someone will find something I overlooked. If not I will just try swapping out the NEC 303-1 chip with an NTE1416 if nothing changes then back to the drawing board. I know to most me talking about this
Thats all folks Last edited by liammc00; 03-23-2023 at 11:09 AM.
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#29
03-25-2023, 10:33 AM
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I got the part and installed and no change so the original chip is good and the controls test good I will attempt to use my oscilloscope to see if there is any color signal making it to the ic.
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#30
03-25-2023, 01:13 PM
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Did you check those IC DC voltages ?
You may want to see if you can find a data sheet. Any MFG markings on it ? The OEM is probably 612303-1 (?) You also have the NTG / ECG numbers. There was a backwards ECG disc it could list every sub. Maybe its out there still. With that you can find the REAL OEM for the chip & data sheet. BTW I probably have a C-5 training manual. It would cost apx a 12 pack of beer via PayPal PM if interested but try those voltages first. 73 Zeno LFOD !
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