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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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Rewinding pc coil for 9-1270 Zenith boards ?? anyone know inductance? 9-1270-02 9-1270-3 mod# SR3587DT
Ok here's an update,
I did rewind the coil (ref# LX3201) and while I did, I measured the length of the wire and compared it to the length of the wire on the older Zenith coil p/n# 20-4284-01, and determined that if you add 7-9 turns to it, it should work as a replacement for the coil on the 9-1270 board. Sorry I can't say the part no# for the coil on the 9-1270 board as the top of the part with the p/n# is missing. Anyway, interestingly enough, the rewound origional coil measured .39mh which was darn close to the 20-4284-01 coil which has approximately 8 less turns wich weighed in at ..38mh. Not surprising since I wound it rather imperfectly by hand. Ok, so then I added 8 turns to the 20-4284-01 and measured it. It measured .48 mh which I'm guessing is probably what a new coil for the 9-1270 board should read. Ok, the results? I put the 20-4284 coil with the additional 8 windings @ .48mh, in the set. The set now works better, but still not quite right. The coil and the pincushion xstr both run hot, but possibly acceptably hot. I just don't know. Uncomfortable to the touch, but not boiling water. Antone know? Is it the norm for these parts to run fairly hot in these sets? Before I reworked the coil, the set would work, but shut down during bright scenes. Seems to be overcurrent protect. Now with the coil reworked, it still shuts down on some really bright scenes, but it has a very much obvious improvement in tolerance. In fact it might run for 15 minutes or more. I guess I'm going to have to get the schematic on this one. Oh, one thing I forgot to mention was, I replaced the Flyback origionally. I ordered the part from http://www.slelectronics.net/fl.zenith.htm# I ordered the origional part p/n# 95-4134-28 and they sent me a 95-4134-11 which they claim is a valid sub. The part had both numbers on it and appears to be aftermarket. I ordered a different flyback from them for a Zenith PTV awhile back, and it worked just fine, but they didn't give me a sub in that case. Anyone have any opinions about whether this supposedly valid sub could be the problem with this set? Also.FWIW, I checked out the brightness limiter circuit, best I could without a schema that is, and it seems to be ok. Don't mean to go on so, basically I'm just speaking to the archives here, which is why, as you may have noticed, I put so many model and board numbers in the title. Ok thanks. =^^=DM "Dave Moore" wrote in message ... Hello folks. I came across this article by the great Dave D., about rewinding these coils, ref.# LX3201 http://groups.google.com/groups?hl=e...6C.A54D88A9%40 locl.net Being faced with this problem, I have decided to rewind rather than wait. However, I have a few coils from older Zenith boards that I could just add a few turns to. Only, to do this, I need to know the inductance value to shoot for. Anyone know what the value of this coil is supposed to be? Thanks =^^= DM |
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Rewinding pc coil for 9-1270 Zenith boards ?? anyone know inductance? 9-1270-02 9-1270-3 mod# SR3587
Subject: Rewinding pc coil for 9-1270 Zenith boards ?? anyone know
inductance? 9-1270-02 9-1270-3 mod# SR3587 From: "Dave Moore" Now with the coil reworked, it still shuts down on some really bright scenes, but it has a very much obvious improvement in tolerance. In fact it might run for 15 minutes or more. one. Oh, one thing I forgot to mention was, I replaced the Flyback origionally. I ordered the part from http://www.slelectronics.net/fl.zenith.htm# Dave, the problem is your replacement generic flyback. Every one I tried did this, sometimes shutting down as soon as the CRT lit. Basically, one of the secondary sources off the flyback is too high, I don't remember which one. You need to fudge this voltage with a dropping resistor, or fudge the shutdown circuit. The board is actually marked and cut for a shutdown pot that was never used. It's near the front of the board (away from the flyback). You'll need a schematic to locate this, but it's an easy mod that will allow the replacement flys to work properly. BTW, those coils run really hot even when everything is normal. John Del Wolcott, CT "Nothing is so opportune for tyrants as a people tired of its liberty." Alan Keyes (remove S for email reply) |
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Rewinding pc coil for 9-1270 Zenith boards ?? anyone know inductance? 9-1270-02 9-1270-3 mod# SR3587
"John Del" wrote in message ... Subject: Rewinding pc coil for 9-1270 Zenith boards ?? anyone know inductance? 9-1270-02 9-1270-3 mod# SR3587 From: "Dave Moore" Now with the coil reworked, it still shuts down on some really bright scenes, but it has a very much obvious improvement in tolerance. In fact it might run for 15 minutes or more. one. Oh, one thing I forgot to mention was, I replaced the Flyback origionally. I ordered the part from http://www.slelectronics.net/fl.zenith.htm# Dave, the problem is your replacement generic flyback. Every one I tried did this, sometimes shutting down as soon as the CRT lit. Basically, one of the secondary sources off the flyback is too high, I don't remember which one. You need to fudge this voltage with a dropping resistor, or fudge the shutdown circuit. The board is actually marked and cut for a shutdown pot that was never used. It's near the front of the board (away from the flyback). You'll need a schematic to locate this, but it's an easy mod that will allow the replacement flys to work properly. BTW, those coils run really hot even when everything is normal. John Del Wolcott, CT Ah, thanks John, I really appreciate the info you gave me, really took a load off my mind,,, this bugger's really been eatin da' icing off me cake. I kinda thought that something like that might be the case, and is the reason I've been trying to get a schematic. Ron gave me 3 alternative Models that use this board and Zenith doesn't have a single one of the schematics for any of them! You just may have saved me $20 as I was about to pay that much more for a service manual from http://www.servicemanuals.net/service.asp Now I can probably knock this one out now and just order the $13 manual from Zenith for myself and suffer the backorder wait. I'm willing to wait a month, but my friend with the tv probably wouldn't. Come to think of it, I guess you saved him $20 since I woulda just passed the charges on to him anyway. I'm pretty sure I can find the unused pot and rig something. Thanks again =^^=DM "Nothing is so opportune for tyrants as a people tired of its liberty." Alan Keyes (remove S for email reply) |
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Rewinding pc coil for 9-1270 Zenith boards ?? anyone know inductance? 9-1270-02 9-1270-3 mod# SR3587
Subject: Rewinding pc coil for 9-1270 Zenith boards ?? anyone know
inductance? 9-1270-02 9-1270-3 mod# SR3587 From: "Dave Moore" Now I can probably knock this one out now and just order the $13 manual from Zenith for myself and suffer the backorder wait. I'm willing to wait a month, but my friend with the tv probably wouldn't. Come to think of it, I guess you saved him $20 since I woulda just passed the charges on to him anyway. I'm pretty sure I can find the unused pot and rig something. Thanks again =^^=DM I remember a diode that you can cut out that will prevent the shutdown entirely. I'll see if I wrote it down at work. If I can give you the board location, you can fudge some resistor values (you don't need to add the pot). John Del Wolcott, CT "Nothing is so opportune for tyrants as a people tired of its liberty." Alan Keyes (remove S for email reply) |
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