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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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Mitsubishi CS-2655R vertical jitter.
This Mitsubishi CS-2655R tv came into the shop with a blurry picture and not
much else wrong. I touched up the focus control and the picture is crystal clear except for some slight vertical jitter. I replaced all the C400 series electrolytic caps and the vertical output IC, AN5521. The jitter is apparent whether you are watching a tv program or viewing the on screen display menus. A Google search for this fault didn't turn up much. Thanks for your reply. David Farber David Farber's Service Center L.A., CA |
#2
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Mitsubishi CS-2655R vertical jitter.
check for leaky low value caps in the vicinity of the jungle IC; I remember
seeing one doing this, but I don't have the scheme, and can't remember which one it was |
#3
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Mitsubishi CS-2655R vertical jitter.
Change all the caps on the PIP assembly if your set has one. Clean the
debris off the traces and check them for being destroyed by the electrolyte from the caps. Then check and change the rest of them on the main board including those near the jungle ic that even check questionable. . "BWL" wrote in message ... check for leaky low value caps in the vicinity of the jungle IC; I remember seeing one doing this, but I don't have the scheme, and can't remember which one it was |
#5
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Mitsubishi CS-2655R vertical jitter.
Not on this set...no PIP module. Look for a bad coupling cap in the video
path or a bad filter cap on one of the supplies. Leonard "Art" wrote in message ... Change all the caps on the PIP assembly if your set has one. Clean the debris off the traces and check them for being destroyed by the electrolyte from the caps. Then check and change the rest of them on the main board including those near the jungle ic that even check questionable. . "BWL" wrote in message ... check for leaky low value caps in the vicinity of the jungle IC; I remember seeing one doing this, but I don't have the scheme, and can't remember which one it was |
#6
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Mitsubishi CS-2655R vertical jitter.
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#7
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Mitsubishi CS-2655R vertical jitter.
Don't forget to get all the yellow/brown glue off everything.
Good Luck, Bill Jr "Chuck" wrote in message ... On 29 Apr 2004 17:48:41 GMT, (David Farber) wrote: This Mitsubishi CS-2655R tv came into the shop with a blurry picture and not much else wrong. I touched up the focus control and the picture is crystal clear except for some slight vertical jitter. I replaced all the C400 series electrolytic caps and the vertical output IC, AN5521. The jitter is apparent whether you are watching a tv program or viewing the on screen display menus. A Google search for this fault didn't turn up much. Thanks for your reply. David Farber David Farber's Service Center L.A., CA You need to clean the main circuit board, top and bottom, particularly the video section after replacing the faulty capacitors. I have had board leakage cause vertical jitter multiple times. Chuck |
#8
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Mitsubishi CS-2655R vertical jitter.
I'm not making much progress here. Every cap I've checked has acceptable ESR
and that goes for the ones I initially replaced. None of them shows any signs of leakage. I've scraped off some minor glue deposits in a couple of areas. The picture still jitters. One weird phenomenon occurs when I use an external video input. If I send a crosshatch pattern in through the video input, the TV shuts down after a few seconds. The same crosshatch pattern sent through the RF input does not shut the TV down. A color bar pattern sent to the video input does not shut the TV down. There is an X-Ray check toggle switch which I thought had been moved to the "check" position but trying it in the other position makes no difference. (Sometimes these plastic toggle switches have three positions even though there are only two selections.) Thanks for everyone's suggestions so far. I'll keep plugging away at this. Regards, David Farber Subject: Mitsubishi CS-2655R vertical jitter. From: "Bill Jr" Date: 04/30/2004 3:21 PM Pacific Daylight Time Message-id: Don't forget to get all the yellow/brown glue off everything. Good Luck, Bill Jr "Chuck" wrote in message .. . On 29 Apr 2004 17:48:41 GMT, (David Farber) wrote: This Mitsubishi CS-2655R tv came into the shop with a blurry picture and not much else wrong. I touched up the focus control and the picture is crystal clear except for some slight vertical jitter. I replaced all the C400 series electrolytic caps and the vertical output IC, AN5521. The jitter is apparent whether you are watching a tv program or viewing the on screen display menus. A Google search for this fault didn't turn up much. Thanks for your reply. David Farber David Farber's Service Center L.A., CA You need to clean the main circuit board, top and bottom, particularly the video section after replacing the faulty capacitors. I have had board leakage cause vertical jitter multiple times. Chuck David Farber David Farber's Service Center L.A., CA |
#9
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Mitsubishi CS-2655R vertical jitter.
David Farber wrote:
I'm not making much progress here. Every cap I've checked has acceptable ESR and that goes for the ones I initially replaced. You've probably already checked this, but it needs to be said: Even if their ESR is just fine, if one or more of them are no longer acting as capacitors, they could cause symptoms. -- John Miller Email address: domain, n4vu.com; username, jsm The opposite of talking isn't listening. The opposite of talking is waiting. -Fran Lebowitz, "Social Studies" |
#10
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Mitsubishi CS-2655R vertical jitter.
David,
This is not one of the sets that has lots of bad caps. This one is more likely to have some caps that may be low in capacitance due to age than lots of high ESR or physically leaky ones. I'd be checking them with a capacitance meter or looking at the response of the circuit in addition to ESR checks. Look at the output from the regulators with a scope and see if they are noisy. Like Bill said, look for any old glue on the board. Some of these old sets had some glue that dried out and absorbed moisture from the air after years in service and this would cause some strange symptoms that have caused many techs to chase their tails. Leonard "David Farber" wrote in message ... I'm not making much progress here. Every cap I've checked has acceptable ESR and that goes for the ones I initially replaced. None of them shows any signs of leakage. I've scraped off some minor glue deposits in a couple of areas. The picture still jitters. One weird phenomenon occurs when I use an external video input. If I send a crosshatch pattern in through the video input, the TV shuts down after a few seconds. The same crosshatch pattern sent through the RF input does not shut the TV down. A color bar pattern sent to the video input does not shut the TV down. There is an X-Ray check toggle switch which I thought had been moved to the "check" position but trying it in the other position makes no difference. (Sometimes these plastic toggle switches have three positions even though there are only two selections.) Thanks for everyone's suggestions so far. I'll keep plugging away at this. Regards, David Farber Subject: Mitsubishi CS-2655R vertical jitter. From: "Bill Jr" Date: 04/30/2004 3:21 PM Pacific Daylight Time Message-id: Don't forget to get all the yellow/brown glue off everything. Good Luck, Bill Jr "Chuck" wrote in message .. . On 29 Apr 2004 17:48:41 GMT, (David Farber) wrote: This Mitsubishi CS-2655R tv came into the shop with a blurry picture and not much else wrong. I touched up the focus control and the picture is crystal clear except for some slight vertical jitter. I replaced all the C400 series electrolytic caps and the vertical output IC, AN5521. The jitter is apparent whether you are watching a tv program or viewing the on screen display menus. A Google search for this fault didn't turn up much. Thanks for your reply. David Farber David Farber's Service Center L.A., CA You need to clean the main circuit board, top and bottom, particularly the video section after replacing the faulty capacitors. I have had board leakage cause vertical jitter multiple times. Chuck David Farber David Farber's Service Center L.A., CA |
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