I see it's requested that repairs be documented as well as troubleshooting, so this is one I recently repaired without asking questions here:
Note: I added DP26648 to the title because the User's Manual does and leads me to the thought that maybe both sets use the same boards. If this is not the case, sorry to have misdirected any readers.
The trouble manifested as a red LED for about three seconds, then nothing, for three attempts. Then, nothing further until the set was unplugged, at which time I could get three more tries.
Voltage checks showed 5VDC, but no 12VDC or 24VDC at the appropriate connectors (CN902 & CN903). There was 163.5VDC across the main capacitor (C800). With each power on attempt (for three attempts), PSON showed 5.01VDC for about three seconds.
There are two MOSFETs (Q601 & Q602) connected somewhat in parallel with C800. Q601 measured 161.0VDC at the drain, 0.0VDC at the Gate and 10.7VDC at the Source during the three second window. Q602 read 1.2VDC at the Gate, 10.7VDC at the Drain and 0.0VDC at the Source during the three second window. I had trouble measuring the MOSFETs in circuit with the diode setting on my meter, so I removed them for testing. They were both FQP16N25C types, but I got different readings comparing them out of circuit, so I ordered and installed two new ones. BTW, readings of the new ones were different from both of the originals, but, of course, matched each other fairly closely.
With the new ones installed, the set appears to be functioning normally.
Note: I added DP26648 to the title because the User's Manual does and leads me to the thought that maybe both sets use the same boards. If this is not the case, sorry to have misdirected any readers.
The trouble manifested as a red LED for about three seconds, then nothing, for three attempts. Then, nothing further until the set was unplugged, at which time I could get three more tries.
Voltage checks showed 5VDC, but no 12VDC or 24VDC at the appropriate connectors (CN902 & CN903). There was 163.5VDC across the main capacitor (C800). With each power on attempt (for three attempts), PSON showed 5.01VDC for about three seconds.
There are two MOSFETs (Q601 & Q602) connected somewhat in parallel with C800. Q601 measured 161.0VDC at the drain, 0.0VDC at the Gate and 10.7VDC at the Source during the three second window. Q602 read 1.2VDC at the Gate, 10.7VDC at the Drain and 0.0VDC at the Source during the three second window. I had trouble measuring the MOSFETs in circuit with the diode setting on my meter, so I removed them for testing. They were both FQP16N25C types, but I got different readings comparing them out of circuit, so I ordered and installed two new ones. BTW, readings of the new ones were different from both of the originals, but, of course, matched each other fairly closely.
With the new ones installed, the set appears to be functioning normally.
Attached Files
I've been working on a 1984 Sanyo 27" color TV which had a smattering of bad caps in the video switching circuit. I found this oddball little 1uF 25V cap which looks to me like an early polymer, but I can't find concrete info proving it. I know Sanyo was a big player in early polymer cap development and this is the time period where they were just getting on the market, so I'm wondering if anyone has crusty old datasheets that could help identify it and determine if my suspicions are right? It has the same epoxy end seal and font/formatting as some old stock Os-Cons I've got laying...
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