#16
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Hmm. That rules out the divider at least. If the voltages are then wrong, it appears that something is conducting heavily when the set is running if the voltages are incorrect. Can you provide the as measured voltages against the voltages the schematic advises? This may provide the clue. |
#17
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#18
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The next point should read +135 volts to chassis.It may be accessed at C148B positive connection. The voltage at the C147C positive should read -60 volts to chassis and the can of C147 should read -120volts to chassis. |
#19
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1st term (under trans) 202v 2nd term 340v 3rd term 0 4th term 15 5th term 31 measured in dc scale, black to chassis |
#20
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The second terminal which is supposed to be +135 volt measures 340 volts: is that correct? I assume you have changed the electrolytics. If the 135 volt line is so high, it may be that the wiring may be incorrect. Please check the wiring closely around these points. In addition, the -15 volts and -31 volts show the correct division ratio of about 2 to 1. (It should be -60v and -120v). This would imply that the other end of the divider is open or high resistance. Otherwise something is pulling down the -120v. Please check the wiring. |
Audiokarma |
#21
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The set is recapped, ecaps and paper caps. There was no negative readings. Checked e cap wiring many times over already.
I think this chassis has more than one problem and I won't find them all. I have another chassis on the bench that is practicly the same thing, using as reference. That one did display a test pattern,weak and washed out, but after replacing 3 paper caps I lost it. Got a vertical problem with it now. Ecaps were replaced. Last edited by stusnyder; 05-13-2011 at 05:53 AM. |
#22
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#23
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Figures I picked a real complicated one to start with. The latter one is really the one I'd like to get going, because it has a nice wooden case.
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#24
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I would be glad to help. I have owned and used an 8T243 for 42 years and have fixed a number or these chassis since. It is my favorite design.
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#25
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Are you familar with the 6-t-71? I got a odd problem with one.
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Audiokarma |
#26
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What is the problem? |
#27
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On the bench hooked up to a 5" test crt I get a decent picture. Back in the cabinet hooked up to the 16" crt I get no vertical lock.....
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#28
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I assume that you have replaced the capacitors in the sync separator section? Do you have a scope to check sync amplitude? Do you notice with the test CRT if the contrast control setting is higher? Does adjusting the control to increase the contrast help with vertical sync? Otherwise it is checking voltages, waveforms and substituting tubes in the sync section? |
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