#241
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I have been working on solving a ghosting issue in the picture. Checking resistors on the IF board only revealed 2 out of tolerance resistors. Two 68 ohms coming off the cathode of the 6az8 IF tubes then to ground. Next thing I suspected was the 1n60, but it tests fine on the diode test. Should I still replace it? I need to check around the video amp tubes now.
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Admiral C322C2 Regent (Restoring) RCA CTC-7 Pensbury (Restored) RCA CTC-5 Westcott (Restored) CRA CTC--4 Director 21 (Restoring) |
#242
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Found an open inductor on the video out tube. L72 on sams 180 Microhenry 9.5ohm. Is this an appropriate replacement? http://www.mouser.com/ProductDetail/...o%2f1lu29zY%3d
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Admiral C322C2 Regent (Restoring) RCA CTC-7 Pensbury (Restored) RCA CTC-5 Westcott (Restored) CRA CTC--4 Director 21 (Restoring) |
#243
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#244
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Did you check L71 and R68 also?
Edit: also R69, L70, and the contrast control - these are all things that load the input or output of the delay line and need to match the impedance properly to prevent echos. Last edited by old_tv_nut; 08-14-2017 at 07:38 PM. |
#245
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Everything tests fine except for maybe the contrast control. It reads 21ohms at full clockwise and about 1k at full counter-clockwise. I dont think that is right.
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Admiral C322C2 Regent (Restoring) RCA CTC-7 Pensbury (Restored) RCA CTC-5 Westcott (Restored) CRA CTC--4 Director 21 (Restoring) |
Audiokarma |
#246
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You didn't say which terminals of the contrast you are connected to, but if you don't disconnect one end, you will read a bunch of other things in parallel, particularly the delay line and its 1.2K input resistor. So, the 1K reading is probably normal or close to it for an in-circuit reading. I would just wait to see what the replacement coil does for your ghosting, rather than disconnecting things unnecessarily.
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#247
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Just ordered new coils and resistors. Found another coil that was bad L94 that read about 1 meg when it should be 27 ohm.
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Admiral C322C2 Regent (Restoring) RCA CTC-7 Pensbury (Restored) RCA CTC-5 Westcott (Restored) CRA CTC--4 Director 21 (Restoring) |
#248
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Wow that set is going to be better then originally new once it's done, lots of troubleshooting. Looking good keep at it .
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#249
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By ghosting, do you mean ringing (parasitic amplitude ripples tagging after fine detail in the pic)? If so, try subbing the last IF tube if you haven't already. It can cause ringing even if it tests good on a tester.
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#250
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Yes. I believe I did try subbing that tube with no difference.
__________________
Admiral C322C2 Regent (Restoring) RCA CTC-7 Pensbury (Restored) RCA CTC-5 Westcott (Restored) CRA CTC--4 Director 21 (Restoring) |
Audiokarma |
#251
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This can also be caused be improper termination of the delay line, check all parts for value on either end of it.
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Evolution... |
#252
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So adding the 180uh choke in place of the open one (L72) makes the ghosting WORSE! Ugh! Something else has to be causing this then. Left photo is with no coil, right is with coil attached in circuit.
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Admiral C322C2 Regent (Restoring) RCA CTC-7 Pensbury (Restored) RCA CTC-5 Westcott (Restored) CRA CTC--4 Director 21 (Restoring) |
#253
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Suggestions:
1) make sure the value isn't off by a decimal place or something 2) check for open resistor in parallel with either L72 and/or L71 If it's not those, check all other parallel L-R combos in the video amp chain. |
#254
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Value is fine. Checked all coils and resistors that may be in parallel with them and they all check fine except for a coil on the B-Y amp that reads 1.2 meg, but I dont think that one really matters for my current problem. I hope its not the delay line causing this!
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Admiral C322C2 Regent (Restoring) RCA CTC-7 Pensbury (Restored) RCA CTC-5 Westcott (Restored) CRA CTC--4 Director 21 (Restoring) Last edited by SwizzyMan; 08-19-2017 at 08:05 PM. |
#255
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Quote:
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Audiokarma |
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