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#16
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Yes--you can use that 500UF, since I do not see another cap on the doubler ckt. Though it looks like some of the schematic is MISSING. There SHOULD be another cap in the ckt.
BUT....you REALLY need to make sure that resistor and the thermistor in line with that cap are not open. RE71 and RW71. |
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#17
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Fine for quick test, be sure its a 200V +
The temp rating is important on these, dont remember but I think they were 85 deg C. Our cap expert is probably reading the mail but hasnt piped in yet. Was too common for a lazy tech to use the wrong thing just to get it out & save buying a part. Could tell lots of stories about the butchers in the biz that made us look bad...... 73 Zeno ![]() |
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#18
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Quote:
Quote:
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#19
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Success - I clipped in the 500uf cap and got a raster with a color picture. Picture isn't great, I'll likely ask for more help once I get the correct cap installed.
Would it be a good idea to replace the few white ceramic tubular caps? I've replaced them on Portacolors because I've heard they can go off with a bang. This delay line in this set is also marked Made in Taiwan. |
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#20
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Quote:
__________________
Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
| Audiokarma |
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#21
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Put in a 330 uf at 250 or 200 volts...and you will be fine. it should mount under the chassis.
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#22
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BTW...I am GLAD you are 'rounding third" on this set. i was hoping it was a ps problem....and NOT a bad fly or such. Now--it looks like the fly has potential after all.
I HAD One of the 13 inch sets like this...about 1981 or so....but was too YOUNG at the time...and with NO schematic or ANYONE to help me....I was not able to figure out MY dead set wiht tubes lit problem....and was MADE to dump the set in spring of that year" for my safety"... likely had a bad doubler cap or open thermistor or such...but I will never know... It would be NO problem today....and NO ONE is going to make me dump ANYTHING anymore... |
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#23
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They just bubble-gumed the repairs, to sell them. It's old enough to have some kind of history behind it. |
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#24
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Quote:
I had a strange problem with one of the first Taiwan built 19" Admiral chassis. It had a bad hum bar running through the picture. Naturally, I bridged the PS 'lytics, no improvement! Finally, took the scope to it. Same wave-form on both sides of the choke. I subbed it with one from a scrap RCA chassis. The Taiwan made choke had shorted turns. Left the RCA one in there, as it worked fine. I see the set in the picture, has the low voltage focus CRT, blue gun on the bottom. |
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#25
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So as a general rule did all LV focus tubes have the blue gun at bottom? On those tubes did they have the HV connector at top and the blue gun at bottom, or did they put the HV connector and blue gun on the same side and only upside mount the CRT upside down?
__________________
Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
| Audiokarma |
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#26
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The CRT in my RCA CTC22B had the blue gun on the bottom and the HV connector on top or right side, I don't remember. It was not installed upside down.
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#27
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I had a Toshiba low voltage focus, Blue on top, and HV lead on top also.
12 or 13" set... only a few transistors in it, mostly signal & color, rest tubes... .
__________________
Yes you can call me "Squirrel boy" |
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#28
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I replaced the bad electrolytic as well as the ceramic tubular caps. I now get a color picture with very poor contrast and diagonal horizontal lines. Two of the attachments show the picture with a signal, one should be snow. The brightness and contrast controls have no effect on the picture. Color and tint do. The vertical is also very unstable. I got a copy of the Sams schematic I can reference.
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#29
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Looks like a loss of the VIDEO signal. You have COLOR....but NO video 'behind it" to "control it". Looks a LOT...like an open delay line.
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#30
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Classic case of loss of the luma signal with color information intact. Most frequently caused by
1. Dirty service switch (if set has one). 2. Heater-cathode short in the CRT. It will usually show up by tapping on the CRT neck. (The video/luma signal does not "control" the color signal. They are two separate signal chains.) |
| Audiokarma |
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