#31
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Quote:
Did you have any trouble with the chroma section? Seems my 3.58 oscillator isn't running at all since there is zero color. -- Matt Davala |
#32
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If it was not running, you would have the telltale greenish hues when you turn up the color, can post a pic later.
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために |
#33
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-- Matt Davala |
#34
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__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために |
#35
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When the 3.58 reference signal is missing, the chroma signal cannot be demodded in phase but only in amplitude, so it's displayed as just that yukky green color. Has to do with how the signal's phase is baselined.
Last edited by old_coot88; 03-13-2024 at 08:21 PM. |
Audiokarma |
#36
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Yay! Or maybe not yay... I found an open 6.8k 7 watt supplying B+ to the first chroma tube. R172. Above the resistor the chassis looks rather dark. I'll ohm out the transformer that connects to the plate. What the heck caused that to get so darn hot?
EDIT: I do have continuity through the transformer to plate. I do not have a 6.8k in stock unfortunately. I miss being able to buy stuff locally. -- Matt Davala Last edited by Davala; 03-13-2024 at 09:45 PM. Reason: Check resistance |
#37
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I would expect to find more bad resistors!
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために |
#38
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I can't tell for sure from the low res pics in the sams, but it may look like the set has many paper caps, and if it does many may be bad and leaky and need replacing, if C142 is very leaky, it could very well have toasted the resistor.
__________________
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#39
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Quote:
-- Matt Davala |
#40
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If it's ceramic, then the chances are rather small that it's shorted, but not unheard of, the DO short, but it's really rare, as mentioned above, I could not see clearly what kind it really was, you will know rather soon if the new resister starts to heat up way to fast if something took it out like a short or something.
But if there are paper ones in other areas, best not to trust them.
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために |
Audiokarma |
#41
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Example, there looks to be a bumblebee capacitor on the horizontal PCB, cant see what the others are. :O
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために |
#42
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It's all been recapped... At least 45 capacitors. Wowiee. Maybe my Dumont ra-103 had more but I'm not sure!
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#43
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I love finding former wierd repairs... I was investigating why I need more focus range so obviously I check resistors after the 1v2. The bleeder resistors were all high, they should all be 10meg. One was 16 meg, one 14 and the other actually close at 11 meg. Not an issue there as I did buy some 10meg two watts. Being NOS resistors most tested high so I found the ones closest to 11megs each. None were bang on 10, not even close. I'll get those in after I finish this post..
The former technician repair job that surprised me was the bit of wire jumping over the two 1 meg load resistors R155 and R156. I removed the jumper and tested the resistors and they are spot on 1 meg. The other bodge I found was a ceramic cap from the 1v2 cathode to ground. A bit of filtering perhaps? It looked crunchy and they ripped part of the cap where the wire leading into the cap goes. I tossed it. No value printed I could find. Is this another CTC-7 mod they were applying or was this them being lazy because they didn't have 10 meg bleeder resistors in stock? I'll have to wait a couple days to get the chassis back in to evaluate these issues with the focus and to see if my R172 replacement gets my color to return. I'm waiting on some .01 ceramic caps to replace the ones going to V22 as they looked bubbly and hot. I want to reduce my chances of burning out my replacement 6.8k R172 replacement. -- Matt Davala Last edited by Davala; 03-19-2024 at 04:09 PM. Reason: Forgot about a cap I found |
#44
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You will see the resistor I am talking about. Check it is not open and if there are any charred components around it. |
#45
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-- Matt Davala |
Audiokarma |
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