CRT dramatic image shrink (Color Classic)

[mraroid]

Some good news.  I dusted off the working pull of a analog CC board, slid it in, and my CC is working great now.  I have a little bid of adjustment to center the screen making the black bars on the right and left centered.  But the image looks like one would expect from a CRT of this quality.  I don't know long this will last as this analog board has never been re caped..... ;-(
 
I located the vertical IC under the metal box in the enter of the analogy board.  I have enclosed some photographs.
 
To the left of the IC is a 1uF 50V cap - CL11 
To the right of the IC another cap 4.7uF 50V -CF2
And behind the IC is another cap, 2.2uF, 200V -CL 13
 
A resistor is in front of CF2 but I can't read the value.  And I see another component in this metal box right next to this resistor - Also a resistor?  It is a orange color.
 
Just outside the metal box on the analog board, I see CF8 and a diode called DF2.  Next to that diode is a resistor which looks like it ether could be burn.  Also next to CF8 (it could be CFB) I see two dark corroded diodes- DL21 and DL22.
 
I need to find a few more values, and then order some parts. 
 
Should I order some caps that typically go bad?  I found this list of all caps on the analog board - but no sizes...

0.47uF 100v, 85c [x1]1uF 50v, 85c [x11]2.2uF 100v, 85c [x2]2.2uF 200v, 85c [x4]4.7uF 50v, 85c [x1]10uF 100v, 85c [x1]10uF 250v, 85c [x1]47uF 100v, 105c [x1]100uF 6.3v, 85c [x1]100uF 25v, 85c [x7]100uF 100v, 105c [x2]220uF 25v, 85c [x1]220uF 35v, 85c [x1]330uF 400v, 85c [x1]470uF 25v, 85c [x2]470uF 35v, 85c [x1]1000uF 10v, 105c [x1]1000uF 16v, 85c [x1]1000uF 16v, 105c [x1]1000uF 35v, 85c [x1]3300uF 16v, 85c [x1]3300uF 16v, 105c [x2]5600uF 10v, 105c [x2]Total Caps on Board: 47

I don't know for how long, but my CC is working great with that original analog board in it....

mraroid

 

 

[bibilit]

The two corroded diodes are usual for the Classic Color AB, most important here CF8 is bulged, 3300 uf 16v IIRC.

Change as many caps as you can and look under the board for lifted traces on the area of the two diodes, many boards have the same weak point.

 

[mraroid]

Hi
 
I did not notice that bulge in CF8 until you pointed it out to me.  Thank you.   It is rated at 25V - should I change that to 50V? Visual inspection under the diodes look OK, but will put the board under the low powered microscope to make sure. 
 
Looking at CF8 one can see a diode called DF2 next to it.  Above that diode is a resister stuck in the glue.  The resistor is discolored.  But after looking at it under good light using my dissecting microscope, I can't see that it has been burning.  But then I can't explain the discoloring on it.  I would like to replace it, but I can't read the value very well.
 
I looked at my second, working (but not re caped) analog board.  I have posted a photo of that resister here.  I am calling it orange, yellow, brown, + or - 5%.. or 340 ohms.  Is that what it looks like to you?  I can get sort of color blind looking at resistor bands....
 
I thought I would replace the IC, CF8 the resistor and and a handfull of other caps.  Do you see anything else in the area I should swap out just for fun? New diodes will just turn dark again, right?
 
Thank you for your help.
 
mraroid

 

[bibilit]

25 v is ok.

Have a look on the underside of the board, this is where heat start making troubles.

have you seen the similar post ?

https://68kmla.org/forums/index.php?/topic/30512-color-classic-analog-recap/

 

[mraroid]

I can't find legible writing on the vertical IC in my working (but not yet re caped) analog board.  I see some writing on my second (bad) analog board.  So I am going to pull that IC and see if I can read it. No one knows the part number or any other details?  I am so *&^% off that I can't find the name of this vertical IC anyplace.
 
I noticed something odd (or maybe not) about this IC.  It has thermal paste between it and the metal cage it is in.  But between it and the change is some tape on the metal cage.  I have seen thermal tape on the top of CPU heat sink fans.  I usually remove it and then apply a very thin layer of thermal paste.  Is that what I am looking at?  Thermal tape and also paste?  This can't be right can it?
 
The tension wire on this vertical IC looks very poor to me.  Should I loose any sleep about how the heat sink is currently built?  I don't want to spend my time gold plating something that works just fine.  I thought about attaching the new vertical IC directly to the metal cage with just thermal paste and a more robust ​metal spring to put more tension on the IC - pushing it tighter against the metal cage.
 
Am I going over board?  Please tell me if I am.  I don't need the extra work.
 
My analog board is a 820-0360 rev C. 
 
Thanks everyone for the help.
 
mraroid

 

[techknight]

Your putting wayyyy too much thought into this. 

And that "Tape" isnt tape at all, its a silpad. And that is a tension retaning clip. this was common practice in the early days of solid state up until recently, and I still see it from time to time. 

Also the Vertical IC is a TDA something. I cant recall off the top of my head, I will have to pull out my material and figure it out. 

 

[mraroid]

I appreciate the reality check techknight.  I will quit trying to re invent the wheel and do some real work.  Now if I could only find which box I put my solder sucker in, I could pull that IC.  I know it is around here someplace.....
 
mraroid

 

[MJ313]

I work with a small group of plants which have an interesting representation here on the equator...

Aroids!! Well, I just finally got it. lol.  Jack-in-the-pulpit! 

 

[mraroid]

I found my solder sucker and other tools.  I was was just getting ready to pull the vertical output IC so I could figure out the part number.
 
I noticed that on the underside of the analog board it has a small metal can over part of it (where the bottom of the IC is soldered to).  I removed the can (a faraday cage?).  Under it I found my analog board quite dirty.  I guess the guy I paid to re cap and clean my board never did remove it.... I had other issues with him.....
 
Looking under this can I found some soldered areas that were red colored.  They look to be soldered OK, but I can't tell if this is bad or not. Two different places have this red color as well as the four pins of the vertical IC.
 
Looking at photo b1 you can see this red color to the right of CV23.  In photo b2, you can see this red color to the right of RL8.  The bottom of the IC is in photo icb.  You can see the red on 4 pins.
 
Before I do anything (stupid) I want to know what that red color is.  Should I re flow the solder in this area?  Is it left over flux?  Is it a problem?
 
The entire area under the board, under the metal can is dirty. I want to clean it.
 
As soon as I figure this stuff out I will pull the vertical IC, post the part number, and start looking for a replacement.
 
Thanks to everyone for the help.
 
Mr. Aroid
 
You got it MJ313

 

[techknight]

Flux

 

[mraroid]

Leave it. or worry about it?

mraroid

 

[Themk]

Flux is harmless. You may clean it off if it bothers you.

 

[mraroid]

OK  Thanks.  I cleaned the board with a soft brush and no chemicals.  Going to pull the IC today....

mraroid

 

[mraroid]

I now have the part number for the vertical IC on the color classic analog board.  It is called a TDA 8172.  I will enclose a pdf of the data sheet.  Maybe this data sheet can be archived someplace (the 68K wiki?).  A schematic of the CC analog board is un available and this may be good info to keep....
 
mraroid

TDA8172.pdf