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CRT dramatic image shrink (Color Classic)

mraroid

mraroid

6502
Hi...
 
I was using my Color Classic II yesterday.  Everything was fine.  I turned it on today to find the image you see here.  While you can't see it in my photo, you can see the Mac image between the lines - the hard drive is trying to load...
 
I un plugged it, remove the board, re seated it, let it set for an hour and fired it up again.  Same issue. 
 
I will take the case off and start looking around.  Before I jump into this un informed, I was wondering if anyone has any suggestions on where to look.
 
My CRT looked about as perfect as it could be before this.  I did not have any issues with it.
 
Suggestions welcome
 
thanks
 
mraroid
badCRT.jpg

 
CAPS CAPS CAPPPPSSSS!!!

Probably. It COULD also be an adjustment pot issue, but I dont think letting it sit overnight would turn them that much out of adjustment....

Also dont leave that screen on for long because it will get burned!

 
Last edited by a moderator:
Could be capacitors. If they haven't been replaced, I believe the Color Classic is one of the models that has problems with its analog board.

I think its the vertical output IC. Usually, some other component on the analog board fails, and takes out the IC with it. You will need to replace both the IC, and the component that failed.

This could be totally of the mark, but this is my $0.02

 
Vertical output IC failure here. For sure. 

You will need to have an oscilloscope to troubleshoot other circuits. 

Remove the vertical output IC, and scope the signal coming into it, it should be a clean sync pulse coming from the sync processor. Once you know that is good, then you can replace the IC, but before replacing, changing the associated capacitors and checking the resistors to make sure none have burned open from the failure. 

the Ramp generator is internal to the IC so your fine there, Also you will need to check the diode off of the flyback transformer which feeds that circuit to make sure it didnt short, or burn open the fusible resistor there. 

You need to perform these checks first prior to installing a new IC, because you can cause immediate destruction of the new IC is if there is another fault. Been there done that zillions of times. 

 
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This color classic II has had the board washed and totally re capped maybe less then 2 years ago.  Same for the board with the CRT on it.

Thanks for the input folks.  I will look over what literature I have and try to find the vertical output IC. This IC is not on the logiuc board, right?

I am about to place an order with mouser.  I guess I had better hold off until I find out what the problem is....

Gez, I have literature on the Color Classic, but now need to look for Color Classic II literature....  :(

Thanks

mraroid
 
Thank you TechKnight....

I am about to place an order with Mouser.  Do you happen to know, or know where I can find the part number for this IC? 

No 'scope here, but I will do my best.

mraroid

 
Looking at my CC collection of parts I have here in Ecuador....

I have a working pull (non rebuilt - original caps) analog board from a Color Classic.  I also have a working pull (non rebuilt - original caps) analog board from a LC 575.  I read someplace that one could swap out the analog board of a Color Classic with the one from a LC 575.  Only later did I find out I had to cut up my Color Classic and the analog board to make it fit.  So I backed off. 

I have a nice VOM and know how to use it, but no 'scope.  I am not sure if I should try to fix my clean re capped analog board, or just swap it out for the working one which has not been rebuilt.....

I can ship my analog board out of Ecuador to be fixed, but the import duty that Ecuador would charge me to get it back would be massive, not to mention postage.  The normal post office is broken here, so anything that you need has to arrive by FedEx or another high priced shipping vendor.  I just paid $200 to ship a very light weight and very small package (about the weight and size of a box of cigarettes) from the USA to Ecuador.  It's value was $60 and the import duty was $52.50. 

Mouser has a south american distribution chain so I can buy parts from them and not pay very much for postage.  And if Ecuador wants to charge me $15.00 for $20.00 worth of caps and such I am OK with that. Maybe I should just replace anything down wind of that IC??

I will look for and read the schematic and think about this....

Thanks everyone.

mraroid

 
mraroid,

When you say the post office is broken there, are you trying to say it's corrupt? Is it unreliable? Do they steal the mailpieces?

Also, sorry to hear about the terrible import duties.

 
Yes, all of that.  Almost all the stuff sent via the public post office is stolen or is un delivered.  My sisters sent me birthday cards (with nothing in it) and they never arrived.  Letters don't make it.  Boxes with anything of any value never make it.  Internally, the power company and the water company use a private service to deliver bills to homes. Banks in Ecuador never mail anything to you here.   Many homes do not have an address.  I live in a medium sized city and I do have an address so I am lucky. Private companies and private currier services are used if you need to mail a document or ship a package.

But it is not all bad here.  The people are very friendly, warm and polite.  Fresh locally grown food is available at good prices.  The botanical diversity is stunning (I work in a botanical garden).  The government of Ecuador has set aside vast amounts of land as parks and wildlife reserves - much more percentage wise then the USA.  The countryside is lovely.  I do miss Amazon and Ebay.  I guess life is a trade off no mater where you live...  

mraroid

 
So... why are you living there? 

Anyways. Just take the vertical IC out of the 575 analog board and stick it in there. Same shit. 

 
Last edited by a moderator:
techknight said:
So... why are you living there? 

Anyways. Just take the vertical IC out of the 575 analog board and stick it in there. Same shit. 
Click to expand...
I work with a small group of plants which have an interesting representation here on the equator.  I was offered a dream job in a new botanical garden so I took it.  I love my work.
I looked over my working pull of a Color Classic analog board.  I can not tell which IC is the vertical IC. I have not been able to find a analog board schematic as of yet.  Still looking. I am pointing to my best guess in this photo.  Can someone tell me if I have located the correct IC or not?
 
Thanks
mraorid

 
Last edited by a moderator:
I found a photograph of a CC analog board on another forum  It has the vertical IC listed in this photograph.

Yea!

Q1rpu0h.jpg

 
I am swapping out analog boards for a test.  I have the black and red speaker wire plug that is suppose to plug into the CC analog board.  I see two connectors - one called BD11 and one called BD13.  MY speaker wire will reach both. 

Can some one tell me which connector to use?  Thanks

mraoid.

 
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