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P560/CC Screen Issue

raoulduke

Well-known member
I just recapped a Performa 560 motherboard and put it in my Color Classic chassis.  I had noticed coloration issues with the screen (it kept changing tone and I had to keep adjusting it).  And I'd noticed some "column" issues - where it looked/looks like it's bending inward slightly toward the middle left.  Now I see flickering horizontal lines with slightly different tones of gray (against the background).  I can post a pic if this was a garbage description.  Could it be a 'cold solder joint?'  (I looked through colourclassicfaq but that might be the closest I found).

I will note also this is a totally inconsistent symptom.  I basically would like to confirm more than anything else whether any symptoms resembling what I've described can be attributable to caps, because that'd be by far the easiest problem to fix.  As I install a new OS, it randomly changed from normal to more violet tone when I inserted the disk then went back to normal...

[As an addendum, I would be very grateful to uniserver if you posted a 550/560 board on Maccaps; that page of boards is a fantastic service, though our wiki should steal it with attribution.  I can take a picture if you'd like.  I pulled all the caps off and washed the board only to realize there was no template pic lol.  But it was fairly easy to figure out.  The 6V 100uF (I think) caps go right above the PDS slot; the small one goes in the middle and there are 5 16V 47uF (I think).]

 
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Bunsen

Admin-Witchfinder-General
The fact that it's intermittent points towards a cold solder joint - possibly more than one, as you have a few different symptoms going on there.  Could even be dodgy contact between the motherboard edge connector and socket pins.

Is the AB recapped?

 
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CC_333

Well-known member
Yeah, it could be an intermittent connection on the edge connector. Try spraying some DeoxIt (or other contact cleaner of your choice) in both sides of the connector (logic board side and wiring harness side) and see what happens.

If the issue persists, removing the analog board and check for cold/cracked solder joints would be a good idea. Perhaps spray cleaner in the adjustment pots as well, as since they're horizontal (I think?), they're probably more prone to getting dirty).

c

 

raoulduke

Well-known member
Oh I didn't even think of that.  That's a fair point.  I washed it a few weeks ago, but I did notice it was unreasonably dusty/dirty.

I figured it'd be in the monitor.  I just wanted to make sure I didn't screw up the caps since I wasn't mindlessly using a diagram.  Will report back.  Thank you.  [Also I tried to snap a pic; it wasn't meaningfully possible.]

 
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raoulduke

Well-known member
Contact cleaning helped but not totally.  So I rechecked the board and C12 wasn't secure on one of its leads, so I resoldered that.  Then the SCSI totally died, so I looked again and C5 was missing [no explanation for that; it was there before I redid C12].  Mostly fine now; if symptoms recur I'll give a more complete picture.  Thanks.

 

raoulduke

Well-known member
No, it still flickers seemingly at random.  This time on power on it started out a bit magenta and then reverted to normal.  But as noted it'll basically sort of flicker at random - not often; not enough to be really bothersome.  But enough to be a little annoying.

 

Bolle

Well-known member
Mine started like that as well... now it is magenta all the time as the green signal gets lost somewhere on its way.

Taking everything apart and putting it back together did help a for some time but it went bad again.

I did not yet take the time to redo the procedure and look for bad connections everywhere. Solder joints on the AB and the neck board on the CRT look good so it most probably is a bad contact on one of the edge connectors.

 

raoulduke

Well-known member
Hmm. I was thinking solder joints. Since it seems nobody here knows, I'll do a little research when I have time.

 

raoulduke

Well-known member
The relevant part of the manual says this:

"1 Verify that adjacent computer equipment is properly grounded.

Move electrical devices away from monitor.

Temporarily shut off all fluorescent lights in area.

2 Check that all ground cables are secure.

3 Disconnect internal hard drive and floppy drive.

4 Replace analog board."

I think my Step 1 will be disconnecting the HD and floppy.

[Relevant to the jitters; if the color problem becomes permanent, all the manual says (implies) is an A/B board issue.]

 
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Bolle

Well-known member
So this thread made me taking a look at my CC again.

I noticed quite a few spots on the A/B that seemed to have suffered from some resistors which get pretty hot. Especially the big ones right next to the mains filter cap.

I also noticed that the traces on those resistors came off from the board but are still intact.

Except for that and a lot of dust everything looked like it was in a good shape.

I did give all connectors a good cleaning and resoldered the wires that go to the CRT neck board on the A/B. I did also renew all soldered connections on the neck board itself.

This seems to have fixed it for now.

Btw caps on the A/B all looked good and did not have any leaked goo below them.

 

raoulduke

Well-known member
Resistors are a problem on SE/30 A/Bs, potentially for screen jitters, but we don't have a color comparison. I also haven't tried replacing the resistors on my /30 AB yet.

I haven't had time to open my CC again, but when you get a chance, any thoughts on which resistors looked problematic?

I guess if I do AB work I'll try the solder joints first.

 
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Bolle

Well-known member
Those two (or three in my case - instead of one large one that I usually see in that place my A/B has two smaller ones in parallel) are the worst looking. The resistors itself did not change color yet but the board below them did.

There are a few other spots with signs of excessive heat staining the board itself around the usual suspects like DL21/22 and their surrounding resistors.

IMG_8670.JPG

 
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