P575 Analog Board Maintenance

[Matt32]

Hello to all here and kudos on the great knowledge base that this site is. I'm here as someone who has proudly kept the same Performa 575 chugging along for over 15 years. Recently I started having a problem with a total loss of red hue at the monitor level. This was never a problem up until I recently removed the CRT/analog board case to peer inside, and since the red occasionally flickers back on (restoring normal display) I'm thinking that a connector is just loose somewhere. That and also I'm not really into the idea of having to replace the CRT, but anyway...

Right now the whole computer is 100% disassembled, so that all the decade-old dust can be cleared out (and because it was a fun experiment). I'm hoping that once all the connections have been reseated the missing red will be a thing of the past, but there's one other potential cause I'd like to look into as long as the Mac is in pieces, and that's the possibility of a failure on the analog board. Particularly the power source, as I think it's been responsible for some weird sounds on boot, and it's proven a little tougher to diagnose (at least, for me) than, say, scanning the logic board for busted capacitors.

First off, here's an overview shot of the whole analog board:

http://img203.imageshack.us/i/img0027hk.jpg/

Then there's this, on the power source:

http://img413.imageshack.us/i/img0029tk.jpg/

I'm not sure what this big piece is. I'm guessing it's more complicated than a capacitor. It jumped out at me, however, due to the trace amounts of syrupy stuff on the paper(?) covering. I'm not sure if this is a leak, or if it's supposed to be this way.

Finally, a couple capacitors look like these two:

http://img140.imageshack.us/i/img0032vt.jpg/

Sorta off to their sides rather than standing up. Again, I'm not sure whether this isn't just normal. These two are right above the power source, and there are two more like them near the flyback transformer, as well as a couple others scattered throughout. Also, it might appear that the left one is leaking, but seen from a better angle it appears (at least, to my very untrained eye) to just be red marker.

I'm basically posting these to make sure there aren't any glaring faults. I don't have any experience soldering, so replacing capacitors feels a little far out there, but I figure for the time being it would at least be good to know if something is egregiously wrong. On the other hand, if nothing jumps out from this quick peripheral glance, then I'll probably have this machine sewn back up in a couple days and take care of whatever leftover troubleshooting down the road.

For the record, this was my first computer wayyy back when, and having done all I can to keep it "modernized" (installed an Ethernet card, and there will be VRAM upgrades and a new hard drive in the distant future) I intend to keep it going indefinitely. Though it seems the fan favorite is the Mac Classic (got one of those too and will maybe restore it one day) this Performa has really been a blast to work on. If nothing else, learned more about SCSI than I ever would have!

Thanks in advance to anyone who takes the time to assist.

 

[beachycove]

Well, as nobody has responded, I will have a go. Maybe this will encourage others more knowledgeable than me to chime in.

In view of the intermittent effects, and given the fact that movement of the housing seemed to affect the way the video works, I would suggest renewing the solder joints on the analog board in obvious areas of stress as a first strategy. The capacitors pictured are no doubt old, but these images look perfectly normal to me. Solder joints on flybacks and similar components seem to be more common points of failure.

 

[Osgeld]

the second image is a transformer (or maybe a big inductor I am not up on my mac schematics), and they are usually slathered with that "gorilla snot"

caps standing out of place is not unusual, look at the size of the caps and then look at the holes, it needs a little leg space (those leads pull right out if you start forcing them) but it is a good focus point, the small black one looks a little puffy and the blue one could be red marker but ...

as far as actually doing the work there are people around here who will do it for a fair price, but its really not that difficult with though hole stuff, get a fine point medium wattage iron and some solder and some solder wick

then go to the thrift store and buy some old chunky electronics and take them apart for revenge practice }

 

[Matt32]

Thanks for the response, guys. I had a feeling that the transformer(?) was nothing to worry about. I think beachycove's hypothesis about bad solder joints, particularly bythe flyback and/or other video components, might be on the spot; that's the one area I didn't check thoroughly but - from the brief look I did take - believe could use some work. I do think that the capacitors are fine, for now - not that this is the most logical way to diagnose, but they definitely haven't started to fail on the logic board yet - and they seem to look fine on the analog board when viewed naturally; the light and angling of the camera may make objects appear worse than they actually are.

Meanwhile I'm about to finish treating the case parts with Retrobright (which so far has worked like a charm), so when that's done the Performa is getting reassembled, red video display or not. I'll try to snag a few photos of the bottom of the analog board before then, though.

Because of the sentimental value of this machine I actually would be interested in paying someone to spruce up the analog board (and hell, might as well re-cap the logic board, if they're all gonna fail eventually). As it stands, though, I'm leaving in about a week for ten months of volunteering and travel. Probably that wouldn't even leave enough time for one-way shipping. Maybe when I get back - I'm sure this place ain't going anywhere - it better not be! Soldering is definitely something I need to learn too, so maybe on some old cheap parts when I get back as Osgeld suggested.

Again, the input and suggestions are much appreciated.

 

[Matt32]

Just to follow up, when I reassembled the 575 today the missing red hue problem apparently solved itself. I've booted it about a dozen times and the monitor output has been perfect, no missing colors and crisp as can be. I guess it probably was just a loose connection somewhere (I also dusted the bottom of the analog board, not sure if that would relieve problems with bad solder joints in the event there were any). But I'm grateful for the help here. Maybe before I ship out I'll throw up some pics, or at the very least post here from the computer (once the keyboard stops acting up perhaps).

 

[Osgeld]

if there is a bad solder joint you could have bumped it enough to make a connection, just keep that in mind if you go moving it and it starts back up again