PCJr HELP!

[strollin]

I know Mike mentioned checking for bent pins but I just wanted to say to check very carefully for bent pins on the video connector on the back of the system. I've fixed a couple of PCjrs with bent pins that showed the exact symptom you're describing. It's also possible for a pin to be broken off so make sure all pins on the video connector are present.

If possible, can you post some pics showing the connectors on the back of the system unit?

 

[cebuscapucinis]

Will post pics of it here in a second, strollin.

I discovered something rather odd -- when I disconnect the keyboard cord as if to use the IR for the keyboard, it causes the system to spin up the fan. I don't know about the disk drive but it looks as if a pin on the keyboard connector is shorting out the power supply card somehow.

Will take a look at those display pins, because now I'm thinking that might have a lot to do with it. Pictures pending in about 4 minutes!

Okay, here are the pictures of the system back:

Here is the outside of the connector. It appears there is some corrosion on it.

Here are the internals for the monitor connector.

First connectors. Here is a bent pin! This is why there's problems when the keyboard is connected. A bent pin on the keyboard connector!

More connectors on the back, quite a few with bent pins:

Two images of the display adaptor pins, ironically it looks like these are the only ones that are doing okay:

The other end of the pins:

Whoa. These are really bad. I didn't think they were from the naked eye but are they bad enough to actually make the system do what it's doing?

 

[mbbrutman]

Apologies if I'm continuing to post in a thread that should for all intents be considered kaput, but I'm wondering now if it's the mobo at all or if it's just the power supply card.

I moved the Jr from the living room to the office and plugged it directly into the wall rather than through a power strip and now the fan won't spin and the drive won't spin when the controller card is taken out.

However, when I take the power supply card out of the mobo and just set it down on the desk and plug it in, then turn it on, the fan spins perfectly fine and the disk drive actually does more than just spins up -- it's like it tries to boot from disk.

Would this mean that the power supply is the problem rather than the mobo or that the mobo is the problem right at the power supply card connector? Perhaps trying to clean the points would make a better connection?

You can bench test the power card a little bit, but you really need a multimeter to do that. The power card takes AC from the line cord and converts it to DC voltages for use on the motherboard, fan and diskette drive.

I wouldn't test the power card on your peripherals any more though. The fan probably isn't going to get damaged by anything, but if the power card is borked then it might be putting out the wrong voltages. Having it move the floppy around without the benefit of knowing the voltages are correct (or without the floppy controller involved) might not be a great idea.

Also, if the power supply card is not plugged into the motherboard, that drive isn't trying to boot from disk. It's more along the lines of a chicken with no head ..

It can't hurt to clean and check the contacts and look for broken pins or shorts. But be careful with the experiments ..


Mike

 

[mbbrutman]

Will post pics of it here in a second, strollin.

I discovered something rather odd -- when I disconnect the keyboard cord as if to use the IR for the keyboard, it causes the system to spin up the fan. I don't know about the disk drive but it looks as if a pin on the keyboard connector is shorting out the power supply card somehow.

Will take a look at those display pins, because now I'm thinking that might have a lot to do with it. Pictures pending in about 4 minutes!

This tells me you have a short somewhere .. I think I even mentioned that you don't need the keyboard plugged in to get the splash screen.

Plug absolutely nothing in, and check those pins again .. two bent pins touching is exactly the kind of thing I've been warning about.


Mike

 

[cebuscapucinis]

This tells me you have a short somewhere .. I think I even mentioned that you don't need the keyboard plugged in to get the splash screen.

Plug absolutely nothing in, and check those pins again .. two bent pins touching is exactly the kind of thing I've been warning about.


Mike

When I was testing earlier I didn't have the keyboard plugged in. I just happened to plug it in after I moved the Jr to the new desk.

 

[NeXT]

Those supposedly bent/missing pins look deliberate. let em pull out my technical reference manual and confirm.
EDIT: Actually, those missing pins are actually keying so you don't incorrectly plug the wrong piece of hardware in. You should not need to worry.

 

[cebuscapucinis]

But would the pins being bent as they are actually cause a short in the system? The bent pin on the keyboard was obviously causing issues, but I don't see how they're bent enough to prevent a POST-beep.

 

[NeXT]

So long as the "bent" pins are not touching anything else they should not be a problem.

 

[CIPSTER]

You schould check all tantalum capacitors on motherboard and expansion cards with multimeter. One or few may cause short circuit and this can be reason of your problem. It's pretty common issue and I had this in two of my XTs and in some clones.

CIPSTER