Video card faulty?

[modem7]

I have some ideas about what might be causing the latest symptom (floppy LED). One possible cause happens on 5150 motherboards.

First, I need you to verify that your 5150 still has a 5150 motherboard fitted.
Take a look at the photo at http://members.dodo.com.au/~slappanel555/misc/P1200004.JPG
That is a 5150 motherboard. Is your motherboard the same?

If you think it is, what is the seven-digit number on chip U33.
In the photo, I have placed a yellow oval around U33.
Is the number 5700051 or 5700671 or 1501476?

 

[Jtterbug]

It will not power on. It Says "Not system disk or disk error. Reinsert system disk and press any key"
I am using DOS 5.0. It is on the same disk as Alley Cat.

 

[Jtterbug]

PS None of the above, same MB but differant chip.

 

[modem7]

PS None of the above, same MB but differant chip.

What is the writing on the top of chip U33?

 

[Jtterbug]

5000023
AM9264DPC
34180 8350ZAP

With that logo like the one next to it on the photo to the left.

 

[modem7]

5000023 is the IBM part number of one of the four IBM BASIC ROMs, the one found in socket U32.
We are instead after the part number of the chip in socket U33.
I'm expecting it to be 1501476.

 

[Jtterbug]

You are right!!! It is 1501476. Give this man a Prize!
So What now?

 

[modem7]

You definately have a 5150 motherboard (with 5150 ROMs). That's good, because I know its behaviour well.

And so with the HDD controller removed, and no floppy disk in the floppy drive, a 5150 should boot into BASIC. Does your 5150 do that?
If not, confirm for us that the floppy LED lights at boot time (about 50 seconds after power-on), then remains lit until the 5150 is powered off.

Remember, no floppy disk is to be used.

 

[Jtterbug]

No. Only a white screen. Do the DIP switches need to be changed?

 

[modem7]

No. Only a white screen. Do the DIP switches need to be changed?

A white screen on a 5153 monitor usually means that the 5153 is not receiving signal. It sounds like you've bumped something. Is the 5153 still plugged into the EGA card?

 

[Jtterbug]

Yes, it is.

 

[modem7]

Can you remember at what time it changed from being 'white text on black background' to an 'all white' display ?
Was it when you pulled out the HDD controller.

 

[Jtterbug]

Yes, When the HDD card was pulled.

 

[modem7]

Yes, When the HDD card was pulled.

It is most likely that in pulling out the HDD card, that you disturbed the EGA card. With power off, pull out the EGA card then re-insert it, then reattach the 5153. Let us know how that goes.

 

[Jtterbug]

Do the DIP switches need to be changed?

 

[modem7]

Do the DIP switches need to be changed?

1. I take it from your responce that a reseat/reattach did not get rid of the white screen.
2. No. Removal of the HDD controller does not require DIP switches to be changed.

 

[Jtterbug]

No. Still a white screen :[

 

[modem7]

The 'white' screen is a huge negative step.
Two questions:

1. Do you hear/see signs that the computer is going through its POST? A good indication of that would be the single beep heard about 50 seconds after power on.

2. When you pulled out the HDD controller, did you simply lay it on top of the computer? If so, that could be shorting out the power supply (with the 5153 still getting AC power).

 

[Jtterbug]

I don't hear a POST. The card is not on the computer.

 

[modem7]

I don't hear a POST.

Your motherboard or PSU has stopped working.

A common failing device on the motherboard and expansion cards is failure of tantalum capacitors - see http://members.dodo.com.au/~slappanel555/failure.htm
Sometimes they fail siliently, and without indication. You may have had one fail somewhere on power-on after the HDD controller was removed, and its failure mode was short-circuit. But it's speculation at this time.

Time to go to minimum configuration. If only the power supply, motherboard (no cards inserted) and motherboard speaker are connected together, do you hear a beep from the speaker abot 50 seconds after the power supply is turned on?