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How can I tell if Dead or alive

M

Marty

Veteran Member
Joined
Jul 26, 2009
Messages
3,141
Location
Boulder , Colorado USA
Hi All;
I have two motherboards one a 286 and one a 386, I can Hook up my Power supply from my 486, But since neither one makes the Screen lite up with either of my VGA Monitor Boards.. What Would I need to Look at to tell If the Processor is Functional or Dead.. I realize that what is in the Bios Eproms might not work with the VGa's I have, so I am looking for another way to find out If the processors is processing.. I have a Scope and some 16 pin Led clips..
THANK YOU Marty
 
Do the boards have ram? Is it enough? What kind? DRAM? SIMM? SIPP?

Is there corrosion near the batteries? This is a real board killer.

Are you sure the VGA cards work? What board(s) do they work with?

Processors are nearly bulletproof so that's the last place I would look.
 
Hi All;
Stone, Thank You for your prompt response.. Yes, both boards have corrosion around their batteries.. The 286 board has four banks of Rams and 2 Eproms of unknown origin.. The labels are Hand written.. On the Keyboard chip it has "286 Bios set up keyboard AMI Ser num. 0007059.. the support chips say VLSI there are 5 of them.. the Osc is 24.00 MHZ and the CPU is Flat-pac, it has the 40 pin 287 in it as well, but I put that in since I had it..
the 386 board has 8 Simm boards, of unknown origin, since I took what I could find from my collection.. 3 OPTI chips, and pin type of 386 CPU, on its Bios it has 386 bios AMI ser num ZA856064 and 9 4M257 ram chips.. Neither Board has a label telling who made it, but they do say made in Taiwan.. Both Batteries are about 1/2 to 3/4 in diameter and about 3/4 inch long and blue.. Also, which one would be the most likely to attack first, or easiest to try and bring up.. I would think the 286 since it doesn't have any simms.. but, you tell me.. one VGA board is a Trident VC512TM and the other is a Cirrus Logic (on the back it has printed PN 4611).. I don't know If either of them work. I Could plug them into my 486, but would they show anything, since they are different from What is already in there ??
THANK YOU Marty
 
The video cards should be fine to swap around. When the system boots up it's just doing generic VESA mode and should display something either way (as long as there is only one video card) *well and as long as there isn't an IRQ conflict.

That'd be one other thing to try as well but it sounds like you don't have much if anything in the system. But start removing parts and get it to bare minimum for testing. Some chips have power on the first pin that you could take a probe or multimeter to and confirm that voltage is getting to a specific chip (i.e. the bios).
 
Forget the eproms and other chips. Little or no relevence there.

The VGA cards can go into any ISA slot on any board to test them.

If the batteries are corroded (onto the boards) your chances are vey slim that these boards will work, IMO. I've got lots of corroded boards and despite what anybody has told me about cleaning them up and getting them to work again I've *never* gotten one to work. That's been my experience and while I've gotten plenty of so-called *dead* stuff to work again corroded boards are just not one of them. YMMV but I'd say it most likely a waste of time.
 
Just curious, but I presume these boards use AT-style power supplies with the two motherboard connectors? Have you made sure that they're plugged in correctly, with the black wires on either piece seated next to each other?
 
Hi All;
On either board there is very little corrosion, and I can de-solder then out.. On the Power issue, I will remember that, I thought the power plug went in only one way.. So I'LL remember next time I try and put power to them..
THANK YOU Marty
 
It's not the corrosion on the battery -- it's the leakage onto the board that hurts.

Commodorejohn was referring to the relative positions of the two motherboard plugs, e.g., left and right. They need to be inserted so the four middle wires (5, 6, 7, and 8 are all black.
 
Hi All;
OK thanks, Stone, I see no leakage.. but, it could have dried up years ago.. Yea, I figured out what was ment on the power plugs.. I need to try out the VGA boards on my 486, before I unplug its power supply and try it on the 286 or the 386 board.. If I see no Flicker or Video, what else should I look for on the VGA boards ??
THANK YOU Marty
 
Hi All;
The 486 style board has the VGA built into the Motherboard, I have no Idea Who built it either.. its an Asian board, and can take different CPU's and either style power supply.. If that helps identify it.. Can I plug the ISA VGA board in or is or do I need to change a jumper (IF there is one) on the VGA Board to make it a second or alternate monitor board ??
THANK YOU Marty
 
You'd still see it. It leaves a blue-green residue that doesn't really fade with time. :)

Hey, if the VGA cards don't work on the 486, a known working machine, they're probably ready to toss. But, IIRC, when you have a bad video card the machine responds with a long string of beeps at boot time.

You can try plugging it in. Some motherboards with onboard video accept a video card just by plugging it in. Try it. Or, you might be able to disable the onboard video.
 
Hey, Marty, what bandwidth does your 'scope have ?
If it's a good enough scope, just check the system clock, and then, when you power it on, one of the low order address or data lines. If you see activity there, it tells you that something is executing somewhere.
patscc
 
Hi All;
I remembered I had my Pentium II machine and it has a removeable VGA card, so I removed it and tried Both VGA Cards, they are Both Good.. Stone, I have NO information on jumpers on any of my boards except for the Pentium II which is a Dell.. Pat, I hopefully could try and see if there is Activity on the ISA Buss, looking on A0 or D0 or someting like that, right ?? Thanks for the Suggestion.. And Yes, I have a good enough scope its a Tektronix TDS 1012..
THANK YOU Marty
 
Hi All;
Pat, you were right, there is Activity on the Eproms and on the Ram chips and on the ISA Buss.. Still nothing on the Screen, though..
THANK YOU Marty
 
Hi All;
I have tried Both video cards in every slot.. No activity, But, on both machines, there is activity on the Eprom lines.. I even checked on the 286, to make sure that the correct Eprom was in the Correct socket, they were.. Even to Even, Odd to Odd.. Does anyone have any AMI Bioses, for a 286 that You would have the .Bin file for that you could send me, I know this is a long shot ?? Unless anyone has other suggestions.. The 386 is soldered in, whereas the 286 has sockets.. Untill I can find one of many Pararell Printer cables, that I need to make my (borrowed) Eprom burner/reader work, and then read the (286) Eproms and see whats in them.. They are 27HC256's..
THANK YOU Marty
 
Long shot! Are you kidding? You'd have a better shot at winning the lottery. :)

BTW do you know what the true definition of a lottery is?

It's a game for people who suck at math!!! :)
 
Hi All;
Stone, That's also why I said I am open to suggestions.. Both Boards have ram and the VGA card plugged into them, no Keyboard, no Floppy drive and no Speaker, on the 386 I know where to plug it in, but not on the 286.. I have activity on the Eproms and on the 386 I can tell for sure, when I push the reset, the activity changes.. not sure where the reset is on the 286.. What am I missing, other than being able to read the eprom ?? I guess, I could rewire, my Eprom/ram serial board, for two 27256's instead of one 2716.. The board has a Ram chip that I can either program from a PC or for very small programs by switches, that would plug into a Eprom socket and using the Ram instead of the Eprom, change the program in the ram when ever I re-download a new program into it.. It also has LED's on all its lines to monitor the activity of the Ram or read a particular address and its data..
THANK YOU Marty
 
Hi All;
On the 286, what If I took Out its Bios Eproms, and just put in the Trident VGA card with its Built in Bios.. Would or Should I get something on the Screen then ???
THANK YOU Marty
 
Okay, Marty, now go to pins 13 & 14 on the VGA cards, and see if you get HSYNC and VSYNC pulses, respectively.
You can use your scope hooked up to where the speaker connects to see if there are any 'beeps', by turning the horizontal timebase way up and counting the pulses.
On the 286, you can try manually jumpering the reset line on the processor. Not knowing what packaging you have, I can't tell you on what pin it is.
patscc
 
I have wasted hours on several boards like this, only to find that the problem is in one of the soldered-in VLSI chips linking CPU, RAM and bus. They can be knocked out by bad peripherals, power surges, or failing cards and there is no recovery.

A POST card can help - they plug into the ISA or PCI bus and return you a beep code and/or a hex display indicating how far the BIOS code can run, if at all. ISA versions turn up online from time to time. They are not 100% reliable though.

Try connecting a floppy drive with a bootable diskette in it, plus a keyboard. If the keyboard flashes, that's a good sign. If the system seems to access the diskette and try to boot from it, then you will know CPU, RAM and ROM are cooperating and the problem is with your ISA bus or system chips.

Also it makes a big difference if you can identity the boards. Looking through the visual motherboard index at stason.org/TULARC has helped me find IDs, connections and config options from nameless boards.

Rick
 
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