PM 6100 and Dos Compatible card overheat

[just.in.time]

Entire system worked fine last weekend. Went to upgrade the main Macintosh RAM Simms from 8mb modules to 32mb modules (to bring total to 72).

Upon restart, PC Card would no longer start up. Just a black screen. I tried reseating it's RAM Simm (16mb), and when I restarted I still had the same issue. However, when it the computer was running the entire DOS card felt hot and the RAM simm memory modules felt extremely hot. The new 32mb Simms on the Macintosh logic board felt like they were only a few degrees above room temperature.

Any ideas what went wrong, and if it is fixable?

Edited to add: Macintosh side still works fine.

 

[just.in.time]

Okay, removing the PC card's dedicated RAM simm got the PC environment to come back on. Not sure what went wrong with it. For now I'll just have to share main memory.

 

[CelGen]

Could be a bad stick.

You have any upgrades or overclocking going on? The ventilation with the PC compatibility card was really poor. and you had to dress your cabling correctly or you had no ventilation passages.

 

[just.in.time]

Hoping it was just a bad stick. No overclocking, standard 66mhz cpu speed, same on the PC/486 card.

Any photos of these cables being dressed properly? It's definitely tight on space so any extra airflow would be good for the system.

 

[Unknown_K]

The 6100 DOS card has the major problem of little to no airflow with no fan on the CPU heatsink and the heatsink being upside down.

 

[Nathan]

Weird. It's not like I have a temp monitor, but I don't seem to recall my 6100/66 having any issues of that sort. Granted that I got fairly frustrated after playing with the DOS card a bit (which was many years ago at this point).

Maybe the ram stick in the DOS board blocks airflow? The clearances are pretty tight and my board doesn't have a stick of ram on the card. I'm fairly sure SCSI cables (where the fold is?) should sit on top of the metal shield/cage around the card. Not sure about if there's a best way to route the sound cables.

Maybe try propping the computer up on wooden blocks or something to get some airflow to the bottom?

P.S.

Very tangential, but...

I recently purchased some 64mb sticks from eBay ($25( to bump my 6100 up to 136 mb. They seem to be working okay, although my hard disk seems to be alive, but not booting and I am using 7.5NAD. A little hard to test them easily.  

http://www.ebay.com/itm/Lifetime-Memory-64MB-72Pin-16x32-EDO-SIMM-60ns-Non-Parity-5V/122379200440

 

[Nathan]

I was just changing the cd-rom drive on my power mac (old one doesn't eject tray so I found another on ebay) and fired it up just for kicks and then I shut it down and unplugged when we started having a thunderstorm. The DOS card or at the least the plate behind it does seem to get quite warm, strange that I never noticed. With everything packed in it really doesn't get much airflow though even if the top of the case is off. Not sure how to improve that. I'll probably leave it out it if I ever get all the necessary bits to really use the machine (I've got a sonnet g3 hanging around somewhere).

 

[slomacuser]

Try to upgrade the DOS card with Kingston turbo chip 133 AMD with a fan

 

[Nathan]

I believe the current chip is soldered down. Thanks for the tip, though. How does the fan help though, since there is still the issue of airflow? I have plans to put in a sonnet g3 upgrade in any case, which will displace the DOS card.

 

[Dandu]

Try to upgrade the DOS card with Kingston turbo chip 133 AMD with a fan

kingston-tc5x86133-turbochip-133mhz-processor-486-missing-fan-1.20__22661.1490240704.jpg

It's not a good idea on the Power Mac 6100 : the x86 is on top of the PowerPC 601. If you install a fan on the x86 CPU, the heat from the x86 goes direct to the PowerPC, and after go the top of the card... on the x86 CPU.

I believe the current chip is soldered down. Thanks for the tip, though. How does the fan help though, since there is still the issue of airflow? I have plans to put in a sonnet g3 upgrade in any case, which will displace the DOS card.

Nope. The x86 on the ODS card is a 486 DX2 (5 V) and you can replace it with a better CPU, like a AMD 5x86 133 or a Cyrix 5x86 GP100 or GP133 (much better). But find a CPU with the correct voltage (5V and not 3,3 V) is complicated. I have tried with an AMD, it works with a "upgrade CPU" (Visiontek), but i can't launch Windows 95 on the card (a weird probem).

 

[Nathan]

Ah, well, same difference anyway. I don't care much one way or the other, but I agree the fan wouldn't do any good in a 6100 anyway.

No idea about voltage or compatibility, but here's someone selling (on ebay) what looks like the other guy's suggestion.  

http://www.ebay.com/itm/Kingston-Turbo-Chip-TC5X86-133-/332289628369  $22.99

^ they say untested, but anything could be dead by now, so it'd be a gamble either way. certainly more affordable than similar chips (compatible or not).

 

[stepleton]

I ran into similar symptoms as those in the original post: blank screen, hot DOS card, and so on. The only difference is that removing the RAM didn't work.

The culprit turned out to be the power cords I was using: one good, standard BS1363 (UK plug) to IEC cord for the monitor, and one NEMA 5 (US plug) to IEC cord for my 6100, plugged into a dodgy UK-US plug adapter.

The terrible adapter wound up not connecting the ground pin to anything, and reversing the connections on the two other pins (that is, connecting live to neutral and vice-versa).

After disconnecting the monitor from the 6100, I was able to measure 240V, 50Hz (!) between the D shells of the monitor's VGA cable and the VGA adapter attached to the DOS card's octopus cable.

Using proper cables for both the computer and the monitor solved the problem. Surprisingly, nothing was permanently fried; I assume that the 6100 was grounding itself through the monitor, but not well enough to run the DOS card normally.

Cheap adapters are dangerous. I should have known better, and now I do.

 

[just.in.time]

I'll have to double check that there aren't and loose electrical sockets. Maybe that is causing a grounding issue for me as well.

 

[AlpineRaven]

Happened to me years ago - I think these dos cards were temperamental and fussy over memory sticks. Happened to LC630 as well.
Cheers

AP