VOGONS


First post, by creepingnet

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Ok, so last night I was upgrading my FIC 486-PVT motherboard to a AMD 486 DX4-100, and in the process, broke a pin off this weirdo thing......

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I got it working for awhile by just sticking a piece of wire in the hole. At some point the machine was shifted, locked up, and now I can't get it to POST. I looked around online and found on this forum someone posted something similar regarding a 486-PIO3 board by the same manufacturer that these "RN16,RN17,RN18,RN19" thingies are actually a group of jumpers built into one unit.

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I'm starting to wonder if I should just work around it by using some staples or something put in to do the same job and if there are any issues caused by this, or if there is a source for these things. So far the closest thing I can find are SIP Resistor networks, which I don't think I want nor would they work.

I spent about 2 hours last night soldering pins on, and trying different things to no avail and the damn thing would not POST despite continuity between the pin and whatever else, it seems I may have just been latching onto the plastic packaging. This is with both the old Intel 486 DX2 and AMD DX4, not sure what's going on - I set the jumpers for both properly....so this is very odd. The board had no issues till I swapped out the CPU, and it ran GREAT for a few hours under the DX4 but then I went to change Audio inputs to reboot and it just would not POST again after that for whatever reason.

I'll say this, when I had that chip working, that thing was stupid-fast as soon as I enabled WriteBack Cache and all of the other cache settings.

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Reply 1 of 9, by Tetrium

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When you shifted the machine and the machine subsequently locked up, did the resistor also fell out?

I don't really know what could be the cause here. Superficially it seems several things are going wrong.

Sorry I can't be of any more help atm.

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Reply 2 of 9, by creepingnet

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Tetrium wrote:

When you shifted the machine and the machine subsequently locked up, did the resistor also fell out?

I don't really know what could be the cause here. Superficially it seems several things are going wrong.

Sorry I can't be of any more help atm.

Nope, when the machine locked up, I'm assuming it's because the friction-fit makeshift pin I put on RN18 moved slightly, losing contact with the 0 ohm resistor SIP that is used to configure the CPU. I tried making it work some with the DX2-66.

I think tonight I'm going to try the staple-trick on it, maybe even make my own Duc-Tape cased SIP using that because finding a component like this has proven futile. I'm starting to think this was a custom-order Single Inline Package 0 Ohm resistor used by FIC to keep people from blowing up their board making errant jumper settings. I was mulling it over this morning some between buildings and I can't think the minimal resistance has any effect, after all, to my continuity tester, it's pretty much as good as a closed circuit between each pair of pins. A more elegant solution would be maybe to use a single row 8pin header and use jumpers to configure it, but I'd rather not stoop that far, I have the board out and laying around, so I might stay up tonight a little and build out my own little "staple jumper pack" and put it on there and see if that works with the DX2-66, and then after that, put the DX4 in, change the jumpers, and see if that works.

Talking to the guys on VCF, they mentioned soldering a pin on it after filing it off, that's tempting but last night I did have some problems, plus one of the other pins broke off, I'd rather just build something more robust and use that as soldering pins onto this thing using wire and solder has proven hard to impossible.

I'm just hoping there's not some other problem like the DX4 was faulty and fried, or that the system board had some other problem that came to light when the CPU was upgraded to a faster one with WriteBack Cache. Would be a shame if that CPU was a dud now b/c that thing performed shockingly well.

Maybe it's for the best though, if I can't get it going, maybe I'll just order another chip and wait, by then the Cache RAM and 128MB upgrade I got it will be in. Then I can just do it all one-fell-swoop.

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Reply 3 of 9, by meljor

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Maybe a bit ghetto but i would try and put a small screw in each hole so it would be a bit secure and then connect them with wrapping around some wire. Finishing the top of each 2 pins with wire with some electrical tape so all stays in place. Replacing the whole thing (unless there are some resistors in there?).

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Reply 4 of 9, by Ampera

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I suggest you replace this. If you can prove it's a series of jumpers (And NOT a resistor array) then you can either solder wires across the holes, or get another series of jumpers. An idea is to see if you can get some headers and solder those in so you can just use standard jumpers.

Reply 5 of 9, by creepingnet

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Ampera wrote:

I suggest you replace this. If you can prove it's a series of jumpers (And NOT a resistor array) then you can either solder wires across the holes, or get another series of jumpers. An idea is to see if you can get some headers and solder those in so you can just use standard jumpers.

I'll share how I came to this conclusion......let me reference this thread involving the FIC 486-PIO3 - FIC 486-PIO3 mobo - why's it so slow?

When I was first looking this part up a guy on VCF told me it was a "resistor network" - he was pretty much right on on that in a way - except each resistor in this non-bussed resistor network (or so it appears) measures 0 ohms resistance (0.0003Ω on a 200Ω Scale on my Multimeter to be exact). When I was testing the module, the VCF user said to hold the test probe to pin 1 and test all the other pins, thing is, only the pin next to it would give me the "beep" for continuity.

then I found that thread and THIS picture was posted by the user
jumper.jpg

Now here's my part - using the same sort of red-lines to show the continuity path between the pins, which is similar to a non-bussed 0 Ohm resistor
file.php?id=31581

I did some looking up on 0Ω Resistors and learned the following about them, they are used in manufacturing in place of a jumper or a plain wire when automated machinery is used. I could see FIC having some variant of Resistor network of 0Ω on multi-layer motherboards and components to allow a smaller footprint by tying different circuits through one, but I think in this case here, FIC was just trying to make sure people were not going to blow up their CPU/Motherbards with errant settings (kind of odd when you consider the variable voltage configurations).

I also did a resistance and continuity test on the part and the red lines over the legs display the path through it. I tried many other combinations, seems it's just 4 male jumpers in a plastic 8P4R Package - 8P4R standing for 8-pin 4 resistor package. Resistance reads on the 200Ω Scale at 0.0003Ω.

I tried the staple "trick" last night on it with both the DX2 and DX4 chips and neither worked, so I think something more is amiss now with this. Unless of course this component really was a resistor pack and something went awfully wrong turning it into a jumper - but I'm doubtful because all electronics experts (3 total) I've talked to say it's a 0Ω resistor network acting as a jumper, which to all of them seems strange.

It could be I had a bad CPU chip possibly, or maybe errant BIOS settings - I did change a BUNCH of BIOS settings on the board including changing the Memory speed and other speed settings to Turbo.

I won't rule it out being the DX4 chip possibly too, I bought what was a "gold scrapper special" - it had some bent pins, but it did work after straightening them and with some finagling on the first try. Maybe the faster RAM I have coming in could cure it too. Will have to check that out tonight when/if I have time to mess with it tonight. could also be Cache related because I enabled some Cache settings and may have errantly enabled the L2 cache which has been running for 3 years totally mis-configured with the wrong chips (a 16Kx8 Tag and 4 8Kx8 chips - I've got a 32Kx8 and 4 128Kx8 chips on the way to max it out at 512KB). I also glued the HSF onto it using superglue as a short term test, which seemed to be working quite well as the chip was running nice and fast right up till the machine locked up which was almost 4-5 hours After the superglue dried, and while I did see some seepage, it seems to have stayed away from the pins

when I run the DX2 chip, the chip gets warm like it should, I don't seem to feel the same effect from the DX4-100, but then the DX4 is 3 volts, and in a heatsink so I probably can't get as close to the source of heat. I did also have some problems with VLB cards popping out of their slots too at one point, so I'm not ruling that out, hopefully it's not a system bus failure issue - that could be a bit above my head to troubleshoot.

I did order my first Motherboard Testing card so maybe I can decode where it's getting, I know it's finding the keyboard and getting a power-good signal that much is for sure - hit the power switch, Keyboard lights blink, I'm just not getting any POST beeps or a screen. Also tried pulling the CMOS battery, but I might pull it for a longer time next time. Also tried a different ISA video card (OTI 077 VGA), no response from that card either, so it may not be BUS related. Reseated all RAM and tried starting without, still no beeps - but then I could have a flaw in my methods as I am using the audio passthrough on my SoundBlaster AWE64 Value to get any POST beeps from the system, and that's not the most reliable method.

Maybe if a POST redo does not work, maybe the darned thing just realized the errant Cache and will start working when I put the PROPER chips in - ie that 32Kx8 along with the 4 128Kx8 chips. That might be over a month though.

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Reply 6 of 9, by creepingnet

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Update - just to not leave you guys hanging - I figured out what was going on last night, got some time to figure it out.....

Turns out the DX4-100 burned itself out due to improper thermal work (my bad) - so I have another one on order. I put the DX2-66 back in and got it working. Seems my idea of using a certain adhesive for a heatsink compound did not work so well, it liquefied, and got into the socket, some cleaning of the 486 Socket with the .024w Ernie Ball guitar string dabbed in Acetone fixed it (this is how those hobbies intersect), plus some cleanup of the DX2-66 which had some kind of brown gunk on the bottom that I cleaned with an old toothbrush, water, and a dab of dish soap, and it booted right up. Also, here's some information for VOGONS if anyone else uses a FIC 486-PVT motherboard.....

RN16-RN19 are just there to identify the CPU's brand it seems. I left it in the AMD position, and my Intel 486 DX2-66 fired right up as a "80486 DX2-66 MHZ" chip instead of "Genuine Intel DX2 @66 MHz" or something like that. I'm leaving it there for now and not reassembling the machine until I have all of the parts in, which should take me over a month as I'm still waiting for the ISSI Cache RAM from China to get here (it's still in "posting" status since the 10th of February). The new 486 DX4 (exact same chip, AMD 486DX4 100SV8B - 8K L1 w/ WriteBack Cache) + the Heatsink I bought (a proper one) which I plan to retrofit my 3 pin motherboard powered fan to (this board is insanely modern for something so old in a lot of ways). The other CPU is getting cleaned up, might use it as a inlay on a Retro PC themed guitar or something.

I also found out something funny, I'd been running that Intel DX2-66 at a reduced voltage all this time - 3.3 Volts! I set it up at 5V, seems to POST a little faster now, maybe certain programs were going a bit slower than I remembered because the CPU was not getting enough juice.....I dunno. When the DX4 comes in, I'm moving the jumper back to the 3.0V position, and then the new heatsink is getting polished on the contact surface and a nice spread of some fresh thermal compound (the good stuff, I may even use a dab of my arctic silver on it) - and then that Fan is getting screwed on it. Not making the same mistake twice. But then that other chip may have had issues as it was listed as "gold Scrap" whereas the one I have coming in was listed as "tested, working" and has a return policy (and free shipping).

I also got my 128MB of RAM in, I'll be installing that tonight. What a relief that I won't have to buy a new Motherboard!

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~The Creeping Network~
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Reply 7 of 9, by Tetrium

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Personally I don't like AS, I've always preferred the white goo like MX-2. It's WAY easier to clean and for testing and doesn't seem to be any worse at all!

And for 486 stuff, TIM doesn't really seem to be critical in almost any way. It becomes more important when going to stuff that uses 100MHz FSB and anything Athlon or Coppermine isreally better off using TIM. Actually, running any earlier Athlon without any TIM is an easy way to fry them within the blink of an eye 😵

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Reply 8 of 9, by Matth79

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Tetrium wrote:

Personally I don't like AS, I've always preferred the white goo like MX-2. It's WAY easier to clean and for testing and doesn't seem to be any worse at all!

And for 486 stuff, TIM doesn't really seem to be critical in almost any way. It becomes more important when going to stuff that uses 100MHz FSB and anything Athlon or Coppermine isreally better off using TIM. Actually, running any earlier Athlon without any TIM is an easy way to fry them within the blink of an eye 😵

Yep, TIM is critical for a CPU with no heatspreader, as any part of the chip not making thermal contact will burn - though that said, I did run an Athlon Thunderbird using my old power transistor "silicon grease" - only temporarily.

Reply 9 of 9, by creepingnet

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Matth79 wrote:
Tetrium wrote:

Personally I don't like AS, I've always preferred the white goo like MX-2. It's WAY easier to clean and for testing and doesn't seem to be any worse at all!

And for 486 stuff, TIM doesn't really seem to be critical in almost any way. It becomes more important when going to stuff that uses 100MHz FSB and anything Athlon or Coppermine isreally better off using TIM. Actually, running any earlier Athlon without any TIM is an easy way to fry them within the blink of an eye 😵

Yep, TIM is critical for a CPU with no heatspreader, as any part of the chip not making thermal contact will burn - though that said, I did run an Athlon Thunderbird using my old power transistor "silicon grease" - only temporarily.

I don't have any of the old silicon grease stuff I used to buy at Radio Shack when they sold Socket 3 Heatsinks in the 2000. Just using what I have. I have a old tube of AS, and a bunch of tubes of leftover stuff from my I.T. career doing stuff for OEM's, I think I have some Toshiba stuff I bought when I rebuilt my laptop that's very similar to the white silicon stuff Rat Shack used to sell. Most of it is also just me being a tad OCD after having my first experience burning up a CPU. I've been working on computers seriously for over 15 years and have never once burned up a CPU until this year. I feel kind of...uh...silly about that because I should have known better.

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