Currently having an issue with my 80486 - Page 1
Forum section: electronics / general

author: Ampera
author_rank: Super Contributor
timestamp: November 15, 2016, 09:48:41 pm
content: So I am building an 80486 based PC, and I have everything together, it turns on, beeps once, and then stops at a blinking cursor and doesn't test the memory, respond to keystrokes, or do anything.At this point I only had a video card installed, so for the sake of trying things, I decided to install my controller card and sound card, thinking maybe it was upset it didn't have a controller card.Lucky me, it posted! It tested the memory and allowed me to enter into bios. And it did this multiple times over. So I decided to turn it off, and add a floppy drive. I hooked everything up, made sure it was all plugged in right, and back to no full post.For the next 30-60 minutes I played a massive game of musical chairs on the machine, moving cards into different VLB slots, trying with or without different cards, but nothing worked not even in the configuration I had it in when it was working fine.So for now I've decided to see if anybody had any ideas. I know it's not much to go on, but stranger things can be solved with even less to go on, so I am giving this a shot.I have reseated practically everything on the board. RAM, CPU, Every card, and to no avail. I even tried to clear CMOS, but either my board doesn't have that jumper and I am putting jumpers on random jumpers, or that just didn't do anything.The board is an EXP4045, with a DX4-100 clocked @120 Mhz, a Diamond Multimedia Stealth SE, 32 MB of FPM DRAM, and a DTC VLB based controller card.

author: Ampera
author_rank: Super Contributor
timestamp: November 15, 2016, 10:02:27 pm
content: Quote from: elgonzo on November 15, 2016, 10:00:44 pmDon't own one. The BIOS loads, and there is a splash, it just says what CPU it has, displays more board info, and halts without testing memory or doing anything else.

author: elgonzo
author_rank: Unknown
timestamp: November 15, 2016, 10:06:13 pm
content: Quote from: TwoOfFive on November 15, 2016, 10:02:27 pmSorry, i did delete my previous post because i wanted to expand it a little bit. Anyway, that's not necessary anymore...Okay, so your BIOS actually does more than just initializing text mode before freezing. That the BIOS shows hardware info is a good sign.Have you tried removing memory? How does the BIOS behave then?What if you boot with only one or two memory sticks (don't remember how many sticks are required for a 486 to boot)? Do you have a chance to test the memory modules somewhere else?EDIT: What about the cache chips? Are they okay and function properly?

author: Ampera
author_rank: Super Contributor
timestamp: November 15, 2016, 10:28:24 pm
content: Quote from: elgonzo on November 15, 2016, 10:06:13 pmCache is fine, and I only have a single stick.

author: kolbep
author_rank: Frequent Contributor
timestamp: November 15, 2016, 10:55:05 pm
content: Havent used them,but how about an ISA POST Card to tell you whatever it tells you:http://www.ebay.com/itm/Cfly889-PC-Motherboard-Diagnostic-Card-4-Digit-PCI-ISA-POST-Code-Analyzer-/222075951060?hash=item33b4c217d4:g:f1wAAOSwJQdXA6W5

author: edpalmer42
author_rank: Super Contributor
timestamp: November 15, 2016, 11:50:06 pm
content: The first thing you should do is stop overclocking it. Next, check the power supply with both a DMM and a scope, if possible, to make sure it's okay. This type of boot hang often happens due to either of these sources.

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 12:02:47 am
content: I don't own a scope, and the PSU is brand new and works fine. I see no reason how that could affect anything.I will stop overclocking it, see if that changes anything, but I don't imagine it will.Update: Changing the clock speed to 100 Mhz did nothing to solve the problem. And as I mentioned above, the solution I previously had to the problem, which no longer works, had to do with inserting more cards into the system. This however does not work anymore.

author: Halcyon
author_rank: Unknown
timestamp: November 16, 2016, 12:29:54 am
content: Quote from: TwoOfFive on November 16, 2016, 12:02:47 amBecause new things can be broken too, particularly if you're using some "new old stock" AT power supply that's been sitting on a shelf for two decades. If voltages are slightly out of spec it can cause all kinds of problems. Merely powering up is not necessarily a sign of 100% working power supply. I've seen machines before that boot and appear to run fine but are unstable and lock up intermittently and have traced it back to a dodgy power supply.I personally use brand new ATX power supplies in most of my old AT machines with an ATX to AT adapter and one oftheseso I can still use the ATX supply with "big clunking" latching type power switch.When I run into issues like this, I normally pull everything out of the case and just set it up on a desktop (with a non-conductive surface of course). Can you post some pictures of your set up?Also get yourself a copy of theTotal Hardware 1999Guide. It is an invaluable resource for old hardware (and not just motherboards). I use it all the time. It's my absolute first go-to reference for jumper settings and pinouts.

author: Halcyon
author_rank: Unknown
timestamp: November 16, 2016, 12:47:20 am
content: To expand on my previous post, if I was you in this situation these are the steps I'd take:1.First and foremost, de-solder that RTC/CMOS backup battery and replace it. Those things are notorious for leaking and destroying traces. If it hasn't leaked yet, you are very lucky but get rid of it! Since your board has a 4-pin external battery connector (at position JP40), rather than trying to find a drop-in replacement for the one that came out, just get yourself something like aSAFT T1AA/C with leads. They are cheap and readily available. While you're at it, check for corrosion on both sides of the board, if you find some, clean it immediately with some Isopropyl alcohol and hit it with Deoxit or similar to hopefully stop it going any further. Check for broken traces (with a multimeter). The first things to normally go are the keyboard connector and controller and the back up battery traces.2.Double and triple check all the jumper settings. Not just the CPU settings, but ALL of them. Referring tothis page, there seems to be a lot of factory configured jumpers marked "Do not alter" just make sure someone hasn't put a jumper link in there. Also check the CPU jumpers according to the table (JP6, JP16-17, JP19-32, JP34 and JP36) and continue working your way down the page checking the rest.3.Make sure you have the correct RAM modules in their proper slots. A lot of old boards didn't operate with just one RAM module installed. Particularly with EDO type RAM, they wanted to be installed in pairs and in particular slots. Refer to theDRAM Configuration Tableto make sure you install RAM according to that and only that. Bank 0 must always have a memory module installed before you populate the others. For your 32MB, you have the options of 4 banks of 2Mx36 modules, 2 banks of 4Mx36 modules or 1 bank with a 8Mx36 module.4.Check the power supply. Even though you said it was new, check that the voltages are what they should be.Start with those and let us know how you go.

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 01:33:44 am
content: I am planning on replacing the battery, it won't be in there for long and I have a 3x NiMH AA battery pack ready to be bolted onto it (3.6v)The jumpers are all fine, that's the first thing I did even before I turned the system on.I have a 1x 8Mx36 module that expressly came with the motherboard that was proven working.I can check the PSU real quick, I will return with the results, I do have access to a scope, but it's not set up and impractical for me to use, so I really want to use that for when I get desperate.The reason I am so hesitant to the fact that it's the PSU is that it just doesn't seem like the sorta thing that would go off, especially with me using VLB and it suddenly working when I had it in a specific configuration. But I will check the voltages, and return with the result.

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 01:43:31 am
content: All 5V lines read 5.2v on my DMM12V lines are a bit low, but by .4 vand the rest is about right.I don't see this being an issue for the board as these are hardly deviations, and could even be an inaccuracy on my less than professional grade DMMThe chip is also a 3.3v chip, supplied by a regulator on board.The board was working out of it's home in Russia, and it was packed better than some of the great packaging you see here (Seriously, Russians pack stuff well)I don't see it being a more minute error than something not in right, but I could also be wrong.Would love more advice, and I feel the need to say that I doubt that a .4v deviation (A very solid and non fluctuating deviation at that) could cause such a seemingly minor thing such as that, it just doesn'tseem like it could be the cause.

author: Halcyon
author_rank: Unknown
timestamp: November 16, 2016, 03:42:22 am
content: Just be aware that NiMH batteries have quite a high self-discharge rate, typically around 10-15% per month but can be as high as 20%. They aren't really designed for long-term memory retention. You'll be recharging them relatively frequently which means you'll need to reset your CMOS settings each time. External 'computer batteries' are typically Lithium Thionyl Chloride cells which have a very low self-discharge rate (typically around 1% per year) and a long shelf life (10+ years from manufacture). You'll typically start to see SRAM becoming corrupt or erased once you get down to about 1.5-2.0v. Just something to keep in mind.A 0.4v drop on the 12v rail should be fine. +/- 5% is still considered in-spec for most boards. Outside those bounds you will start to have issues with stability.The only other thing I can think of is there could be an issue with one (or more) of the VLB slots. If you weren't careful, they were known to place quite a bit of stress on the connectors and board when inserting/removing them. Overall VESA Local Bus wasn't particularly well designed, back in those days, I personally avoided them where possible. Do you have a regular ISA video card you can try?Did you also check that your clock multiplier jumpers were set to 3.0x (open position). I think all the AMD 486-DX4's ran with a 3.0x multiplier.

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 04:08:49 am
content: FIXED ITBROKE IT....Solution leads to another problem. It was the video card not being seated properly, after seating it as well as I possibly could, it finally counted the memory and let me use the computer.Except, with no lock attached nor physically existing it's complaining I activated the keyboard lock. It did not do this before when I could go into BIOS and it complains of this if I completelydisconnect the keyboard. I tried to put a jumper on the lock action and ground pins, and even removing it after bootup didn't solve the issue, it is still locked (Why ANYBODY thought this was a good idea I will NEVER know, I can see why it was abandoned quickly.I honestly am using VLB because I think it would be way more interesting and challenging than simply ISA or PCI. It's a strange oddity from a bunch of idiots that couldn't get shit done. ISA is already longer than PCI 64-bit (Basically the same thing as VLB, just with PCI) and adding a PCI 32 bit connector to the back was not a good idea.But it's just the sorta thing I absolutely LOVE for it's unique status in history, and something I wanted to try wrestling with.I wonder if I can't just throw a CR2032 on there, because you said they drop out at around 2v, and the CR2032s are 3.6vEither way it's better than having acid eat through the traces, the sad, sad death of many old machines.

author: Halcyon
author_rank: Unknown
timestamp: November 16, 2016, 04:25:59 am
content: Hooray! But that just goes to show VLB is dicky, not just in the physical sense but it had all sorts of reliability issues due to clock timing etc... that's pretty much why it sucks. You're right when you say it will be challenging, but hey, this is also how you learn.With respect to your keylock, if you've already tried shorting/unshorting pins 4 and 5 on J1, try clearing the CMOS (some CMOS set ups had a keyboard lock option). I'm willing to bet that one of the "factory configured" jumpers (JP15, 35, 37 or 38) will clear the CMOS when shorted. Disconnect all power and short these pins out for a few seconds and try again.

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 04:44:00 am
content: Quote from: Halcyon on November 16, 2016, 04:25:59 amDid and (found) that, it was a jumper that had no physical jumper soldered in, rather it had a single bridge like you would normally find with a jumper. Just shorted the whole deal out and it cleared the CMOS, horray.Right now I am currently trying to get the graphics card seated properly again, I had a piece of paper supporting the board in one area since Baby AT doesn't fully match ATX with screw layout, so it could of been that what was causing it, but when I removed it I got the same deal with no memory scan.I am at least better off than when I started, I now know what the general problem with the memory thing is, and it could of been that paper somehow making a slight bridge across the keyboard lock?It's midnight here, I was told by a friend to stop working a few hours ago for the rule of longer you work on it, the more pissed off you get, so I will return to it tomorrow.This is definitely what I like to do, it's a project and I rarely get those outside of educational stuff. I am 14 and working on this, if you didn't know. I never had the chance to use something like this, and until I got my first card in the mail, I had never seen VLB in person before. This has been fun just from looking at the parts, but getting them work will be amazing.And on a side note, do NiCad batteries tend to leak? That's what is on there and it just doesn't seem the sorta battery that would leak. I am not cutting it off for now, and just keeping an eye on it, not that I thing NiCad won't leak, it's because if I find the board to be defective in some way, I can't return it if the battery is clipped....Sooo yeah, thanks for all the help, I have been filming a video on this (in the "would anybody be interested" post) and I will definitely thank everybody here for helping me, it's more of a small thing I intend to share with friends, but I will post it here, and I am happy everybody here helped.

author: Halcyon
author_rank: Unknown
timestamp: November 16, 2016, 04:57:36 am
content: Quote from: TwoOfFive on November 16, 2016, 04:08:49 amYep, you could but it would involve rigging up a holder. You'd also need to put a diode in there so the motherboard doesn't damage it by recharging it when the machine is running (remember, there is a rechargeable battery in there so when powered on, power will be applied to it). For the sake of a few dollars, you're better off with a Lithium-based external battery that you can just plug in.Quote from: TwoOfFive on November 16, 2016, 04:44:00 amPaper won't short anything. Not at those low voltages. But if your board doesn't fit properly, get some plastic stand-offs. Especially if you insist on using VLB. The more support the better.Quote from: TwoOfFive on November 16, 2016, 04:44:00 amYes, they do (and will at some stage) leak as they get old. Get rid of it as soon as it is practical. Don't just cut it out though, do the proper thing and de-solder it (don't be lazy or cut corners). JP40 is there to be used, so take the easiest and most effective option. A new lithium battery pack plugged into that will last many years (it also gives you an easy way to physically reset the CMOS if you ever need to).

author: CJay
author_rank: Super Contributor
timestamp: November 16, 2016, 08:01:23 am
content: Quote from: Halcyon on November 16, 2016, 04:57:36 amOr, possibly better still, if the board has tinned solder rings around the screws, fasten it in using metal screws and brass pillars, sometimes those grounding rings need to be grounded to chassis or you see odd things happening.

author: Halcyon
author_rank: Unknown
timestamp: November 16, 2016, 11:10:12 am
content: Quote from: CJay on November 16, 2016, 08:01:23 amNot at all. All board have tinned rings around the mounting holes. They aren't designed for grounding at all (that's why AT and ATX power supplies have several ground connections). In fact, you will find many boards/cases actually supplied cardboard insulating rings specifically for those holes.

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 03:03:45 pm
content: Quote from: Halcyon on November 16, 2016, 11:10:12 amNot to mention some cases don't even have screw holes in most places, and require nylon clips that ratchet into the holes, and slip into the case. Neat design, because you can just slide the whole board up and out, but it's a pain to remove the one time one use nylon clips, and if you don't have any, your case is useless.As I said the case has like 3-4 screws actually lined up with the board, enough to keep it in place, but the top is a bit bendy bendy.

author: stj
author_rank: Super Contributor
timestamp: November 16, 2016, 03:58:24 pm
content: if your using 72pin sims, make sure your not using EDO in a motherboard that can only run FastPageMode ram.

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 06:04:02 pm
content: Quote from: stj on November 16, 2016, 03:58:24 pmThe memory is fine, although the 128MB upgrade I purchased is incompatible for a yet unknown reason. The only think I can think of is that Parity memory is turned off in the BIOS?Anyways I am up, and will continue to work on it soon.

author: CJay
author_rank: Super Contributor
timestamp: November 16, 2016, 06:09:03 pm
content: Quote from: Halcyon on November 16, 2016, 11:10:12 amYeah, they're just decorative and should be insulated, the board designers went to the trouble of adding the contact and routing them to the groundplane of the multilayer board just to make the board look pretty.

author: Halcyon
author_rank: Unknown
timestamp: November 16, 2016, 07:10:30 pm
content: Quote from: CJay on November 16, 2016, 06:09:03 pmPretty much. Yes, you're right in that they are grounded but they are not needed for proper operation. Look at the ATX connector, there are 8 ground points (10 if you use the P4 connector as well) and 4 on the AT connector. Not to mention all the ground pins to the I/O cards (which are also screwed into the chassis).What you should be concerned about is ESD from yourself -- Wear a properly grounded wrist strap.I know out of the many hundreds of machines I've built and worked on, I have never ever had a issue with grounding. You'll even find some case designs where you must insulate these standoffs otherwise you create a short that shouldn't be there.

author: John Coloccia
author_rank: Super Contributor
timestamp: November 16, 2016, 07:13:41 pm
content: Generally speaking, the plated holes get screwed directly to the case. The non-plated mounting holes (just a plain old hole in the PCB) would get a washer so you don't tear up the board. You usually just use the plated holes these days for screws, but you still get washers anyway.

author: John Coloccia
author_rank: Super Contributor
timestamp: November 16, 2016, 07:17:28 pm
content: Quote from: Halcyon on November 16, 2016, 07:10:30 pmCan you give an example? I don't think I've ever seen anything like that.

author: Halcyon
author_rank: Unknown
timestamp: November 16, 2016, 07:23:49 pm
content: Quote from: John Coloccia on November 16, 2016, 07:13:41 pmYes that's right. You also commonly see those plastic mounts that allows the board to slide on and off the mounting plate.The point I was making though was those plated holes - grounded or not grounded - it makes absolutely no difference. But hey, like any good person, I'm willing to be proven wrong with the appropriate data.Quote from: John Coloccia on November 16, 2016, 07:17:28 pmSure. Have a look at the image below. I used to come across these all the time, not so much in recent days though. The standoff clipped into square holes on the mounting plate. They varied in size and shape depending on the case manufacturer. If you didn't insulate these, depending on the design of the board, you could inadvertently short out something near the mounting holes.Yes, you'll still achieve grounding through the screw itself, but this is not what these standoffs are designed for (mind you I wouldn't consider those clip type standoffs as a reliable grounding point anyway). Their primary purpose is to hold the board in place and provide support for upward and downward forces from inserting/removing cards and cables. As I said, the board is already sufficiently grounded just through the AT/ATX connector. You also get a good grounding to the case through the I/O shield.

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 08:06:31 pm
content: Update:Strange things, so I tried to attach everything I was going to to the computer, just to see if it was upset that nothing existed, didn't work, but I found something odd.If I power the machine on, unplug the keyboard, plug it back in, and bend the board on the top left corner slightly, not enough for it to touch the case, it starts counting the memory.It proceeds to complain the keyboard is locked out, but this is infinitely reproducible, unlike my previous idea that it was a bad mount for one of the VLB cards.This lead me to think it was a memory SIMM, so I proceeded to clean the contacts for both the memory and slot with 91% IPA (I am aware it leaves a residue, but it's not as much of a concern with 91%, and it has never once caused problems for me.The stuff about ESD I never follow, I have never lost a single part due to electrostatic in my entire life, and I am normally plugged in, but not on while working, so I am grounded (The PSU and thus the case is connected to ground). If you are paranoid to want a strap, attach it to your ankle, that way it's not on your arm and bugging you. The reason I don't like it is I have to unplug myself whenever I run around tograb something, which is often, and I don't feel the need to shackle myself constantly to ground.

author: Halcyon
author_rank: Unknown
timestamp: November 16, 2016, 08:14:49 pm
content: Quote from: TwoOfFive on November 16, 2016, 08:06:31 pmStrange. Can you post a photo of where you apply pressure to the board to cause it to work?Quote from: TwoOfFive on November 16, 2016, 08:06:31 pmA rubber band wrapped around your finger or a soft pencil eraser works well too.Quote from: TwoOfFive on November 16, 2016, 08:06:31 pmNeither have I. Electronics like that are pretty robust. But yes, leaving the power cable plugged in to the power outlet (but switched off) is a good way to ground yourself by simply touching the case.

author: rrinker
author_rank: Super Contributor
timestamp: November 16, 2016, 08:19:53 pm
content: Quote from: Halcyon on November 16, 2016, 07:23:49 pmGot to say - the last purchased computer I had was a 486, Every one since then I've built myself, and during the Pentium 133/166/200 days, the company I worked for built hundreds for clients, and I have NEVER seen a motherboard standoff like that. I've see the slide in plastic clips that have been mentioned - and ones that screwed into the spaces on the case and then clipped to the MB, which were a MAJOR PITA to get out as you tried to lift the MB while squeezing each slip in turn and hoping one you didn't already release would snap back in. The most prevalent mounting hardware though, was a basic screw-in standoff. I used to grab up all the extras laying around to see how long a chain I could make - once you got past a meter or so they were very unwieldy though I did have on group laying on the bench that had to be better than 3 meters long - you couldn't pick it up without taking it apart though. I have bags full of them from more recent builds. On some cases, they've taken to punching the case material itself into a standoff for certain of the locations, mainly the ones that will absolutely have a screw hole regardless of the overall size of the MB. I recall some older ones like that as well. But definitely never saw anything like this type of metal slide in standoff. It looks more like a rack cage nut with an extra long clip, except it is obviously motherboard size and has the proper motherboard screw.Mostly I recall teh holes without the solder mask were NOT to be used for mounting screws, either plastic clips or none at all because they often had traces running within the screwhead area so driving a screw into those holes was just asking for trouble.

author: TheBay
author_rank: Unknown
timestamp: November 16, 2016, 08:28:35 pm
content: Quote from: Halcyon on November 16, 2016, 07:23:49 pmThe motherboard screw holes are used for grounding the board to the chassis, those red washers were just there to stop the screw coming loose.If you observe the top and bottom of a PC motherboard where the screw is it usually has a circle of solder on both sides, sometimes a bit thicker to make sure it makes contact with board mounting standoffs.Grounding/shielding doesn't really work as effective from single points such as the power connector and IO shield, to prevent ground loops, EMI, RFI etc etc etc the whole motherboard groundplane ideally needs to be at ground/earth potential.Some cases, especially complete systems built by OEM's will go one step further and have sprung loaded grounding points around the chassis making contact with those points on the motherboard.There used to be clear acrylic cases some time ago, they were awful for stability and interference etc.

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 08:32:14 pm
content: Quote from: TheBay on November 16, 2016, 08:28:35 pmThey still exist? I mean people build computers in frigging aquariums with mineral oil now. Even my main rig has a plastic window in it.

author: TheBay
author_rank: Unknown
timestamp: November 16, 2016, 08:34:55 pm
content: Quote from: TwoOfFive on November 16, 2016, 08:32:14 pmDoes what still exist?My NZXT s340 has a plastic window like most, but every one of my motherboard mounting screws is grounded to the chassis.You can get away with not grounding all of them but it's better if you can ground them.

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 08:35:30 pm
content: Quote from: Halcyon on November 16, 2016, 08:14:49 pmhttp://prntscr.com/d85s0pThis is a picture out of it's case, no jumpers have been changed, that is the memory used as well as the processor.The circle is where I press it down, just on that corner, and not enough to touch the case.

author: TheBay
author_rank: Unknown
timestamp: November 16, 2016, 08:40:04 pm
content: Quote from: TwoOfFive on November 16, 2016, 08:35:30 pmThats deffo meant to be grounded to the chassis on those points.Those red washers that were supplied with cases served 2 purposes, 1 protect the board if the screw was too wide to stop it damaging traces, 2, some oddball boards weren't grounded in some places and to stop you cutting through the solder mask and shorting it out.

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 08:42:09 pm
content: Quote from: TheBay on November 16, 2016, 08:40:04 pmAs I said it never touches the board. I'll gator clip it to the case to ground it, but this doesn't seem like it will work.

author: TheBay
author_rank: Unknown
timestamp: November 16, 2016, 08:43:24 pm
content: Sorry just read the post about pushing down.Sounds like a few things could be happening here:1, Simm not sat in properly2, Edge connectors on ram not clean, try cleaning them with an eraser or IPA3, Simm socket connectors dirty/corroded4, Dry joints on Simm socket or other components5, A broken trace in the motherboard

author: Halcyon
author_rank: Unknown
timestamp: November 16, 2016, 08:46:08 pm
content: Quote from: TwoOfFive on November 16, 2016, 08:35:30 pmMmmm. It could be the memory slot, but that doesn't explain why you get a keyboard lock error when there is no keylock.Can you tell if that CMOS battery has been replaced before? Are there signs of re-soldering or is there a date code on the battery itself which might indicate it has been recently replaced?I'm just wondering if someone has replaced that battery and the previous one leaked and caused some corrosion which has been cleaned up. As I mentioned in a previous post, keyboard problems were usually the first things to occur when those batteries leaked and started corroding traces and contacts. I would probably remove the keyboard controller (Winbond W83C42) and just having a look to see if any of the dual wipe contacts in the IC socket are corroded or broken. While you're at it, check those other two sockets.

author: TheBay
author_rank: Unknown
timestamp: November 16, 2016, 08:47:09 pm
content: Also looking at those SIMMS the one in the socket has a Parity chip on it, does that board support EDO Parity?Are all the SIMMS the same?, have you tried 2 different pairs at a time and moving them around the SIMM sockets?

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 08:48:38 pm
content: Quote from: TheBay on November 16, 2016, 08:43:24 pmAgain, read the posts, I already cleaned the slots.Gator clipping did nothing, and I will remove the chip real quick and take a look at it.

author: TheBay
author_rank: Unknown
timestamp: November 16, 2016, 08:55:50 pm
content: Quote from: TwoOfFive on November 16, 2016, 08:48:38 pmLooking back at all the posts it seems a lot of people have been trying to help constructively but you seem quick to make the assumption thatthe answers given will not help and that the items you have are being assumed working correctly.Please go back over everything that has been said and check it all thoroughly.

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 09:01:37 pm
content: Quote from: TheBay on November 16, 2016, 08:55:50 pmI have, everything has been tried or is impossible for me to try.The PSU is fine, the Memory has no substitute, I have altered the positioning of all the cards, I have changed the clock speeds multiple times, it didn't work.I cleaned and reseated both the BIOS and KB controller, neither had corrosion, and neither made a difference. There is no evidence of the battery being ever replaced, and there is no evidence of corrosion. The board has screenshots of it working.

author: CJay
author_rank: Super Contributor
timestamp: November 16, 2016, 09:02:10 pm
content: Quote from: Halcyon on November 16, 2016, 07:10:30 pmMhmm, been working with and repairing to component level since the first 4.77MHz IBM PCs, I've repaired, built and rebuilt many thousands of machines, I've seen damage that could be directly attributed to ESD with immediate failures on the bench when wrist straps were 'forgotten', intermittent and random hang ups that could be reasonably attributed to sloppy or non use of ESD protection gear and just random problems that may or may not have been anything other than a failure through 'natural' causes.It's amazing how often people who don't use ESD precautions will say they 'have never killed anything with static' but have random lockups, random refusals to boot, boards that die prematurely few weeks later or any combination thereof.As for the mounting holes and grounding, yes, maybe and no, they've been explained to me in many different ways over the years by people up to and including engineers in the Compaq Scotland factory but lowimpedance grounding for EMC and signal integrity on high speed busses, to me, stand out as the most sensible reasons.As an aside, my first Pentium machine ran, reliably, bare board and peripheral cards sat on a Maplin catalogue for a number of months until I could afford a decent case for it.

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 09:05:20 pm
content: Quote from: CJay on November 16, 2016, 09:02:10 pmAs I said, the machine is grounded whenever I work on it, and I am standing on hard laminate.

author: Halcyon
author_rank: Unknown
timestamp: November 16, 2016, 09:16:24 pm
content: I think your only option at this point is to start testing traces with a multimeter. If you say the board works when you apply downward force in that corner and it's repeatable, it's clearly something not making contact when it should. If it's one of the memory slots you should get a repeated beeping error code. Actually test this: remove all the RAM, press down in that corner to make it "work" and see if you get an error beep (it'll depend on the BIOS, some will give you error beeps, others will do nothing).If you DO get error beeps with the RAM removed, but you don't when it's installed (and you're not pressing down on the board), that indicates to me the problem is not with the memory slots but somewhere else.

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 09:19:36 pm
content: Quote from: Halcyon on November 16, 2016, 09:16:24 pmBut it's more subtle than that. You forget that this ONLY works if I unplug and plug back in the keyboard. ONLY this, and never anything else, you can press it all day and it won't do anything, only when the keyboard has been reseated while the system is running, will this work.

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 09:27:00 pm
content: Your suggestion had no effect, unfortunately.I am going to leave the machine running in it's hanged state for a few hours to see if it does anything. Maybe I am just not waiting long enough and it is gonna take a while.

author: TheBay
author_rank: Unknown
timestamp: November 16, 2016, 09:30:52 pm
content: When is it hanging, on some boots or only if you remove the keyboard?AT Keyboards (And PS/2) do not like being removed when the system is running.

author: TheBay
author_rank: Unknown
timestamp: November 16, 2016, 09:38:31 pm
content: Just had one thought.Are the jumpers set to 5v or 3.3v for your CPU?

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 09:39:24 pm
content: Quote from: TheBay on November 16, 2016, 09:30:52 pmIt hangs 100% of the time for the amount of time between this post and my previous one and counting. Removing and plugging the AT keyboard back in, and THEN bending the board slightly makes it count the memory, then it complains the keyboard/computer is locked.

author: John Coloccia
author_rank: Super Contributor
timestamp: November 16, 2016, 09:39:29 pm
content: Quote from: Halcyon on November 16, 2016, 07:23:49 pmHa ha...can't say I've ever seen that ugly monstrosity. LOL. Looks like a modified shelf clip.Incidentally, I thought you meant "short out", like the case wasn't sitting at ground potential or some other weird configuration. Yes, I've definitely seen where a standoff or screw was too big and could short out neighboring traces. Now I understand what you meant.

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 09:41:30 pm
content: Quote from: TheBay on November 16, 2016, 09:38:31 pmIt they were 5v I wouldn't have a boot hang, I would have molten slag where the CPU was.And yes, it is 3.3v

author: Halcyon
author_rank: Unknown
timestamp: November 16, 2016, 10:29:36 pm
content: Dodgy keyboard controller maybe?? Gees, this issue is getting stranger.

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 10:32:41 pm
content: Quote from: Halcyon on November 16, 2016, 10:29:36 pmSomething is dodgy, but considering the seller had pictures of the thing working, I am inclined to believe I am doing something wrong myself.

author: Ampera
author_rank: Super Contributor
timestamp: November 16, 2016, 11:29:48 pm
content: Can somebody shoot me for a second? Thank you.I fixed it.I was about to type that this was the most boneheaded mistake I have ever done, but that would never be true nor fair.This just goes to show it's always the really stupid thing.SO LADIES AND GENTLEMEN, WOULD YOU LIKE TO KNOW WHAT I DID WRONG?There was a standoff still screwed into the case even though it shouldn't have been. That's why when I bent stuff it started to work.I am just really really lucky it wasn't in a worse place and I am lucky it didn't end up frying something (Although who knows, *Crosses fingers*)My dad, who had been giving me advice on this, said to try putting it outside of the case, saying he once had a problem like this where a screw was jammed into the board and case and was shorting something.It worked, and to rub salt on an open wound I made a thread over at Vogons.org (Check them out they have cool stuff for retro computer geeks) and the person there said the same thing right after I did it and it worked.Anyways, I will return if I have more issues, and if I do not, I will return with a video and at the end credit everybody who has made a post here and helped me. Thanks everybody, excuse me while I drill a new hole in the wall with my head.

author: timb
author_rank: Super Contributor
timestamp: November 16, 2016, 11:36:24 pm
content: Quote from: Halcyon on November 16, 2016, 04:57:36 amWhat I did awhile back for my Compaq Portable III was to rig up a CR2032 holder on a small round PCB, with a resistor added to limit charging current. Then I simply used a LiR2032 battery, which is a rechargeable coin cell. Worked great and I've since performed the mod on other machines.Quote from: TwoOfFive on November 16, 2016, 11:29:48 pmOne of the first replies in this thread was someone advising you to remove *everything* from the case and hook it up on your desk... just sayin'!Quote from: Halcyon on November 16, 2016, 12:29:54 am

author: Halcyon
author_rank: Unknown
timestamp: November 16, 2016, 11:42:07 pm
content: Quote from: TwoOfFive on November 16, 2016, 11:29:48 pmI wrongfully assumed you'd already tried this. But yes, just goes to show, with issues like these, go back to basics. Eliminate every part that isn't absolutely necessary including the chassis.

author: Ampera
author_rank: Super Contributor
timestamp: November 17, 2016, 12:34:48 am
content: I didn't even see it. Just add to the pile of dumbarse.

author: Ampera
author_rank: Super Contributor
timestamp: November 17, 2016, 01:36:22 am
content: On a side note, if you are currently running a Vista based windows version (Vista or 7) DO NOT WRITE AN IMAGE TO A DISK, ESPECIALLY WITH WIN32DISKIMAGER.You will turn your C: drive into whatever image you were imaging. It normally doesn't happen with flash media, but if you do it to a floppy, Well my C Drive got turned into a 6.22 boot disk.Thank god for backups, I will never stop making them.The machine is working fine, DOS is currently formatting the drive I had, 6.22 can't detect past 500MB on that system so I will probably use Dos 7.1 when I get around to it.Damn.

author: Halcyon
author_rank: Unknown
timestamp: November 17, 2016, 02:18:45 am
content: Quote from: TwoOfFive on November 17, 2016, 01:36:22 amNever had this happen to me on Windows 7 before and I write a lot of disk images.Quote from: TwoOfFive on November 17, 2016, 01:36:22 amDOS 6.22 actually supports partitions up to 2GB. It's your BIOS which limits the disk to 504 or 528MB. You can get around this limit though by installing a translator such as OnTrack Disk Manager or MaxBlast Plus (See:http://vintage-pc.tripod.com/hdd_utils.html)These utilities install a device driver that loads before DOS to circumvent BIOS limitations. I used OnTrack a fair bit back in the day.I'd recommend not bothering with DOS 7.1 The last official standalone MS-DOS version was 6.22. It was stable and widely used. MS-DOS 7.x came with Windows 95 and later versions. There was a "China DOS Union" version of 7.1 which was basically copied from Windows 9x, modified and bundled with some tools. I honestly wouldn't bother with it. Hardly anyone ran it. Plus it apparently comes with a dicky splash screen while loading...(Image: "China DOS Union 7.1" startup screen)If you're after an alternative to MS-DOS, have a look at PC-DOS which was written by IBM.

author: Ampera
author_rank: Super Contributor
timestamp: November 17, 2016, 02:24:47 am
content: Quote from: Halcyon on November 17, 2016, 02:18:45 amI have used Dos 7.1 multiple times without any issue.And the BIOS recognizes all 4092 cylinders and give me the right disk size.I don't really care atm, 500MB is perfectly large enough.Another question, anybody know by chance the pins for a microsoft PS/2 combo mouse to get to RS-232? I know my combo mouse can use RS-232, I just don't know the pinout, if anybody just happens to have that on hand so I can add an RS-232 lead off the end of it.

author: timb
author_rank: Super Contributor
timestamp: November 17, 2016, 12:27:35 pm
content: FreeDOS is an even better alternative IMHO. Comes full of free tools, supports very large drives and fixes a lot of niggling MS-DOS bugs.