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CannedBread
May 1st, 2012, 12:38 PM
I bought a broken IBM 5155 a while ago, and cosmetically it's fine, but it doesn't do anything when I turn it on. I've taken some of the boards out and one of the batteries has leaked, and a few capacitors exploded. I have a very limited understanding of these old computers, but I would really like to get it working. Do you think there would be any chance of that happening? would replacing the broken boards fix it, or could it be the power supply?

pearce_jj
May 1st, 2012, 01:05 PM
Start with the PSU and work out from there. PC/XT (5160) motherboards come up on here fairly frequently.

Chuck(G)
May 1st, 2012, 01:08 PM
Please learn to solder and repair electronics. Please don't be one of those who operate on the basis of "if it doesn't work right away, it's garbage". Capacitors age and can be replaced. Power supplies use capacitors and if anything, are more prone to that type of failure.

The bottom line is that you can probably resurrect it with a little determination--unless it's been through extreme conditions, of course.

ChrisCwmbran
May 1st, 2012, 01:10 PM
If you take photos of the problems I'll help you all I can. I'm about 30 miles from Bristol.

barythrin
May 1st, 2012, 02:08 PM
The quick and simple answer is yes it can likely be fixed. Just a little practice work and determination and you can replace those bulging capacitors and likely fix the problem for minimal cost. Chris's help will probably be a good experience too.

CannedBread
May 2nd, 2012, 02:39 PM
Sure, I'll take some pictures and put them up tomorow. From what I remember, one of the boards was fine, one had exploded capacitors and one a corroded battery. From what I could see the rest seemed fine, but I didn't delve any deeper than that... I think I need a screwdriver with a different bit to get to the rest.

k2x4b524[
May 2nd, 2012, 03:16 PM
from the sounds of it you may be dealing with an expansion board that went south. An old RTC board perhaps? Try taking out all the board BUT the graphics card and start from there, pics will help greatly though :)

CannedBread
May 3rd, 2012, 10:38 AM
I started to take it apart again, but I only got as far as the cards and one floppy drive (it's got two, but one is different). I'll get the motherboard out over the weekend, but I could see the 8088 in the back :)

So here are the pictures (sorry some of them are a bit blurry):

8806

The Computer itself, with two floppy drives

8808

Here's how the boards are laid out. The thin cable coming in from the left goes to the far left board (board 1), the two coloured ribbon cables are coming from the middle board (board 2), going out the back of the computer. One of the thick ribbon cables is coming from the smaller board on the right (board 3), and goes to the floppy drives. The 8088 is in the top left behind the cables (there is an empty slot for a similar size IC beside it, I don't know if there's something supposed to be there.

Board 1

8809

Here's a close up:
8810

The exploded capacitor is the only fault on that board, and so far (I haven't taken it apart fully yet) the only exploded capacitor.

I can only attach 5 files a post, so I'll do another one in a minute. Sorry for the long posts :P

Chuck(G)
May 3rd, 2012, 10:55 AM
That capacitor is a tantalum--they detonate on old gear with remarkable regularity. But that isn't going to keep your system from booting, so keep digging.

If I'm trying to work on a system, I'll take it apart and reassemble the boards, peripherals and power supply on a tabletop, so I can see what's going on.

juicylemon
May 3rd, 2012, 12:01 PM
but it doesn't do anything when I turn it on.
This could indicate that the fuse in the power supply has blown, because of a short circuit that could have been created by one of the exploded or damaged capactitors.

SpidersWeb
May 3rd, 2012, 12:38 PM
While I haven't used a 5155 PSU, the power supplies normally have an auto-cutoff if their outputs are shorted. You can tell if this is the case because when you turn them on you see the fan nudge a little but not spin. To keep it alive, my 5160 board has had to have ~4 capacitors removed now.

Just to clarify, is the system turning on but not displaying anything, or does literally nothing happen when the power switch is flicked?

p.s. http://www.minuszerodegrees.net/5150_5160/MDC/minimum_diag_config.htm (test at bottom is extremely useful, still applicable to a 5155, would recommend you follow it through)

lucasdaytona
May 3rd, 2012, 12:54 PM
Please learn to solder and repair electronics. Please don't be one of those who operate on the basis of "if it doesn't work right away, it's garbage". Capacitors age and can be replaced. Power supplies use capacitors and if anything, are more prone to that type of failure.

The bottom line is that you can probably resurrect it with a little determination--unless it's been through extreme conditions, of course.

I really missed the "Like it" from facebook :cool:

Get the PSU disconnected from everything, and turn on the PSU, take a look if the FAN spins, if not, then it's time to disassemble it, and try to fix. If it spins, then it's time to begin to repair that dead components.

SpidersWeb
May 3rd, 2012, 12:59 PM
I can't remember weither or not the 5155 has a fan :(
If it doesn't then you can use a sacrificial hard drive (make sure it's a hard drive you don't like, just in case).
If it does, then ignore this post :P

lucasdaytona
May 3rd, 2012, 01:28 PM
I can't remember weither or not the 5155 has a fan :(
If it doesn't then you can use a sacrificial hard drive (make sure it's a hard drive you don't like, just in case).
If it does, then ignore this post :P


Whops, I didn't think about this... One time I grabbed a 5155 Clone around here, and there was a fan on him... my bad.

SpidersWeb
May 3rd, 2012, 01:31 PM
yeah I'd forgotten to check that as well lol
it might do, I just can't remember.

pearce_jj
May 3rd, 2012, 01:34 PM
5155 fan is mounted such that it is drawing air mainly through the back of the CRT. You can't see it without removing the shield but you can certainly hear it. Note to the OP - exercise extreme caution working with the CRT shield removed as there are serious voltages in there.

Chuck(G)
May 3rd, 2012, 02:15 PM
I really missed the "Like it" from facebook :cool:

Sorry, I don't do Facebook:

http://i.eatliver.com/2011/7775.jpg

lucasdaytona
May 3rd, 2012, 02:26 PM
Yeah Chuck, you're right about Facebook. But it's a very good way to stay in touch with people, maybe it's a Brazil fever, like Orkut. We've the highest users numbers on every social network.

ibmapc
May 3rd, 2012, 03:57 PM
...Get the PSU disconnected from everything, and turn on the PSU, take a look if the FAN spins, if not, then it's time to disassemble it, and try to fix. If it spins, then it's time to begin to repair that dead components.

Don't disconnect it completely. The power supply fan won't come on without a load on it(One hard drive may not be a big enough load). So if you disconnect it completely and turn it on, the fan won't spin up and you might mistakenly assume that the PSU is bad. (I did that myself once but fortunately the good people hear straightened me out)

I suggest removing ALL cards including the display adapter (I've seen two of the old IBM CGA display adapters go bad causing a short that prevent's the power supply from starting up.) Leave the power supply connected to the mother board and turn it on. If the fan spins up, let it run and after a minute or two you should hear the speaker beep (as long as it's connected) . At this point you can assume that the PSU is fine. If when you turn it on, the fan spins up, but you don't hear any beeps, then check the voltage at the floppy power connecter with the mother board power leads still connected. You should have + 5v and + 12v. Then, if it's determined that the PSU is ok, power it down and plug in one expansion board, like the CGA card and turn it on. If the fan doesn't spin,then that board is probably shorted. Keep pluging in more boards(WITH THE POWER OFF) one at a time untill the bad one is found.

lucasdaytona
May 3rd, 2012, 05:47 PM
Don't disconnect it completely. The power supply fan won't come on without a load on it(One hard drive may not be a big enough load). So if you disconnect it completely and turn it on, the fan won't spin up and you might mistakenly assume that the PSU is bad. (I did that myself once but fortunately the good people hear straightened me out)

Are you 100% certain about this?
I've never used an original IBM PSU, but all others PSUs I've ever seen spins the fan when you power on, even with nothing connected. I will try to find a 5150 PSU schematic to take a look, I'm very curious to understand this circuit now.

ibmapc
May 3rd, 2012, 06:18 PM
Are you 100% certain about this?
I've never used an original IBM PSU, but all others PSUs I've ever seen spins the fan when you power on, even with nothing connected. I will try to find a 5150 PSU schematic to take a look, I'm very curious to understand this circuit now.
Yep, when I thought I had blown the PSU in my 5155, I disconnected it from the motherboard, then turned it on and nothing. I then posted HERE (http://www.vintage-computer.com/vcforum/showthread.php?21187-Help-I-shorted-out-my-5155-s-power-supply&highlight=5155+power+supply) about it in a panic and I believe it was Chuck(G) who informed me that some power supplys would not come on without a load. So I then connected it to a known good motherboard and it came to life and I was both embarassed and relieved.

pearce_jj
May 3rd, 2012, 10:02 PM
5150 PSU is different as it uses an AC fan. The 5155 PSU is powered from a separate 12v connector comming out of the unit, P13 according to my notes (http://vintage-blog.peacon.co.uk/wiki/IBM_Model_5155_PSU).

Denniske1976
May 3rd, 2012, 11:15 PM
Maybe this won't help at all, but here's something else you might try: Just remove all the cards and insert them again.

Might sound stupid, but i've had this happen to an IBM 5155. It just sat in the closet for about 4 years, I took it out, turned it one and nothing happened. Opened up the case and all seemed fine (no blown up caps). Then an ex IBM employee told me I should "reseat" everything since it was the first thing they did when a machine seemed dead without any reason. So, took everything out, disconnected the floppy drives and put everything in again... and prompto! it worked again.

But since it's been in the closet again for about 8 years now there's a good chance it won't boot again when I take it out :-) But I'll know what to do ;-)

Maybe it won't fix your problem, but it did mine and my 5155 didn't do anything either when turned on. Although mine only has the CGA adapter and a memory board (to get to 448K memory), nothing with a battery on it (I'd leave that one out anyway).

CannedBread
May 4th, 2012, 12:47 PM
I'll get to the rest over the weekend, but here are some more pictures of the boards.

Board 2


8845

This is the board with the leaked battery. It is a Varta SafeTronic, 2.4V, 100 mA.

8846

I don't know if it's really needed, but here is a close up of the battery. Other than that, this board seems fine.

Board 3

8847

As far as I can tell, this board seems fine. I think it is the floppy controller.


That's as far as I've got in taking it apart, but here is a photo of the motherboard anyway:

8848

I'll probably have it apart on Sunday, although I've got Monday as well because it's a bank holiday :D

Chuck(G)
May 4th, 2012, 01:01 PM
Board 2 is a Quadram Quadboard--a serial, parallel, game, clock and memory expansion board. For purposes of testing, it's not needed, so you can put that in the "later" pile.

Board 3 is indeed a floppy controller. Those rarely go out of whack.

pearce_jj
May 4th, 2012, 01:45 PM
Have a look at that monitor shield - it looks like it's not clipped in at the bottom and could short across the back of the CGA card.

Mobo removal is easy enough (1 screw) but you need to remove both the FDDs to get at it IIRC.

modem7
May 4th, 2012, 06:55 PM
5150 PSU is different as it uses an AC fan.
Early ones, yes. Later ones, no. On this LINK (http://www.minuszerodegrees.net/5150/5150_psu_from_sams_computerfacts.pdf) is is a circuit diagram for a later 5150 PSU.

modem7
May 4th, 2012, 08:33 PM
I've placed some information on the 5155 power supply at
http://www.minuszerodegrees.net/5155/psu/5155_psu.htm

modem7
May 5th, 2012, 12:47 AM
I placed my 'CRT shield removal' procedure at
http://www.minuszerodegrees.net/5155/crt/5155_crt_shield_removal.htm

ibmapc
May 19th, 2012, 11:15 AM
I'll probably have it apart on Sunday, although I've got Monday as well because it's a bank holiday :D

@CannedBread
Have you made any progress with your 5155? I have a soft spot in my heart for the old 5155 and would like to see you succede in getting her up and running again.
I have two of them myself. One is the first computer I owned back in 1986 when bought new by my father who is a retired long time IBM employee, and the other was purchased from EBAY as a non working unit. The latter one had a shorted CGA board, and after replacing it, and doing some maintanance, the unit works perfectly.

Please update us on your progress.

Greg

CannedBread
May 26th, 2012, 05:53 AM
I got the motherboard and power supply out, and from what I can tell the PSU is broken. The fan doesn't come on at all, and the motherboard looks to be in good shape. There's also a cable hanging out the back of the CRT, I don't know if it's supposed to be there... I'll take some pictures soon. If it is the PSU, does anyone know where I could find a working one?

CannedBread
May 26th, 2012, 10:21 AM
I took the cover off the PSU and found a blown fuse:

9059
I tested it, and it is definitely blown. It is a 250V 3A fuse.

That's the only problem I could see in the power supply.

9060

I noticed a cable dangling out the back of the CRT:

9061

Here's the end:

9062

Would it be an earth cable, and should it be plugged into something? The Motherboard looked fine, so I didn't take any pictures of it. If I changed the fuse and turned it on with just the motherboard plugged in, would that do anything?

Chuck(G)
May 26th, 2012, 10:33 AM
Note that you usually cannot run a switch-mode PSU without a load. Hook a hard disk to the output and give it another shot before declaring it bad (and after replacing the fuse).

The lead that you show looks as if it might be a chassis ground. Such leads usually attach to a clip or "ear" attached to the system frame or case. I suspect this is more for RFI shielding than anything.

CannedBread
May 26th, 2012, 11:37 AM
I don't have an old hard drive, would two floppies do it, although I assume they would have to be running?

pearce_jj
May 26th, 2012, 01:27 PM
Modem7 posted already that the 5155 PSU needs quite a lot of load on it to function:

"Some loads that you think may be sufficient are not.

* An IDE drive (eighties/nineties vintage) is not enough of a load. My experiments with two 5155 power supplies show that approximately four to five IDE drives are required.
* Even some full height multi-platter MFM drives fail to enable this power supply to start.
* The 5155's CRT unit is not enough of a load.

* The 5155 motherboard is enough of a load to start/operate the power supply. This is the case even if P8 is disconnected (but note that the motherboard requires both P8/P9 to operate)."

modem7
May 27th, 2012, 12:48 AM
I noticed a cable dangling out the back of the CRT:

Would it be an earth cable, and should it be plugged into something?
Take a look at the photo at http://www.minuszerodegrees.net/5155/crt/5155_crt_unit%20-%20black%20wire.jpg
I think the black wire you pointed out is the one that attaches to the point I have circled in yellow (top-left).

It is possible that your 'floating' wire was the cause of the fuse blowing (i.e. the end touched something it shouldn't have).

CannedBread
June 9th, 2012, 06:53 AM
I took the cover off the PSU (despite the yellow warning sticker), and found a blown fuse. I replaced it with a 2.5 A (the blown one was a 3 A), and unplugged everything except the motherboard. When I turned it on, the fan spun for a second, and then cut out. I follow the instructions on the minuszero site, and unplugged the P8 connector. The fan the spun continuously. That means that there is a short in either the +12 or -12 volt rails. It says to check the capacitors, but I can't see that any are broken. What should I do now?

ibmapc
June 9th, 2012, 01:49 PM
.... That means that there is a short in either the +12 or -12 volt rails. It says to check the capacitors, but I can't see that any are broken. What should I do now? First, you should be able to isolate which line the short is on using an ohm meter. Then You need to figure out which caps are on the +12v or -12v traces depending on where the short is. (someone here should be able to help with that. ie schematic which I don't have immedediate access to) Then you'll need to start clipping off caps untill the short goes away.

modem7
June 9th, 2012, 02:11 PM
First, confirm that all expansion cards (including video card) have been removed from the motherboard.

On the assumption that you did, yes, there is a short on either the +12V line or the -12V line on the 5155/5160 motherboard. Or, it be both.
As you may have seen, we are daling with that siuation now with the 5155 thread started by latvija13.

On the 5155/5160 motherboard, the only devices on the +/-12V lines are capacitors.
The capacitors are:
+12V line: Capacitors C56 (10 uF tantalum) and C55.
-12V line: Capacitors C58 (10 uF tantalum) and C57.

It is the tantalums that often fail.

As ibmapc wrote, a resistance check will inform you as to which line is short. You would then remove the tantalum cap on that line, then confirm that that action removed the short.

Alternatively, you could simply cut off C56 first, see if that corrects the problem, and if not, then cut off C58.

The 5155/5160 motherboard will operate without C56/C58, but ideally, you should fit a replacement/s later for the shorted capacitor/s.

CannedBread
June 10th, 2012, 02:34 AM
I checked all the capacitors, and all of them gave a reading on the outside legs, but C58 did on all 3 legs. Does this mean it's shorted?

modem7
June 10th, 2012, 03:44 AM
I checked all the capacitors, and all of them gave a reading on the outside legs, but C58 did on all 3 legs. Does this mean it's shorted?
You didn't confirm that all expansion cards have been removed from the motherboard. I'll assume that they are removed.

It sounds like you did resistance checks on the actual capacitors. Your measurement results don't mean that C58 is shorted, because if C57 (being in parallel) is shorted instead of C58, you'd see the same results. It tells us that there is a short on the -12V line, and because C57 and C58 are the only motherboard devices on the line, one (or possibly both) are short circuit. C58 being of the troublesome tantalum type is highly suspect. Try removing it (by desolder, or clip it off) and then see if your problem has gone.

CannedBread
June 10th, 2012, 04:17 AM
That appears to have done the trick, with both the P9 and P8 connectors plugged in, the fan comes on and the speaker does one long then two short beeps. Should I put it back together and test the video?

and yes, I removed all the cards, on the motherboard and speaker are plugged in.

modem7
June 10th, 2012, 04:31 AM
That appears to have done the trick, with both the P9 and P8 connectors plugged in, the fan comes on and the speaker does one long then two short beeps. Should I put it back together and test the video?
An early post of yours shows that C8 on the CGA card is damaged. It might be short. If you haven't already removed C8, then do so. If/when C8 is removed, then yes, I'd say it's time to see if it all works when reassembled.

CannedBread
June 10th, 2012, 05:06 AM
After removing C8, I put everything back in the case and plugged it in, but no text comes on the screen. Just a very faint line about 1/3 down from the top of the CRT. Does this mean the CGA card is still broken or the CRT? It's too faint to get a picture of.

mikey99
June 10th, 2012, 05:51 AM
How does the internal display attach to the CGA card ? I recall its through a small cable
that attaches to a header (pins) on the CGA card. Make sure this cable isn't damaged and
is oriented correctly. Do you have access to any other PC where you could test the CGA card ?

Also, the IBM CGA card has a composite video output connector that could be attached to
a TV or other device with a composite video input.

ibmapc
June 10th, 2012, 12:15 PM
How does the internal display attach to the CGA card ? I recall its through a small cable
that attaches to a header (pins) on the CGA card. Make sure this cable isn't damaged and
is oriented correctly. Do you have access to any other PC where you could test the CGA card ?

Also, the IBM CGA card has a composite video output connector that could be attached to
a TV or other device with a composite video input.
There is a four pin header, with one pin (2nd from the top) removed for keying, that is used for an RF
modulator and is also where the cable for the 5155's monitor connects. Unless the the 3rd pin from the top is missing, then the cable to the monitor can only connect in one direction.

To OP
To bad you're accross the pond from me. I have a spare CGA card that I would be willing to loan to you for testing purposes, but I fear shipping would not be cheap. If you would like to look into the cost of shipping from Oregon, USA to your location, maybe something could be worked out. To be honest, that "faint line" sounds like a fault in the monitor, not the CGA card.

modem7
June 10th, 2012, 01:51 PM
Also, the IBM CGA card has a composite video output connector that could be attached to a TV or other device with a composite video input.
Also, for those who have a CGA monitor, hooking that up to the CGA card's external 9 pin connector will show video on the monitor.


There is a four pin header, with one pin (2nd from the top) removed for keying, that is used for an RF modulator and is also where the cable for the 5155's monitor connects.
As circled (or should that be "ovaled") below:

http://www.minuszerodegrees.net/5155/photo/ibm_cga_p1.jpg

CannedBread
June 11th, 2012, 08:26 AM
When I took the CGA card out and turned it on, the CRT lit up:

9306

Does this mean the CRT isn't broken?

ibmapc
June 11th, 2012, 11:07 AM
When I took the CGA card out and turned it on, the CRT lit up:

9306

Does this mean the CRT isn't broken?
Nope. That's how it looks without an incoming signal(nothing attached).

modem7
June 12th, 2012, 02:37 AM
Confirm that switches 5 and 6 on the motherboard are set per:
5 = on
6 = off

CannedBread
June 12th, 2012, 07:42 AM
Aha! switch 6 was on. I turned it on, and now it counts up the memory :)

Not quite fixed yet I fear, it gets to 256kb, and then resets. Is it to do with the expansion board (I think that's what it is), or are the switches still wrong?

Switches are:

1 = on
2 = off
3 = off
4 = off
5 = on
6 = off
7 = off
8 = on

marcoguy
June 12th, 2012, 08:21 AM
If that is the same as a 5160 mobo, switch 1 needs to be off or it will put it in a loop test (Exactly what it's doing, by the sounds of it)

ibmapc
June 12th, 2012, 11:23 AM
Aha! switch 6 was on. I turned it on, and now it counts up the memory :)

Not quite fixed yet I fear, it gets to 256kb, and then resets. Is it to do with the expansion board (I think that's what it is), or are the switches still wrong?

Switches are:

1 = on
2 = off
3 = off
4 = off
5 = on
6 = off
7 = off
8 = on

Switch #2 is suspect. Do you have a math coprocessor?(8087) If not, #2 should be on for "dissable"

Ole Juul
June 12th, 2012, 11:48 AM
Marcoguy and ibmapc are both right. But for goodness sake, there is no discussion or arguing about these switch settings. You set them for what you've got and leave them alone. :)

marcoguy
June 12th, 2012, 12:35 PM
As far as switch 2 goes, I have messed with that switch multiple times and found that it doesn't really matter if you don't have a 8087. The only time it matters is that if you have an 8087 installed and the switch set to disabled, you can't use it.

CannedBread
June 17th, 2012, 02:47 AM
It works, hurray! Thank you all for helping :D

9386

The only problems now are that it doesn't seem to pick up the additional memory from the Quadboard (it counts to 256KB), so I assume that doesn't work (the only visible problem is a corroded battery, and a DIP switch I messed with). Also, the 1 key on the keyboard doesn't work, but it does on the numpad (I just hope I don't kneed an ! any time soon!). But other than that, it works fine :)

What should I do about the capacitors I removed? I suppose I can replace them with modern ones, but does anyone know the type they were? I removed C58 on the motherboard and C8 on the CGA card. Thank you again for helping :)

modem7
June 17th, 2012, 03:13 AM
The only problems now are that it doesn't seem to pick up the additional memory from the Quadboard (it counts to 256KB), so I assume that doesn't work (the only visible problem is a corroded battery, and a DIP switch I messed with).

Possible causes:
1. DIP switch settings on Quadboard are now wrong (likely because of your, "and a DIP switch I messed with").
2. Failure of one the Quadboard's RAM chips.

The RAM related switch settings for the Quadboard are controlled by SW1 (switch 1) - shown at http://www.minuszerodegrees.net/images2/quadboard_switch1.jpg
Try setting Quadboard SW1 to ON/OFF/ON/ON/ON/ON/ON/ON (start at 256K, populated with 256K of RAM).


(the only visible problem is a corroded battery,
You need to remove that battery before it does damage.
The purpose of the battery is to keep the real time clock on the Quadboard going (ticking) when the 5155 has no power.


Also, the 1 key on the keyboard doesn't work,
Try removing it (it pulls out) and then putting it back in.

modem7
June 17th, 2012, 03:45 AM
What should I do about the capacitors I removed? I suppose I can replace them with modern ones, but does anyone know the type they were? I removed C58 on the motherboard and C8 on the CGA card. Thank you again for helping :)
I've confirmed that both capacitors are 10uF/16V 3-legged tantalum with negative-positive-negative pin configuration.
They are available at Mouser Electronics:
Mouser part number is 80-T398E106M16AT
(Kemet part number is T398E106M016AT)

Alternatively, you can use 2-legged 10uF/16V tantalums if you observe correct polarity - positive leg into positive hole and negative leg into negative hole.
2-legged tantalums will be easier to locate.
http://www.minuszerodegrees.net/failure/tantalum_2l_in_3l_hole_npn.jpg

CannedBread
June 17th, 2012, 06:26 AM
I had to fiddle around with the 1 key, but it works now. I removed the battery (pulled it out), and set the switches as you said, but when I turn it on it says:

301
256 KB OK
ERROR. (F1 TO RESUME)

f1 didn't do anything.

After booting a couple of times, it now just counts to 256 as normal.
I think the battery had been bad for a long time, and it doesn't look good...

93879388

ChrisCwmbran
June 17th, 2012, 06:56 AM
I would think that is saveable. It only appears to be a single track on the PCB that is really damaged.

I'm sure that someone here can advise better than me, but I'd think either with care and the use of some conductive paint that you could fix that.

If you follow that track and check the continuity between either end does it still work?

I suspect that the battery damage there isn't why that board isnt working though.

If I recall correctly, isnt a 301 error a keyboard error?

Chuck(G)
June 17th, 2012, 08:30 AM
Use some fine wire (I use AWG 30 wire-wrap wire) and connect the endpoints of the bad trace. Tack the middle of the wire to the board (to keep it from getting snagged) using clear nail polish or some glue (Duco would be good, but even a couple of drops of Gorilla glue would work--the advantage of nail polish is that it dries quickly).

pearce_jj
June 17th, 2012, 10:09 AM
Re keyboard, they are a picky at this age. The problem is that the foam inside will be degraded and somewhat powdery, and gets where it shouldn't. Often I find 301's are resolved (for a while) by giving the keyboard a sharp tap against the bench.

ibmapc
June 17th, 2012, 04:56 PM
Actually the 5155 keyboard doesn't have any foam inside. It can get dirt and corrosion inside though, both of which can be remedied with a complete dissasembly and cleaning. I've done this on mine. It's not for the faint of heart though. It's a long and tricky proccess, especially the reassembly. Sometimes some of the buckling springs don't go back in quite right and won't buckle.

modem7
June 18th, 2012, 12:27 AM
I had to fiddle around with the 1 key, but it works now. I removed the battery (pulled it out), and set the switches as you said, but when I turn it on it says:

301
256 KB OK
ERROR. (F1 TO RESUME)

f1 didn't do anything.
After booting a couple of times, it now just counts to 256 as normal.
Your last sentence suggests to me that the "301" (keyboard) error disappeared.

Regarding the RAM count-up of only 256K.
The Quadboard manual is at http://www.minuszerodegrees.net/manuals.htm
The layout of the four RAM banks is shown on page 6 (PDF page 5). How many of the four banks on your card are populated with RAM chips?
If there are less than four, then:
1. Ensure that the banks are populated in order - 1st, 2nd, 3rd, 4th.
2. Adjust SW1 to reflect the number of populated banks.

If the damaged track is open circuit, then obviously that may be the cause of the Quadboard's RAM not functioning.

Another possibility that I mentioned earlier is that of failure of RAM chips. It is due to the methodology that the IBM 5155/5160 uses to determine how much conventional RAM there is. Because of that, if one or more chips in the Quadboard's first RAM bank has failed, the 5155/5160 will incorrectly determine that the bank of RAM does not exist, and thus stop after counting 256K of motherboard RAM.
Try swapping the chips between the first and second banks and then seeing if your 5155 then counts past 256K to 320. For that to work, all the chips originally in the second bank need to be good, and so if you don't see a count to 320K, then swap the chips between the first and third banks, etc.

CannedBread
June 18th, 2012, 08:15 AM
Counting the RAM chips on the board, there are 9 rows of 6 chips. There is also only 1 DIP switch, where as in the .pdf there are 2. I don't know if this means anything, but on the board it says REV-6 under the RAM chips, and there is a sticker on the bottom that says it's trade name is QUADBOARD 384.Also, the board is from 1984, but the manual is dated 1982.

9396

I counted 4 wires already on the board, joining various parts that look slightly damaged.

marcoguy
June 18th, 2012, 09:05 AM
If Quadboard 384 means it has 384k on it, the system is likely not reading any of it's memory and only reading the mobo's 256k memory.

modem7
June 19th, 2012, 12:24 AM
Counting the RAM chips on the board, there are 9 rows of 6 chips. There is also only 1 DIP switch, where as in the .pdf there are 2. I don't know if this means anything, but on the board it says REV-6 under the RAM chips, and there is a sticker on the bottom that says it's trade name is Quadboard 384.Also, the board is from 1984, but the manual is dated 1982.
Okay. So I now know that there are variations of the Quadboard. Your Quadboard's "9 rows of 6 chips" is six of 64 KB sized banks (totalling 384 KB).

The switch and jumper settings for your '384' version appear to be at http://th99.dyndns.org/i/P-R/52510.htm
It's a good match to your card.
The column name of "SIZE" in the "DRAM SWITCH CONFIGURATION" section is obviously wrong. That will be the starting address for the RAM.
So try setting SW1 to:

1=on: Game port enabled
2=on: Clock/calendar enabled
3=on: Parity for Quadboard RAM enabled
4=on: Quadboard RAM enabled

5=on / 6=off / 7=on / 8=on: Start Quadboard RAM at address 256KB