IBM 5150 Restoration

[Theretrogamingroom]

A little about my system: Not too long ago, I picked up an IBM 5150 with keyboard, a couple of Okidata printers, and a bunch of manuals and disks (Including the Guide to Operations, BASIC, and DOS boxes), as well as a Princeton Monitor. Installed in the system are 2 5-1/4" Single Height Floppy Drives, a Single Height Hard Drive (Unknown size, probably around 5-10MB), and fully used expansion card slots, which is easy to do, given that there are only 5 slots (well, there are really only 2 slots available when you consider that 3 are used by graphics, floppy, and hard drive controller cards in my configuration). Aside from what I believe is a Color Graphics/Printer card (I received a color monitor, which theoretically the card is color?), floppy drive controller card, and hard drive controller card, there is a modem (Unknown manufacturer- black in color. I will probably uninstall this and replace it with a color graphics card for dual displays or a sound blaster card) and an AST SuperPak (Which should boost my ram to 640k, given that I have a later board with I believe 256k built in).

Anyways, I recently got around to restoring this. I had some concerns, given that it is so old. One of these was that something might blow up as it wasn't used in some time...

And guess what happened?

The second I flipped the power switch, a tantalum capacitor exploded (C13). I figured that would happen, given that the previous owners have long since left it unused, but what can you do? Anyways, although I would like to replace the capacitor, I don't have any soldering skills (yet), and because I would much rather leave the system as-is (and not potentially mess it more with bad soldering/messing with the inside of the system in general), I would much rather not make any changes, other than removing the cap. Is it possible to still use the system with it taken out? Could I simply snip it off and not worry about it?

Thanks

 

[fatwizard]

Exploding capacitors are just going to happen on this old equipment. Since I started working with the old ones, I've learned, before I fire up any new acquisition, to warn the wife so she can dive under her desk. Unfortunately I doubt you can expect normal operation of the motherboard without replacement of the blown component.

Also, the graphics/printer port combo card is typically mono graphics. I'm sure there are exceptions however. Is it a full length card? With more details I'm sure it could be identified.

I have been soldering all my adult life, but I totally understand not wanting to start learning on a prized antique. If I had the board here, I could repair it quick enough. The motherboard has to come out for repair, so if you can do the diss assembly and reassembly it saves having to ship the whole PC for repair. I'm pretty new here, so perhaps someone on the forum would have a better recommendation for your motherboard repair.

 

[modem7]

A little about my system: Not too long ago, I picked up an IBM 5150 with keyboard

The second I flipped the power switch, a tantalum capacitor exploded (C13).

From the circuit diagrams of the two types of 5150 motherboard:
16KB-64KB: Capacitor designations only go as high as C9 (includes many caps named "C3", 6 caps named "C6", and 11 caps named "C7")
64KB-256KB: Capacitor designations only go as high as C9 (includes 23 caps named "C3" and 14 caps named "C7")

You can't have a 5150 motherboard. Your motherboard, having C13 on, sounds more like a 5160 motherboard. And a 5160 ties in with the presence of a hard drive.

A 5150 motherboard will have one of the following two markings.

 

[Theretrogamingroom]

The graphics card isn't full length. I was thinking that the graphics card was monochrome too, its just weird that they would have a color monitor with said card.

The motherboard has the 64KB-256KB CPU as shown in the bottom picture. My IBM 5150 also only has 5 expansion slots, unlike the 5160, which has 8. The hard drive might have been added on later, as with the floppies. I don't think that I got the cap designation wrong, but I'll check again.

 

[arrow_runner]

I would suggest that you find some scrap electronics and watch some youtube videos on soldering. If one cap goes bad in a system, I usually replace all of that type of capacitor. And as fatwizard said, exploding/bad/leaking capacitors is almost the norm for older electronics. If don't plan on messing with anything but your 5150 then you might be better off finding someone to send or take the board to for repair.

I wouldn't recommend just pulling the capacitor and leaving it like that, especially without knowing how it fits into the circuit design.

 

[MikeS]

Why not actually see what it says on the display adapter (not necessarily a "graphics card") and the other ones including the HD while you're at it, instead of just guessing/assuming?

You might also mention whether the system actually works or not; if it works with the exploded cap then you're probably OK.

 

[SpidersWeb]

I wouldn't cut your teeth by learning to desolder/solder those caps on a 5150. The pads are small and the solder goes through the board - tricky for a beginner. Last time I did a bunch I heated from one side with a fine tip, and had my girlfriend use an air pump on the other. Personally I'm waiting until I have a proper temp controlled desoldering station with an electric air pump - so I can do a fast and clean job - and get all of them at once.

In the mean time the machine should run fine, I have a 5160 with four of those caps missing and it's never given me any grief. (Although if it became unstable, it would be the first thing I replace).

 

[vwestlife]

My 5150 PC blew two of those tantalum caps -- one on the motherboard and another on the CGA card. After removing the remains of both, it continues to run fine without replacing them. Those are just ground filtering caps; they serve no active purpose other than to help remove electrical noise that might develop in the circuitry.