Fixing Video Cards (Compaq Portable 486)

[raisedabar]

I have a Compaq Portable 486 (actually, I have quite a few compaq portables), I absolutely love, okay, that's a little strong, more like -- really, really like these machines... let's say the video card goes bad for whatever reason. Is it possible to fix it? I mean with available parts today or is there ever a time when, regardless, the card is just deemed unrepairable?

 

[Agent Orange]

I have a Compaq Portable 486 (actually, I have quite a few compaq portables), I absolutely love, okay, that's a little strong, more like -- really, really like these machines... let's say the video card goes bad for whatever reason. Is it possible to fix it? I mean with available parts today or is there ever a time when, regardless, the card is just deemed unrepairable?

Yes, it's possible to fix it if you have a tub of parts and the right tools at your disposal. What with the availability of legacy video cards these days, why would you what to? I might take it on if were the the last card on earth. Don't have the time, patience, or desire anymore.

 

[raisedabar]

It is pretty tough finding the parts you need, or at least for me. So by asking that question, it gives hope as the a very possible last resort solution =)

I am still narrowing down the culprit so to speak. My machine boots up right away straight into Windows 3.1 wavy hort. lines moving up and down the screen. It almost looks like interference or something... reminds me when I had my old CRT monitor too close to an oscillating fan and could figure out why monitor all of a sudden had these tweaking wavy lines, then I move the fan and it was gone... it is very similar to that only I do not have a fan near my computer. I took the entire computer apart thinking it might be a loose ribbon, tighten and refitted the ribbon (I forgot to clean the ribbon) and nada, still look the same. Maybe in my mind after doing all that I told myself it looked like it improve it, but it didn't. If you know of any good resources, places that known for having vintage parts, I would be much obliged... thanks in advance!

 

[MikeS]

Yes, it's possible to fix it if you have a tub of parts and the right tools at your disposal. What with the availability of legacy video cards these days, why would you what to? I might take it on if were the the last card on earth. Don't have the time, patience, or desire anymore.

Do you even know what a Portable 486 is? If cards for it are so available, why not be really helpful and post a link to an available one somewhere...

 

[MikeS]

I have a Compaq Portable 486 (actually, I have quite a few compaq portables), I absolutely love, okay, that's a little strong, more like -- really, really like these machines... let's say the video card goes bad for whatever reason. Is it possible to fix it? I mean with available parts today or is there ever a time when, regardless, the card is just deemed unrepairable?

Most components needed for repairs are still readily available except for some specialized parts unique to a certain piece of equipment, and even those are often reverse engineered and remanufactured or emulated. The trouble is finding documentation and someone with the necessary knowledge, equipment and experience; replacement assemblies or even a spare machine for parts are always a good idea if you can find them.

Is your problem on the internal monitor, the external, or both? Kind of sounds like it might be a power supply issue; don't suppose you have an oscilloscope or a friend with one?

 

[raisedabar]

Is your problem on the internal monitor, the external, or both? Kind of sounds like it might be a power supply issue; don't suppose you have an oscilloscope or a friend with one?

No, I do not own an oscilloscope, but it sounds like I should... can it be a handheld? Any suggestions?
- I think I should pick one up
- Then learn how to use it =)
I have only tested with the internal monitor. I could not use an external monitor because its not vga... hmm, powersupply... I heard that before. Thank you. I will see if swapping that out fixes it.

 

[Agent Orange]

Do you even know what a Portable 486 is? If cards for it are so available, why not be really helpful and post a link to an available one somewhere...

So, you in the business of repairing video cards - got the schematics and all? Mike, why don't you finish your nap.

 

[Chuck(G)]

I have only tested with the internal monitor. I could not use an external monitor because its not vga... hmm, powersupply... I heard that before. Thank you. I will see if swapping that out fixes it.

It sounds as if you have the monochrome display 486, but you can still hook up a VGA monitor (at least according to the manual).

That aside, the wavy bar thing sounds almost like what's called "hum bars", caused by AC getting into the power supply outputs. Perhaps recapping the PSU is all that's required.

 

[raisedabar]

Hi all, thanks for all your assistance. I really do appreciate every comment because I am new to the vintage computer world. I just think its so cool that I can now own the computers I dreamed of owning when I was young but
couldn't, albeit a little needed tinkering, but that's the fun part right.

That aside, the wavy bar thing sounds almost like what's called "hum bars", caused by AC getting into the power supply outputs. Perhaps recapping the PSU is all that's required.

So if I had an oscilloscope I could test the capacitors in the power supply to see if they are good or not... Is that how it works. If so, very cool... that seems like it would save me some trial and error.

It sounds as if you have the monochrome display 486, but you can still hook up a VGA monitor (at least according to the manual).

Yes, this is for my mono 486 (I have both, 486/c and 486 mono) but on my video card the connector is missing a hole, its made that way so when I to plug my vga connector to it, it can not because there are more pins on the vga connector than the video card connector <= phew, that's long winded... that's what happens when you are not familiar with the terminology =)

Thanks again Agent Orange, MikeS and Chuck(G) for taking the time and helping a newbie =)

 

[Chuck(G)]

Well, I suppose a 'scope might tell you which power supply line needed attention, but the simples thing to try is to replace all capacitors in the power supply that are 470 uF or larger. Electrolytic capacitors eventually dry out (especially when they're run in a hot environment) and need to be replaced. Not a designed-in failure mode; just The Way Things Are.

 

[raisedabar]

Well, I suppose a 'scope might tell you which power supply line needed attention, but the simples thing to try is to replace all capacitors in the power supply that are 470 uF or larger. Electrolytic capacitors eventually dry out (especially when they're run in a hot environment) and need to be replaced. Not a designed-in failure mode; just The Way Things Are.

Okay Chuck... I like simple. I will pull out the PSU and have a looksie... I could just buy these 470 uF capacitors at any electronics store, they are pretty standard, no need for the vintage stuff? Thanks for pointing me in the right direction.

 

[Chuck(G)]

Note that I said "470 uF and above", so that would include things like 1000 uF, 2200 uF, etc. I tend to use eBay for the stuff--I'm in no hurry and I usually get shipments from China in about a week. That suits me. There are some good guides on what to do and what not to do on the web when re-capping.

You might think about pulling the PSU from your 486C, if it's the same, just to see if the problem goes away when you swap it in. That would certainly confirm that what you're looking at is a capacitor issue.

 

[raisedabar]

You might think about pulling the PSU from your 486C, if it's the same, just to see if the problem goes away when you swap it in. That would certainly confirm that what you're looking at is a capacitor issue.

That exactly what I was going to do... I am checking to see if they are the same before I swap... less I make things worst =)

 

[raisedabar]

Okay, I did not get a chance to check the PSU... got sidetrack with another computer the logic board for one of my macs came in and I had to do that first =)

This weekend for sure...

UPDATE:
Yea, just got the word that my new purchase will be sent out next week, so I will have yet another color 486... gotta have backups. So I really got to learn this recapping so I can prolong my toys... I was almost going to post a resource for a company that had new PSU in stock, I thought I hit the jackpot, and maybe they had all the overstock... then they called back and said its unavailable... they got my hopes up... I guess I was being naive because after what you said Chuck... just sitting on the shelf, even though they are new they would go bad after 20+ years... the only sure way is to know how to fix them yourself... which leads to my next post...

 

[raisedabar]

I have another question related to above but will create a new POST instead...