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IBM ps2 P70 portable repair thread

First one is fitted with a 486 75mhz overdrive. The one with the fan is a 586 133mhz. Both have 64MB memory.
You also have a choice of going to the original 386 during boot, and then it's like the MCMaster isn't even there.

mc1.jpgmc2.jpg
 
Torch said:
First one is fitted with a 486 75mhz overdrive. The one with the fan is a 586 133mhz. Both have 64MB memory.
You also have a choice of going to the original 386 during boot, and then it's like the MCMaster isn't even there.

View attachment 1275496View attachment 1275497
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Our boards have a different layout. Look at my photos and you will see the 386 slot is to the left of the 387 socket. yours is up behind the top MCA board.
 
Yeah, they're not even close, I wonder what the reason was for the design change?
I'll have to run checkit and see how the numbers compare. They are impressive for a late 80s portable.
 
oh yes. I love luggables and this one has a design all its own. Too bad it had to be microchannel.

I dunno, for a second I thought maybe you had a P75 but those are 486 cpus.
 
I ran Checkit on both of my P70s. For some reason it doesn't seem to like the 75mhz Intel overdrive as it's reporting unrealistically high.
I see yours is also reporting 307mhz, yet it's only 12.04X faster than an XT? Mine in original 386 mode is reporting 19.99mhz and 12.35X faster than an XT. Dhrystones on mine is also 4250 vs yours at 4143. Did you do a benchmark on your original 386? It seems your performance may have went down slightly. Do those games play better with the 486 installed?

The system with the 586 133mhz seems to be accurate, see photo below.

For disk drives, I removed my original 3.5 drives and picked up some new Memorex drives when they were $4 including shipping on Amazon. They even included cables that I modified to work with the P70. Fit beautifully, only thing I couldn't make work was the blue eject button off the originals. One of these days I'll replace the bad caps on the originals.
As far as batteries, mine use a Duracell 223.

ckit3.jpg

ckit2.jpg

ckit4.jpg
 
This is the way i bought it. With the 486 Cyrix. The seller didnt have the original 386 so i never got to try it stock.
 
VERAULT said:
Was the corrosion to bad to replace them? I think there are 5 caps in total. I did two and my drive started working I have the other bipolar caps on order as a preventative measure. Do you still have the broken drive?
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I still have the broken drive. Yeah the corrosion was pretty bad, I recall the pads being gone on at least one of the caps. I might have pics, I’ll check.
VERAULT said:
Networking would be nice but it’s not the end of the world now that I have a CF card hdd setup.
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Wow, I didn’t know there was an MCA CF card option, that’s awesome. I thought you were kinda screwed if you didn’t have one of those rare ESDI hard drives.

VERAULT said:
But I think I am going to go with the adlib card clone for the mca bus by texelec for a few dollars less, check it out: https://texelec.com/product/resound...ble-card-for-ibm-ps-2-microchannel-computers/
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This sounds like a great option, I may have to pick up one of these too. I like the idea of routing audio to the internal speaker.

You motivated me to turn on my machine after 1.5 yrs. I had to try starting it multiple times but eventually fired up. Plasma screen isn’t working again so used the external VGA. My hard drive still boots fortunately, I think it’s around 120MB drive. I’ll have to try getting some more software on the drive. Not much on there now as I did a fresh DOS install previously.
 
agentb said:
These are the only two I have handy right now:

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Im not seeing any pad issues. Are these old photos before you attempted repair. I do see trace damage from leaky caps but all the caps are still in place.

Anyway. If you got a new floppy and have no use for it. Would you sell it for the cost of shipping? If I can fix it it would be a good backup for my system since I only own one ps/2 system.
 
Thanks for the post! I just fixed mine this week (keyboard fuse busted) and you inspired me to get the cf and resound 2 mca cards. Did you figure out sd2lpt? Seems like an interesting device. My floppy also died. I receive the capacitors today and will be replacing the 5 floppy caps tomorrow. Hoping to get this thing in tip top shape since it has been sitting on a shelf for 3 years.

Last thing I need is a mouse, but would really like it to be that classic offwhite look, but dont want to go pre-laser. I have had enough rolling the ball on a white piece of paper for one lifetime.
 
I'm about to restore a P70. I've got a couple of them but one of them is distinctly unloved so I'm going to start next week. I've ordered a McIDE-CF like you, and hoping it'll be a simple setup - any additional notes after you've been thrpough it?

I should be able to restore and service the floppy drive first...

I seem to remember last time I attempted this, I couldn't work out how to remove the floppy drive - any tips?
 
Ok so word of warning to anyone with a P70. I originally only had a fault with my floppy drive, which was fixed by replacing the 5 capacitors with ceramic sm ones, lubricating the corkscrew thing and cleaning the head with IPA.

All 5 surface mounted caps on my floppy were leaking and crusty. I used non-polarised ceramic caps as a replacement.
This got it working:

Starting Point



Top 3 original non-polarised caps going bad:



See the fishy crust?



Cleaned:



Replaced with ceramics:



Bottom two polarised caps:



See the even-worse fishy crust?



Cleaned and reflowed:



And replaced:



I then went to check out the backup battery and order a new one and without even touching the video card, when I turned the machine back on, no video output and a long, low beep - indicating a video board problem.

I reseated the card to no change, so I removed it and the 4 capacitors on it were all leaking - with C1 in particular beginning to eat through all the tiny tracks that go around it:



See how rotten the through-holes were going, so close to lots of tiny tracks? I got to mine probably in the nick of time...



And replaced. Amazingly this brought my video back to life!



If you have a P70, take the back off, remove some of the expansion card stuff, remove the video card and replace these caps today - if they're left much longer, no more video!

One last thing, if the backup battery is dead and you get a 163/161, the first time you load the reference disk it takes aaaagges to boot - this isn't a fault with the drive or the disk, it just hangs at about 2 minutes instead of booting from floppy. Have a cup of tea and give it a few minutes.
 
Last edited:
solidpro said:
Ok so word of warning to anyone with a P70. I originally only had a fault with my floppy drive, which was fixed by replacing the 5 capacitors with ceramic sm ones, lubricating the corkscrew thing and cleaning the head with IPA.

All 5 surface mounted caps on my floppy were leaking and crusty. I used non-polarised ceramic caps as a replacement.
This got it working:

Starting Point



Top 3 original non-polarised caps going bad:



See the fishy crust?



Cleaned:



Replaced with ceramics:



Bottom two polarised caps:



See the even-worse fishy crust?



Cleaned and reflowed:



And replaced:



I then went to check out the backup battery and order a new one and without even touching the video card, when I turned the machine back on, no video output and a long, low beep - indicating a video board problem.

I reseated the card to no change, so I removed it and the 4 capacitors on it were all leaking - with C1 in particular beginning to eat through all the tiny tracks that go around it:



See how rotten the through-holes were going, so close to lots of tiny tracks? I got to mine probably in the nick of time...



And replaced. Amazingly this brought my video back to life!



If you have a P70, take the back off, remove some of the expansion card stuff, remove the video card and replace these caps today - if they're left much longer, no more video!

One last thing, if the backup battery is dead and you get a 163/161, the first time you load the reference disk it takes aaaagges to boot - this isn't a fault with the drive or the disk, it just hangs at about 2 minutes instead of booting from floppy. Have a cup of tea and give it a few minutes.
Click to expand...
I wish you could have show some larger photos of the video board. Is it removable? Where is it in the system exactly? I have a sound card coming in so I can look into the machine again to address this. What are the values of this cap? is it polarized?
 
Sorry, I was in a stress because time was passing and I only meant to do the floppy and then was in a hurry going by a few ideas given to me at the time that the video board was the issue.

The video board most of the way across the top and has the external SVGA connector on it. You have to pull the power plug out of one end, then remove all the expansion bay metal including 6 of the connector bolts (for VGA, parallel etc) and finally about 4 screws holding it down (some with ground connections on them) and then you can slide if out of it's flat connector at a wierd angle. I'm going to have to do another one in a few days, so I'll take more detailed pictures of the work when I do that one.
 
Caps on the video board:

C1 10uf 50v
C3 47uf 25v
C4 10uf 25v
C6 22uf 25v

All standard, through-hole electrolytics.
 
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