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Sharp PC-6220

T

Twospruces

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Any thoughts about this machine? There is one for sale locally and at first in was keen. 12MHz, compact, AT, internal HDD. But...it has one of those connor 20MB drives. And no floppy.

I'm thinking an XT CF card might be really hard to accomplish.

Getting files in and out is via serial cable. Ouch.

Am I looking at this correctly?

Thx
 
Twospruces said:
Any thoughts about this machine? There is one for sale locally and at first in was keen. 12MHz, compact, AT, internal HDD. But...it has one of those connor 20MB drives. And no floppy.
Click to expand...
Some info at [here] and [here].

Twospruces said:
I'm thinking an XT CF card might be really hard to accomplish.
Click to expand...
From what I see/read, you would need the optional expansion unit to host it.

Twospruces said:
Getting files in and out is via serial cable. Ouch.
Click to expand...
Also, a parallel port.
 
thanks, appreciate the note. That system connector sounds promising. need a pinout! Guess I need to download that service manual.
 
So, I could not resist, and I picked up this non-functional PC-6220.
And yes it was certainly non functional. The Nicd battery pack was just a mess and done for.

Some nice surprises:
* it came with an external FDD, so that helps to transfer files
* it was fully intact, just not working

Or course, I tore into it to find the issue. And.. I did.
The PSU needed to be recapped. It was a real learning experience. Under my microscope, all of the surface mount electrolytic caps had beads of fluid on their pins, and some of the pins were quite corroded.

Anyhow, I found enough parts in my various bins to get the nasty caps swapped, et voila! A perfectly fine PC-6220.

Best of all, I found the service manual for 6$ online. and I have what I need to make an XT-CF adaptation.

Other nice surprises:
* what a nice piece of compact engineering! very impressive
* the old Connor 20MB disk is working fine. Quite loud though. I wonder if that means imminent death.
* the LCD is really super nice and readable - which is why I ultimately wanted it as an improvement over my Zenith Z-171.

So, stage 1 success.
stage2 = add 80C287 and a homemade nimh batt pack
stage3 = design a clever XT-CF adaptation (and get away from that loud spinning disk
 
I must say I am really thrilled with this ultra compact AT machine!

It is all working great. Added an 80287 chip also. I'm using it to develop an algorithm in Turbo C.

All in all, an excellent compactly engineered machine. Really very nice. I'm not going to bother with adding a CF card until I have to. The Prarietek 120 is spinning away just fine as it is.

There are only a few threads here on this machine. I can only assume there weren't many sold. They were quite pricey at the time.

Anyhow, now with the schematic available, the power supply fix is pretty straight forward. Other machines may be saveable.
 
I see that I never really finished this story. So this cool little laptop had an 80287 socket... should have been an easy upgrade right?

So I bought an IIT 80287 compatible chip off ebay. With excitement I plugged it in... no go! Why??!?!!

Luckily I have a scope and a schematic.
So I dig in. Turns out one of the signals between cpu and 80287 was open circuit! Shock.

I can't see any board defects to explain the open circuit. So, I bodge wire it up. To my general surprise that fixes the issue! I wonder if I just got really unlucky and had a board defect, or was this a design issue?

End result a nice compact fully equipped pc-6220. I still think this is a great example of a low power compact design. Reminds me of the evolution path that the trs80 m100 to tandy 200 could have been.
 
Twospruces said:
So, I could not resist, and I picked up this non-functional PC-6220.
And yes it was certainly non functional. The Nicd battery pack was just a mess and done for.

Some nice surprises:
* it came with an external FDD, so that helps to transfer files
* it was fully intact, just not working

Or course, I tore into it to find the issue. And.. I did.
The PSU needed to be recapped. It was a real learning experience. Under my microscope, all of the surface mount electrolytic caps had beads of fluid on their pins, and some of the pins were quite corroded.

Anyhow, I found enough parts in my various bins to get the nasty caps swapped, et voila! A perfectly fine PC-6220.

Best of all, I found the service manual for 6$ online. and I have what I need to make an XT-CF adaptation.

Other nice surprises:
* what a nice piece of compact engineering! very impressive
* the old Connor 20MB disk is working fine. Quite loud though. I wonder if that means imminent death.
* the LCD is really super nice and readable - which is why I ultimately wanted it as an improvement over my Zenith Z-171.

So, stage 1 success.
stage2 = add 80C287 and a homemade nimh batt pack
stage3 = design a clever XT-CF adaptation (and get away from that loud spinning disk
Click to expand...
Did you need replace all capacitors on the power supply board? Photo of mine attached here. Further away it looks clean. But I suspect something being wrong there.
I've got here TravelMate 2000 (same as PC-6220) which is dead, no single light coming on. I bought it new sometime 1990/91. 80287 was added around 1993. Battery died 10 years ago and was leaking inside.
 

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jmenninkainen said:
Did you need replace all capacitors on the power supply board? Photo of mine attached here. Further away it looks clean. But I suspect something being wrong there.
I've got here TravelMate 2000 (same as PC-6220) which is dead, no single light coming on. I bought it new sometime 1990/91. 80287 was added around 1993. Battery died 10 years ago and was leaking inside.
Click to expand...
I did replace most or all of the eletrolytic caps. I found spares that I could make work. I did not order any new parts this time. Kind of a hack job.

Do you have the schematic? It is posted at minuszerodegrees.
 
Thanks for advice. I have been staring at the schema at minuszerodegrees. And trying to understand. I'm not so familiar with this.

Capacitors don't look very bad, heads not exploded, not awful clear leaking. I was measuring some of those, and values looked just fine - on my understanding. But maybe... one, or some, of those is broken, or tired.

But clearly output voltages from the board aren't right, only the 15V (from power source) goes through. Now suspecting *TR3 transistor being dead. Signal shapes all dead - so far I can see.

Nice to see there is somebody else interested on this old computer :-)
 
Hard to see the board damage unless you lift a Cap to see under. I would recommend that you try to recap and as you do that, visually inspect. Goodluck, very tricky to follow the way that JRC psu works.
 
Tr3 drives the gate of the switching fet.
Is the signal SW-DRIVE also flatline?

For this psu to come on you need 5V at the controller.

Check that IC2 is regulating 5V.
 
I just got one of these in an unopened box. Can you please confirm if it requires the battery to be installed in order to turn it on @Twospruces?

Also, were you able to add a NiMH battery pack and replace the hard disk with a CF card?
 
I don't recall any specifics anymore. I would have to reacquaint myself with this.
In my 6220, the hdd was fine. I think the only real challenge was getting the JRC psu rebuilt. The electrolytic had all leaked.
I did not bother with attempting an nimh battery pack. Mine runs on the adapter only.
 
Thank you! I have found the manual here and I believe my unit needs a repair even though it is NOS because it's not turning on using the AC adapter only (I didn't bother trying the battery).

I have no experience performing this type of repair though so I have no idea where to start.
 
Repairing this little psu module is not easy. I've been doing this a long time and I am an electrical engineer. I saw that ebay auction, and I thought there was zero chance it will work without some repairs.

I have also found that the pc6220 is a little fragile inside, so I recommend being very gentle with things when disassembling and reassembling.

Unfortunately I'm not in a position to be able to help you out. Maybe someone on this forum would be into such work for the learning experience. I believe the biggest expenses are the shipping and the time. Parts are not pricey. With the schematic available, it is very repairable.
 
No problem! Thank you for the information. The PSU you had to repair is the same one of the pictures shared above? Did you replace only the capacitors?

I used to have a machine like this in the past - in fact it was the first computer we owned at home! I was on the lookout for a while already.
 
I did pull and replace all of the electrolytic. The tougher issue is cleaning the board and repairing damaged traces.
Possibly there is a cmos battery on board to replace.
 
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