PC-100 US Version

[albertofenini]

Hi Everyone,

We have acquired a PC-100 (can't remember now if A, C or just PC100 but we'll check and update the post) from the US
We would like to change the internal transformer in order to make it easily usable in Italy
Does anyone has done it before and know what specs the transformer needs to have ?

We could also open the European unit we have but we would prefer to avoid ...

Thanks for help !
take care !!!

[Maximilian Hohmann]

Hello!

Why not just use an external US->European (120V -> 240V) adapter? They cost next to nothing (I bought two for less than 10 Euros - together!) and come with the matching sockets for US mains plugs. No need to change cables or plugs, no risk to break anything and safe, hassle-free operation. In my view these things are essential for a collector, just as much as a regulated DC power supply and a multimeter.

Regards
Max

[albertofenini]

Hi Max

thanks for getting back to me,
it's a good point, we already have one that we use when we need to test
some US power supply for our calcs, and I agree it is a very affordable solution,
but we would like to go for something more definitive

Thanks for help !

[Maximilian Hohmann]

Hello Alberto,

(03-07-2022 03:05 PM)albertofenini Wrote:  ...but we would like to go for something more definitive.

I have several of these units but must confess that I never opened one. Doesn't seem difficult though. I found a picture of the inside on this website from the Netherlands: http://www.vintage-calculators.nl/P1000679as.jpg

You can see that there are four (!) cables coming from the secondary side of the transformer which either means three different voltages of two completetly separate supplies (which would be rather uncommon I guess). I don't think it will be easy to find a transformer of the correct size with the exact same windings. You will probably need to get one made...
However if you are lucky Ti used the same transformer for 110 and 220V and it actually has two primary windings. This is not visible in the picture above and will of course require to open the printer and remove the transformer...

Saluti
Max

[Maximilian Hohmann]

Hello again,

you made me curious enough to open one of my PC-100 Printers (this one is a PC-100C) to look inside and take some measurements.

This is what the transformer looks like from the bottom side:

http://www.bombie.de/tmp/20220308_114815_crop.jpg

Is is 67 x 55 x 48 (height) millimeters big. The power rating is 20W. There is only one primary winding for 220V and two separate secondary windings. Between the red and yellow cables I measure 24V and between green and blue there are 9.5V

Beside the transformer there is quite a lot of empty space in the housing. I am pretty sure that a small 110V to 220V tranformer (mayby taken out of one of those cheap adapters) would easily fit there. If I were you I would try that solution instead of finding a matching 220V transformer. Unless you can find a broken PC-100 that you can cannibalise for parts.

Hope that helps,
Max

[albertofenini]

Thank you very much !!!!
Over the weekend I'll open two of mine, a 220V and a 110V so that we can see
the differences, and I'll check if the transformer is the only real difference
I'll keep you posted !
Thanks again !

[Duane Hess]

I often type stuff in notepad over several days & paste into posts. Didn't notice Albertofenini and Maximilian's latest posts. I'll check my unit again. Maximilian's voltage measurements are very close to the schematic mentioned below.

Since Albertofenini has 110V & 220V versions, it'll be interesting to see what he finds. After all, we all know service manuals/schematics often often are not complete or different version levels.

Already typed the below, so now you must be punished! For your reading pleasure, but after the last 2 posts mine appears unnecesssary.

----------------------------------------------------------------------------

I'm in the USA and most consumer electronics from the 70's did not have universal power supplies. i.e. if its rated 115VAC on the product label it will only take that rating. i.e. using a plug adapter to convert physical types would blow stuff up.

I have a PC-100C and looked inside. There was no evidence of additional tap points on the transformer; i.e. not convertable between 115/120 & 220V.
*** note the transformer always runs when the power cord is plugged into the wall. i.e. some circuitry is live with the power switch off. This allows the spare battery charging feature to operate. Wanted to point out the internal supply (mains) connections are not well covered should you forget its plugged in & open it.

I found schematics at:
ti58c.phweb.me/download/system/PC-100B_Printer_Cradle.pdf
airy.rskey.org/CALCDOCS//TI/ti59-pc100-schematic.pdf
airy.rskey.org/CALCDOCS//TI/ti59-service-manual.pdf

One of the schematics has the voltage ratings on the secondary (circuitry) side of the transformer. I'll dig it out again and measure the voltages on my unit. Which you would expect to match the schematic voltages on the secondary sides. A cursory examination of the two schematics (one was a user supplied UK 220V PC-100B) show my unit is identical/very close to the schematics.

Have errands to run & will take a while to dig in my spare room again. So maybe later tonight I'll have voltage values. Hopefully they match the one schematic. That imply there is no difference in power with 100B/C models.

I feel funny making a TI post. Having about 200 calcs, I have one whole TI setup (TI-59 and the PC-100).

It will be interesting to see what you all find.

[Duane Hess]

*** Edited as prematurely posted somehow.

Measured the voltages across my transformer and they agree with Maximilian's and the ti58c.phweb.me schematics:
- Red-Yellow 23.5 VAC
- Green-Blue 9.2 VAC
This certainly implies if you can get a transformer that matches the power and voltage ratios you should be good. Tried to measure the ohms across all the coils, but my meter is screwy.

The transformer is marked:
1014877-2
TEX TRANS
1181 7827

Attached a couple pictures. They are poor; only have my flip phone and cannot hold my hands still. However, they show the transformer has only the number of taps needed. I took it out and all non-shown sides are plain other than the markings above were stamped on one side. The circuit board is quite blurry, but it shows the unit closely matches any pictures I've seen on the web. i.e. the 100B & C are very similar if not identical in overall layout.

Its very hard to see in my pic, but from what shows in Maximilian's photo does match my unit. Except the big CAP in the lower right of his picture is orange, where mine is dark blue, color differences in some other items and a very small ceramic capacitor directly right of the printer motor cable.

datamath.org seems to indicate the B&C models are very similar. Where the original PC-100 (no suffix) and A likely have pertinent circuit board differences due to different calc model support.

My 100C is marked at 120VAC and 0.35A.

The various PC-100 models supports different calcs, but seem to have the same printer (judging from pictures). Also, all the different calcs supported between the various PC-100s use the same battery pack, but some have different power adapters (output voltages and amps). So, the original 100 or 100A might have different transformer values for the spare battery charing compartment. (personally doubt it)

From datamath.org its hard to tell if earlier PC-100 support for various calcs was in terms of how it communicates with the calculator or had different power for charging the batteries. Would make sense it was for communications differences, as they all use the same battery pack (BP-1A).

You'd assume since the various calc models take the same battery pack, PC-100 powering the attached calculator and printer circuits should be the same. i.e. older calcs had different power adapters, but might simply be an "age revision level thing" of plug and charging circuits, but internally all operated at the same levels?

Just my guessing.

[albertofenini]

Hi Everyone,

had the chance to take few pictures yesterday evening,
it is a PC-100A, and I bought it together with a SR-52 which I have restored

Actually I'm restoring few SR-52 so if anyone is interested in pictures let me know
and I'll be happy to post them

The printer has been damaged during shipping, and I will restore it in the near future

It works, and I will measure the voltages as soon as possible

One thing I have noticed is that if I keep a finger on the metal plate
where the printing head is attached applying a gentle pressure the quality
of the printing improves a lot, still is missing a pixel (on the right)

How can I increase the pressure without keeping my finger in place ?

I have cleaned the head with alcohol and I have read that passing a strip of
normal paper should help, any other known technique ?

Pictures can be seen here : PC-100A 004030 LTA4076

Thanks again for the support, I'll post soon more info
take care

[albertofenini]

Hello everyone,

I have had a chance to work on the printer

In the updated images link you will see the values and I confirm that the values
are the same measured on the 220 V version

Possibly, a transformer swap could do the job

However, I'm afraid that the power cable connector at the printer side is different between the 220V and the 110V version,
I'll take a picture later today, and this is probably more difficult to solve ...

Over the weekend I have also tried to fix the pressure problem,
applying a gentle pressure on the thermal head from the outer side makes the
printing much more readable

I have tried to put some spacer both at the end of the spring that keeps the head
pushed toward the paper, and at the bottom of the metal plaque that holds the
thermal head

Both tries were unsuccessful, has anyone ever solved this issue ?

Thanks to everyone and take care

Updated pictures link here : updated PC-100A 004030 LTA4076 Album

[Maximilian Hohmann]

Hello!

(03-14-2022 02:39 PM)albertofenini Wrote:  However, I'm afraid that the power cable connector at the printer side is different between the 220V and the 110V version

Yes it is very different. The 220V version uses a "standard" European 2-pin socket (very similar to this one here: https://www.reichelt.de/kleingeraetestec...8FEALw_wcB) which is certainly smaller than the US socket. You will proably have to 3D print a part that will let you use the Euro-socket in the US cutout. If it helps I can take precise (as precise as my caliper allows...) measurements of the socket. Worth the effort? Only you can tell :-)

Here is a quick picture I took with my phone:
http://www.bombie.de/tmp/20220314_161014...1024px.jpg

(03-14-2022 02:39 PM)albertofenini Wrote:  has anyone ever solved this issue ?

Until now I did not know that this issue even exits. But this is becuase I hate thermal paper printouts so much that in most cases I do not even try if the printers work at all... (Now with a proper mechanical printer, as for example in an HP-46, that is very different. I even keep one from an othewise defective calculator for spare parts.)

Regards
Max

NB:

(03-14-2022 02:39 PM)albertofenini Wrote:  Over the weekend I have also tried to fix the pressure problem,...

I spent quite a few hours this weekend getting the stuck batteries out of a 4D cell LED Maglite... Now that was an unpleasant way to pass one's time. I had to combine the hints from several YouTube videos and other fix-it sites from the internet to finally succeed. Fixing calculators, even thermal printers, is a much nicer work by comparison :-)

[rprosperi]

(03-14-2022 03:04 PM)Maximilian Hohmann Wrote:  I spent quite a few hours this weekend getting the stuck batteries out of a 4D cell LED Maglite... Now that was an unpleasant way to pass one's time. I had to combine the hints from several YouTube videos and other fix-it sites from the internet to finally succeed. Fixing calculators, even thermal printers, is a much nicer work by comparison :-)

Indeed, I have a D-cell Maglite that needs the same work. What clue(s) can you summarize to tackle this, Max? I was going to start with letting the swelled end soak in some vinegar to loosen it, then switch to a flat-blade screwdriver and light hammer...

[Kees Bouw]

(03-08-2022 03:45 PM)albertofenini Wrote:  Thank you very much !!!!
Over the weekend I'll open two of mine, a 220V and a 110V so that we can see
the differences, and I'll check if the transformer is the only real difference
I'll keep you posted !
Thanks again !

To be honest, I can't see why you would want to bother. There are plenty European PC-100's around, to restore one of those would be much more practical. Just use the US version as a parts machine.

[Maximilian Hohmann]

Hello!

Sorry for the off topic, but people who repair calculators seem to like repairing other stuff too :-)

(03-14-2022 04:53 PM)rprosperi Wrote:  Indeed, I have a D-cell Maglite that needs the same work. What clue(s) can you summarize to tackle this, Max? I was going to start with letting the swelled end soak in some vinegar to loosen it, then switch to a flat-blade screwdriver and light hammer...

I guess I should have taken some pictures...

Pouring some vinegar in will certainly make things easier because it dissolves the electrolyte which may have accumulated between the batteries and the housing. But my batteries had swelled considerably so that alone was not enough.

To remove the upper two batteries I basically used the method shown in this video: https://www.youtube.com/watch?v=3aZCns5yaLU
Drill a hole (8mm approx.) into them, drive a thick wood screw with hexagonal head into them and either pull or hammer them out.

But the third and fourth batteries are too deep inside for that method to work, unless you can get hold of a very long drill and screw. So the flashlight needs to be opened from the top as well. Remove the rubber guard over the switch (it can be popped out with the tip of a screwdriver) and loosen the screw that fixes the switch/lamp holder unit in place. You will need an allen key for that, I guess it is an american size but one of my metric keys worked also, there is no big torque that needs to be applied.

Without the batteries in place this unit would normally now just fall out the back end of the flashlight, but here of course the stuck batteries are in the way. To get it out the front side, a securing circular spring has to be pryed out of it's groove. This is the difficult part because the spring needs to be moved out of the groove and pulled upwards at the same time with considerable force. And the operation is performed mainly by feel because it is all very tight and difficult to see - a bit similar to lockpicking.
The only way I could get the spring out was to drill a shallow hole (using a 5mm drill, a smaller one would have been sufficient but was not long enough to reach all the way down) next to one end of the sping (see the photo below).
Now I filed a little nick into the side of a screwdriver close to the tip. And using this "special tool" and the extra room provided by the drill hole I could apply enough leverage to get the end of the spring out of it's groove. With luck it gets caught in the indentation made into the screwdriver and can be pulled out. I still took quite a few attempts...

Now the other two batteries are accessible just like the first two. After that I used plenty of vinegar to remove the remainig electrolyte, applied a thin coat of silicon oil and put everything together again. It looks like new and if no more batteries leak inside may last another 20 years!

Regards
Max

It looks as if the spring is y-shaped but that's only the reflection!

[rprosperi]

Thanks Max, very helpful, I'll give it shot. Mine is probably easier as it has only 2 x D Cells, since this unit uses an LED bulb.

And now back to our regularly scheduled Calculator Topics....

[albertofenini]

Hi everyone,
I may have found a mechanic solution to a what could be an electronic problem ..
Credits go to the author of this link where I have found the instructions to follow:
How to clean a printer
I have applied three little battery springs, and I must say it works well
Take a look at the update photos link:
updated album for PC-100A 004030 LTA4076
I hope it can be of help for someone else ....
take care !!!

[Duane Hess]

Been absent in the hospital for a while. Various posts have made the physical differences clear. I have nothing real to contribute.

But:
1. I'm retired and bored.
2. Also a bit of a busy body, if not fuss-budget.
so, wanted to make a comment. Should you convert the unit to 220V, do not throw the USA socket/cord away. The specific USA connector/cord you have is somewhat rare here. Many devices older than the PC-100 use the same connection and collectors may be interested in the cord and device socket. For example, some very late 60's/early 70's USA Monroe devices have that connection.

My 100 does not have a detachable cord. However the grounding does match your unit. The ground wire goes to the transformer frame. In all units the transformer is mounted via plastic support points. So, the ground attachment appears to be simply for plug compatibility. Certainly, attaching ground to the frame isn't bad. Hence, changing the power cord and plug on your 100A should not affect device reliability or safety.

The picture Maximilian showed at http://www.vintage-calculators.nl/P1000679as.jpg clearly is a 2 wire connection and no ground.

The 220V and 120V pictures show removable power cord units. It seems the plug is held in place via shield which is screwed down. Hence, replacement obviously looks feasible.

The real concern is not to forget insulation. Swapping the socket/cord and transformer to 220 should warrant swapping the socket to transformer wires. And possibly the fuse holder. The plug to transformer wires are sheathed together in one and cable tied together in the other unit. There is a real concern reusing the 120V wires may result in insulation breakdown (arcing) or heating if used with 220V.

I have various 120-220V and 120-100V (Japan) tranformers for my stuff. And I've had your feelings many times. Much easier if I could simply convert the unit. Especially since numerous detachable cord units of mine have USA looking sockets. An accident waiting to happen!

My 2 cents, for whatever its worth.