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Need help with TRS-80 PT-210 Data Terminal

Haha, of course, same here - home phone? Never heard of it, at least since broadband replaced the phone line's primary purpose some 20 years ago. I'm just thinking, you'd created a modem of your own... could do that with a VOIP bridge to create a local phone network and use an old phone that fits it, then feed data to the phone system somehow (alternate firmware on the VOIP bridge, other hacks).

I'd be only mildly worried about capacitor leakage, as the 80s stuff didn't seem as prone to leakage as the 90s stuff in my experience. Not sure what the keyboard construction on that thing is like, but it may benefit from a fiberglass brush on the contacts - if they could be reached.
 
id love to see some kind of generic device or gadget let us connect old dislup modems to the wireless.. but not yet.

nah these caps are perfectly fine. I dont replace good caps.
 
Very cool you got it working. I just picked one up yesterday and need to go through it. Mine doesn't have the RS-232C board so I'll have to cobble something up. Lovely little device, though.

It uses the MCS-48 8039, my favorite classic microcontroller.
 
Amardeep-AC9MF said:
Very cool you got it working. I just picked one up yesterday and need to go through it. Mine doesn't have the RS-232C board so I'll have to cobble something up. Lovely little device, though.

It uses the MCS-48 8039, my favorite classic microcontroller.
Click to expand...
reply to @OS9dude from one of the earlier posts on this thread. he mentions his plans for reverse engineering the rs232 board. I hope someone does as more people with these units can actually use them.
 
Just realized it's even documented in the service manual.
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About as close to a silver platter as you can get, maybe? Only thing left from here is to get physical dimensions, but those could be implied from the PCB layout based on the pin header spacing.

Alert for noob trap: The schematic and other diagrams' reference to CN1 and CN2 appear to be swapped.

FWIW, ... I'm firing up DipTrace because I like the challenge. Might just make a 1:1 replica. Hardest part will be finding the switches they used...
 
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meh. Well, that was an experience. Struggled too much with trying to match up components with schematic. Got the schematic wrangled out, ended up becoming a complete mind-melting crap carnival on PCB layout. Ended up throwing away all schematic associations and wiring it all using the board print photos.

I have zero idea if this will work, but it's a carbon copy of the service manual info.

A few photos of a real board might go a long way to confirming some questionable routing and major differences between schematic and board.

I'm also not sure about the function or availability of the 75-series interface chips, or anything about updating the design, but I'm fairly confident I'm a few mouse clicks away from making a 1:1 replica.
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Files are attached, in case I drop off the face of the planet. DipTrace is pretty awesome for quick tricks like this. Board images are in the file, but one's set to 0% opacity (bonus points if you can find its grab handles!).

Should I order it?
 

Attachments

  • trs-80 pt-210 rs-232 board.zip
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Before I'd feel confident printing the board (even if it's only a few bucks), I'd really love to see a board from someone's existing machine... keeping in mind I don't have one of these myself, so I can't even test it, haha. Closest thing I could do is match it up as closely as possible to the original board (and hope there's no undocumented bodges or board revisions). You, or anyone, feel comfortable taking the cover off and getting a few photos of the board - at least one unit with and one without the board installed? (So we might know what's present in the non-RS232 one, e.g. does it need a ribbon cable added too)
 
FalconFour said:
Before I'd feel confident printing the board (even if it's only a few bucks), I'd really love to see a board from someone's existing machine... keeping in mind I don't have one of these myself, so I can't even test it, haha. Closest thing I could do is match it up as closely as possible to the original board (and hope there's no undocumented bodges or board revisions). You, or anyone, feel comfortable taking the cover off and getting a few photos of the board - at least one unit with and one without the board installed? (So we might know what's present in the non-RS232 one, e.g. does it need a ribbon cable added too)
Click to expand...
Here you go: https://photos.app.goo.gl/fMQ14EXp5GB7LA719
 
Wow! Yep, that's similar to what I had in mind, but I had a few details wrong.

Shows the mounting hole positions, which should let me get it Close Enough with an eyeball.

Shows the switches, which I had no idea how were implemented... and frankly I had no idea how I'll match up, but I'll try and find something modern that'll fit in there.

Shows that it's using SN75* chips, just the same as what I found on eBay, so there's a 100% chance this'll be possible.

Connection to the terminal is a right-angle, which I can match up as well.

Their style of DB25 port is exotic as heck, but no worry, it's already adapted to a modern DB25 port style in mine. I'm guessing it fits into a neat cutout in the case, so I shan't go swapping it for a 9-pin... yet.
 
It's an elongated db25, but I figure thats the least of your concern. The cutout the card slots into has two small notches facing the back of the unit; those are for the two nuts on the bottom side of the board.
 
Found an identical match to the switches. And a matching cap. Pinout and all, matches 1:1. So with the exception of the DB25 header being of fairly different dimensions, this is a perfect 1:1.

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The pin header will be right-angled like the original though.

Now off to have 5 of them built. I'll mail these 5 out to anyone that wants one to test, since I can't test it myself. Probably slap them up on eBay for $60 which reasonably covers parts ($43 of parts on each board in qty=5, woo!) and labor.
 
I know the struggle of not being able to acquire a much-needed accessory, and today this thing is basically unusable without this interface board. It's simple enough, I figured I'd be able to apply at least minimum effort to it :)

Oh! And updated files... and Digi-Key cart: https://www.digikey.com/short/4q8v7dwd

I can only hope it all snaps together, haha

(Expect the parts to arrive around Dec 28-31)
 

Attachments

  • trs-80 pt-210 rs-232 board.zip
    74.8 KB · Views: 8
Amardeep-AC9MF said:
Very cool you got it working. I just picked one up yesterday and need to go through it. Mine doesn't have the RS-232C board so I'll have to cobble something up. Lovely little device, though.

It uses the MCS-48 8039, my favorite classic microcontroller.
Click to expand...
Hey, does your PT-210 have the ribbon cable to connect to the RS232C board? Or does it plug directly into a socket on the main board? I think it might just be a socket if I recall from the service guide, but not sure.

Does it need any mounting hardware (e.g. nut & screw) to adapt the non-optioned one to fit the option board?

Parts (chips, chip sockets, switches, diodes, caps, resistors, & ports) arrived quite in advance of the boards. Everything looks awesome so far, but I can't tell 'til the boards get here, and unfortunately no shipping yet (I used BasicPCB in the US - they're cheap, ideal for simple boards like this, but a bit slow :) ). So, it may not be a thing 'til next week, but the moment they arrive, I'll build 'em and post back.
 
I dont think there is a ribbon cable. I think it just plugs into a socket on the board. No hardware needed, I assume they make it so someone who didnt purchase this can easily add it after the fact if they choose to.
 
All right, you know that feeling when you build a project and it just works perfectly the first try?

I don't have it quite yet...

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Because I need a way to test it! Who's got dibs? Reply here and send me a PM with your address (or however you prefer), and I'll send it out!

I have parts for 4, so there's 4 dib slots, just built one for now since traffic seems a bit low here. :)
 
If you cant find anyone who is missing one, I cant test it and send it back to you. I dont need one but am happy to help out.
 
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