The modems were fairly proprietary. While being obviously standard (with typical components).
However, there are two ways. You can take the board out and flip it over to look at the main IC, which may shed some light. However, the modem on my T3100SX had even more sparse info. Just dead links for the IC.
Also, windows can detect the modem and usually makes the right choice. On my T4400C, even though I couldn't find info on its modem (other than being a 2400baud modem) windows loaded it as a Hayes Smartmodem 2400, and it worked flawlessly.

Also, the modem doesn't have a speaker. It instead uses the PC speaker.

Thanks yourpicfailure, I had tried it briefly with checkit and procomm but at 1200 bps. a quick retry at 2400 bps and its responding to AT command.
Actually I see it auto detects baudrates from 300 to 38400 at the command prompt. I dont know why it wasn't responding before.
Hayes smartmodem 2400 sounds fairly generic so thats good.
I'll connect it to a line and see if it works, maybe have a look at the chipset as you suggested too.
Thanks again, David.

yourepicfailure wrote on 2021-05-12, 20:55:

The modems were fairly proprietary. While being obviously standard (with typical components).

Do you happen to know the connections of the 4 way modem socket? The cables I have use just the two inner cores but when I try this it just grabs the line off hook immediately when I plug it in. Some modems I know use just the outer two cores. I'll have a look for a cable like that tomorrow.

Kind regards, David.

I have messed up with the modem, i tried a few cables and thought I was getting somewhere but then following a stream of received garbage I've seen no response at all to anything I send it. I think its broken now, drat.
The modem connector is a 6 way, not four as I thought. Attached are some photos, in memorial. I'm not surprised as there seems to be no opto couplers or transformer on the boards. Oh well, I still have the pace ISA modem.

Hey!
Recently became the owner of this beautiful computer! And read the whole topic. I have 12 MB of memory installed. So I do not need to do the memory mod. I burning a new BIOS v5,30 LOMEM and it works. I made a cable for the internal floppy disk and it works. I installed the IDE to CF adapter. Made a cable of an external floppy drive for Gotek - FlashFloppy v3.25. But the computer does not see him. Perhaps I have an affirmable configuration file CFG. I download files from here, but why it does not work.
https://github.com/keirf/FlashFloppy
I ask you to give me the right configuration file, if possible! Pleas!!!
Best regards from Finland!

Hi, attached here is the configuration file I'm using on the T3200SX external FlashFloppy. Firmware V3.13a, May 2020.
Jumpers closed: S1 JC, J5
Piezo sounder on JC
Oled display fitted.
Kind regards, David.

Hi! Many thanks! Have a nice day!

Thank you David! Everything works fine! Best regards from Finland!

Thanks for letting me know, great.

Hi guys!
Unfortunately, I could not find the processor that IanB recommended. But I bought two other processors and they work.
Texas Instruments TXI486DLC/E-33GA
Texas Instruments TX486DLC-40BGA
But be careful when installing, do not confuse 1 contac!!!
Tests show that both processors operate at a frequency of 20.6 MHz.
Only I do not know if there is a sense to do the cache mods.
Will it work and what contacts need to be used?

Greetings, I see some 486 cpus on ebay listed as "TEXAS INSTRUMENTS TI TX486DLC/E-33GA CPU" are these a plug in replacement for the T3200SX CPU? If I add one what will be the benefit? Could I for example then use a more recent version of the linux kernel? Or maybee just a speed increase is gained and more memory is the key to a better system in which case I may have to rob the memory from my other t3200sx. David.

i'm not sure if the 386sx cpu of the 3200sx is compatible with the TI dlc chips. I've only used them to upgrade 386dx cpu's.

I have a T5200 with a TI 486 sxl-40 (the clock doubled cup) and an ITT 487dlc-40. without doing the flush mods IanB did (I don't thrust myself not killing the mainboard in the process) i get just shy of double the speed in benchmarks compared to the original 386dx 20.
I had a TI 486 dlc 33 in there before and i think you get about 30% increase in benchmarks. The biggest bonus of these cpu's is the on chip cache memory.
Although setting the Dram refresh to a higher number (as is explained in this thread aswell i believe) helps a lot with performance.

16ShadesOfOrange wrote on 2020-08-22, 12:08:

• In an attempt to quieten the fans and give them 6V instead of the 12V from the PSU connector, I shorted out 2x 12V PSU fan connectors 😱(they're dead) so I'm now running 3x 12V fans in parallel from the single left-side fan connector. I opened up the PSU but can't see any obvious issues, so for now it's running
• I busted my screen somehow 😥. Seems to work OK in graphics mode eg full screen stuff like in Windows, but in DOS mode it's almost inverse, eg black is orange, the display sometimes becomes distorted/picks up interference, text becomes wobbly and almost unreadable.

Hey all, I gave the screen issue another look with fresh eyes (12mo later!). It's no coincidence about the PSU short and the screen being weird.

I've found I've lost the 24v rail (yellow PSU wire). I guess the good news is the screen's probably unharmed 😃

I found a replacement PSU on ebay for $95USD which is steep, so I'll poke around in the PSU to see what "popped" 🚬. If anyone has a PSU schematic please hit me up!

BTW, has anyone attempted to build their own PSU or replace it with an off-the-shelf one?

Do anyone know if it is possible to pop in (isa slot) another graphics card in this machine? (Presume that the built in card needs to be detached)

my03 wrote on 2021-06-20, 13:46:

Do anyone know if it is possible to pop in (isa slot) another graphics card in this machine? (Presume that the built in card needs to be detached)

Yes. I have a Trident VGA 16-bit ISA card in my T3200.
It works just fine.

Hi all, i've bought a partially flooded T5200 at flea market 2 weeks ago, half covered in mud, half in rust to be used as a container for a cyberdeck ... BUT i ended in this rabbit hole forum and tryng to fix it.

Status so far
- Dismantled cleaned and recapped the PSU now i have a stable 4.9v(could be better) and 12v.
-Dismanteld cleaned all boards
- Dismantled plasma cleaned and cleaned all contacts
- Removed all rusty parts (planning to paint them)
- changed FDD drive with a 34 pin rewired using fly wires (thanks to this thread for the pin matching)
- Formatted the conner 40mb drive: 1mb of bad sectors but spinning happy on the remaining 39.

Issues: The RAM is nightmare, every boot gives me different error:
i've 8MB installed, in some cases it see 6MB and boots,other it gives error after 1mb and beeps irritated, mostly see 2mb and boots.
i've already permuted the 4 modules but errors are still present.
any Clues ? i'm getting crazy around it.

Projects:
Add an ISA ethernet and a SBpro2 i've lying around and buy a serial mouse
Play monkey island and all my old Floppys.
i would like to upgrade the bios but Eprom programmers are too expensive so far.

Hi.
I have T3200sx.
It's been a while since I took it out and turned it on.
However, the gas plasma display darkened.
When normal, the brightness is a quarter.
What could be the problem?
Do you think the gas plasma display is out of life?
Please advise me if you know how to fix it.

My money is probably the electrolytic caps on the two side inverter boards have probably gone out of spec.

yourepicfailure wrote on 2021-08-25, 19:06:

My money is probably the electrolytic caps on the two side inverter boards have probably gone out of spec.

Thank you very much for your kind reply.

This is the board on the back of the plasma display.
Should I replace all the ALUMINUM ELECTROLYTIC AXIAL CAPACITORs that are here?

Or should I replace all the CAPACITORS on the main board?
I'd really appreciate your advice.

PS. I'm asking this question because I have almost no electrical knowledge.
Are ALUMINUM ELECTROLYTIC AXIAL CAPACITORS and regular electrolytic capacitors just different in shape?
Or are the electrical properties different?
The reason I'm asking you this question is because there's a price difference and it's hard to get.
If I can replace it with a regular electrolytic capacitor, that's what I want to do.

Getting at all the electrolytics on all the boards are a good idea to get at while you're in there.
I see you also removed the left and right inverter boards. I'd swap the electrolytics on those.
Electrolytic, in regards here, is still electrolytic. No matter the type they can still leak, degrade or otherwise fail and cause wierd things to happen. Axials are essentially another making of electrolytic.
The only electrical properties that matter are the capacitance and voltage rating. You can go as high as you want with the voltage rating, as long as it'll physically fit, but never lower than the original. You can't, however, use a capacitor of different capacitance.

This is the PDP from a T3100SX. The two removable boards in the red boxes are the inverter boards I'm referring to.