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Toshiba T3200SX D.O.A

PostPosted: Sun Jul 20, 2014 9:52 pm
by Clym5
Hello all,

I have just received a Toshiba T3200SX that doesn't work, and before I pull it apart, I was wondering if anyone could give me any clues as to what might be wrong.

I get no power light when it is turned on, and I can hear a faint buzzing/squealing sound that turns on and off from around the power supply. I'm not sure if that's enough information to have a clue as to what is wrong.

Also, are there any common faults in this machine? Screen connector snapping? And am I right in thinking there's a slide-out bottle opener on the bottom right corner?

Re: Toshiba T3200DX D.O.A

PostPosted: Mon Jul 21, 2014 8:03 am
by SpidersWeb
That buzz from the PSU is quite likely the automatic protection kicking in.

There isn't very many caps on this motherboard, and I haven't seen one short, so the first step might be to remove any ISA cards it has installed. This is quite easy, just remove the rear panel (you don't need to open the entire case). Behind that panel you'll find two normal ISA slots just like you would in a desktop PC.

If this doesn't help, I'd open it properly and disconnect the power supply connector (behind the floppy drive) and test the resistance of the lines. You can work out which is which by what colour wire it was connected to - red/black/white etc. If you get 0 ohms, then you need to find the short, if you get good resistance then you need to look at the PSU.

Working inside the machine can be awkward because the screen does not come off - the cables are soldered - the best you can do is lift up and rotate the top of the machine to get access to what you need to.

Re: Toshiba T3200DX D.O.A

PostPosted: Mon Jul 21, 2014 3:07 pm
by Clym5
Alright then, thanks! I'll take it apart this evening and have a gander.

That screen sounds like a pain, but hopefully I'll be able to find my way around in there!

Any ideas about the bottle opener on the side?

Re: Toshiba T3200DX D.O.A

PostPosted: Mon Jul 21, 2014 7:38 pm
by Clym5
No visible damage, and the lithium battery hasn't done anything bad, apart from going flat.

I'm just about to test the board for shorts.

Is the hard drive an IDE one? If so, I might replace it with something that might be slightly more reliable.

And what type of RAM does this computer take? I tried google, but got multiple different answers.

Re: Toshiba T3200DX D.O.A

PostPosted: Mon Jul 21, 2014 7:52 pm
by Clym5
And it seems to be the power supply. Resistance between ground and all the other pins seems to be alright, and the supply doesn't spin the fans, and makes the same noise when powered up, disconnected from the computer.

I should probably stop replying to myself, so I'll just edit in the updates.

UPDATE: Just what I didn't want. No visible damage in the supply either! I've never fixed a switching supply before either. Are there any methods of testing, or common failures that I could look for? Maybe a smoke test?

Working inside the machine can be awkward because the screen does not come off

I didn't have this issue. I read through the maintenance manual, and disconnected some cables, and the screen lifts off.

UPDATE2: The hard drive doesn't sound healthy. It spins up, moves the head, and spins down. But when it does, it sounds like the platter motor is having trouble. Replacement time then!

Also, I meant T3200SX, not DX! I blame my phone's keyboard.

Re: Toshiba T3200DX D.O.A

PostPosted: Tue Jul 22, 2014 8:02 am
by SpidersWeb
It comes off :shock: Honestly every guide I'd read said it didn't, and it felt like it was going to snap something if I pulled the connector off the motherboard.
I haven't actually read the maintenance manual, where did you find it? Is there a diagram for the PSU?

With the PSU - I'm not quite good enough with actual electronics yet to tell you how to diagnose - but I can tell you a bit about how they tend to work in PCs and why they shut down. There is almost always two sets of protection circuitry - over current (shorts) and voltage. Voltage is usually measured against each other - using resistors and a voltage comparator (like an LM337) - so if any of the rails are higher than the others it'll shut down - even if it's not over-volting. Since it's "buzzing" I'd guess the high voltage side and the initial stage is ok, but something further south - either the measurement circuit itself or one of the regulation circuits for +12,+5,-5 (maybe) or -12. Just a theoretical guess.

One thing of use I did test for you last night, was that these power supplies DO power up when not connected to a motherboard. This means if you're testing it, you do not need it connected to the laptop (most older power supplies need a load - this one doesn't).

Edit: oh and the bottle opener, that puzzled me for a while, but I believe it's so you could padlock/tie the machine to your desk so people couldn't run off with it. Apparently the weight wasn't a big enough deterrent.

Re: Toshiba T3200DX D.O.A

PostPosted: Tue Jul 22, 2014 9:34 am
by Clym5
The disassembly guide is near the bottom, slightly below Page 110 or so.

Doesn't look like there's a diagram for the PSU, but I haven't read through the whole thing yet.

Thanks for the handy info about not needing a load! That makes everything easier, and safer.

School has started again, so I don't have all afternoon to poke around the inner workings of things anymore, so updates won't happen at any great rate.

Re: Toshiba T3200DX D.O.A

PostPosted: Tue Jul 22, 2014 10:30 am
by SpidersWeb
Cheers for the link :D

Be careful working with it, I noticed it has 205V DC output for the Plasma, that could hurt, a lot.

Re: Toshiba T3200DX D.O.A

PostPosted: Tue Jul 22, 2014 11:16 am
by Clym5
After a few close calls with high voltage supplies in vacuum tube gear, I'm much more careful!

By any chance, do you have any copies of the diagnostic programs for the T3200SX? I see them mentioned in the maintenance manual often, and I thought they'd be handy to have.

Re: Toshiba T3200DX D.O.A

PostPosted: Wed Jul 23, 2014 2:40 pm
by Clym5
After poking at every possible component, I can't find anything too out of spec. With the PSU case off, the buzzing is MUCH louder. I can clearly hear it from 5 meters away. I'm not too keen on putting my ear up to it, to see where it's coming from either. I might try sweep a directional microphone past it a few times or something. I've never really fixed a switching supply before, apart from replacing obvious faults, like capacitor-gone-rocket components. I'm used to linear supplies. Much easier!

I'll see if I can upload a recording somewhere.

EDIT: Here it is. The buzz is around 12700kHz. Can't see anything though. Warning! It might be very loud! I had to crank up my microphone's gain to get this.

Re: Toshiba T3200DX D.O.A

PostPosted: Thu Jul 24, 2014 8:36 am
by SpidersWeb
The buzz is more likely a consequence than the cause. I'd take a guess at it being a transformer being switched at an audible frequency.

I need to look inside mine to tell you where to look, but I'd start by:

- making sure all outputs are 0V (just so it doesn't upset any resistance measurements)
- taking a resistance measurement between each rail and ground and making sure it's not shorted
- connect scope ground lead to ground
- turn on PSU
- look at each low voltage output rail (+12 +5 -5 -12)- they wont come up to full voltage but you may be able to see if any one of them is out of proportion to the others. Hopefully because it's cycling/buzzing you'll be able to lock in to a waveform.

I have lots of 386/486 supplies that buzz when in a protection state. Quality supplies usually go in to a safe mode and wont restart until power has been disconnected for 30 seconds, but I suspect yours just cuts/restarts.

Then after that you'd probably need to open it and look at what signals the PWM circuit (or IC) is putting out / being fed.

If the inputs were failing, they'd either be locked on 100% or dead at 0%. The fact it's audible means something is continually turning the transistors off.

NB: I'm not a pro at this, I generally order replacements off ebay lol, just trying to point you in the right direction from what bits I have picked up. I only just got my CRO and my last dead PSU didn't "cycle" so it's all theory with no practical experience.

Re: Toshiba T3200DX D.O.A

PostPosted: Thu Jul 24, 2014 9:35 am
by Clym5
Thanks for the tips. I did check the resistance between ground on the PSU side, and nothing was shorted. Forgot to mention!

I'll put the scope on it this evening. Not sure why I didn't earlier! Hopefully ebay will have something if I can't fix this.

Also, I've heard that the T3200SX will ONLY work with Conner hard drives of a certain size. Is this right?

Re: Toshiba T3200DX D.O.A

PostPosted: Thu Jul 24, 2014 10:04 am
by SpidersWeb
Clym5 wrote:Also, I've heard that the T3200SX will ONLY work with Conner hard drives of a certain size. Is this right?

You probably heard that from me lol I only ever wrote one article for the site, but it was on the T3200SX

Back when I was investigating it, I found multiple sources that indicated these models looked for "CP" in the drive model - but I never actually confirmed it - and now when I search for it, the only resource I find is my own damn website. I will add it to my "get off your ass" list since I have a T3200SX open. No matter if it is or isn't required, if you need a Conner CP I can send one - I kept a stockpile of the things just in case I needed one for a Toshiba - sizes ranging from the original 40MB up to 540MB.

The BIOS only officially supports two drive configurations - "Normal" and "Alternate" both are 40Mb in size. Ways to get full access to the rest of the disk are the same as for any other 286/386:

- download ROM, edit drive table entries in hexideciaml, recalculate checksum, erase/write to a fresh EPROM and install (hardest)
- throw in a network card with the AT version of the XT-IDE ROM in the Boot ROM socket (this gets past any HDD limitations - even LBA, so you could put in almost any IDE drive you want) - this auto detects on startup, and replaces the built in hard drive routines. (solves a lot of issues, but will use up at least your 8 bit ISA slot)
- drive overlay software (like "OnTrack" - usually you want the version from the company that made the hard drive you're installing)

Options 2 and/or 3 I can send up what you need preconfigured.

NB: that XT-IDE ROM will also let you boot from another PC using a serial cable, that could be a godsend if you ever have an issue with the FDD.

Edit: oh and your MFM controller worked perfectly, did low level formatting and media analysis with it the other night, so I owe you some bits :)
Edit2: you don't really need it, but that Toshiba Diagnostics program can be found here thanks to Ray's awesome collection skills: ... ostics.htm In the ZIP file you'll find test32ce in the "HIGH" folder.

Re: Toshiba T3200DX D.O.A

PostPosted: Thu Jul 24, 2014 6:21 pm
by Clym5
I wonder if a CF to IDE adapter would work, if the computer doesn't require a Conner drive? It'd cut down on some weight too.

The drive overlay software sounds like a good way to go, as I don't have a EPROM programmer, and I'd rather leave my 8 bit ISA slot available. But as you say, being able to boot using a serial cable would be extremely handy if the floppy drive died. I'll look into the AT-IDE though.

Great to hear the controller worked! I was a bit worried, considering the condition of the rest of that computer. I've put it in my too hard basket for now anyway. Fixing my T3200SX, CD32, some strange Mac and an IBM 5100 (not mine :( ) is keeping me busy!

Regarding RAM, I see on your site that you say that 1mb to 2mb 80ns. Is this per stick? Or the total of what it ships with? I have two 30 pin sticks that I'd like to put in, but I'm not sure if you mean that the computer can only use 1 to 2 mb sticks, or ships with 1 or 2mb. I've got 4 sticks installed in mine.

Re: Toshiba T3200DX D.O.A

PostPosted: Thu Jul 24, 2014 7:01 pm
by SpidersWeb
IBM 5100?

The T3200SX comes with 640KB conventional memory and 384KB extended on the motherboard - just enough to run Windows 3.1. You can expand it with the 30 pin SIMM slots but finding compatible RAM is quite challenging - a normal 30 pin SIMM will not work - I believe this is because there is a couple of pin differences (similar to IBM's PS/2) that let the computer identify the chip. I ended up just leaving mine as a 1Mb machine. You wont damage anything by trying just be careful with the clips.

What were you going to put in the two ISA slots? In mine I usually pop in a sound card and network card. I had wondered about putting a SCSI card in one of them though.