fm towns Marty universal PSU

[unstablewarpfield]

Howdy!

For my fm towns Marty I am trying to work on its power supply (Tamura version!!!).

Since I have to wait for my replacement ELCO's for quite some time I decided to try and unravel the schematics for it (I think they don't exist on the web)

Here they are... I was wondering if some PSU gurus could take a look at them since I am not sure they are entirely correct


Furthermore... I decided to get crazy, remove all components and scan the empty PSU pcb. This way I can use it's dimensions to create a pcb in Eagle that uses the original on/off switch, AC mains input and metal bracket but has modern power Modules installed on it. In theory we could have a "drop in" PSU without the need to cut into the case.

Solder side


Component side


Curious to see what you guys think. I'll make the Eagle file public as soon as they're done

Cheerz!

[kamiboy]

Neat, I am a fan of clean drop in PSU replacements like this for vintage Japanese computer systems. Someone did a similar thing for the X68000 as well. While both my machines work well after I replaced their caps, it is nice to know there are neat alternatives to resort to in the future if need be.

Always makes me sad to see a laptop adapter hanging out of a system that originally came with an internal PSU. Especially if getting the whole wonky thing to work the owner had to hack things apart, leaving a general mess.

[unstablewarpfield]

Here is what I have so far.

The power switch, AC input and metal bracket will need to be stripped from the original PSU, unless I can source them. Even though the power modules have their own build in protection I decided to go with a fuse anyway. Wouldn't feel good without it. Also added some caps on the output lines to filter a bit more ripple away.

Top


Bottom

[kamiboy]

I suppose that since the Marty is just a FM Towns386SX PC in a smaller box this replacement PSU design should be relatively easily translated to work in regular FM Towns computers as well. They have really dodgy PSU’s, let me tell you.

The form factor would be different but I imagine the output voltages and general functionality should be the same.

[unstablewarpfield]

I suppose that since the Marty is just a FM Towns386SX PC in a smaller box this replacement PSU design should be relatively easily translated to work in regular FM Towns computers as well. They have really dodgy PSU’s, let me tell you.

The form factor would be different but I imagine the output voltages and general functionality should be the same.

I don't think the output voltages are thesame. I have no experience with the FM towns PC's, but from the little info I read they require +5V, +12V and -12V. The marty is on +5V, +9V and -9V. Not that it is harder to create those voltages since it is a matter of putting on the appropriate power modules. Creating the dimensions of the board is easy enough. My main motivation was the fact that this machine was designed for Japanese voltages. I'm on 230V here, so with the re-use of some of the original components the idea is that the outside of the console is unchanged while I will still be able to directly connect it to the mains without a stepdown transformer

[unstablewarpfield]

I made some progress on the Marty uni psu. As you can see, this is what it became. Unfortunately it did not revive my Marty and I will have to resort to reflowing as my next step to get my unit workin again. As soon as I can verify that this psu works I can upload files and part numbers. As you can see it is a non invasive, fully reversable mod.

[kamiboy]

That is very sleek. I am tempted to do this mod on my own Marty, even though the PSU in it is fully functional. It would make sense since it is multi voltage and I live in the 240V part of the world.

Can you tell me more about the replacement parts? Where do you buy them, what is their cost?

[unstablewarpfield]

That is very sleek. I am tempted to do this mod on my own Marty, even though the PSU in it is fully functional. It would make sense since it is multi voltage and I live in the 240V part of the world.

Can you tell me more about the replacement parts? Where do you buy them, what is their cost?

At the moment I am struggling to get my Marty to work (gives me NMI interrupts during boot) but I'd like to test run this first a bit to ensure there is no funny business going on. The components are rather simple. Just a 2A fuse, a 5V power module, 2x 9V power modules en 3x 470 uF caps on the output lines. Designed the pcb in Eagle and presto... one drop in Marty psu.

As soon as everything checks out theway I want it to I will upload the board files (or I might even do a small run of them) and the exact component list.

[kamiboy]

Okidok, following this project with great interest. If you need help with testing let me know.

[unstablewarpfield]

I had the Marty running for a full day on this powersupply. No problems. Discdrive was playing a cd and constantly active. Shoot me a pm if you are still interested in testing. I have a board left and a quick guide with BOM to assemble it

[shane0]

I am interested in this

[Jurger]

As a soon-to-be owner of FM Towns Marty (in Europe), some kind of Universal PSU would be very interesting. Could this be available to purchase somehow some day?

[waali]

Extremely interested in this PSU. Any chance of buying a board or getting the design files?

This is some amazing work!

[unstablewarpfield]

Thank you very much

Board files will be released of all the projects I've done. So far this is:

- NEC PC-fx uni PSU (universal power supply)
- fm towns Marty uni PSU (universal power supply)
- Intellivision uni PSU (universal power supply, work in progress)
- Atari Lynx LIPO qsb (10000mAH LiPo battery board)
- Videopac G7000 rgb mod (very small rgb board. Solders directly to the motherboard)
- Intellivision PAL rgb mod (based around an adv7125. PAL only. Work in progress)
- Casio Loopy rgb mod
- Bandai Playdia rgb mod

I will release all these files in one go on a new website I'm building that covers all my endeavours in hobby electronics and retro gaming. It will include BOM's and installation tips and tricks. I hope people will be able to use them and improve upon them

[waali]

Wow... just wow!

I can use all but a couple of those mods on my collection. Looking forward to the website release.

Cheers!

[supermulder]

Hi unstablewarpfield,

wow, great job you did there.

Would it be possible to get the PCB files and the parts list by mail? I have a Marty myself that I would like to use without a power converter

I would be eternally grateful!!!

[waali]

Thank you very much

Board files will be released of all the projects I've done. So far this is:

- NEC PC-fx uni PSU (universal power supply)
- fm towns Marty uni PSU (universal power supply)
- Intellivision uni PSU (universal power supply, work in progress)
- Atari Lynx LIPO qsb (10000mAH LiPo battery board)
- Videopac G7000 rgb mod (very small rgb board. Solders directly to the motherboard)
- Intellivision PAL rgb mod (based around an adv7125. PAL only. Work in progress)
- Casio Loopy rgb mod
- Bandai Playdia rgb mod

I will release all these files in one go on a new website I'm building that covers all my endeavours in hobby electronics and retro gaming. It will include BOM's and installation tips and tricks. I hope people will be able to use them and improve upon them

Keen to get in to some new projects, how goes the website?

[cloverskull]

Hi! Is there a way I can get this power supply replacement? Are the boards and/or parts available? My power supply is fried - actually flamed a bit, I noticed the previous owner soldered a wire to connect the fuse holder. So it's totally broken

[toyxforce]

Hey wondering if there was ever an update to this project? My Marty PSU is giving me the same error.

[Syntax]

Would this work?
https://townsworld.com/2021/06/01/fm-to ... eration-1/

[kamiboy]

I have an early version of the OP project board in my Marty. It works pretty well, though those TEACO modules are quite pricey.

A near solution, but I think work stopped on it some time back. My Tower Towns 20F needs a new PSU as well and since work stopped I have toyed with the idea of making something similar form that machine myself.

Alas I never could get anyone to tell me how the logic of the two power signals that control power on/off state on those machines is supposed to work. Without a working unit I can’t reverse engineer it either, so I never made anything of it.

That other alternative works fine too I am sure, but I’ve always found it a but absurd that it uses a pico pi for interpreting and controlling the power on/off state logic.

I mean, the pico is a computer that is most likely much more powerful than the Towns computer, and all it does inside there is control power on/off.

It is comical in the most absurd way.

[kamiboy]

Actually, I still have my original Marty PSU that I took out to replace with this, it works fine too, the reason I wanted to do a swap is because I live in 220V region and the new PSU was multivoltage so now I can plug it into the wall directly without any step down convertors, very convenient. I did remove the power button and whatever other necessary component from the board to use in the replacement, but I guess someone with a working unit could just grab it off their broken PSU. Maybe I should sell the original PSU…. Though some thing wants me to keep the useless old thing, just because it is the original part which I could always put back in and make my Marty stock again….

[VEGETA]

Hello,

the original PSU is a typical flyback converter with center tap transformer to achieve positive and negative rails. You used Traco power modules which is a sane choice, I believe you can find other better modules like Recom and Meanwell. Some modules do have both rails in one module so you won't need 2 of them.

I suggest you hook an oscilloscope and probe the inputs and outputs, post the images here. I highly recommend you put some minimal constant load on all outputs, something like a resistor to drain couple of milli-amps which ensures stability. check datasheet for this.

I have done a similar but bigger more advanced project for Dreamcast universal power supply:



I used a Recom module and then my own circuitry which does 3.3v and 5v rail + 2nd stage filtering and so on... not gonna be simple to design and layout. Sample board is coming to me as we speak.

My plan is to sell it for a retail price of 80$ which is very sane price due to the high production price and very high quality robust design. what do you think?

I HIGHLY encourages people to do such designs to enhance the basic building blocks of retro systems... not just scalers and so on.

[kamiboy]

That design is certainly a lot more complicated than the one relying on TEACO units. I'd say 80 buckaroos is reasonable for a high quality replacement PSU, but the retro community tends to be quite miserly when it comes to such things, so you never know. I'd like to think that there is a market for higher quality replacement parts, though my instincts tell me most people sway heavily towards the cheapest option.

[VEGETA]

That design is certainly a lot more complicated than the one relying on TEACO units. I'd say 80 buckaroos is reasonable for a high quality replacement PSU, but the retro community tends to be quite miserly when it comes to such things, so you never know. I'd like to think that there is a market for higher quality replacement parts, though my instincts tell me most people sway heavily towards the cheapest option.

yes the price is not optimal, but for higher quantities i could make it about 70$ or even a bit less but for less quantity which I can manage then 80$ is the way to go. still not so expensive too.

retro community pours money on nearly anything. a small board can cost 5$ to make but is sold for 40$ or so... shortage of money is not a problem but the will of people to actually invest in their system using very high quality solutions.

I do have another product which will come before this which is a mod board for dreamcast, which is soldered on top of its controller port board after removing original battery... this mod board allows installing a 18650 battery instead which gives nearly infinite charge and allows charging and protection of 18650 battery... to act as a replacement of original battery solution which always gets drained and requires the use to re-enter time and date. this board is meant to retail for mere 40$ but I bumped it down to 35$.

[VEGETA]

I have finished the design and it works perfectly fine, about 2-3 times better than original!

here are the oscilloscope measurements: https://imgur.com/a/3Lqw5NZ

and here are the device pictures inside dreamcast: https://imgur.com/a/7YnZJyx

and this is the real-life measurements:

3.3v no load:
mine: 29mV p-p
org: 70mV p-p

5v rail:
mine: 7mV p-p
org: 33mV p-p

3.3v full load - main menu screen:
mine: 47mV p-p
org: 70mV p-p

3.3v full load - crazy taxi game (should be max it can take in its operation):
mine (ripple only): 26 mV p-p
mine (ripple + noise spikes): 65mV p-p
org: 90mV p-p

[kamiboy]

Nice job. Hopefully there is a market for this. Seems like nice piece of kit.

[Konsolkongen]

You should make your own topic for it though. No one will find it in a Marty-tread

[VEGETA]

You should make your own topic for it though. No one will find it in a Marty-tread

yes i will hhh you are correct.

I made a small update and now it is literally PERFECT as seen in scope reading: https://imgur.com/a/CtI4VAn

less than 25mV p-p total noise + rippe at full load with game. Nothing can beat it this way.

I will make another sample using the latest change tomorrow, and will consider it final.

[Alugard]

Thank you very much

Board files will be released of all the projects I've done. So far this is:

- NEC PC-fx uni PSU (universal power supply)
- fm towns Marty uni PSU (universal power supply)
- Intellivision uni PSU (universal power supply, work in progress)
- Atari Lynx LIPO qsb (10000mAH LiPo battery board)
- Videopac G7000 rgb mod (very small rgb board. Solders directly to the motherboard)
- Intellivision PAL rgb mod (based around an adv7125. PAL only. Work in progress)
- Casio Loopy rgb mod
- Bandai Playdia rgb mod

I will release all these files in one go on a new website I'm building that covers all my endeavours in hobby electronics and retro gaming. It will include BOM's and installation tips and tricks. I hope people will be able to use them and improve upon them

Hi unstablewarpfield,
Any chance you can share the Gerber files of your board? And what are the voltage of the capacitors you used? I got my first marty and the PSU is dead, hope to revive it somehow. Thanks a lot in advance!