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I have similiar problem. Cold console resets itself even with GDEMU but after some time when when it starting to get warm starts to work normally. Since I detached laser I assume it's not a problem here. PSU connectors are cleaned so probably capasitors needs to replaced. But which ? All on PSU are in really nice visual condition. I don't see and sign of aging or corrosion. Could I use polymer instead of electrolitic ?

Many thanks Fix_Metal. This informations will help me a lot

Hi,

I've just checked on my switched PSU - non genuine Sega - perfectly compatible with my MD1/MD2/MCD1/MCD2/32X boxes. Measured with a standard caliper with 1/20 mm accuracy.

The MD1 is 5.225 mm on the outside. The inside ring is harder to measure, but it looks something around 2.225 mm.

The MD2 is exactly 4 mm on the outside. The inside pin is impossible to measure with the caliper, but a good approximation would be ~ 2.15 mm.

I've fixed so many DC plugs in the past and I have to say none of them failed me while playing any of these consoles due to bad connection (read it: too large on the inside to touch the pin).

Proszę bardzo, and welcome to the forum

@Segasonicfan I have some ISL59885 chips at home so I thought I would try to build your circuit, but your Photobucket pictures are no longer available. Do you have backups anywhere?

What are exact dimensions are for PSU plug for Sega Megadrive 1/Mega CD, Megadrive 2/32X, NEC PC Engine (orange), PC Engine CD ROM addon (again orange version), Famicom 2AV, SNES USA/NTSC (very close to Dell PSU plug)?

I have some 4.8mm 1.7mm conversion plugs for Sega Megadrive 2/32X and those fits actually. Some sources however claim only 4.0mm 1.7mm.

The same problem I have with Megadrive 1/Mega CD plug. Converters are usually 2,1 to 2,5 auto fit but I would prefer to know exact size as some DC splitters are not auto regulated. Famicom 2AV and PC Engine seems to be also using 5,5/2,5 plugs. SNES USA is probably using very close to 7mm/5mm with pin 1mm.

Does anyone have a clonecd dump of the V2.1 L31 OS CD? , I haven't had much luck with bin/cues.

Quote from: leonk on November 27, 2025, 06:30:45 AMYou need to follow my instructions as documented here: https://gamesx.com/wiki/doku.php?id=fm_towns:sdscsi

Thanks, I have made some progress but still having some issues

1.) Drive Mappings



I think have the drive mappings setup correctly but here is a screenshot of setup.exe just in case i have something setup incorrectly

2.) Booting



Booting from the HDD image looks to have worked as mapped drives all appear and TownsOS loads with G: showing the following installed files

I didn't take a screenshot unfortunately (though happy too if needed),  however if i click on any drive like the i: (games) the window is empty.  Nothing is showing.

If i close g: and reopen g: the files have disappeared!  i am at a total loss as to what might be the issue. 

I am speculate the files are present in g: at least as the system boots.  But can't work out why i can't see any files/icons

Hookay so bit of an update ,
I managed to actually get it to read burnt discs , so what I ended up doing was to use my Windows 98 retro PC to burn some CD's at 4x speed with an old pioneer burner from circa 2000-2003ish and so it looks like I wont need to adjust anything. I'm pretty chuffed right now.

Quote from: UD2 on November 27, 2025, 08:59:29 AMFYI the RAM doesn't operate at full speed in 16MHz mode, the I/O slot bus always runs at 10MHz. If you don't want slow memory past 2MB, you need a RAM expansion that goes in the slot near the CPU. These only go up to 8MB (6MB module + 2 onboard) but in practice that's fine because nothing actually needs more than this.

Very interesting, thanks for the info!

By the way, you actually do need more than 8MB if you want to load certain games from this HDD image (e.g., Valis II) due to the extra RAM they consume with virtual floppy mounting. Granted, those are just a handful of titles.

I have too many programmers. I didn't feel like buying another programmer (USBTinyISP) to program the DFO programmer, so it could program DFO's. 

I spend all evening trying to program the Atmega48A on the DFO programmer (it has a proper ICSP port) But nothing I tried was able to communicate to the Atmega48A. I tried Arduino_as_ISP on an Arduino Nano, AVR USBasp and lastly avrdude on a Raspberry PI.  None wanted to communicate. But I was able to communicate to the Atmega8 on the AVR USBasp.

Given an Atmega48A is pin compatible with an Atmega8 (found on my AVR USBasp), I swapped microcontrollers and was able to easily program the Atmega48A installed on the AVR USBasp through AVRDUDESS, using the Arduino Nano as the ISP.  The only difference I noticed is that pin 14 (/SS) is held to pin 29 (/RESET) and not floating like on the DFO programmer.

The Atmega48A detected fine, programmed, and now CDCE9XX is able to detect the DFO programmer.

Hope this helps someone in the future.