One of my C128 (PAL) Powersupplies let the magic smoke out. After some research I found some inconsistencies in the schematics available, so I drew my own and verified it against 6 PSUs in total.

The C128 PSUs have been considered as rather stable, undoubtly better than the C64 PSUs, but during my process repairing the broken one I noticed some concerns.

Several of my PSUs had cold solder joints.

No fuse on the +5V rail.

There is a crowbar circuitry which will short/pull down the voltage if output exceeds 6.2V, however if it fails, then the full overvoltage may be output on the 5V rail, and this is exactly what happened with my PSU, everything went south in just matter of minutes.

The underlying problem was the 4700uF capacitor C9 which is across the 5V rail. If this capacitor fails to the extent that there will be no continuity, then the 5V rail kicks up to somewhere between 12 and 15 Volts (!). The crowbar circuitry pulled it down and after it failed, I could measure 12V on the +5V rail. Fortunately I didn’t have my C128 powered on.

Needless to say, I recapped all my C128 PSUs. Capacitor C4 and C9 replacements below are LOW ESR, 10000 Hrs @ 105°. Replacements for V8 and V10 are similar according to some equivalent tables but do your own research on these.

I gathered all documentation used during the repair below.

 

 
 

 

 

 

 

Green: Different, but equivalent or similar, components found in PSUs.

Red: Components found in PSUs with differing values.

Later revision PSUs have an additional capacitor, C12, and these PSUs are equipped with a 100Ω R13.
 

 
C12

C12 capacitor can be retrofitted as picture above.

 
Failed PSU

Leaked cap and a blown(bent down for visibility) V10

 

 

 

 
 
 
 
 
 

 

C-128 Integral P/N:310639-02
The C128D, non-CR, a.k.a. plastic model PSU is different compared to the C128DCR PSU. This model/PSU also has a (noisy) fan. I have seen a few of these machines where the fan has been disconnected or connected to a switch resulting in overheating and a fried PSU.

 

 
 

 
 
Original fan

Panaflo FBS-06A12H
Panaflo FBH-06A12L
Panaflo FBP-06A12H

FB = Motor type: FB=panaflo
S/H/P = Bearing type (?)
06 = Housing size, 60×60 mm
A = Housing thickness, 25,5 mm
12 = Rated Voltage, 12V
H/L = Speed. H=high, L=low

 

Couldn’t find a datasheet for the original fan but FBA06 might be a close match.
FBA06A12L1A: 3200 RPM / 14.1 CFM
FBA06A12H1A: 4200 RPM / 19.1 CFM

Possible substitute, haven’t tried it though, nf-a6x25-flx

 
 

d2d64 was written for x86 and an older version of opencbm which is bundled with the Zoomfloppy installer package, if upgrading, or having a later version of opencbm will cause compatibility issues.
 

Probable causes:
1. d2d64 does not find the required (x86).dll files at C:\Windows\SysWOW64\
2. Zoomfloppy device is named differently between opencbm versions.

 

Using the Zoomfloppy installer package on a machine without previously installed opencbm will not cause these problems, even with an later x64 OS.

 

If stuff has hit the fan, there is a trick to get things running without needing to uninstall and reinstall everything. I put together a package that allows you to run d2d64 with a newer opencbm version. (d2d64 will probably not be updated, sorry).

1. Prerequisite: opencbm-0.4.99.104 and drivers installed.
2. Download the package below, unzip and use c:\d2d64 as destination folder.
3. Copy the file from c:\d2d64\Windows_SysWOW64\opencbm.conf to c:\Windows\SysWOW64\
4. Remove any old x86 opencbm*.dll files from c:\Windows\SysWOW64, otherwise these will be conflicting.
5. d2d64 should now be working running within the c:\d2d64\ folder.

If you want to use another destination folder, change the path in the opencbm.conf to your preferred location.

 

Above has been tested to work on a Windows 10 22H2 (OS build 19045) with opencbm-0.4.99.104. Hope this helps.

 

Took some pictures of my 1541-II mechanics, found four different models.

Update 20230922: Thanks to Jarkko from Oulu for the fourth, Kwanasia, drive.
  

  
Newtronics / Mitsumi D500


 
NOT the same Mitsumi D500 as in 1541/C
 
 
 
 
 
 
 
 
Chinon FZ-501M REV A


 
 
 
 
 
 
 
 

JPN Corp. DS-50F


 
Same as Digital Systems Inc. DS-50F and Safronic DS-50F ?
 
 
 
 
 
 
 
 
KWANASIA


IC datecodes are 1988.
 
 
 
 
 

C128 DCR PCB ASSY 250477

 

 

 

SX-64 PSU PAL (220V) / Mitsumi Model SR35
Input: AC220-240V @ 50Hz
Output: AC9V 0.2A, DC5V 3.15A, DC12V 2.76A
P.NO. 250623-02

SX-64 PSU NTSC (110V) / Mitsumi Model SR34
Input: AC117V @ 60Hz
Output: AC9V 0.2A, DC5V 3.15A, DC12V 2.76A
P.NO. 250623-01

 

 
 

This is continued from the Action Replay 6 Clones but deserves a separate mention since the information applies to other equipment having a 82s129 PROM.

The AR6 clones have a 82s129/TESLA74287 which is a 1024-bit (256×4) programmable read-only memory with three-state outputs. Empty/blank PROMs are available but a programmer which accepts these chips are harder to come by.

Whilst trying to understanding the innards of the Action Replay v6, together with Sukkopera, we had the challenge to understand the functionality of the PROM and to find a suitable replacement.

Zimmers has logic equation for the PROM but we had to verify it.
 
 

READING OUT THE PROM

1. Use Arduino Arcade ROM dumper to test through all combinations with an arduino and output the result to the console:

 

 

 

 

 

  This solution gave an identical output as the one on Zimmers, so we could conclude it was correct.
 

2. Use OldPromAdapter to read out the contents, this also allows for replacing the PROM.

 

 

 
This will be a binary file, the first 256 (0x0100) bytes are only needed. I made a tool to convert the binary data to the same layout as used in the Arduino ROM dumper, and the result was the same.

 

ACTION REPLAY V7.3 PRO (Atrax) vs ACTION CARTRIDGE (R) PLUS V5
The PROM on both AR clones is identical.

 
NORDIC/ATOMIC POWER PROM
Jens (icomp.de) posted the logic equation for the NORDIC POWER cartridge on Forum64, and this was almost identical to the Zimmers, and ours. It was an easy conversion to binary format for the OldPromAdapter.

 

REPLACING THE PROM
For testing purposes and to verify the data we got out, the PROM was first replaced with the OldPromAdapter.

 

 

 

 

 

 

 

 

 

…although it does work, there is an obvious issue with this solution 🙂 This is a simple solution to where space is not an issue (unless the eprom is too slow to replace a PROM). We could also run the Nordic Power ROM on our hardware as a bonus.

 

REPLACING THE PROM WITH GAL

 

 

 

 

 

 

 

 

The pinout of the PROM and a GAL is almost identical, you can wire 1-7 to 1-7, 8 to 10 and 9-16 to 13-20 assuming you build the equations accordingly.

Sukkopera managed to convert the PROM to GAL16V8 and added logic to be able to switch between Atrax/Action Cartridge and Nordic Power mode.
 

…stay tuned for another update 🙂

I converted the C128 Kernal sourcecode from Zimmers to 64tass compatible syntax. The original sources are in BSO/Assembler(VAX/VMS) format and is split to different sources for the EDITOR, Z80 BIOS and KERNAL. I combined it all together into a single build still keeping the sources as original as possible.

It compiles to an identical file as kernal.318020-05.bin, containing the EDITOR ($C000), Z80 BIOS ($D000) and KERNAL ($E000), this is the same as upper part of the 318023-02 ROM.

The sourcecode included an updated / unreleased(?) revision 318020-06, I added a variable so it is possible to select if you want to build revision 05 or 06 (c128kernal.tas).

The source code is well commented and documentation included (readme.doc / relnotes.src).

To build the sources:
64tass -Wno-star-assign -a -b c128kernal.tas -o c128kernal.bin

PROLOGIC DOS Classic, floppyspeeder by Jann Datentechnik/REX Data Technology.

The Prologic DOS Classic consists of two parts, one PCB for the drive and a cartridge-port PCB for the C64.

I bought one of these and it was in very poor condition and non functional. I removed all components, cleaned up the PCBs, replaced components and sockets and soldered everything back together and now it works. 🙂

User manual(german), Installation manual(german) and receipt.

Software (copiers etc) to go with the card.

 

 
C64 CARTRIDGE PORT PCB

 

 

 
DRIVE-SIDE PCB

 

 

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