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Tag: Drives

FD-148 is a third party floppydrive for the Commodore 64.

 

 


 

 


Remove the screws marked with red and lift the cover.
 


You need to loosen 4 screws to remove the shielding and additional 3 screws to release the PCB.
 


Detach the white connectors and lift the main PCB. There is a ribbon cable beneath the PCB which also needs to be detached. The back plate can now be removed.
 


Remove the 3 screws marked in the picture. There are spacers below that PCB which you need to take care of.
 


Spacers marked with red.
Two voltage regulators(7805/7812) are fastened to the black heatsink to the right.

 


Flip the drive around and remove the 4 screws.
The drive mech is now loose, lift the plastic casing.
 


 


 


 


 

I have repaired a fair amount of drives, and every time I find myself loading a test or a diagnostic software from disk. This is a bit of a contradiction since the drive being tested, or repaired, might not even be able to load a program. I also have a variety of tools for different purposes and wanted to have everything in one place.

 

This is why i created a 1541 Diagnostic Cartridge.


 

The challenge was to get all these tools to fit into a 8K cart. I wanted to keep the hardware simple and a 16K cart would have overwritten the Basic interpreter.

Therefor I have optimized both code and visual on the tools to keep the size down. Some tools are old, others were written from scratch and a few I rewrote in machine code instead of basic. A couple of the tools are still in Basic, but optimized.

The cartridge is an 8K ROM at $8000-$9FFF

You can also use RESTORE to return to the menu.

You may need to send a “I0:” or turn the drive off/on before running further tests if an previous error has occurred.

 
Alignment
Occasionally I get questions about alignment and aligning the drive. There are some differences of opinion how to align a diskdrive, my personal view, and how I do it, is to use a special analogue disk and a dual trace oscilloscope. The analogue disk is a factory produced disk and has patterns written on specific tracks. An analogue alignment disk can not be duplicated.

1541 Diagnostic Cartridge Alignment Check. This program was distributed with a computer magazine and gives a quick drive alignment health instead of hooking up an oscilloscope. The program was completely disassembled, compacted (code and texts) and disk routines rewritten to share I/O routines just to fit onto the cart with the other tools.

The Alignment check program can (I, however, do not recommend doing it this way) be used to adjust the alignment but it will only be as accurate as the drive, or system, the disk was written with.

The two first columns should be identical, otherwise the alignment is off by a whole track(or more), most often this indicates an incorrectly positioned head stop. The third column indicates how well the drive can read data off each track, its alignment, and should be 100%, or atleast very close to. Fourth column is between tracks (or half tracks), this value can fluctuate a bit even on a well aligned drive. The 1541 allows for some tolerance and therefore some values can be within reasonable limits.

It is very seldom when you actually need to align a drive for proper functionality. If the drive works in daily usage and does not make noise or do continious re-reads or searches it is probably ok. If a drive fails to read disks, begin with cleaning the head and lubricate the rails. If this does not help, the R/W head might be damaged, quite often seen on the Mitsumi D500 mechanism. You can verify it by measuring the R/W head using an ohm-meter. Remember that a slightly misaligned drive is probably able to format and read its own formatted disk.

Most important, if it works, don’t fix it 😉

Recommended reading : Commodore Diskette Diagnostic Manual Version 2 (3140451-01) and Commodore 1541 Troubleshooting & Repair Guide (SAMS)

 

 
Update 2019.12: A few words about alignment.
Update 2019.12: TFW8B is selling their version of the cartridge.
Update 2017.09: The Cartridge is also available at the Protovision shop.
Update 2015.12: Upon request from their customers, The Shareware PLUS Commodore 64 & 128 Blog asked me if they could offer the 1541 diagnostic cartridge in their product sortiment.

 

 

I had a broken 1571 on which I located the problem to the powersupply.

The PSU is relatively easy to refurbish with new caps and so forth, but I wanted to try out a switching powersupply i had.

The new powersupply is a MeanWell PT-65A and is rated 5VDC/7A and 12VDC/3,2A. It also has a -5VDC/0.7A output which was not used. This specific model was on a €4 sale at a electronics distributor and the current ratings were good, hence the selection.

 

WARNING! LETHAL VOLTAGES ARE PRESENT ON THE POWERSUPPLY.

 

 


1571 with original powersupply.

 

 


Mounting plate.

 


Testmount.

 


A very tight fit, I had to make a cut on the left side.
The PCB is mounted on spacers and the cables were crimped.

 

Finished assembly.

 

 

 

 

 

 

RapiDOS professional is a floppy speeder based on the Professional DOS by Klaus Roreger. More information on Professional DOS can be found at : http://www.d81.de/ProfessionalDOS/ and http://ar.c64.org/wiki/Category:Professional_DOS

RapiDOS was sold in the US by Chip Level Designs with kernel code written by Lawrence Hiller (aka Mr.Nike). Mitch/ESI gave ideas and feedback to the code resulting in RapiDOS having lots of “hacker enhancements” over Professional DOS, for example the built in monitor. It also functions on PAL (50Hz) Machines.

On this page you will find pictures of the RapiDOS hardware. The ROMs are also available for download.

Thanks to Mitch / ESI for information and for the hardware/ROMs !

 
Update: Added a .pdf with all reviews and advertisements regarding RapiDOS from Ahoy/Info/Gazette Magazines. Thanks to Stone Oakvalley for the information 🙂

Interesting to note is that Compute Gazette Issue 51 (1987-09) has an advertisement saying RapiDOS is “soon coming” and in Issue 54(1987-12) it is available. Later on C128 and CP/M is mentioned to be supported.

 


 

1541 with RapiDOS professional
Drive controller board and the CIA board installed. The wire lead is used for switching the RapiDOS on and off through the User-port board.

 


RapiDOS Professional User-port Board.
Switch to the left turns on/off the RapiDOS in both the C64 and the 1541.


C64 ROM Adaptor board

[No picture available]
The C64 ROM Adaptor board has a wire lead connected to the User-port board.

 


More pictures of RapiDOS Professional.

 

 

 

Parallell cable for Oceanic (OC-118) / Excelerator Plus drive.

You need to connect the following pins (identical to 1541). This drive works with Zoomfloppy.

 

There are four screws that hold the bottom plate, turn the drive upside down and remove the screws. Now you have access to the PCB.

 

Locate the correct chip by the pictures below (i soldered the wires directly to the legs).

Parallell cable for Oceanic (OC-118) / Excelerator Plus

 

Parallell cable for Oceanic (OC-118) / Excelerator Plus closeup