I recently picked up an old 1541 Commodore Disk drive for my Commodore 64. It was a bit ugly so I cleaned it up on the outside and inside before testing it.
I started by taking the case off of course as seen in the pictures. First I used some WD40 to break down the adhesive on the sticker on the top. Then I tried some Isopropyl Alcohol on the permanent marker, but it did not do much. I guess the marker was protected by the dirt.. I went on and used water and regular dish soap with paper towels and a toothbrush for the grills. From there I went to baking soda with a little water to make a paste to scrub the various black marks and the permanent marker with an old toothbrush. It didn’t get all of the marker but it make a big improvement. I then washed it all down with some dish soap again to get any remaining Baking Soda off the pieces. Once I dried it off, I took 91% Isopropyl Alcohol to the remaining marker, and it was able to take care of it just fine. The case is quite browned from the sun, but I don’t know if I will do anything about that.
Internally it was quite dirty too, but I did not think to take any pictures of it. Here is what it looked like cleaned up.
It looked far better and seemed like it may have been in working order. Unfortunately after I put a disk in it was unable to read it, although it attempted to. It turned out that the read write head of the drive was burned out. This is a very common failure on these Newtronic Mitsumi based drives back in the day due to corrosion in the heads or something. Based on the IC dates on the board it is a late 85 or maybe 86.
Above is a picture of the bad head pulled from the drive mechanism. The unit seems to operate normally in every other way, but new heads just aren’t available. With the head being a common failure I considered the odds of getting another Newtronics Mitsumi drive that had a good head as being a big risk. So I looked around for another 1541 listed as needing repaired that had the ALPS drive mechanism instead.
Well we need parts so..
The parts drive came in, it was reported as not working. It made a noise when plugged in but no lights on the front. I looked at the label here, and being in the US the “220V” just won’t work here. The drive wasn’t getting enough voltage to power the 5Volt electronics. It was getting enough to run the 12Volts for the drive motors though atleast to some degree. There may have been nothing wrong with this drive other than that. Still I picked this up for parts. The drive unit itself actually, as this is the ALPS style unit. The drive units are fully compatible, and it is just a matter of pulling the unit and putting it over into my other drive that had the bad head for the Newtronics drive.
While I was in there I did look at the transformer sections. For the 220V there is a “red” tap connected to the fuse, and for the 117V unit the black wire is connected to the fuse. Both transformers are almost the same model number, and both have red and black taps, with the extra tap insulated. Even though they look about the same, minus the last few bits after the dash on the model number, they are different transformers. I did check if switching the Red wire for the Black one on the 220 Volt would change it over to work like the 117 Volt one, but it doesn’t. The only Voltage conversions I have seen on these drives involved swapping out the transformer, basically like I did. The transformer could be changed, also it would be possible to put in and bypass the existing regulators, or supply a proper voltage that can be regulated down by them.
The boards are the same revision in both drives and appear to have been built just a couple years apart.
The main 6800uF capacitor was dented, so I picked up a set of new Electrolytic Capacitors for the drive from Console5.com. After testing it the capacitors I found one with a ESR of 40 Ohms, so it probably was a good idea to get them replaced. I also redid the solder at the serial ports and a few touch ups of connections that could have been a bit better out of the factory but were ok.
Here is the combined drive assembled. I did basic testing and the drive did read a disk and format a disk fine. I will look to do an alignment check shortly, but it looks like it should be finally working. I have since cleaned up the case from the 220V unit and swapped the converted 117V drive setup back into it. It is less “brown” overall, and doesn’t have a light patch on the top where the sticker was on this one. It did however have a large sticker on the right side, but still looks a fair bit better overall. The change of case doesn’t look significantly different in a picture so I won’t be positing a specific picture of it.
I have also looked over the board from the 220V unit. Someone tampered with it, I don’t think “repaired” is the proper term. I think they realized the 5Volt wasn’t working and removed it and reinstalled it (poorly), they pushed the traces off of the board. I repaired that and a capacitor they had pulled and very poorly reattached as well as one of the jumpers. I also touched up a few of the original solder joints that could use a bit of attention. I then cleaned the board and tested it. The board seems to operate fine, I didn’t do any extensive testing, but is did respond. I figure it is either working fine, or should be reasonable to repair. At this time I am only keeping it for a spare so I packed it up in an anti-static bag for safe keeping.
I am tossing the idea around of turning the extra 1541 chassis into a Pi1541 & Tapuino. I am not sure I feel right putting extra holes into an otherwise good case though. All of the controls would be on the 5.25″ Plate, but it would involve quite a few holes in the back of the case than are there now.
Muldrf's Hobbytronic 