RommudohMay 6, 2024
After getting the #Commodore #C64 and #C128 running again, the next device to repair is the #C1571.
It had #corrosion and #rust on the main board and the power supply is beyond repairworthiness. I'd replace the latter with a #meanwell RD-35 with 5 and 12 volt output.
One #diode was rusty, a few traces needed #cleaning and five #resistor looked bad. Hope the black hybrid chip is still okay.
Sadly, the lower read head seems to be broken, my work might've been in vain.
#floppydrive #retrocomputer
Show threadRommudohMay 9, 2024
Here a comparison of the old #powersupply and the replacement.
I already cleaned the old board, removed two rusted diodes, and unsoldered the ICs, but there might be more defective components, that's why I decided to replace it with something completely different.
Still unsure if I'll leave the cable binders for keeping it in place.
#commodore #c1571 #retrocomputer #restoration #meanwell #psu
Show threadRommudoh
Good and bad news... the replacement #PSU works, and the repaired PCB seems to work, too.
But the bottom read head is now confirmed dead. I measured the coils directly at the head. Like before, only the erase coil is intact.
#Commodore #C1571 #floppydrive #repair #retrocomputer
May 11, 2024 at 6:14pmWeb
Show threadRommudohMay 12, 2024
At least my three #Commodore 1541-II drives are fine. They read my floppies and pass the tests. One of them even shows perfect #alignment scores.
I'll leave the 1571 alone for now, until I find a replacement or other solution.
Next, I still have a VC-1541 to repair. It had a bit of rust, too. Also, an #ALPS drive this time.
#retrocomputer #1541ii #1541 #VC1541
Show threadRommudohMay 19, 2024
I took the #commodore #1541 completely apart, removed rust, and reassembled the power #transformer part. It shows 16.9 and 10.6 Volts without load. Maybe I'll change it to a modern switching PSU, too.
The read head and motors show reasonable resistance values, so it should work.
The #74LS14 looks a bit dirty, I will give it a good clean and replace the dirty socket.
It is a rev B board, but without the reset fix shown in the manual, so I might add it, too.
#retrocomputing #repair
Show threadRommudohMay 22, 2024
Some progress with the #Commodore #VC1541 - I added the reset bodge, socketed a few logic chips, and turned it on.
At first, the drive was spinning constantly, but all the logic signals looked fine, including the reset signal.
I then swapped the 6502 from a working 1541-II, and it worked again.
Now, I have a few mechanical issues. An inserted #floppy is thrown out again most times, and the tray doesn't latch in closed position easily.
#retrocomputing #Alps #floppydrive #repair
Show threadRommudohMay 29, 2024
To make absolutely sure that the 6502 #processor is defective, I built a #NOP test #circuit on a #breadboard with a 100kHz #NE555 clock and a couple of LEDs on the address lines.
A known working 6502 looks fine, I can clearly see the higher address lines counting up (I accidentally inverted the LEDs).
The one from the 1541 doesn't show any activity. Only address lines A0 to A3 look normal on the oscilloscope.
#retrocomputing
Show threadRommudohMay 30, 2024
Some more progress on the #Commodore #VC1541 today.
The #alignment from the diagnostics looks okay so far.
But when trying the performance test, it gets stuck at the "formatting" stage. The red LED lights, but the spindle motor doesn't start.
When trying the "fast format", the spindle motor starts, but the red LED doesn't light up.
Both programs, and any other from the diagnostic, seem to freeze until I switch the drive off, resulting in a "device not present" error or similar.
#retrocomputing
Show threadRommudohJun 6, 2024
I finally #fixed my #Commodore #VC1541 by replacing all the crappy IC sockets!
I checked every connection against the #schematics and noticed a few higher resistance values when measuring at the IC pins - still low enough to beep, though.
They were very cheap sockets with only one-sided connections, which can result in poor connection.
After swapping them (#unsoldering and #soldering 256 pins), it works like a charm. Very quiet purring since I cleaned the mechanics, too.
#retrocomputing #repair
Show threadroot42May 30, 2024
@rommudoh does a regular format using OPEN and N0:… work?
What does OpenCBM say?
Show threadĸurthMay 12, 2024
@rommudoh that is one grimy 1541 :D good luck