This Commodore 1541 hides a terrible secret.

foreign what now [Music] in 1982 Commodore released the 1541 floppy disk drive to pair with the new c64 home computer the original model shown here was built with an Alps Drive mechanism these early units can be distinguished by the pull-down tab used to close the drive door a number of problems plagued these drives including overheating as well as frequent misalignment due to manufacturing defects and the characteristic head knocking which was implemented to work around the lack of a track zero sensor to remedy this Commodore switched suppliers in 1984 and revised the 1541 to use drives made by mitsumi's neutronic subsidiary this resolved the alignment issues but introduced a new problem the heads of these new Tronix drives were improperly sealed allowing moisture to penetrate to the delicate coil inside and resulting in a short that renders the drive inoperable these failure-prone models can be distinguished by their more conventional flip lever the fault can take decades to manifest but it's Relentless and it is pervasive one user on the lemon 64 Forum lamented that of the nine 1541 dry sealed eight of them failed simply while sitting unused in climate-controlled storage and it's not just bread bin Brown models that are affected either certain 1541c and 1541 twos also contain neutronics mechanisms and are also susceptible to read right head failure let's take a look at a few examples here are a couple 1541 2 drives this one is in good working condition this drive is the one we just experienced the read error with and suspect it may have suffered a head failure I've already removed all the screws so let's start by testing the working unit here's the read write heads Carriage assembly this is a single-sided drive so there's only one head located at the bottom which makes it a little hard to see if we follow the cable from the head to the circuit board and disconnect it we can see that the pin header is keyed with pin 2 being absent to test the head all we'll need is a multimeter set to resistance mode to perform the test we'll measure the resistance between all four conductors this will give us six possible permutations what we're looking for is measurable resistance below 100 ohms if we see no resistance at all we've got a dead short and the head is toast here okay pins one and three look good one and four checkout one and five three and five four and five are good and not shown are three and four which are also fine the read write head of this drive is within spec okay now let's swap the good drive for the one we had a problem with earlier as we can see from the label this 1541 2 has a neutronics drive mechanism oddly it has much longer wires than its sibling all right let's perform the same test as before starting with pins one and three at a bear down hard to make sure I'm making good contact with the probes here nothing how about one in four nope one in five nada three and five that looks better four and five [Music] that looks good too but pin one is short we have a dead read write head this drive cannot be repaired and is now only useful as spare parts both of these 1541 two drives have neutronics mechanisms and one is already dead I guess it's only a matter of time until my good drive here fails too here's how you can identify a 1541-2 with a belt driven and failure-pro nutronics drive it looks nearly identical but take note that the lever sits flush with the front housing here in contrast the 1541 2 with the slightly recessed lever uses a direct drive chinon mechanism instead now you know what to look out for when you see what looks like a good deal on eBay earlier I mentioned that repairing a failed head is not possible I want to talk a little more about that now here's a useful blog post on retrohacks.net discussing various 1541 repairs that will help to illustrate this point a link is in the description below a floppy drive's read write head is comprised of copper coils wound around a ferrite core a basic electromagnet not only is this device incredibly small but it's also potted in epoxy making removal difficult similar to a crt's deflection yoke repair is within the realm of possibility but beyond the skill of the average Enthusiast as a result replacing the head or the entire Drive mechanism with a known good part is really the only option replacing just the drive head is no walk in the park either since spare parts are not readily available one lemon 64 Forum user discussed using a donor part from a chinon PC drive to retrofit his 1541 as seen here he goes on to link to a photo gallery of the process wherein he removes the failed head and glues in the donor part getting the head properly aligned after the swap was necessary but the drive was fully functional after the procedure this route seems a bit more approachable assuming you are able to Source a compatible donor and have the tools necessary to perform an alignment now that you're armed with this information you can go shopping with confidence because let me tell you there are a lot of these drives out there take this one for example the ad says it powers on but gets a file not found error message but it worked six months ago it goes on to say it'll probably work fine after an alignment and cleaning are you willing to take that bet because I think we know better now I don't need to tell you this but if it says untested for parts there's a high probability the seller knows it's bad sure there are Parts on there that are useful the PCB and chips on it for instance but the neutronics drive itself not so much powers on is another code word for untested or worse I know it doesn't work steer clear even better are these untested neutronic strides for literally 10 times the price is anyone actually buying these things well here's your answer yes someone just paid a hundred and fifty dollar ship for this one that powers on and Spins I'm sorry whoever you are out there I failed you by not making this video sooner and here's one more for good measure untested as is and it's a neutronix bought by someone for 140 bucks so there you have it the Commodore 1541 and which ones you should avoid don't forget to like subscribe and check out our patreon or Channel memberships if you'd like to help support future retro bits videos I hope you learned something new thank you so much for watching and see you next time [Music] [Music] [Music] thank you

Channel: retrobits

Views: 113,769

Keywords: retro, diy, commodore, c64, 1541, 1541-II, newtronics, disk drive, floppy disk, read head, read/write head, mitsumi, alps, computer, c128, test, testing, 1541c

Id: ByHdBD16DRg

Length: 8min 53sec (533 seconds)

Published: Fri Nov 18 2022