DEC TK50 common failures?

emanuel stiebler emu at
Thu May 14 08:28:29 CDT 2020

On 2020-05-14 08:22, Martin Reilly via cctalk wrote:
> I'm trying to bring a pdp-11/83 back to working order. Challenge right now
> is storage - I have RQDX3 and RD54 but the RD54 appears to be unserviceable
> (never goes ready) 

As you like to go for the MFM emulator anyway, lets just talk about the
TK50 ...

> and TQK50 with a TK50 which never gets to a stage of
> allowing me to operate the handle to load a cartridge - the green LED
> doesn't come on, the red LED is solid for a short time after power applied
> but then flashes rapidly. I plan to go with an MFM emulator in place of the
> disk, but would like to get a TK50 working as I have a lot of old stuff I'd
> like to try reading off cartridges.

You hear it doing anything?

The solenoid, which locks the cartridge got stuck?

> I have a spare TK50 drive, which behaves exactly the same. The TQK50 LEDs
> suggest it passes diagnostics, and the boot menu recognises it and will
> attempt to boot from it before saying there is no such drive. I don't have a
> spare controller.

If you look for one, go an get the tqk70 ...

> There is a lot of very detailed documentation for the TQK50/TK50 as far as
> the electronics and interfacing is concerned but I haven't found much in the
> way of information about the mechanical side. Are there common failure modes
> for these drives when they've been stored for a long time? Last time they
> were powered up is probably close to 20 years ago. Without much in the way
> of test kit (I have multimeter but no scope) is there anything I might be
> able to check easily?

Very short one:

As this says, they suck up dust better than most vacuum cleaners, so
cleaning is a must ...

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