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RK05 Drive and Controller Work

ftcnet said:
re: comments regarding the need to replace the RK05 head-retract battery pack. For this type of application does it need to be a battery pack? Could a 'supercap' be just as effective? Would the RK05 battery charging circuit need extensive mods to work with an appropriately sized supercapacitor?
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I did that a while ago after the replacement battery pack I put in died. The capacitors in the drive provide some retraction by themselves. Supercapacitor adds more though sloping discharge profile and ESR make them different than battery. They charge with resistor so it will be slow to charge supercap without change. -15 is used to charge caps so ypu probably need a clamp. Suspect I changed something to allow faster charge to reduce unprotected time. Battery will also prevent heads from loading onto platter with jolt to drive such as moving it. Capacitors likely will have discharged. If the battery pack has died on you it won't protect drive which is why I put in the caps since they should last longer. Some of my drives don't get powered on that often which batteries don't like.
 
My preference would be to keep the drive in its vintage form as much as possible. Isn't it just a NiCd pack? NiMH should suffice as a replacement.

If the battery needs to be replaced because if unavailability, I'd probably look into designing an active charging and regulating circuit around a Li-ion cell, but that would be a last resort.
 
DougIngraham said:
Another option would be to run the drive on a UPS.
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Um. I don't know how a modern "UPS" would handle a massive inductive load (motor, fan, and that head positioner"). I have an APC Matrix 3000 in my shed that needs fixing, it has a massive transformer in the bottom and would probably handle RK05's.

Or just use the NiCDs.
 
I bought a new filter for the shop vac over the weekend -- hadn't been using it since removing the mouse mess from that RL02 a couple weeks ago, it'd been out in the tin building as the whole thing smelled of mouse! Vacuumed up the exploded plenum elbow, used the shop vac + screwdriver to get all of the loose foam chunks/dust out of the drive. Made the critical mistake of sticking the shop vac nozzle in the chad bucket of the PC05, ended up causing more of a chad mess!

I removed the bottom covers of the drive to do the cleaning, and discovered two things: first, there's a red tag on one of the Flip Chip modules saying the drive was having intermittent read problems. Second, it was resold by Amercian Used Computer out of Boston!

Picked up an assortment of draft-blocking window foam from the hardware store when I picked up the shop vac filter. I was going to get more window AC washable filter foam, but they were reorganizing that part of the store and didn't have it out on the shelf, I suppose because cooling season is coming to an end here. Should be ready to start refoaming the RK05 this week!
 
Started digging into the first RK05 today. Removed the blower, HEPA filter, what was left of the pack air plenum elbow, and the air fitting that connects to the pack itself. Disassembled the blower, the squirrelcage was rusted to the shaft but was freed with WD-40, a brass drift, and a small engineer's hammer, with the back of the blower behind the bushing supported by an open end wrench clamped in the bench vise. Blower motor bearings oiled, though they're still rough -- if they don't run in, I'll strip down the spare blower I have and put actually new bearings in it, which is probably the best long-term strategy anyway.

Cleaned the chassis, front panel, door, etc. The door area was very filthy inside and out but cleaned up nice. Is there a trick to removing the lamp covers? Three came out easily, I didn't want to pry.

Stole a good plenum elbow from the parts unit RK05 that came from @Conmega -- the back end of that drive is super rusty, but the front half is actually pretty OK. It's like it stood door-end-up in very damp storage or something. All of the above cleaned thoroughly, the stuff that fit went in the ultrasonic cleaner.

Removed the backplane, doesn't look bad, probably helps that the slots face down. There was a M930 terminator in this one, I guess it was the last drive in a chain, or the only drive. Going to give it the usual alcohol on cardboard cleaning, followed by DeOxit on the card edge fingers. One broken maroon DEC handle I might replace, I have spares from scrap boards.

Removed the power system, which comes out surprisingly easy considering this thing is still racked! Going through the regulators now.

Attitude toward success on the first drive has improved considerably upon disassembly :p
 
The RK05 is now stripped down and base assembly cleaned:



As you can see below, basically everything that's not the head and spindle system is out:



I vacuumed the chassis out, cleaning in the hard-to-reach places with a big paintbrush and/or toothbrush. I wire brushed the remaining foam off, as well as any loose corrosion. I tried to wire brush the plenum elbow residue off, but it won't do it. I'll try Goo Gone, and razor scrape it if that doesn't work.
 
PSU recapped and reinstalled, air system refoamed and reinstalled. Pulled air the wrong way thru the HEPA filter with the shop vac, realized I forgot to put the little piece of velcro in, snuck it in without fully removing the blower :p

Tomorrow I get to clean the backplane and board set up, and then I think we're ready to power it up!
 
Can't format a pack, I've tried two scratch packs with the same result: after I set the switches for drive 0 and hit continue, it seeks way toward the spindle and back to 0 a few times, WR flashes, RD flashes, then prints SYSTEM ERROR on the console and halts. Thoughts?
 
Dug into the microfiche, looks like the SYSTEM ERROR output is what happens when there has been four consecutive errors to format a track. I'm pretty sure I'm seeing the cleaner with the head seek dance bit, looks like that will happen 6 times. Write format or read format can cause the SYSTEM ERROR printout. Digging into the printsets to figure out where that's likely coming from.

Probably the next step is hooking up the oscilloscope and verifying all the timing and level checks in the quick guide.
 
Had a random failure to boot from the Emulex UC18, so I ran diagnostics, but I mistakenly ran VMSA?? instead of ZMSD?? and thought the PDP-11/34a was *really* broken! ZMSD?? ran fine for 22 passes while I Did Something Else.

Different head amp board and sector/index board changed nothing. I did change the sector/index board that came in this drive because I never got ON CYL with the original -- not sure if it's a blown lamp driver or some other failure, figured I'd chase it later since I have spares.
 
After executing the formatter and having the PDP-11 stop with SYSTEM ERROR, I examine the RK11-D error register at 777402, and the contents are 001000, which is DLT, or "Data Late." Not quite sure what that tells me yet.
 
I was running the controller test part 2 incorrectly, one needs to stop ZRKK?? and zero out memory location 40, then restart at 200, if the drive to be tested is #0. Looks like this is a safety mechanism to prevent fragging your diagnostics boot pack. Now getting failures, which is actually an improvement :p It will happily accept drive #0 as the one to test without the safety bypass, and will just print repeatedly that it is passing diags.
 
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