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RL02 use and restoration - Hive knowledge request please!

R

Radix

Experienced Member
Joined
Dec 7, 2022
Messages
316
Location
Midlands, UK
Hi All

I am looking at a couple of RL02 drives in otherwise reasonable condition and both have the following "condition" where the sealing gunk around the intercooler pipes seems to have shrunk or receded, or indeed split like in the close up photo below...

The joint seems to be sealed on both sides and the inside of the rear joint as seen from inside the drive looks very similar to the photo below on both drives.

Has anyone seem or had experience of dealing with this? - Is it a "leave well alone"? - Or is there a preferred way to deal with it?

Also - any good ideas for replacing the washable coarse air filter material? I have removed them at present as they have basically turned to dust.

Also any other tips for these drives for occasional demo and file copy use, rather than day-to-day 24x7?

Any ideas or other info much appreciated!

Robin

20240414_122746875_iOS.jpg20240414_122658128_iOS.jpg
 
Hi Radix, I'm also in the process of rebuilding an RL02 ( sold by another member on this forum ).

I had the same problem with the sealant and mine was leaking so I replaced.

After looking at a number of alternatives I went with a non solvent / non-acid based product from Screwfix - OB1. The main reasons were non-corrosive / neutral PH, non-shrink and able to adhere without attacking the plastics. That said, its very hard to remove easily, so lots of masking tape etc was needed.

If you already have a viable seal, I'd leave it.

That said I gave the existing filter a dry clean whilst it was all dismantled.

With respect to the foam filter I went for Multicomp Polyurethane Foam UL94HF-1 which is a 45 PPI grade foam, although RS also do 827-9608 which may also work. I stress that I could not find a specification for the existing foam that stated a minimum particulate size or Cubic Foot Per Minute flow rating, but it seems sufficient and comparable with the blower - no guarantees though ( at your own risk etc) . Since no-one else has responded I suspect the information may not exist.

I'm almost finished with my one, but managed to damage the sector transducer - so if anyone wants to sell me one I'm open to offers. Its actually a simple inductive sensor, a coil nominally 38Ohms, from my measurements, not a Hall sensor as all posts on the web seem to indicate. Oh and an RL02K also !

If you want to have a chat, I'm based in Bedford, UK
 
Hi - Thanks for the reply, I'm Robin

It seemed like there was still likely to be a seal on one side or the other, and actually any leak would be of pressurised filtered air when the disk was spinning, so I left it alone...

The coarse filter material was a very coarse open material, that we used to wash out when servicing the drives - is was not like a foam material as such, very like the material inside the back door of the cabinets, so I have left that out at present - I'll have a look at that material though - thanks!

Shame about the sector transducer - the position is critical, but simple to fit - I hope you find a spare one!

What system are you hooking it up to? I used to repair Q-Bus systems and compatibles back in the 80s and am restoring and repairing them now for myself and TNMoC at Bletchley - currently trying to get my RLV12 operational so I can test the RL02!

Robin
 
Radix said:
Hi - Thanks for the reply, I'm Robin

It seemed like there was still likely to be a seal on one side or the other, and actually any leak would be of pressurised filtered air when the disk was spinning, so I left it alone...

The coarse filter material was a very coarse open material, that we used to wash out when servicing the drives - is was not like a foam material as such, very like the material inside the back door of the cabinets, so I have left that out at present - I'll have a look at that material though - thanks!

Shame about the sector transducer - the position is critical, but simple to fit - I hope you find a spare one!

What system are you hooking it up to? I used to repair Q-Bus systems and compatibles back in the 80s and am restoring and repairing them now for myself and TNMoC at Bletchley - currently trying to get my RLV12 operational so I can test the RL02!

Robin
Click to expand...
Hi Robin,

As PM are not yet possible, I'll keep this short and say 'Thanks'. I'm just round the corner from TNMoC. I have a working RLV12 if you want to try it out, on that, next time you are over here. I have a 11/23+ (with FPF11) without a case and a 11/84 with 4MB PMI and FPU. Various Cards etc and a QBone.

Next time you are up this way drop me a PM

Jack
 
scojack said:
Hi Robin,

As PM are not yet possible, I'll keep this short and say 'Thanks'. I'm just round the corner from TNMoC. I have a working RLV12 if you want to try it out, on that, next time you are over here. I have a 11/23+ (with FPF11) without a case and a 11/84 with 4MB PMI and FPU. Various Cards etc and a QBone.

Next time you are up this way drop me a PM

Jack
Click to expand...
Hi Jack, Ah well there will be some DEC kit on display there later in the year... should be lots on FB about it in a couple of months.. Thanks for the offer - we have a working one in a museum system I can scope around for comparison if need be, but not out of ideas yet... I like the idea of being able to bring software updates on a real RL02 occasionally so people can see one in use from time to time - it will usually be booting off a SCSI card and ZuluSCSI though...

PMs will enable soon, but I'll drop you one anyway... Did you work on these back in the day? - The 11/84 system is a bit of a beast, I would be tempted to move the CPU and ram into a suitable Q-Bus box...

Robin
 
DEC RL01/RL02 drives are built like tanks. That's one reason why there are still so many of them still out there in every condition between still working and parts donor. But none of them have had their filters properly replaced in years due to a lack of new filters. A quick web search didn't even turn up any "God knows how old" NOS filters. If you have one or more of these drives, you'd probably like to do a filter replacement if you could, but you can't so you don't instead crossing your fingers and saying a little prayer every time you fly the heads.. I have a possible solution to the replacement filter problem that I haven't had time to pursue. I'm throwing it out there because perhaps someone else does and could be of benefit to all of us who have these drives.

Years ago I saw an article in "Street Rodder" magazine, a publication now defunct in print that seems to still have a web presence. They needed a custom air filter for restoration of a vintage car and visited K&N Filters in hopes of a solution. The article followed the creation of the tooling needed to create the new filter. Towards the end, the article said K&N was open to providing replacement filters for other obsolete applications. I saved that article but have lost track of it. Although "Street Rodder" is no longer in print. K&N Filters is still very much in business. Perhaps if someone took the time to contact them and provided the specs and a sample of each of the two filters needed, they'd be willing to create the tooling and become a source for new ones.

I have no idea how much demand exists, but if they were willing to make a one-off for a magazine article, perhaps they'd be willing to make a few hundred for us.
 
DDS said:
I have no idea how much demand exists, but if they were willing to make a one-off for a magazine article, perhaps they'd be willing to make a few hundred for us.
Click to expand...
One issue is that "street rodders" don't use HEPA (0.3 micron) filters, do they? It's the "absolute filter" that's key. https://web.archive.org/web/20200424101345/http://hepa.com/ is no longer with us, but certainly the equivalent material(s) are used by many manufacturers. A basic description of that filter seems to be:

DEC P/N 1213097: Plastic Frame, Alum Separators, no gasket, 99.99% eff. @ .3 micron Scan, Plastic bag, 33CFM@ 1.0' W.G. Nominal

https://www.knfilters.com/ does discuss "customizable filters" and mentions MERV in the industrial (data center) section. Looks like we'd need a filter rated at MERV 18 based on the following chart from https://www.iso-aire.com/blog/what-are-the-differences-between-a-merv-13-and-a-hepa-filter

1714659017558.png
 
There's a lot of discussion about this on Discord - and apparently the original manufacturer will make them for a run of 100 off.

One of the sellers on eBay takes orders and then cancels them, fyi
 
pbirkel@gmail.com said:
At what cost? Who was the original manufacturer; I thought that it was HEPA Corporation?
Click to expand...
HEPA is actually an acronym, like NASA.

www.epa.gov

What is a HEPA filter? | US EPA

HEPA is a type of pleated mechanical air filter. It is an acronym for "high efficiency particulate air [filter]" (as officially defined by the U.S. Dept. of Energy). This type of air filter can theoretically remove at least 99.97% of dust, pollen, mold,
www.epa.gov www.epa.gov

With two asthmatics in the house, we run an Alen HEPA rated filter in every room and I use equivalents in my garage shop vac.
 
I would b as reluctant to use a "pulled from working system" as I would be a sealed in plastic NOS filter that had been sitting on a shelf for 20 years. Either might well be better than what's already in your drive, and certainly better that running unfiltered. But it seems to me that a piece of aged decomposing plastic would crash a head as quick as a piece of plain old dust. As we all know, heads are hard to come by as well.

If you guys know of a ready source that requires a minimum purchase, I'd be willing to buy at least four. Surely we could get 100 spoken for just from folks on this site.
 
My plan is to refurb my existing filters or 3D print new housings if the existing housings are degrading. Find suitable filter material to stick in there. Find a suitable glue that does not outgas something terrible. The glue in the one I looked at a couple of years ago looked like some kind of hot melt glue and was clearly applied by hand. Too messy to have been assembled by machine. I will have to look again but the glue is probably all on the dirty air side of the filter. And if not on the original filters that is the way I would arrange it. But it would be so much more convenient if I could just buy some. I think I have 7 drives two of which are RL02. Do they have the same filters?

I wish I could find my copy of Steve Martin's book "Cruel Shoes" . There was one story in there that mentioned how thoughtful the cigarette manufactures were to provide us with a filter so that we are inhaling only squeaky clean filtered smoke.
 
DDS said:
HEPA is actually an acronym, like NASA.

www.epa.gov

What is a HEPA filter? | US EPA

HEPA is a type of pleated mechanical air filter. It is an acronym for "high efficiency particulate air [filter]" (as officially defined by the U.S. Dept. of Energy). This type of air filter can theoretically remove at least 99.97% of dust, pollen, mold,
www.epa.gov www.epa.gov

With two asthmatics in the house, we run an Alen HEPA rated filter in every room and I use equivalents in my garage shop vac.
Click to expand...
I'm aware of that. However the designation "HEPA" is trademarked by the HEPA CORPORATION (at least until 2027 it seems; renewed in 2017 for another ten years) according to: https://trademarks.justia.com/736/54/hepa-73654415.html

The FRU for "Absolute Filter" on page II/1-3 in http://www.bitsavers.org/pdf/dec/disc/rl01_rl02/RL02techDescr.pdf is "12-13097-03" -- not a typical DEC PN.

This is a HEPA CORPORATION PN. See the photos in this recent eBay listing: https://www.ebay.com/itm/295601714292 (shows the variant "12-13097-00").

It seems that DEC used HEPA CORPORATION as their supplier for the "Absolute Filter" in the RL01/RL02. Hence my inquiry.
 
As I have said in other threads: Unless the filter is dirty/plugged it's probably fine.

I've been running RL01/02's since 1986 or so and the only problem I ever had was with a pair of drives that came from the Solarex plant. They were used on the floor to run the machines to cut silicon solar wafers and the drives ate a disk pack (scratched it). First time I ever saw that happen.

Pulled the heads and they were angle shaped instead of flat. Took a look at the filter and it was *plugged* with silicon dust. Replaced filter and heads and unit is fine (other is parts).

Now, compared to that every other RL02 I have seen has had a clean filter. Which makes sense as the filter basically recirculates the air around the pack and the only time you get external air in is when you open the lid. So unless you were in a silicon dust factory on a system that swapped disks a lot you should be fine.

C
 
czunit said:
I've been running RL01/02's since 1986 or so and the only problem I ever had was with a pair of drives that came from the Solarex plant. They were used on the floor to run the machines to cut silicon solar wafers and the drives ate a disk pack (scratched it). First time I ever saw that happen.
Click to expand...
Sounds rather like management didn't care about silicosis -- in either their workers lungs, removable drives/packs, or both.

The DEC reference states "replacement of the absolute filter is only required on a yearly basis." Not sure whether that would actually be 8760 hours of operation or something more like a single "office hours" shift daily. One filter replacement would certainly last me the rest of my hobby life on either basis!
 
pbirkel@gmail.com said:
Sounds rather like management didn't care about silicosis -- in either their workers lungs, removable drives/packs, or both.

The DEC reference states "replacement of the absolute filter is only required on a yearly basis." Not sure whether that would actually be 8760 hours of operation or something more like a single "office hours" shift daily. One filter replacement would certainly last me the rest of my hobby life on either basis!
Click to expand...
I recall they had full PPE on the floor and such, but still over time there it went.

Point being the filters are not handling outside air, only air in the disk tub. Note: Oddly enough RD53s and most other disks also have absolute filters in them which is why I don't worry too much when opening one. All have always been 100% clean.
 
The older electromechanical telephone switches had no filters to speak of. Filers and filter maintenance showed up with the WECo 5ESS and Nortel DMS100. So I have done filter maintenance. We noticed that just replacing filters on a set time interval was a waste of time and money. Filters were removed and visually inspected. Those in high traffic areas of a 5ESS would be visibly dirty where those in the center aisles were not. Visibly dirty filters were just replaced. The clean looking ones would be held up and checked to see if the overhead fluorescents were visible through the filter. DMS frames actually had a flapper and microswitch arrangement that measured air flow and alarmed if the flow wasn't sufficient to hold the flapper up off the microswitch.

But how do I tell if an absolute filter is blocked?
 
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