Looking for Remstar Pro M-series blowers

[DrCharles]

I have two otherwise good Remstar Pro M-series machines in need of repair... one with a bad motor and one that is noisy. I'm quite capable of swapping the motor myself, or even doing internal repair on it, but I can't locate a replacement. There does not appear to be a non-destructive way to disassemble the motor itself.

Any parts sources to recommend? If I buy a well-used parts machine it is also likely to need a blower replacement. Thanks

[zonker]

this is fairly far out there but-
"Hola amigo, tengo todos los repuestos relacionados con tu producto, el que estás buscando tiene un costo algo elevado, puedes contactarme: +57 3007614324

Translation:
Hello friend, I have all the spare parts related to your product, the one you are looking for has a somewhat high cost, you can contact me: +57 3007614324"

this is from apneaboard circa 2020.

ETA:
https://pk.agisafety.com/supplier/respi ... m-supplier

[DrCharles]

Thanks... that site is in Colombia and looks like one of those where they don't actually have any parts, just take requests and then see if they can get it somewhere and mark it up.

Meanwhile I was able to disassemble the blower. It's a simple three-phase brushless motor. With a scope, I can see that all 3 phases have the right current pulses. The shaft has two tiny sealed ball bearings, and between them, a magnetic ring. The chrome plating has worn off the ring, and numerous ferrous flakes were stuck to it and the six pole pieces causing sufficient drag/binding that the motor will not spin up. (On startup the controller pulses the motor twice, looking for rotation feedback signal, then cranks it up to make pressure). I removed all the magnetic debris and the loose plating, and then the motor would start. It worked for several starts and then gummed up again.

The only possible cause (aside from swelling corrosion damage to the magnet which is not in evidence) is radial play in the bearings sufficient to allow the shaft to wobble and strike the rapidly rotating magnet against the pole pieces. I need to take it apart again and measure the bearings, which appear to be readily available off-the-shelf parts. I can't read in place the tiny numbers on them other than NSK (manufacturer) and "R32".

[zonker]

Thanks...

if you get this working, tell us the particulars.

oh! and there is a site that does CPAP repairs. I don't if they would sell to you or maybe reveal their parts source but it's-

https://acbio.com/

good luck!

[DrCharles]

I sent ACBio an inquiry, thanks again. But I'd be surprised if blowers were even available, let alone for sale direct I also asked how much they'd charge to fix it themselves (most likely not worth it for a machine made in 2007...) As an MD and an EE, fixing old machines for my personal use does not present any liability issues.

Meanwhile after some more cleaning and reassembling (with the original bearings), the machine is now working properly.
But the blower is really noisy - breathing through it sounds like a motorcycle race outside So I ordered some R3-2 bearings on ebay (only $10 shipped for 10) and will post more later when they arrive.

[zonker]

So I ordered some R3-2 bearings on ebay (only $10 shipped for 10) and will post more later when they arrive.

sounds like you're making progress.

I wish former forum member pale rider was still hanging about. he knew all about tear downs and repairs of this stuff.

[DrCharles]

Today I removed the blower (only a 5-minute job now that I know where the outer case screws are) and took it apart again.

Pressing the bearings (actually R3Z upon close inspection) and the center ring magnet from the shaft was a delicate process because sintered/pressed magnetic objects tend to fracture easily. But I got them off without breaking the ring after applying a little penetrant to help them slide.

The -Z is a shielded bearing, whereas my replacements are -2RS (rubber sealed). I don't think that will matter since there should be no debris to shield against that the rubber couldn't withstand anyway and there is only a very small pressure differential.

Alleged delivery date for the bearings is the 31st, and with the current crappy USPS it's always one or two days later than "expected". That really means Jan. 1st which of course is a holiday. So probably Thurs. the 2nd.

[DrCharles]

This looks like a possible direct replacement blower. It even has the same connectors. The gasket on the output looks easy to remove. I think I'll gamble the $50 (with tax and shipping) in case my attempt at a rebuild doesn't work!
https://www.aliexpress.us/item/3256806603465735.html

[DrCharles]

Inside the blower. There's one plastic spacer missing (fell on the floor, rolled away and it took me half an hour on hands & knees to find it).
Unfortunately I realized I may have screwed up... if the rotating assembly is balanced as a unit, I didn't mark the orientation of the brass "hat" to the impeller, and both have some balancing holes drilled in them. At 30,000 rpm it'll likely make a difference Will find out when I put the new bearing in!

20241228_183220a.jpg (310.71 KiB) Viewed 19931 times

[DrCharles]

Unfortunately, although the new bearings did help somewhat, it's still way too noisy to sleep with The problem is most likely the balance, as I mentioned, but there is no way for me to rebalance the assembly to the required tolerances.

In the meantime I was interested in comparing relative noise levels with my current Remstar Pro M. But on the shelf, I found the original noisy one (first prescribed for me in 2006!) which has 14,400 hours. It's quite whiny too, but at a higher pitch than my repair attempt.
AND another one I didn't even remember buying, with only 400 hours which is whisper-quiet. That's my backup now.

So now it comes down to whether the China blower I mentioned earlier will fit (crossing fingers), otherwise this machine is spare parts!

[DrCharles]

Update: I got the blower from Aliexpress... the only modification needed was to cut off three molded plastic legs that the M-series doesn't want (the blower is supported underneath by the molded foam). Unfortunately the one I received was not good - the bearings were slightly noisy (audible when winding down to a stop), but more importantly, there was a distinct "flutter" in the airstream. Probably an impeller defect. It didn't improve with an hour or so of running time

So I sent it back for a refund, and ordered another from a different store (although I bet it's the same manufacturer). It won't be here until Feb. 1st, possibly a day or two sooner. If this one behaves similarly, I'll keep it since this will be a backup machine anyway. I think I'd get used to the flutter.

[DrCharles]

OK. I got a similar blower from a different AliExpress store (higher price but free shipping, so it came to about $50 either way).
https://www.aliexpress.us/item/3256805778594612.html

It's missing a 2-pin connector. The 3-pin in the picture is the motor drive, so I installed it and it works properly with the normal amount of noise.
A look at the service manual's schematic showed that the missing wiring is for the motor temp sensor. I have been using CPAP for close to 18 years and never had one overheat yet, so I'm not worried about it.

Now I have a spare M-series And a part number to order when my original M blower wears out someday!