Keith Monks Gemini RCM project questions - Page 1
Forum section: electronics / repair

author: rich121
author_rank: Contributor
timestamp: April 22, 2019, 10:32:44 am
content: Having trouble posting my first post/thread.I have tried 2 times in the 'beginners' forum, but after posting, they never showed up?Anyways, I hope it works this time as I'm very eager to take part in this forum!I have a very nice condition 1970's Keith Monks Gemini (dual platter) record cleaning machine. I have been upgrading a few things on it recently, such as upgrading the vacuum pump to the modern KNF pump that the new Keith Monks machines use. I added a vacuum gauge, replacing all the tubing with high quality Tygon tubing and replaced all the tubing connectors in the jars.Today I noticed that the thread spooling motor stopped working. I removed the motor/gear box assembly and did not find any obvious loose/broken wiring, but the capacitors for both the arm drive motor/gear box and the thread drive motor/gear box (same size/type motor used for each and both using same capacitors) need to be replaced as they are over 40 years old and could be the problem?The values are listed on the capacitors but I'm not sure what modern type I should use? Help with that would be much appreciated.I have included pictures:

author: rich121
author_rank: Contributor
timestamp: April 22, 2019, 10:33:56 am
content: more pictures

author: rich121
author_rank: Contributor
timestamp: April 22, 2019, 10:34:55 am
content: more pictures

author: rich121
author_rank: Contributor
timestamp: April 22, 2019, 10:35:33 am
content: more pictures

author: rich121
author_rank: Contributor
timestamp: April 22, 2019, 10:49:25 am
content: Waiting for new screen 'elastomers' for my Fluke 87, then I can check to see how close the values are on the capacitors... not sure how accurate my Fluke 87 will be doing this?Anyone have experience with these motor/gear boxs? I hope I could get them rebuilt/serviced... they should last forever, hardly any load and only 1 RPM.

author: rich121
author_rank: Contributor
timestamp: April 22, 2019, 11:33:39 am
content: Have located replacement motors and ordered them with corresponding "dephasing" capacitors.

author: Majkic
author_rank: Newbie
timestamp: April 23, 2019, 11:50:00 pm
content: Hi RichJust chanced upon your postings here and am very interested to know how things are going - simply because I have a very similar machine! I'd be especially keen to know how you've got along with the new vacuum tubing, especially the stuff running up the arm. I just tried replacing mine with some Tygon S3 E-3603 tubing which I bought directly from Keith Monks here in the UK, along with a new spool of buffer thread (at a cool £19 per reel - that's $25 USD!!). The new tubing fitted beautifully and - unlike the old stuff that came out - is decently flexible, so that the suction arm now moves freely and smoothly as it dries the disc.HOWEVER - a big "but" - the tubing also seems to have quite "tacky" surfaces outside and, I presume, inside as well, so that it's almost impossible to pull the buffer thread through by hand, let alone under the normal suction from the pump. This is true even with the tubing laid flat on my desk, and much more so when it's curving gently through the arm. The thread then seems to bind and "kag" (is that a real word? hope it translates into US English) against the tube walls, so much so that pulling the thread through by hand is almost impossible; the tubing will fold and buckle under the thread tension, rather than allowing the thread to flow smoothly through, as I'd expected it to.I'm awaiting a respnse from KMAL on this point (having spent over $100 - ouch! - on a handful of basic but supposedly "proper" spare parts) and will let you know what the outcome is. But I'd be delighted to know whether you've had similar experience, or whether everything is fine in this area for your machine... ...maybe you used a different tube type, or different buffer thread? The thread I have is labelled #521 Nylon R.W. (rod wrapping I believe), and tan in colour. This seems to be the "right" stuff, based on other RCM users, as does the Tygon E-6303 tubing, yet the combination together seems doomed to stick!I've tried washing out the tubing with hot water and detergent, but to no avail - it seems as "rubbery" and tacky as ever... I've since gone back to the old arm tubing and, curiously, this seems to also suffer from the buffer thread catching against its walls. I'm starting to wonder about that massively costly nylon thread!The other possible cause of problems is of course the vacuum pump; mine is still the Charles Austen pump, made in the UK in the late 1970's, but which, once cleaned up and serviced inside (a very helpful gent at Charles Austen sent me the spec sheet and service instructions) it seems to work just fine. I get loud suction at the nozzle, but maybe that's an insufficient indicator (and alas I don't have a vacuum gauge to check this - a point I maybe need to address via eBay). I still come back however to the point that surely, the thread ought to be capable of being freely moved by hand, back-and-forth, as it passes through the arm tube?Best regards and good luck with your own machine!MikeP.S. (Edit the following day) - I just ordered a vacuum gauge and hose tail from Ebay to check vacuum level, will also check flow rate as best I can by timing how fast it'll suck up a known volume of water into the waste jar.

author: rich121
author_rank: Contributor
timestamp: April 24, 2019, 01:07:00 pm
content: Hello Mike,Good luck dealing with Jonathan... last time I made an order from him was in 2008, I spent around $450.00USD for basic small parts that should have cost far less than $50.00 for what I actually got.I have tried contacting him over the past 4 years through both of his current email addresses but I have been told he ignores them. Recently I contacted one of the main businesses in the US that 'maintain' the Keith Monks machines and he was only interested in selling me parts for insane amounts of money... I'm sure you seen the prices on the website for a jar lid with one 1/8" bulkhead connector on it... $60.00USD!!!! Insane! Well, all I wanted was the nylon bulkhead and he told me the only way he could sell them to me was with the lid... for $60.00!!! He also told me that I was not the original owner of the machine so I shouldn't feel like I should get any 'customer service' unless I had bought a newer machine... I also had to order more than $100.00 before he would even bother.I buy boxes of 10 lids for $2.00 and bags of '10', 1/8" nylon bulkhead connectors on Amazon for $7.00!!!!As for tubing, I just installed the arm tubing I bought from Jonathan 10 years ago... it is still supple and flexible, as new. There are no markings on it, but it appears to be Tygon tubing, but not sure which type. I assume same as yours. It works fine.Check all your seals too, your jar lids, all the connectors etc. You may need to use some RTV silicone sealant to temporarily seal things so you can find all the leaks.Instead of 1/8" tubing from the pump to the waste jar I am using 1/4" Tygon 2375 tubing. This takes some stress off the pump and seems to have the same flexibility as the arm tubing from Jonathan, but not 'sticky'. It is advertised as having extra smooth inner walls.I plan to replace the tubing for the cleaner/brushes with 1/8" of the same type (2375) and will at the same time purchase the 3/32" size for spare arm tubing:Tygon® AJK00004 3/32" I.D. x 5/32" O.D. x 1/32" Wall (Formulation 2375) 50' Package Length - Ultra Chemical Resistant TubingMy machine was made either 1974 or 1975 as the motors are dated 1974. I also had the same Austin pump as you. It also seemed to work fine, but not quite getting the thread through the tubing.. it gets tangled or caught inside and just bunches up.The new Keith Monk machines use the more modern KNF pump, but wanted over $1000.00 for one...even though you can buy direct from the factory for less than half that! I watched Ebay until a new old stock KNF pump of the same model/type came up for sale.... only paid $200.00USD.After installing the new pump, it is many times quieter, no vibration and MUCH more powerful...sucks that thread directly into the waste jar!I punched a hole in the front of the deck and mounted a vacuum gauge that attaches to the waste jar.I'm pulling about 22.5" Hg while the machine is sucking cleaner from the record. At only 20"Hg is considered 'ideal' and from what I have read, most machines don't get that close.

author: Robw
author_rank: Newbie
timestamp: June 06, 2019, 12:01:40 pm
content: Hi there. I have 1975 K Monk Kmal machine. It still has the original vacuum pump which I’d like to upgrade. I note you have upgraded yours. The KNF pump you’re using seems to have one tube for vacuum suction (excuse my none technical language) mine has 2. One going to the waste jar to draw the used cleaning fluid/thread and one going to a dispenser. How have you configured your pipe work tubing. I can’t quite see from the photos you posted. I’d be very grateful for any advice you may have. Looks like a very neat job from the imagesKind regardsRob

author: yoyocint
author_rank: Newbie
timestamp: August 03, 2020, 08:38:03 pm
content: Regards Rich121 and all others in this thread.I have a Keith Monks CR-502 cleaning machine which I acquired used.I am in the process of refurbishment to get it in full working order, and read your posts on the refurbishment of your. Great job by the way.I already acquired a knf vacuum pump as my model came with a lower spec pump and anyways it is old and not working properly. My machine also came with 3/32" vacuum lines throughout, but I see that you upgraded some to 1/4"...If I can bother you with some questions.Where did you get the fittings for the vacuum system? For the pump the hoses and the liquid traps.which vacuum gauge did you use?Pursuant to having the vacuum working at 20"Hg.. did you have to adjust the vacuum with a valve or did it work at that pressure when connected"The achine had no arm counterweight and I had to obtain one that fitted on Eby.How much down force is set for the arm teflon tip with the counter weight? I read somewhere that it is around 2gm.... The thing is that much pressure will affect the thread pickup and damage it and too little will have the arm lift due to record warping. If you have adjusted the downforce at the tip. did you do it with the pump on or off?Did you get new bottles for the cleaning fluid and liquid trap?I ask because my machine being a more modest model came with plastic bottles and caps and I wish to upgrade them to glass bottles with metal caps for more reliability.Thanks in advance for the response.

author: Majkic
author_rank: Newbie
timestamp: May 22, 2021, 11:05:52 pm
content: Hello yoyocintSorry for the extremely long delay in replying; to be honest I'd more-or-less given up on the Monks machine until very recently - I've simply too much else to do and despite thoroughly servicing and testing the pump, and replacing all the tubing and thread with Monks own spare parts, I was still unsuccessful in getting reliable pull-through of the thread.I took the Charles Austen pump completely apart (a gent at the manufacturer's very kindly sent me both the data sheet and service instructions), cleaned everything again, checked the diaphragms (which are fine) and replaced the neoprene valve discs as a precaution (although the old ones also looked fine, and actually work just as well as the new ones). I've bought a simple vacuum gauge and checked the level of suction; at zero flow I get a maximum vacuum level of about 21-22 in Hg (about -0.7 bar), at both the pump inlet and also confirmed at the nozzle with all the tubing and the waste jar in circuit - so there are no significant leaks anywhere. This level of vacuum is actually somewhat better than the pump's data sheet figure of about 17.5 in Hg. And with the pump on the workbench, operating in the closest I can get to free air conditions (i.e. with negligible inlet and outlet pressure drops) it fills a ~10 litre polythene bag in about 20 seconds, confirming an "open" flow rate of about 30 litres per minute, in agreement with the data sheet curve. So whilst these two tests don't fully check the intermediate pressure-flow behaviour of the pump, it does seem to be performing as it should. {And see also below, re. the flow and pressure with everything connected up.)The one remaining but serious problem is that the buffer thread can be in a loose loop under the cleaning nozzle (having pulled it through by hand from the spool via the funnel and teflon feed tube) and although there's a full length of thread going through the nozzle and all the way into the waste jar, the thread still clings tightly to the walls of the arm tubing, and mostly refuses to "flow" into the waste jar. This problem gets noticeably worse once the thread gets wet with the alcohol/water mix (and incidentally isn't alleviated by adding a touch of PhotoFlo to the chemistry). The arm tubing is Tygon S3 E-3603, which was supplied by Monks directly and therefore should be the "correct" replacement.The result is that although the thread is free to move before it enters the cleaning nozzle, and can even be hanging loose in a loop under the nozzle as it's paid out by the reel motor, it seldom gets drawn through to waste, and it absolutely never moves at all whilst the nozzle is in contact with the wet disc. Under these conditions the portion of thread under the nozzle therefore never gets renewed at all, unless I lift the arm and disturb the thread and/or nozzle (e.g. blocking and unblocking the nozzle with a fingertip to build up some additional vacuum and then release to get a surge of flow).Apart from the arm tubing - which is, as I mentioned, of Monks own specific supply, the tubing from the waste to the pump is actually of larger bore and thicker walls than the original, so I don't believe there's any issues here. (I replaced the old stuff just in case, using a somewhat bigger diameter, simply in order to help slightly reduce the pressure drop in places where it can do no good.)With the vacuum gauge I obtained from a supplier on eBay [see e.g.https://www.ebay.co.uk/itm/274806170260?hash=item3ffbb96294:g:VFYAAOSwim9gqFJq] connected via a T-piece at the pump inlet (also from eBay), the actual working level of vacuum at the pump, when everything's connected up as intended and the nozzle is off the disc, is about 12 in Hg (circa -0.4 bar). The degree of vacuum rises to about 15 in Hg (-0.5 bar) when the nozzle is drying a wet LP, and all the way to the pump's capability of ~21 in Hg (about -0.7 bar) if I seal the nozzle with a fingertip and wait a few seconds. So there are definitely no significant leaks anywhere. I did wonder about the soft arm tubing getting squashed a little where it competes for space alongside the teflon thread feed tube inside the arm, but if I replace the arm tube with a similar length in the open, so to speak, and connect it to the same nozzle, I get just the same pressure readings as with the arm tubing. With the arm and nozzle all connected up as normal, the resulting air flow empties my (not very well calibrated!) polythene bag of its roughly 10 litres of air in about 45 seconds, suggesting a flow of around 13 litres per minute - which again looks pretty much bang-on the Charles Austen F.65 pump curves (for the low-pressure variant with both heads in parallel). So again I'm inclined to give the pump the benefit of any residual doubt.All that said, I chanced to locate a brand-new pump of very similar spec on ebay today, at a very good price (£50) and so I'm going to have a go with that. I'll let you know. Hope the above information is of some passing interes and maybe even helpful.

author: marczee
author_rank: Newbie
timestamp: December 11, 2022, 04:24:55 pm
content: Majkic,Just curious if you had any update to the performance of your RCM? I am also dealing with the thread spooling off to the side of the suction nozzle issue.Cheers-

author: Mortice
author_rank: Newbie
timestamp: December 16, 2024, 07:45:20 pm
content: HiI have problems with the Charles Austen pump in my Keith Monks record cleaning machine (lack of suction). Please could you share the pump maintenance advice that you were given by the person at Charles Austen pumps to save them having to repeat it to me.