L & R Master Cleaning machine

G

Gnomon

Originally posted by Bob Nickles:
If any one has a manual for this machine or a list of parsts spec. I would be willing to pay a fee for a copy. I found an old machine but the rheostat does not work.
Hi Bob,

I don't mean to be cruel, but these things are so simple that you shouldn't need a published schematic to find your way around in one. The rheostat is a wire wound unit, it is rare for them to burn out. Sometimes, the wiper contact will wear so much that it will nolonger make good contact. This is easily determined by inspection. The rheostat's value is usually clearly written somewhere on the body of the unit.

Get out your cheap DVM, start measuring things, and sketch out a schematic of your unit. It shouldn't take you more than an hour. You will figure it out. If you don't think you are up to the task, you should find someone with more experience, and pay them to do it for you. These machines were made before danger and litigation were constantly on the minds of producers of consumer devices.

Good luck,

-Chuck Harris
 
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G

Gnomon

Originally posted by Bob Nickles:
Mr Harris you did not have to be cruel you could have chosen not to reply. I have to thank that you are indeed very cruel. The rheostat in the machine has no legable spec except 3oo volt max. I thank that it was an atempt at a repair.
Bob,

I don't think I was being cruel; and as I said, I wasn't trying to be cruel. I described to you how I fix these machines. The rheostat should have markings on it that tell its value; that is an industry standard practice. If it doesn't, it is fairly simple to measure the total resistance with a DVM. It is, as I said, rare for a rheostat to burn out. They are quite willing to glow red hot for days without burning out the wirewound element.

Rheostats are somewhat expensive. A 750 ohm, 50 watt rheostat, which is typical for what is needed in a watch cleaning machine, is $30, plus shipping, from www.mouser.com. Go to their website. If you have the physical dimensions, you can figure out the wattage you need. As a tip: 25W is 1.56" diameter, 50W is 2.3" diameter, 100W is 3.125" diameter, and 150W is 4" diameter.

I did mean what I said before, in spite of their simplicity, these machines are built in a dangerous way. If you do not understand why they are dangerous, or are not up to the task, pay someone to do it.

-Chuck Harris
 
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bobswatch

Registered User
Sep 3, 2004
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Hi Bob:
I don't know where this fits in as being the correct way to repair your machine, but I bought one that has a AC dimmer switch that works great, as a rheostat.The owner before me re-drilled the mounting screw holes and mounted it in the same location as the old rheostat.I have used it for 4-5 years now.
Bob Edwards
 

Harvey Mintz

NAWCC Life Member
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Jun 7, 2002
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OK, guys - let's get serious about answers to questions without the side issues.

Point #1 - I have in front of me 2 wire wound rheostats removed from L&R cleaning machines. Both were made by Mallory (more specifically, P. R. Mallory & Co., Inc, Frankfort Indiana), and both are labeled on the wiper: 750 Ohms, max. 300 volts. They are also marked on the front: Type 50-K, 30 watt. They are 2 1/4 inches wide.

Point #2 - I looked at the motor on my L&R (a Vari-Matic III, which has essentially the same motor as the L&R Master), and it's an AC/DC motor rated at 60 watts. This means that the AC Dimmer switch that Bob Edwards mentioned would be an excellent Kludge replacement for the rheostat, since the dimmer switch is certainly built to handle more than 60 watts.

Conclusion and suggestion - I'd take a quick look around for a rheostat (to keep things original), and then run down to the local Lowes (or maybe even a K-mart or WalMart), buy the AC Dimmer switch and kludge the face plate to put it in.

As for the danger, make sure no bare wires are touching anything, and that the switch is on the un-grounded side of the circuit (actually, if the old plug is still on it just pick one side and be careful which way you turn the plug when you plug it in). And remember to unplug the thing while you're working on it.

Also, make sure the soldered connections are done right (the solder has to melt against the wires being soldered, not against the soldering iron. Youheat teh wires/terminal with the soldering iron until the solder melts against the terminal/wires). And don't use acid core solder - use rosin core solder. I prefer 60/40 tin/lead solder, but that's because I occaisionally have down some electronics stuff, and that's what you use for electronics.

If you don't understand a lot of what I've written here then you should either
-- learn electrical circuit stuff before you work on this
OR
-- find someone else to fix the machine for you
 
G

Gnomon

I didn't think I was getting into any side issues, but with some creative reading between the lines, perhaps some may think that I did.

I made a major typo in my previous post. I put down 50 ohm when I meant 750 ohm. I have corrected my previous post so my error won't mislead any future viewers. Too many 50s and I got them all run together.

The Mallory rheostat in Harvey's machine, inspite of its labeling, is what is now called a 50W rheostat. Folks were more conservative about things like ratings in the old days. If you buy a new one from www.mouser.com, a 50W Ohmite should fit just dandy.

In your posting where you mention "flux core" solder, replace that with "electronics grade rosin core" solder. All of the non rosin core electronics grade solders require a water wash after you are done to prevent excessive corrosion. Do not under any circumstances use jewler's solders, or plumber's solders! The acid will wick up under the wire's insulation and corrode until the wire is all gone.

-Chuck Harris
 

Harvey Mintz

NAWCC Life Member
NAWCC Member
Jun 7, 2002
536
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South East Florida
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Chuck -

Well, I must admit that I didn't think you were getting into side issues, or that you were being especially mean. Obviously (from the response your first message received), someone doesn't agree with my assesment.

Anyway, I think it's basically better to simply lay out the information if possible and let the reader decide for him/herself whether s/he is capable of do the operation. I will posit no opinion on whether the original poster is able to do this kind of work (it's easy if you've been doing this stuff for 40 years, but what if it's your first time? I can't even remember far enough back to hold someone's hand through the procedure :eek: ).
 
G

Gnomon

Hi Harvey,

I generally do just what you said, explain what I know, lay out the facts, and move on. But when it comes to potentially dangerous stuff, I feel I must put in a warning. Professionally, I am an electrical engineer with more than 30 years of experience. I would have a very difficult time explaining to a jury that I just didn't know that my advice could get joe blow killed.

All of the gear made by L&R, Marshall, and a host of others back in that era has serious potential for doing harm. Safety was not on their collective minds when they designed and manufactured this equipment. The didn't use any kind of safety grounds, and are using singly insulated motors, chassis, etc.. A simple short or failure of the rheostat, motor, heater, some wire's insulation, or a switch can quite easily elevate the metal chassis, with all of its metal handled switches, metal motor, levers, etc. to 120V above earth ground. Add to that the fact that all of their old rubber and cotton wire insulation is by now turning to dust, and you have the potential for a real problem. You should always replace the old 2 pin power cords with new 3 pin power cords, and connect the safety ground (green wire) to the chassis...ALWAYS!

Will 120V arm-to-arm kill you? Probably not, but sometimes yes. You need to have a basic understanding of electricity to safely work on these machines. You can't have that basic knowledge and not be able to trace out a simple circuit like what is in a watch cleaning machine... You just can't!

-Chuck Harris
 
G

Gnomon

Hi John,

Evaporation shouldn't be too much of a problem. I find that the rinse jars, which are just a varsol/naptha mix don't seem to drop at all with the bakelite lids. The ammoniated cleaner loses ammonia from evaporation, though not enough to smell in the shop. If you are working with a normal shop's throughput, you will never notice the evaporation. If you leave the solutions around for a year, you will notice the #1 cleaner degrades.

As for the screw lids, have you tried looking at the Mason jars in your local supermarket? They come in all sorts of sizes, and the thread patterns, for jars, are something of a standard.

-Chuck Harris
 
H

Hugh Patton

Hi Guys'
Just a side question about these movement cleaners. I picked one up off e-bay a few months back. Once in hand after a once over I plugged it in and it ran like a charm. The problem was that I got a low shock from touching the side of the unit. Is the metal base a part of the circuit on these?
Hugh Patton
 

Mike Kenley

Registered User
Mar 4, 2002
664
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If you will contact the AWI I think they will send you what you need. They have helped me before and I am not a member.
 
G

Gnomon

Originally posted by Hugh Patton:
Hi Guys'
Just a side question about these movement cleaners. I picked one up off e-bay a few months back. Once in hand after a once over I plugged it in and it ran like a charm. The problem was that I got a low shock from touching the side of the unit. Is the metal base a part of the circuit on these?
Hugh Patton
Unintentionally, sometimes it is. There is both capacitance, and leakage resistance between the windings on the motor, and the metal frame of the motor, and of course, there could also be a short somewhere. The leakage is sometimes enough to give you a tingle if you happen to be grounded when you touch the machine. The answer to the problem is to replace the power cord with a modern 3 wire/prong cord. Intentionally ground the L&R's case to the green wire on the new power cord, and the L&R's tingling days will be over.

Before you replace the cord, it is a good idea to try reversing it to see if the tingling quits. If it does, when you put the new cord on the machine, make sure that the "neutral" side of the new plug/cord goes to the same side of the L&R's wiring as the big flat pin on the power outlet went to (on the old cord). In otherwords, you would like the polarity of the new cord to be in the non-tingly direction, if at all possible.

-Chuck Harris
 
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