Jump to content

Recommended Posts

8 hours ago, Plato said:

No way I'd reuse that part, it's already been mucked about with, replace it with a new pot. I bet the knob is a standard size used today.

https://uk.rs-online.com/web/c/passive-components/variable-resistors/potentiometers/?searchTerm=potentiometer

that was my first thought.  "This has been messed with" but it's old and this is my first machine, I thought it could have just been a bit crude.                                                                                                                                                      I kind of want to replace it too.  Problem is like with your link you sent me, I don't know what replacement part I actually need.  I talked to Dave at Dave's Watch Parts and said he used to buy them at www.surplussales.com, but I still don't know exactly what to get.  115 volt at 75 cycles and I think it's 60 Ohm.

Edited by SonnyBurnett
Link to comment
Share on other sites

23 minutes ago, SonnyBurnett said:

that was my first thought.  "This has been messed with" but it's old and this is my first machine, I thought it could have just been a bit crude.                                                                                                                                                      I kind of want to replace it too.  Problem is like with your link you sent me, I don't know what replacement part I actually need.  I talked to Dave at Dave's Watch Parts and said he used to buy them at www.surplussales.com, but I still don't know exactly what to get.  115 volt at 75 cycles and I think it's 60 Ohm.

I don't suppose you can find a circuit diagram? I sent the wrong link too, this is the correct link:

https://uk.rs-online.com/web/c/passive-components/variable-resistors/rheostats/

There must be something equivalent to what you need. But, like others have said, it might look/work a lot better when cleaned. 

Link to comment
Share on other sites

9 hours ago, SonnyBurnett said:

Dave contacted me and said this one might work.  Anyone got any thoughts?  Its on the very bottom of the page.

(RWA) A-29418-5

  https://www.surplussales.com//Potentiometers/Rheostats/PotsRheost-3.html.

Do you mean the (RWA) RP151SD750KK? I can't find (RWA) A-29418-5.

75ohm would be near enough to 60ohm for a rheostat provided it can cope with the current/power.

Link to comment
Share on other sites

14 hours ago, Plato said:

Do you mean the (RWA) RP151SD750KK? I can't find (RWA) A-29418-5.

75ohm would be near enough to 60ohm for a rheostat provided it can cope with the current/power.

At the very bottom of the page in the link on the right side.  The last one.  On my screen it shows up as (RWA) A-29418-5

Rheostat, 800 ohm, 50 watt, 0.25 amp. Type R-50. 2-1/4" diameter body, 1-3/8" behind panel depth. 1/4" diameter x 1/2" long round shaft. Made by Memcor. NSN: 5905-01-013-4370.

Dave said this one is close enough it should work.  One thing I noticed is the wattage.  it's 50 watt and the machines are rated at 60.  Also the amperage, seems low.  Can't remember what the machine runs at.

Edited by SonnyBurnett
Link to comment
Share on other sites

10 hours ago, SonnyBurnett said:

At the very bottom of the page in the link on the right side.  The last one.  On my screen it shows up as (RWA) A-29418-5

Rheostat, 800 ohm, 50 watt, 0.25 amp. Type R-50. 2-1/4" diameter body, 1-3/8" behind panel depth. 1/4" diameter x 1/2" long round shaft. Made by Memcor. NSN: 5905-01-013-4370.

Dave said this one is close enough it should work.  One thing I noticed is the wattage.  it's 50 watt and the machines are rated at 60.  Also the amperage, seems low.  Can't remember what the machine runs at.

Is this is the circuit diagram to your machine?

What motor does it use? We could figure out the current.

L&R Master 2 Wiring Diagrams.jpg

Link to comment
Share on other sites

15 minutes ago, Plato said:

One thing I read about earlier was that some of these old rheostats might use asbestos as insulators, another reason to replace it. 

Why. That would be another case of unjustified fears of a danger that scientifically doesn't exist when exposure to the harmful substance non-existent, as when asbestos is firs and solid, and in a minuscole amount. One needs years of continuous exposition to fibers to get in danger of developing lung cancer.

Link to comment
Share on other sites

2 hours ago, jdm said:

Why. That would be another case of unjustified fears of a danger that scientifically doesn't exist when exposure to the harmful substance non-existent, as when asbestos is firs and solid, and in a minuscole amount. One needs years of continuous exposition to fibers to get in danger of developing lung cancer.

@jdm what part of the world do you live in that you don't consider asbestos a risk?! 

Link to comment
Share on other sites

Even a PhD won't be able to tell the correct value for the rheostat with the limited information given. 

The value would depend on the internal resistance of the motor used in the machine. I'm sure the motor must have changed over the decades of production.

But 50 ohms does seem a little low.

Link to comment
Share on other sites

7 hours ago, LittleWatchShop said:

Your hand drawn schematic is wrong at least in one place.  Furthermore, I measure the rheostat on my cleaning machine and it measures closer to 800 ohms.  And, yes, I do have a Ph.D. in electrical engineering.

It's not my diagram, I found it on the nawcc website. 

Link to comment
Share on other sites

6 hours ago, HectorLooi said:

Even a PhD won't be able to tell the correct value for the rheostat with the limited information given. 

The value would depend on the internal resistance of the motor used in the machine. I'm sure the motor must have changed over the decades of production.

But 50 ohms does seem a little low.

I did ask about the motor. 

Link to comment
Share on other sites

11 hours ago, Plato said:

@jdm what part of the world do you live in that you don't consider asbestos a risk?! 

In one where science is taught. I never said asbestos is not risky, but that it is in certain quantities and modes.
Fearing otherwise is unwarranted paranoia. Quote fron the first article I rant into:

A one-off exposure from do-it-yourself renovation is not a major risk
https://www.asbestos.com/exposure/short-term/

There is a major difference between asbestos in tons, or fractions of, and the scarce gram which could a sigle electronic insulator. Beside, isn't even proven than what is being discusses is indeed made of that.

Link to comment
Share on other sites

6 hours ago, HectorLooi said:

Even a PhD won't be able to tell the correct value for the rheostat with the limited information given. 

Maybe a PhD doesn't, but people of practical experience do. As mentioned, 50 or 60 Ohm is little for any "power application".

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.




  • Recently Browsing

    • No registered users viewing this page.
  • Topics

  • Posts

    • people be honest.... Swatch is evil for the watchmakers and repairers, BUT not everything in watches from Switzerland is from the Swatch-Group. As far as i know, Selitta got sacked by Swatch as a Movement-Assembler for them and they started to produce Movements in their own Name with slight Modifications. As far as i know, they sell Parts to the Market for their Movements. In most cases, if a ETA-Movement fails, it is a valid Option to replace it with a Selitta Movement, which i consider the Solution for this Mess with the Swatch-Group...... I have no Connection to anybody at Selitta, but being a Swiss-Guy, i still like to have Swiss-Made Watches, but not from the Swatch-Group.   ok ? regards, Ernst
    • Just one more greedy act by Swatch. They started a number of years ago here in the US..cutting off supplies to watchmakers that could build complications that many Swatch houses couldn't even touch. Old school masters who had gone through some of the most prestigious houses in the world. Otto Frei has some statements on their page about it. I tell all my customers to avoid new Swiss watches like the plague,..unless they just want an older one in their collection that still has some parts out on the market, or they have really deep pockets and don't mind waiting months and paying through the nose to get it back. Plenty of others to choose from..IE Seiko,..or other non-swiss brands Even a number of Chinese brands are catching up with the Swiss,..and I think that in time, their actions will be their downfall
    • Yes. If that's not what you are experiencing...start looking for something rubbing. A 1st guess is that one of the hands is rubbing against the hole in the center of the dial. Especially if you now have lower amplitude in face up/ face down positions.
    • Once a movement has the dial and hands put back and it is recased, would you expect the assembled watch to have the same amplitude as when the movement is in a movement holder and is without hands and dial? Thanks
    • C07641+ not sure what the "+" is for after the last digit.
×
×
  • Create New...