resistors and poteniometers

MaxHeadRoom

Joined Jul 18, 2013
28,620
It would appear that the resistor is for the 240v operation, the current for that type of motor is fairly predictable as its load resistance does not really change.
I assume it is to carry the timer through the cooling cycle and the only other thing it detects that the Hi limit has not opened?
Max.
 

BillB3857

Joined Feb 28, 2009
2,570
It looks like the resistor will indeed drop the 240 volts to 120 for the clock. The difference between the 120 feed and the 240 v feed lies in the HI-LIMIT switch. If the high limit temp is reached, the clock stops until the unit cools enough to again close the hi limit switch. At that point, timing will resume.
 

inwo

Joined Nov 7, 2013
2,419
I'm studying the circuit, and while I agree that the purpose of the resistor is what the op suggests. ie. running timer safely from 240. There are some issues with the circuit that puzzle me.:confused:

Someone might try to enlighten me, but I am very slow to understand.:p

Please take this one step at a time and I might get it.:)
Keep in mind I'm no dummy. :D I work on these things every day. I'm just slow.:(

Ignore door switch, for discussion, as it is not used for normal timed operation. imo

Here is where I'm hung up.

The position of contacts as shown (TM-WB) will run timer continuously.
Then it follows that this cannot be the the "cycle stopped" or static position for the timer.

Am I correct so far?
 

inwo

Joined Nov 7, 2013
2,419
Have to leave for the gym................

Just in case I'm correct and didn't miss some thing obvious.....

The question then is:
Is TM-OR the static position of timer?

Because timer can't start from there unless BK-BU lets motor start.

It may come to me when I'm working out.:eek:
 

inwo

Joined Nov 7, 2013
2,419
The only way I can visualize it working is, TM-OR closed and BK-BU closed, is the static position.

Pressing "start" runs motor/ closes motor switch 1-2 & 5M-6M (latch)/ runs timer motor thru OR and resistor (from L2)/ timer contacts transfer to TM-WB.

Cycle stops when BK-BU opens. Timer continues to run until TM-OR/ motor coasts down/ & BK-BU closes ready for restart..
 

#12

Joined Nov 30, 2010
18,224
TM (left) is always connected to L1. In WB the timer motor always runs if the door is closed.

When switched to OR:
If the high limit opens, the motor is connected back to L1 through the operating thermostat and it stops running.

If the operating thermostat opens (which it always does) the timer motor finds L2 through the heater element and continues running.

WHEN the TM WB OR switch switches is not clear. It might be a function of the timer internal contacts. It might be a sensed cycle that changes operation, and it changes the operation from "run time only" to "heater time on" dependent. I would think the thermostat heater is involved in that.

I typed that at the level I think at. Chew on it for a while and come back if you need something translated.
 
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inwo

Joined Nov 7, 2013
2,419
TM (left) is always connected to L1. In WB the timer motor always runs if the door is closed.

When switched to OR, if the high limit opens, the motor is connected back to L1 through the operating thermostat and it stops running. True, except TM to OR is only for starting. IMO

If the operating thermostat opens (which it always does) the timer motor finds L2 through the heater element and continues running. Same as above

WHEN the TM WB OR switch switches is not clear. It might be a function of the timer internal contacts. I agree! It might be a sensed cycle that changes operation from run time only to "heater time on" dependent. I would think the thermostat heater is involved in that.

I typed that at the level I think at. Thanks for your interest.. Chew on it for a while and come back if you need something translated.
Such a simple circuit, yet so many questions.

My main question was posted above.
I'm trying to determine the "static" position of contacts.
I believe it can not be as shown.
Mainly because TM-WB runs timer motor continually.

Don't ask why I got stuck on this.:D I have no dog in this fight.
When I see something that doesn't make sense, I can't let it go.:(
 

#12

Joined Nov 30, 2010
18,224
TM WB runs the timer motor continuously IF the internal contacts of the timer detect that it is set on anything except an "off" position. (There is an off position between every cycle option on the front panel label.) Those, "Am I turned on?" contacts are not shown on the drawing. It is assumed you know that.

TM OR has nothing to do with starting the motor. It is only a cycle option for the timer motor.
The start switch is up, right at 12,13. It's a manual push button. When the centrifugal switch connects 5M to 6M all that is left in that circuit is the door switch, the motor, the belt switch, and BU to BK.

You need to realize that the timer motor is about 1K ohms and can not carry significant current compared to a heater element or a motor winding.
 
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inwo

Joined Nov 7, 2013
2,419
" It is assumed you know that."

No I don't. Let me think about that.

I'm thinking the TM to WB/OR are the only contacts to run the timer motor.
I can see how it all works that way.
But only if schematic is not drawn to show "cycle stopped".
 

#12

Joined Nov 30, 2010
18,224
" It is assumed you know that."
The problem is that the drawing was made by the dryer designer and he wasn't thinking about what's inside the timer, so he didn't draw the, "Am I on" switch that is inside the timer and in series with the timer motor.

Decades of experience with these has me so well trained about what to assume that I find it difficult to guess which of these assumptions you are missing. (That's why we're having a conversation.) Still, I do remember the frustration I felt the first time I diagnosed a clothes dryer. That was 1978 IIRC.
 

inwo

Joined Nov 7, 2013
2,419
TM WB runs the timer motor continuously IF the internal contacts of the timer detect that it is set on anything except an "off" position. (There is an off position between every cycle option on the front panel label.) Those, "Am I turned on?" contacts are not shown on the drawing. It is assumed you know that.

TM OR has nothing to do with starting the motor. Of course not the" motor" It is what stops the timer motor. It is only a cycle option for the timer motor.
The start switch is up, right at 12,13. It's a manual push button. When the centrifugal switch connects 5M to 6M all that is left in that circuit is the door switch, the motor, the belt switch, and BU to BK.

You need to realize that the timer motor is about 1K ohms and can not carry significant current compared to a heater element or a motor winding.Of course????????????????
I still believe diagram is complete.
 

inwo

Joined Nov 7, 2013
2,419
The problem is that the drawing was made by the dryer designer and he wasn't thinking about what's inside the timer, so he didn't draw the, "Am I on" switch that is inside the timer and in series with the timer motor.
I believe he did.
No other reason for TM contacts.
And it works as drawn.

Of course there is a good chance that I'm confused! :)
 

inwo

Joined Nov 7, 2013
2,419
Ok, I can see your way.
IF there are unseen contacts, timer can pause with BK-R and oper. stat.

Puzzling to me WHY a simple contact would be omitted.
It's the key to the whole thing.
 

#12

Joined Nov 30, 2010
18,224
If the TM WB and OR can be found as labels on the back of the timer, then that switch is in the timer.

If it rests in off position as TM-WB, the timer motor would run any time the door is closed unless there is a, "Am I on?" switch".

If you postulate that there is no, "Am I on?" switch then TM must rest at off in the TM-OR position.

If that be the case, then the timer never runs unless the centrifugal switch has closed and the operating stat is open (The load of clothes is hot enough.) OR anytime you dial to a drying cycle, the TM-WB contacts close and the timer motor runs, even if the big motor never starts.

There lies my disagreement because I have never seen a timer advance unless the main motor was running. Therefore, I persist in believing there is an, "AM I on? switch inside the timer, but it is not drawn properly.
 

inwo

Joined Nov 7, 2013
2,419
There lies my disagreement because I have never seen a timer advance unless the main motor was running. Therefore, I persist in believing there is an, "AM I on? switch inside the timer, but it is not drawn properly.
No disagreement at all.
A problem with the "as drawn" is what started my quest.:)
I was reaching for something that wasn't there, I guess.

A Switch that isn't shown would clear it all up.
Searching many other VERY similar schematics all show timer in an unpowered state.


That was 1978 IIRC.
Got you by about ten years on that.
 

inwo

Joined Nov 7, 2013
2,419
Only for relatives now.
Repaired Speed Queen for homes and Laundro-mats in the 60s.
Now that's when machines were machines.
Real bearings and heavy duty parts. Washers had fluid drives.
I look into a drier now, and think, where's the rest of it?

My curiosity may have made me seem rusty.
Far from rusty, I noticed an issue right away.
When I see a problem, I like to track it down.

I still find it difficult to reconcile, the diagram, showing the timer motor running all the time.
Even though it wouldn't matter much for servicing.

My SQ diagrams were complete. Even showing the timing chart.
 

Thread Starter

sherlock ohms

Joined Dec 24, 2013
25
The TM=OR is a timer dial selection for "Auto Heat" as opposed to "Timed Heat" and is selected prior to the PTS switch.
Is everyone in agreement with BillB's assertion that the resistor's function is to drop the 240v circuit to 120v for the timer?
 

inwo

Joined Nov 7, 2013
2,419
Yes. of course.

Also, I'm sorry that I got carried away and kind of hijacked.:p

Just got caught up in the way it was drawn.

This doesn't explain my concerns, but is good reading.


https://secured.whirlpool.com/Service/SrvTechAdm.nsf/2cd44500d572193285256a45004fd9d6/297f1c9e7e058d0985256b060052aa9d/$FILE/787848%20%231.pdf
 
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