Differences in Hotpoint Motor Controllers

[supermaticjames]

Hi all,

Just a curious question. Hotpoint started off in the 70's boasting Electronic Motor Control. Then when the Next Gen's came along in the late 80's they sounded slightly differnent but still rushed up to speed. The most noticeable change was when the WM Series were launched and they got up to speed more gradually with a nice whine. I thought I read somewhere that this was Digital Control?

James.

 

[hotpoint95622]

hotpoint 95622

I’ve just acquired some service manuals for the 1851/03 which also covers earlier models 1850 1851 and 1828/01 ranging from 1973 up to 1977 the modulus are analogue and the motor voltage is controlled by a thyristor (SCR) which rectifies AC to form DC power which makes the motor sound different to any other.

I also acquired the service manuals for the 18680 18580 18380 1828/07 and many more from 1976 up to 1983 we are still using analogue modules but instead of the thyristor it incorporates a triac which dose not rectify the AC power, which changes the pitch of the motor sound and is more efficient.

This continues into the 95 series where the first hybrid timers come into use with new digital integrated chips and we lose that boom when going into high speeds, still using a triac to control the voltage.

Wikipedia link[this post was last edited: 3/1/2011-12:48]

http://en.wikipedia.org/wiki/Thyristor

 

[hotpoint95622]

hotpoint 95622

Scan from the Liberator De Luxe service book

 

[hotpoint95622]

hotpoint 95622

The module in the photo at the top is from the 18680 fited to the base of cabnet.

Photo below is the 1851/03 located at the top next to timer, note that there is on heatsink because the thyristor (power micro circuit) is mounted separately to the module on part of the front consol which acts as the heatsink.

 

[hotpoint95622]

hotpoint 95622

Photo of the motor from the 1851/03
The round ring in the middle of the motor is the tacho generator which feeds a voltage back to the module which represents the speed the motor is running at.

 

[hotpoint95622]

hotpoint 95622

Hope this helps to answer your question. I’m a bit obsessive about Hotpoint washing machine modules, timers and wiring.

 

[supermaticjames]

Thank's Lee,

That is a very clear definition of 18-95 motor controllers. Then what happened with the WM's? They "howl" when they start up. The WM machines are on of my favourites as they are the twilight machines and they make that "howl". But Liberators No.1! I might be getting a WD71 or something similar soon if I'm lucky! I like Hotpoint Washer Dryers.

James

 

[hotpoint95622]

hotpoint 95622

I think the howl is most likely due to the triac receiving a smother gate signal from the MW’s digital circuits and perhaps the commutator (copper segments) are of poor quality now.

Video of my 1851/03 distributing and then into top speed of 750rpm.

<iframe title="YouTube video player" width="480" height="390" src="" frameborder="0" allowfullscreen></iframe>

 

[hotpoint95622]

hotpoint 95622

Video of my 18680 with more of a refined supply to the motor.

<iframe title="YouTube video player" width="480" height="390" src="" frameborder="0" allowfullscreen></iframe>

 

[supermaticjames]

Speaking of 1851/03, how is it doing?

James.

 

[hotpoint95622]

hotpoint 95622

Not much at the moment, it’s been to cold and wet to work out in the garage.
Waiting for warmer weather and I can start by getting the cabinet paint done.

 

[tolivac]

SCR-half wave device-Triac-full wave device-the motor would run more efficiently off the Triac equipped motor control board.Do those washer motors have any sort of cooling other than the open frames?And the armature mounted fan can act as a safety device-say if the motor is run not connected to a load-the fan acts as a min load to keep the motor from racing or overspeeding.A Triac device can be made by connecting two SCRS together to act as a full wave device-often used for VERY large motors-One example I know of 10,000 HP crusher motors in a cement plant.Used in a "soft start" motor starter.Those GIANT Allis Chalmers motors were quite a sight!and the gearboxes they were connected to!

 

[hotpoint95622]

hotpoint 95622

Tolivac

Your right the triac is more efficient, cooling, no not a thing just the open frames and thermal cut-outs not even a fan. I have found the only time any amount of heat is generated is during distributing speed and when spinning the movement of the armature is sufficient to move enough air to cool it down agene.