Hotpoint TDC30p motor cuts out when heating

[freddofrog]

Re: Hotpoint TDC30p motor cuts out when heating

freddofrog wrote:I’ve had the timer running on a desk and checked the way the terminal connections vary during timer running, and from what I can see, the way everything was connected to the timer was correct.

Although I haven’t made a circuit diagram of the complete dryer, from the sketch I’ve made of the timer, there is only one logical explanantion for what it going on ….

When high currents for the heaters are being drawn across contacts in the timer, it must cause the contacts to the motor to disconnect for some reaon. Now that I’ve taken the timer out, all that I can do is put it back and check the voltages on the various timer terminals while everything is running, and I reckon I should see the “live” feeds to the motor disappear, but everything else remain unchanged (the stats in the heater at the back would also open fairly quickly but that won’t be observable from the timer)

Anyone know where to get a timer at a cheap price ?

btw, one idea I’ve had, is to fit a “heater-relay” in the system, so that the timer only carries coil current to that relay and the relay carries the main heater current …assuming that my diagnosis is correct, this will keep it running for my son (and I’ll tell him not to pass this dryer onto anyone else)

[Martin]

Re: Hotpoint TDC30p motor cuts out when heating

freddofrog wrote:btw, one idea I’ve had, is to fit a “heater-relay” in the system, so that the timer only carries coil current to that relay and the relay carries the main heater current …assuming that my diagnosis is correct, this will keep it running for my son

What an intriguing idea indeed.

I can’t help thinking this thread reads more like the daily log of Albert Einstein’s laboratory experiments rather than a quick fix solution for a Hotpoint dryer. I can’t wait for the next entry. 😉

[Andy jones]

Re: Hotpoint TDC30p motor cuts out when heating

Too much thought going into this me thinks. I assume you’ve made sure the fans are clear of fluff etc. certainly sounds like the motor is just overheating

Sent from my iPad using Tapatalk HD

[freddofrog]

Re: Hotpoint TDC30p motor cuts out when heating

Martin wrote:I can’t help thinking this thread reads more like the daily log of Albert Einstein’s laboratory experiments rather than a quick fix solution for a Hotpoint dryer. I can’t wait for the next entry. 😉

😀 I just need to build dryer this into a De Lorean 😀

Andy jones wrote:Too much thought going into this me thinks. I assume you’ve made sure the fans are clear of fluff etc. certainly sounds like the motor is just overheating

Aye the whole dryer is clear of fluff, first thing I did was clean out everything. But if it was a simple case of motor overheating, then both live and neutral would still be present on the connections to the motor. When the drum stops, neutral is still present on the feed from the relay (chassis to feed = 0.2 volts, live to feed = 234 volts), and both live feeds (fwd&rev) from the timer to the capacitor disappear. With the heaters unplugged, I’ve had it running in the lounge while watching TV, for over an hour, but it cuts out when the heaters are connected, and when it does cut out, the live(s) from the timer are AWOL 🙁

[freddofrog]

Re: Hotpoint TDC30p motor cuts out when heating

Did some more tests this morning.

I’ve run the dryer with everything back the way it should be, but took the connection off the timer to the heaters, and fed the heaters direct from a separate manual switch.

With the switch permananently open, got on with other jobs within earshot while the dryer was on a 120 minute drying time, motor never cut out in the whole 2 hours.

Then started it again, sat down by the switch, and manually turned the heaters on and off. “Off” just before the motor reversed, “on” just after the motor was in the normal direction. The motor cuts out after about 10 minutes 😯 :eeek:
i.e. with the heaters not fed from the timer but manually turned on and off, the motor cuts out ….but with the heaters permanently off, the motor does not cut out.

I have put the heater feed back onto the timer, and have 3 meters simultaneously measuring (a) fwd direction volts (b) reverse direction volts (c) heater feed volts. The timer does switch everything properly, but just when the reverse ends, there is a surge in volts when the timer opens the contacts, and then there are no more volts from point (a) or point (b). The heater volts come back and then I quickly hear the heater stat open.

So there is something happening in the timer reversing contacts when the motor gets “hot”. I don’t know much about AC motors, why is the motor causing a surge in back-emf (I guess) when it gets some heat from the heated air being circulated (there is no fluff anywhere in the ducts) ❓ ???

Finally, I can think of 4 possibilities in order of least cost …
1. scrap the thing
2. replace the capacitor
3. replace the timer
4. replace the motor

Any votes ❓ ???

[freddofrog]

Re: Hotpoint TDC30p motor cuts out when heating

Another question: do these motors have brushes ❓ ???

(if yes, could well be that …heat making brushes begin to lose contact, causing stator current to increase, causing rise in emf when contacts open in the timer. If there are brushes then I’m prepared to take the motor out and strip it down and try to get new brushes …maybe when Nelson gets his eye back though 8) )

[Martin]

Re: Hotpoint TDC30p motor cuts out when heating

Option 5. Replace the relay?

[Martin]

Re: Hotpoint TDC30p motor cuts out when heating

Martin wrote:Option 5. Replace the relay?

The motor is the induction capacitor start type, no brushes.

[Andy jones]

Re: Hotpoint TDC30p motor cuts out when heating

Option 6. Call in a local engineer that should be able to sort it quickly

Sent from my iPad using Tapatalk HD

[Martin]

Re: Hotpoint TDC30p motor cuts out when heating

Andy jones wrote:Option 6. Call in a local engineer that should be able to sort it quickly

Oooooh!…….but Fred has been messing with it, wires removed, switches fitted and stuff…..hmmmmm?….. I’d be a little reluctant at the thought if my phone rang TBH. 😉

[Andy jones]

Re: Hotpoint TDC30p motor cuts out when heating

Good point well put 🙂

Sent from my iPad using Tapatalk HD

[freddofrog]

Re: Hotpoint TDC30p motor cuts out when heating

Martin wrote:Option 5. Replace the relay?

How many times have you suggested the relay now ??

Andy jones wrote:Option 6. Call in a local engineer that should be able to sort it quickly

Yep, dodgy repair man comes, swaps relay, takes money, dryer works for 10 minutes (as before), repair man drives away with smug grin, dryer cuts out again.

Martin wrote:

Andy jones wrote:
Option 6. Call in a local engineer that should be able to sort it quickly

Oooooh!…….but Fred has been messing with it, wires removed, switches fitted and stuff…..hmmmmm?….. I’d be a little reluctant at the thought if my phone rang TBH. 😉
Fred has been more thorough than dodgy “relay swap” repair man

Andy jones wrote:Good point well put 🙂

That makes two dodgy repair men.

Anyway, thanks for all the help here :rolls:

I am sooo glad that I don’t need to call dodgy “relay swap” repair men.

Jeez, it’s definitely the motor on this, it is definitely ok when the heaters are unplugged, and with the heaters running, the timer contacts arc when opening on the reverse cycle.

If you guys don’t get this, then please don’t make daft comments. I’ve come here for help, if you can’t help, don’t comment …unless this forum is no different from most other internet forums of course.

[freddofrog]

Re: Hotpoint TDC30p motor cuts out when heating

why is the motor causing a surge in back-emf (I guess) when the timer contacts open after the motor has got “hot” from the heated air being circulated (there is no fluff anywhere in the ducts) ❓ ???

also, the capacitor is across the fwd and rev feeds from the timer. When running in either direction, there is 234 volts on one feed, and 270 volts on the other feed. Is this normal ❓ ???

I can think of 4 possibilities in order of least cost …
1. scrap the thing
2. replace the capacitor
3. replace the timer
4. replace the motor

[Andy jones]

Re: Hotpoint TDC30p motor cuts out when heating

Personally I don’t appreciate being labelled a dodgy repair man when some of us are giving up some of our precious home time to try and give advise only to get it thrown back

Sent from my iPad using Tapatalk HD

[Martin]

Re: Hotpoint TDC30p motor cuts out when heating

5. Check out the thermal trip embedded in the motor windings?

[Author]

Posts