[freddofrog]

Re: Hotpoint TDC30p motor cuts out when heating

Martin wrote:

freddofrog wrote:
So it is NOT the relay, and it is NOT a thermal trip in the motor.

Thanks for clearing that up, sorry I couldn’t’ help further. Oh, yes I can, why not……

Option #1. Scrap the thing. 😉
give up because we don’t know 😉

[freddofrog]

Re: Hotpoint TDC30p motor cuts out when heating

I’ve created a schematic To clear up any misunderstanding.

Points B and C are for fwd and rev on the motor.

1. With heaters unplugged, the dryer will run ok for a full 2 hours.
chassis to A = 238
chassis to B = 238 then 0 then 270 then 0 etc etc
chassis to C = 270 then 0 then 238 then 0 etc etc
chassis to D = 0.23
live to D = 238

2. With heaters plugged in, the dryer will run ok for about 10 minutes as above.
Then just after the end of a reverse cycle
chassis to A = 238
chassis to B = 0
chassis to C = 0
chassis to D = 0.23
live to D = 238

After about 5 minutes, the volts come back on B and C, then cut again. I open the door (the relay opens), unplug the heaters, close the door, press “on” (the relay latches), then when it starts up it runs ok as in 1 above.

So it is NOT the relay, and it is NOT a thermal trip in the motor.

[freddofrog]

Re: Hotpoint TDC30p motor cuts out when heating

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

Martin, you’ve mentioned a thermal trip in the motor windings before.

It is NOT the relay, there is NOT a thermal trip in the motor windings, because the 240V supply voltages from the timer go absent from the timer contacts. The voltages would still be visible if a thermal trip had opened.

There is an issue with the motor causing either arcing or current overload in the timer contacts, that is 100{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} certain.

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 ???

[freddofrog]

Re: Hotpoint TDC30p motor cuts out when heating

Andy jones wrote: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

Andy, the banter between you and Martin in this thread was not conducive to being helpful. If you are “giving up some of our precious home time” then spend that time wisely m8.

Please offer useful advce, or do not post.

It is NOT the relay, there is an issue with the motor causing either arcing or current overload in the timer contacts, that is 100{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} certain.

[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

[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

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) )

[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

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

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)

[freddofrog]

Re: Hotpoint TDC30p motor cuts out when heating

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 sketche 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 ?

[freddofrog]

Re: Hotpoint TDC30p motor cuts out when heating

iadom wrote:I assume you mean the timer motor when you say ‘thing’. There will not be any wire going to one the the terminals that the timer wires go to, it has internal connections as well. 😉

And a manual will cost you more than a relay. If everything was working, heating, tumbling etc then I would suggest that all the wires are, or at least where on the correct terminals.

Sent from my iPad using Tapatalk HD
aye the “thing” must be the motor 😳

well these are the symptoms …
1. with heaters unplugged in the loom, the dryer runs (empty)until manually stopped (I ran it more than an hour)
2. with heaters plugged in, the motor cuts out after about 10 minutes. Both of the live feeds (fwd & rev) to the motor are cut, they originate on the timer. The front drum thermostat feeds live to the heaters, and also plugs onto a terminal on the timer. The timer continues to run. Note also that the neutral feed to the motor comes from the relay and is ok.

So the problem is definitely related to heat, it is not the relay, it is not the motor.

[freddofrog]

Re: Hotpoint TDC30p motor cuts out when heating

iadom wrote:The stats do not cut power to the motor, only the heater.

aye that makes total sense, and from that logic I can see why you and Martin suggested the relay, or a thermal cut-out in the motor.

I’ve taken photos of all the connections, removed all the tie wraps, and taken out the timer.

There’s a “thing” ❓ on the end of the timer, that has a pair of wires coming round to where all the terminals are on the timer, and there was basically no connection to one of the pairs on the “thing” (I don’t know what it is supposed to do).

I’m going to connect a live and a neutral to the timer and check the terminals with the timer running, I suspect that someone has been in this dryer in the past and not put one of the connections back onto the correct terminal (my son got this dryer in this condition from a friend of a friend :rolls: so I don’t know its history). Dodgy repair-man in the past methinks :clown: (and I’m beginning to think that I should buy the service manual from Hotpoint :eeek: ).

[freddofrog]

Re: Hotpoint TDC30p motor cuts out when heating

hmmm, I thought I better check the live & neutral into the motor with the heaters plugged in. After 10 minutes, the live(s) to the motor disappear. There are two live feeds to the motor (fwd and rev), they come from the mechanical timer. If it’s contacts in the timer that are the problem I don’t see why heat is the cause, however I think that the timer feeds a live coming up from where the front thermostat is …. could be that all along. But it would be crazy to have an over-heat sensor at the front of the drum that only cuts power to the motor. That’s it for now, too many stupid coloured wires in there LOL

[freddofrog]

Re: Hotpoint TDC30p motor cuts out when heating

LOL

I’m an electronics engineer with a couple of decades experience, but this is the first time I’ve ever tried to fix a condenser tumble dryer. As I mentioned in the beginning, if I had a serivce manual (with schematic diagram) this would be easy.

Anyway, I’ve removed the side panel, unplugged the heaters, and put it on a 120 minute drying cycle (empty). Half-way through and it’s still running fine, so it does have something to do with heat.

There must be a seal between the fan that circulates the hot air, and the motor (same housing for both). So my guess is that if there is a thermal cut-out in the motor, then it must be tripping because heat is getting past the seal into the motor.

I’ll post an update when I’ve found out if it is that, or anything else, in case anyone else does a search with a similar problem.

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