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Microwave repair
While warming up the cup of coffee I'd forgotten to drink, I stood there
noticing the slight break-up on the bluetooth speaker that's right next to the microwave ... until I noticed something else, the damned turntable is no longer going round. Can turn the spindle by hand, and tell that it's quite highly geared, it's an 8 year old stainless Neff. Since it's built-in and was difficult to find one to fit, I'd prefer to repair rather than replace. I realise the dangers from the capacitor until discharged, and the beryllium oxide bits, and presume that making sure it's well and truly back together before powering it back on avoids any trouble from tripping the interlocks. That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? |
Microwave repair
Andy Burns wrote:
That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? Oh, and how universal are the "so called" universal motors? |
Microwave repair
Andy Burns wrote:
Andy Burns wrote: That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? Oh, and how universal are the "so called" universal motors? AIUI the only universal thing about them is that they could work on AC or DC, which is unlikely to be an available choice in the context. Just a kind of brush using motor. -- Roger Hayter |
Microwave repair
Roger Hayter wrote:
Andy Burns wrote: how universal are the "so called" universal motors? AIUI the only universal thing about them is that they could work on AC or DC Wouldn't a synchronous motor have "some difficulty" running on DC? which is unlikely to be an available choice in the context. Just a kind of brush using motor. The phrasing of "universal microwave motor" rather than "microwave universal motor" implies to me more about what it's intended to fit, that how it works internally, but interested to hear other opinions ... |
Microwave repair
Andy Burns wrote:
Roger Hayter wrote: Andy Burns wrote: how universal are the "so called" universal motors? AIUI the only universal thing about them is that they could work on AC or DC Wouldn't a synchronous motor have "some difficulty" running on DC? which is unlikely to be an available choice in the context. Just a kind of brush using motor. The phrasing of "universal microwave motor" rather than "microwave universal motor" implies to me more about what it's intended to fit, that how it works internally, but interested to hear other opinions ... OIC, a totally dfferent animal! (In my defence, you did say 'universal motor'.) -- Roger Hayter |
Microwave repair
On 12/03/2018 11:43, Roger Hayter wrote:
Andy Burns wrote: Andy Burns wrote: That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? Oh, and how universal are the "so called" universal motors? AIUI the only universal thing about them is that they could work on AC or DC, which is unlikely to be an available choice in the context. Just a kind of brush using motor. The turntable on ours stopped working five years ago. It still heats things up, although not quite as well. Built in microwaves seem to have come down in price. |
Microwave repair
While warming up the cup of coffee I'd forgotten to drink, I stood there
noticing the slight break-up on the bluetooth speaker that's right next to the microwave ... until I noticed something else, the damned turntable is no longer going round. Can turn the spindle by hand, and tell that it's quite highly geared, it's an 8 year old stainless Neff. Since it's built-in and was difficult to find one to fit, I'd prefer to repair rather than replace. I realise the dangers from the capacitor until discharged, and the beryllium oxide bits, and presume that making sure it's well and truly back together before powering it back on avoids any trouble from tripping the interlocks. That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? In the majority of cases you don't even have to remove the cover to replace the turntable motor. at the bottom of most ovens there is a knock-out hatch that you remove with a rat-tail file or similar. It has lugs so it can be re-fitted in a different orientation , they often even supply the self-tapping screw to secure it parked in a hole. As for the universality of the synchronous motors, they are usually the same size and rating, but the spindle length (usually half-round) can vary. -- Graham. %Profound_observation% |
Microwave repair
On 12/03/18 11:38, Andy Burns wrote:
While warming up the cup of coffee I'd forgotten to drink, I stood there noticing the slight break-up on the bluetooth speaker that's right next to the microwave ... until I noticed something else, the damned turntable is no longer going round. Can turn the spindle by hand, and tell that it's quite highly geared, it's an 8 year old stainless Neff.Â* Since it's built-in and was difficult to find one to fit, I'd prefer to repair rather than replace. I realise the dangers from the capacitor until discharged, and the beryllium oxide bits, and presume that making sure it's well and truly back together before powering it back on avoids any trouble from tripping the interlocks. That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? When the turntable motor on my microwave died, a few years ago, I just looked on eBay for a replacement with the same size shaft and mounting holes. I fitted it. It worked. It happens to rotate at 4rpm when the other one had been geared to rotate at 5 but that was the only difference. Nick |
Microwave repair
Nick Odell wrote:
It happens to rotate at 4rpm when the other one had been geared to rotate at 5 but that was the only difference. I presume the reason many of the motors specify 5/6th of an rpm, is because they were designed for 1rpm in 60Hz land. |
Microwave repair
GB wrote:
The turntable on ours stopped working five years ago. It still heats things up, although not quite as well. TBH, this one is poor enough at heating evenly /with/ the turntable... |
Microwave repair
Graham. wrote:
In the majority of cases you don't even have to remove the cover to replace the turntable motor. I thought I remembered that sort of arrangement from a previous M/O this one being built-in I haven't looked underneath it yet. well, the built-in version has some extra ducting underneath and a radiator panel behind the normal case, secured with self-tappers, so far so good ... .... except I'd inadvertently made life difficult for myself, when fitting the under-cabinet lighting, I had managed to thread one cable (with just 2" of slack) straight between the oven and its radiator panel trapping it inside the cupboard! at the bottom of most ovens there is a knock-out hatch that you remove with a rat-tail file or similar. It has lugs so it can be re-fitted in a different orientation Yep, it's a common TYJ50-8A7 motor, I think I'll go with £6 from eBay, rather than £45 one with a Neff sticker on it |
Microwave repair
In article ,
Andy Burns writes: While warming up the cup of coffee I'd forgotten to drink, I stood there noticing the slight break-up on the bluetooth speaker that's right next to the microwave ... until I noticed something else, the damned turntable is no longer going round. Can turn the spindle by hand, and tell that it's quite highly geared, it's an 8 year old stainless Neff. Since it's built-in and was difficult to find one to fit, I'd prefer to repair rather than replace. I realise the dangers from the capacitor until discharged, and the beryllium oxide bits, and presume that making sure it's well and truly back together before powering it back on avoids any trouble from tripping the interlocks. That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? There's usually a panel on the bottom for gaining access. They used to be screwed on, but nowadays, you have to cut a few thin bits of metal to remove them as it's all a single piece of punched steel. Refitting requires re-orienting the cover so that the screw holes line up, and finding some self-tapping screws to screw it back on. The same motors turn up in many microwaves, except there are different thicknesses of them, and hence some won't fit in other ovens. -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
Microwave repair
Andrew Gabriel wrote:
There's usually a panel on the bottom for gaining access. They used to be screwed on, but nowadays, you have to cut a few thin bits of metal to remove them Yes, very cheese-paring, leaves various sharp bits of metal to cut the un-wary, just for the sake of one fewer self-tapper on the factory ... |
Microwave repair
Andy Burns wrote:
I realise the dangers from the capacitor until discharged, and the beryllium oxide bits, and presume that making sure it's well and truly back together before powering it back on avoids any trouble from tripping the interlocks. That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? IMO, the danger from microwave HV PSUs is a little overstated and little different to CRTs and the common sense needed. I was once given an expensive combi job to mend and to test it was magnetron failure I plugged the magnetron into a £30 Argos one to check it was still duff (it was.) While fiddling in both I measured the voltage on the HV caps and they discharged *very* quickly. I think there were some fairly obvious resistors in parallel. YMMV, naturally. -- Scott Where are we going and why am I in this handbasket? |
Microwave repair
On Monday, 12 March 2018 16:25:23 UTC, Scott M wrote:
Andy Burns wrote: I realise the dangers from the capacitor until discharged, and the beryllium oxide bits, and presume that making sure it's well and truly back together before powering it back on avoids any trouble from tripping the interlocks. That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? IMO, the danger from microwave HV PSUs is a little overstated and little different to CRTs and the common sense needed. I was once given an expensive combi job to mend and to test it was magnetron failure I plugged the magnetron into a £30 Argos one to check it was still duff (it was.) While fiddling in both I measured the voltage on the HV caps and they discharged *very* quickly. I think there were some fairly obvious resistors in parallel. YMMV, naturally. There should always be discharge resistors & normally are. That does not stop one failing, nor do they offer any protection when the machine is powered. The hazard is very different to CRT EHT. The latter does not normally give enough current to kill. Microwave HV PSUs provide enough to kill a whole queue of people in one shot. NT |
Microwave repair
On 12/03/2018 11:38, Andy Burns wrote:
While warming up the cup of coffee I'd forgotten to drink, I stood there noticing the slight break-up on the bluetooth speaker that's right next to the microwave ... until I noticed something else, the damned turntable is no longer going round. Can turn the spindle by hand, and tell that it's quite highly geared, it's an 8 year old stainless Neff.Â* Since it's built-in and was difficult to find one to fit, I'd prefer to repair rather than replace. I realise the dangers from the capacitor until discharged, and the beryllium oxide bits, and presume that making sure it's well and truly back together before powering it back on avoids any trouble from tripping the interlocks. That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? Then discharge the cap. There are several videos on YouTube that show you how to safely do this. You might need to buy a resistor etc -- Adam |
Microwave repair
On Monday, 12 March 2018 20:40:37 UTC, ARW wrote:
On 12/03/2018 11:38, Andy Burns wrote: While warming up the cup of coffee I'd forgotten to drink, I stood there noticing the slight break-up on the bluetooth speaker that's right next to the microwave ... until I noticed something else, the damned turntable is no longer going round. Can turn the spindle by hand, and tell that it's quite highly geared, it's an 8 year old stainless Neff.Â* Since it's built-in and was difficult to find one to fit, I'd prefer to repair rather than replace. I realise the dangers from the capacitor until discharged, and the beryllium oxide bits, and presume that making sure it's well and truly back together before powering it back on avoids any trouble from tripping the interlocks. That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? Then discharge the cap. There are several videos on YouTube that show you how to safely do this. You might need to buy a resistor etc Apprentices and/or students can be used :-) |
Microwave repair
In article ,
whisky-dave writes: On Monday, 12 March 2018 20:40:37 UTC, ARW wrote: On 12/03/2018 11:38, Andy Burns wrote: While warming up the cup of coffee I'd forgotten to drink, I stood ther= e=20 noticing the slight break-up on the bluetooth speaker that's right next= =20 to the microwave ... until I noticed something else, the damned=20 turntable is no longer going round. =20 Can turn the spindle by hand, and tell that it's quite highly geared,= =20 it's an 8 year old stainless Neff.=C2=A0 Since it's built-in and was=20 difficult to find one to fit, I'd prefer to repair rather than replace. =20 I realise the dangers from the capacitor until discharged, and the=20 beryllium oxide bits, and presume that making sure it's well and truly= =20 back together before powering it back on avoids any trouble from=20 tripping the interlocks. =20 That said I expect to be able to get at the turntable motor/gearbox=20 without going near the "active" end ... any other gotchas? =20 =20 =20 Then discharge the cap. =20 There are several videos on YouTube that show you how to safely do this. =20 You might need to buy a resistor etc Apprentices and/or students can be used :-) I think they only work once. -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
Microwave repair
On 12/03/18 11:38, Andy Burns wrote:
While warming up the cup of coffee I'd forgotten to drink, I stood there noticing the slight break-up on the bluetooth speaker that's right next to the microwave ... until I noticed something else, the damned turntable is no longer going round. Can turn the spindle by hand, and tell that it's quite highly geared, it's an 8 year old stainless Neff.Â* Since it's built-in and was difficult to find one to fit, I'd prefer to repair rather than replace. I realise the dangers from the capacitor until discharged, and the beryllium oxide bits, and presume that making sure it's well and truly back together before powering it back on avoids any trouble from tripping the interlocks. That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? It could be as simple as a drive belt having snapped. Our first uwave, one of the early ones, used a simple O ring style drive belt. It was the only thing that actually failed in about 17/8 years. It ended up going to the tip simply because it looked 'tatty' in the new kitchen. If it is the drive belt, try a plumbers' merchant- I got one for the princely sum of 35p (although that was some years back). As for the capacitor etc, just take care. The EHT parts are (normally) well away from the turn table motor etc and pretty obvious. If it is more serious than than the belt, I would think there is a reasonable chance you can still get a motor. The parts tend to be used in a number of makes and, if you know the model, there are loads of companies selling either original or pattern parts. You could even try a local, small, repair place, they may have a scrap uwave with a good motor they will let have for a few quid. The worst thing is if it is something on the control board. If you are able to solder and know what a dry joint looks like, have a check for those. Since the advent of lead free solder I've noticed a lot more dry joints in domestic items. A bit of attention with a soldering iron and all is well. As for replacing the whole unit, they are a standard size so getting one that will fit shouldn't be an issue. Getting one that matches the other appliances may, of course, be more of a problem. |
Microwave repair
On Tuesday, 13 March 2018 11:03:54 UTC, Andrew Gabriel wrote:
In article , whisky-dave writes: On Monday, 12 March 2018 20:40:37 UTC, ARW wrote: On 12/03/2018 11:38, Andy Burns wrote: While warming up the cup of coffee I'd forgotten to drink, I stood ther= e=20 noticing the slight break-up on the bluetooth speaker that's right next= =20 to the microwave ... until I noticed something else, the damned=20 turntable is no longer going round. =20 Can turn the spindle by hand, and tell that it's quite highly geared,= =20 it's an 8 year old stainless Neff.=C2=A0 Since it's built-in and was=20 difficult to find one to fit, I'd prefer to repair rather than replace. =20 I realise the dangers from the capacitor until discharged, and the=20 beryllium oxide bits, and presume that making sure it's well and truly= =20 back together before powering it back on avoids any trouble from=20 tripping the interlocks. =20 That said I expect to be able to get at the turntable motor/gearbox=20 without going near the "active" end ... any other gotchas? =20 =20 =20 Then discharge the cap. =20 There are several videos on YouTube that show you how to safely do this. =20 You might need to buy a resistor etc Apprentices and/or students can be used :-) I think they only work once. Well better than them not working at all ever, anyway what's the problem when you have plenty :) |
Microwave repair
On 13/03/2018 11:32, Brian Reay wrote:
On 12/03/18 11:38, Andy Burns wrote: While warming up the cup of coffee I'd forgotten to drink, I stood there noticing the slight break-up on the bluetooth speaker that's right next to the microwave ... until I noticed something else, the damned turntable is no longer going round. Can turn the spindle by hand, and tell that it's quite highly geared, it's an 8 year old stainless Neff.Â* Since it's built-in and was difficult to find one to fit, I'd prefer to repair rather than replace. I realise the dangers from the capacitor until discharged, and the beryllium oxide bits, and presume that making sure it's well and truly back together before powering it back on avoids any trouble from tripping the interlocks. That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? I have had two similar failures. Both times of a little synchronous motor. Easily accessed from underneath via an access panel. No need to go anywhere near the hot bits. This type of thing https://www.espares.co.uk/search/pt1737/microwaves/motors?mkwid=1AfYGld4&pcrid=11950667713&kword=micr owave%20synchronous%20motor&match=be&plid={placeme nt}&pdv=c&msclkid=00f4dfed7a6a182c97a6854acd47f8ba &utm_source=bing&utm_medium=cpc&utm_campaign=Appli ances&utm_term=microwave%20synchronous%20motor&utm _content=Microwave%20-%20Motor -- Chris B (News) |
Microwave repair
On 12/03/18 11:39, Andy Burns wrote:
Andy Burns wrote: That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? Oh, and how universal are the "so called" universal motors? They tend to be the larger motors sometimes used in washing machines. The motors used to drive turn tables in uwaves (and water pumps in washing machines and dishwashers) are small, AC, motors. |
Microwave repair
On 13/03/18 11:32, Brian Reay wrote:
The worst thing is if it is something on the control board. No, the worst thing is if it is rusted all to ****. Especalially if it was 'stainless' -- You can get much farther with a kind word and a gun than you can with a kind word alone. Al Capone |
Microwave repair
On 13/03/18 11:39, Brian Reay wrote:
On 12/03/18 11:39, Andy Burns wrote: Andy Burns wrote: That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? Oh, and how universal are the "so called" universal motors? They tend to be the larger motors sometimes used in washing machines. The motors used to drive turn tables in uwaves (and water pumps in washing machines and dishwashers) are small, AC, motors. I dont think so for washing machines and dishwasher. Fairly sure the ones I have taken out were brushed. I agree with µ-wave turntables being synchs tho. -- €œit should be clear by now to everyone that activist environmentalism (or environmental activism) is becoming a general ideology about humans, about their freedom, about the relationship between the individual and the state, and about the manipulation of people under the guise of a 'noble' idea. It is not an honest pursuit of 'sustainable development,' a matter of elementary environmental protection, or a search for rational mechanisms designed to achieve a healthy environment. Yet things do occur that make you shake your head and remind yourself that you live neither in Joseph Stalins Communist era, nor in the Orwellian utopia of 1984.€ Vaclav Klaus |
Microwave repair
On 13/03/2018 11:33, whisky-dave wrote:
On Tuesday, 13 March 2018 11:03:54 UTC, Andrew Gabriel wrote: In article , whisky-dave writes: On Monday, 12 March 2018 20:40:37 UTC, ARW wrote: On 12/03/2018 11:38, Andy Burns wrote: While warming up the cup of coffee I'd forgotten to drink, I stood ther= e=20 noticing the slight break-up on the bluetooth speaker that's right next= =20 to the microwave ... until I noticed something else, the damned=20 turntable is no longer going round. =20 Can turn the spindle by hand, and tell that it's quite highly geared,= =20 it's an 8 year old stainless Neff.=C2=A0 Since it's built-in and was=20 difficult to find one to fit, I'd prefer to repair rather than replace. =20 I realise the dangers from the capacitor until discharged, and the=20 beryllium oxide bits, and presume that making sure it's well and truly= =20 back together before powering it back on avoids any trouble from=20 tripping the interlocks. =20 That said I expect to be able to get at the turntable motor/gearbox=20 without going near the "active" end ... any other gotchas? =20 =20 =20 Then discharge the cap. =20 There are several videos on YouTube that show you how to safely do this. =20 You might need to buy a resistor etc Apprentices and/or students can be used :-) I think they only work once. Well better than them not working at all ever, anyway what's the problem when you have plenty :) Indeed. -- Adam |
Microwave repair
On 13/03/2018 11:39, Brian Reay wrote:
On 12/03/18 11:39, Andy Burns wrote: Andy Burns wrote: That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? Oh, and how universal are the "so called" universal motors? They tend to be the larger motors sometimes used in washing machines. The motors used to drive turn tables in uwaves (and water pumps in washing machines and dishwashers) are small, AC, motors. Synchronous? Is that why the turntable on my Daewoo sometimes goes one way; sometimes the other? (And no, it's not a fault.) Electric clocks sometimes had a mechanism to ensure they went the right way. -- Max Demian |
Microwave repair
On 13/03/2018 12:26, The Natural Philosopher wrote:
On 13/03/18 11:39, Brian Reay wrote: On 12/03/18 11:39, Andy Burns wrote: Andy Burns wrote: That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? Oh, and how universal are the "so called" universal motors? They tend to be the larger motors sometimes used in washing machines. The motors used to drive turn tables in uwaves (and water pumps in washing machines and dishwashers) are small, AC, motors. I dont think so for washing machines and dishwasher. Fairly sure the ones I have taken out were brushed. Universal motors of the type I'm describing have brushes. I don't recall seeing one in a dishwasher but I've not looked at many so that isn't conclusive. -- Suspect someone is claiming a benefit under false pretences? Incapacity Benefit or Personal Independence Payment when they don't need it? They are depriving those in real need! https://www.gov.uk/report-benefit-fraud |
Microwave repair
In article ,
Brian Reay writes: On 13/03/2018 12:26, The Natural Philosopher wrote: On 13/03/18 11:39, Brian Reay wrote: On 12/03/18 11:39, Andy Burns wrote: Andy Burns wrote: That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? Oh, and how universal are the "so called" universal motors? They tend to be the larger motors sometimes used in washing machines. The motors used to drive turn tables in uwaves (and water pumps in washing machines and dishwashers) are small, AC, motors. I dont think so for washing machines and dishwasher. Fairly sure the ones I have taken out were brushed. Universal motors of the type I'm describing have brushes. I don't recall seeing one in a dishwasher but I've not looked at many so that isn't conclusive. Main wash pump motors that I've seen in dishwashers are all 2-phase with a run capacitor. The waste pumps in dishwashers and washing machines are all shaded pole motors. Drum motors in washing machines are universal motors (i.e. with brushes) when belt driven, and stepper motors (brushless) when direct drive. Drum motors need good starting torque and a very wide speed range, which the other motors above don't have. I can still recall my parents' first washing machine, which predated any sort of electronic motor control. I'm not sure what the motor was, but it was single speed, single direction. It had a sodding great gearbox attached with a handful of large solenoids around it to do the gear changes. I can still clearly recall the loud bangs as the different solenoids engaged to change the drum speed throughout the program. When it was scrapped, I saved the mains solenoids and some other parts, which got used in a few projects afterwards. They did tend to overheat, as the washing machine was for 200V mains, and had been converted to 240V when the mains voltage changed by fitting a large autotransformer inside the case, which I hadn't kept because it was too heavy. -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
Microwave repair
On 16/03/2018 22:55, Andrew Gabriel wrote:
Main wash pump motors that I've seen in dishwashers are all 2-phase with a run capacitor. The waste pumps in dishwashers and washing machines are all shaded pole motors. Drum motors in washing machines are universal motors (i.e. with brushes) when belt driven, and stepper motors (brushless) when direct drive. Drum motors need good starting torque and a very wide speed range, which the other motors above don't have. I can still recall my parents' first washing machine, which predated any sort of electronic motor control. I'm not sure what the motor was, but it was single speed, single direction. It had a sodding great gearbox attached with a handful of large solenoids around it to do the gear changes. I can still clearly recall the loud bangs as the different solenoids engaged to change the drum speed throughout the program. When it was scrapped, I saved the mains solenoids and some other parts, which got used in a few projects afterwards. They did tend to overheat, as the washing machine was for 200V mains, and had been converted to 240V when the mains voltage changed by fitting a large autotransformer inside the case, which I hadn't kept because it was too heavy. When did the machine date from? Was it an early automatic? My parents had a single drum followed by a twin tub, neither of which required a gearbox or speed controls I imagine as the motors drove dollies and impellers and pumps and mangles and spin driers. -- Max Demian |
Microwave repair
Max Demian wrote:
On 16/03/2018 22:55, Andrew Gabriel wrote: Main wash pump motors that I've seen in dishwashers are all 2-phase with a run capacitor. The waste pumps in dishwashers and washing machines are all shaded pole motors. Drum motors in washing machines are universal motors (i.e. with brushes) when belt driven, and stepper motors (brushless) when direct drive. Drum motors need good starting torque and a very wide speed range, which the other motors above don't have. I can still recall my parents' first washing machine, which predated any sort of electronic motor control. I'm not sure what the motor was, but it was single speed, single direction. It had a sodding great gearbox attached with a handful of large solenoids around it to do the gear changes. I can still clearly recall the loud bangs as the different solenoids engaged to change the drum speed throughout the program. When it was scrapped, I saved the mains solenoids and some other parts, which got used in a few projects afterwards. They did tend to overheat, as the washing machine was for 200V mains, and had been converted to 240V when the mains voltage changed by fitting a large autotransformer inside the case, which I hadn't kept because it was too heavy. When did the machine date from? Was it an early automatic? My parents had a single drum followed by a twin tub, neither of which required a gearbox or speed controls I imagine as the motors drove dollies and impellers and pumps and mangles and spin driers. I misread that as singular "motor" at first, and had this brief mental image of your parents' scullery with a long shaft across one side of the ceiling and a row of domestic appliances all with their own (unguarded in my image) belt drives from the ceiling. Silly, I know. -- Roger Hayter |
Microwave repair
On Fri, 16 Mar 2018 22:55:15 +0000, Andrew Gabriel wrote:
In article , Brian Reay writes: On 13/03/2018 12:26, The Natural Philosopher wrote: On 13/03/18 11:39, Brian Reay wrote: On 12/03/18 11:39, Andy Burns wrote: Andy Burns wrote: That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? Oh, and how universal are the "so called" universal motors? They tend to be the larger motors sometimes used in washing machines. The motors used to drive turn tables in uwaves (and water pumps in washing machines and dishwashers) are small, AC, motors. I dont think so for washing machines and dishwasher. Fairly sure the ones I have taken out were brushed. Universal motors of the type I'm describing have brushes. I don't recall seeing one in a dishwasher but I've not looked at many so that isn't conclusive. Main wash pump motors that I've seen in dishwashers are all 2-phase with a run capacitor. The waste pumps in dishwashers and washing machines are all shaded pole motors. Drum motors in washing machines are universal motors (i.e. with brushes) when belt driven, and stepper motors (brushless) when direct drive. Drum motors need good starting torque and a very wide speed range, which the other motors above don't have. I can still recall my parents' first washing machine, which predated any sort of electronic motor control. I'm not sure what the motor was, but it was single speed, single direction. It had a sodding great gearbox attached with a handful of large solenoids around it to do the gear changes. I can still clearly recall the loud bangs as the different solenoids engaged to change the drum speed throughout the program. When it was scrapped, I saved the mains solenoids and some other parts, which got used in a few projects afterwards. They did tend to overheat, as the washing machine was for 200V mains, and had been converted to 240V when the mains voltage changed by fitting a large autotransformer inside the case, which I hadn't kept because it was too heavy. I can imagine the need for a 10A rated 240v supply which would require a 400VA auto transformer in this case (40v difference at 10A) which could easily weigh some 16 to 20 Lbs. Just as you described, not a lightweight item. :-) I can understand why you didn't hang onto it since any future need to adapt a 200v appliance to 240v mains would be extremely improbable. The only potential use would be in a museum of domestic electrical appliances. Did you ever consider donating it to any such museums? -- Johnny B Good |
Microwave repair
In article ,
Max Demian writes: On 16/03/2018 22:55, Andrew Gabriel wrote: I can still recall my parents' first washing machine, which predated any sort of electronic motor control. I'm not sure what the motor was, but it was single speed, single direction. It had a sodding great gearbox attached with a handful of large solenoids around it to do the gear changes. I can still clearly recall the loud bangs as the different solenoids engaged to change the drum speed throughout the program. When it was scrapped, I saved the mains solenoids and some other parts, which got used in a few projects afterwards. They did tend to overheat, as the washing machine was for 200V mains, and had been converted to 240V when the mains voltage changed by fitting a large autotransformer inside the case, which I hadn't kept because it was too heavy. When did the machine date from? Was it an early automatic? My parents had a single drum followed by a twin tub, neither of which required a gearbox or speed controls I imagine as the motors drove dollies and impellers and pumps and mangles and spin driers. English Electric Liberator, would have been 1961 or 1962. Yes, it was automatic. https://www.gracesguide.co.uk/images...-Liberator.jpg (not my parents' actual one, but identical) You turned the red dial to show the program you wanted in the window, and then selected the number it showed on the dial on the right, which slowly turned to go through the wash cycle. There were contacts on both dials, which combined to form the wash cycle program. The red dial showed 1-3 different programs, and the right dial selected which of those it was going to do. The only thing I ever recall going wrong with it was the clutch, which allowed the drum inertia to freewheel when it was spinning and the gearbox changed down gear for a slower speed without back-feeding the gearbox at high speed. It was a large coil spring slid over the drum shaft which gripped the shaft when driven by the gearbox, but relaxed grip if the drum was turning faster than the gearbox output. (The machine could not reverse the direction of the drum.) The spring broke after around 12 years, but a replacement was obtained and fitted by my father. -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
Microwave repair
In article ,
Johnny B Good writes: On Fri, 16 Mar 2018 22:55:15 +0000, Andrew Gabriel wrote: I can still recall my parents' first washing machine, which predated any sort of electronic motor control. I'm not sure what the motor was, but it was single speed, single direction. It had a sodding great gearbox attached with a handful of large solenoids around it to do the gear changes. I can still clearly recall the loud bangs as the different solenoids engaged to change the drum speed throughout the program. When it was scrapped, I saved the mains solenoids and some other parts, which got used in a few projects afterwards. They did tend to overheat, as the washing machine was for 200V mains, and had been converted to 240V when the mains voltage changed by fitting a large autotransformer inside the case, which I hadn't kept because it was too heavy. I can imagine the need for a 10A rated 240v supply which would require a 400VA auto transformer in this case (40v difference at 10A) which could easily weigh some 16 to 20 Lbs. Just as you described, not a lightweight item. :-) I can understand why you didn't hang onto it since any future need to adapt a 200v appliance to 240v mains would be extremely improbable. The only potential use would be in a museum of domestic electrical appliances. Did you ever consider donating it to any such museums? It was probably 20 years old, and not noteworthy at the time. If it was still around now, I would either find a museum, or keep it going! Although I vivdly recall the sounds it made, it kind of seems a shame there's probably no video or even audio history of such devices running remaining today. I did record an older device which I still have working, a Hoover Constellation vacuum cleaner, playing with it as a frictionless puck much as I did as a child in my parents' house, although they had flatter floors than this one was. http://www.youtube.com/watch?v=VXb8Fo3T5h0 -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
Microwave repair
Johnny B Good wrote:
On Fri, 16 Mar 2018 22:55:15 +0000, Andrew Gabriel wrote: In article , Brian Reay writes: On 13/03/2018 12:26, The Natural Philosopher wrote: On 13/03/18 11:39, Brian Reay wrote: On 12/03/18 11:39, Andy Burns wrote: Andy Burns wrote: That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? Oh, and how universal are the "so called" universal motors? They tend to be the larger motors sometimes used in washing machines. The motors used to drive turn tables in uwaves (and water pumps in washing machines and dishwashers) are small, AC, motors. I dont think so for washing machines and dishwasher. Fairly sure the ones I have taken out were brushed. Universal motors of the type I'm describing have brushes. I don't recall seeing one in a dishwasher but I've not looked at many so that isn't conclusive. Main wash pump motors that I've seen in dishwashers are all 2-phase with a run capacitor. The waste pumps in dishwashers and washing machines are all shaded pole motors. Drum motors in washing machines are universal motors (i.e. with brushes) when belt driven, and stepper motors (brushless) when direct drive. Drum motors need good starting torque and a very wide speed range, which the other motors above don't have. I can still recall my parents' first washing machine, which predated any sort of electronic motor control. I'm not sure what the motor was, but it was single speed, single direction. It had a sodding great gearbox attached with a handful of large solenoids around it to do the gear changes. I can still clearly recall the loud bangs as the different solenoids engaged to change the drum speed throughout the program. When it was scrapped, I saved the mains solenoids and some other parts, which got used in a few projects afterwards. They did tend to overheat, as the washing machine was for 200V mains, and had been converted to 240V when the mains voltage changed by fitting a large autotransformer inside the case, which I hadn't kept because it was too heavy. I can imagine the need for a 10A rated 240v supply which would require a 400VA auto transformer in this case (40v difference at 10A) which could easily weigh some 16 to 20 Lbs. Just as you described, not a lightweight item. :-) My knowledge of transformer theory was never very clear, but why is it not rated for the total output, which might well be something like 10A at 200v, 2000VA? I can understand why you didn't hang onto it since any future need to adapt a 200v appliance to 240v mains would be extremely improbable. The only potential use would be in a museum of domestic electrical appliances. Did you ever consider donating it to any such museums? -- Roger Hayter |
Microwave repair
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Microwave repair
English Electric Liberator, would have been 1961 or 1962. Yes, it was automatic. https://www.gracesguide.co.uk/images...-Liberator.jpg (not my parents' actual one, but identical) You turned the red dial to show the program you wanted in the window, and then selected the number it showed on the dial on the right, which slowly turned to go through the wash cycle. There were contacts on both dials, which combined to form the wash cycle program. The red dial showed 1-3 different programs, and the right dial selected which of those it was going to do. The only thing I ever recall going wrong with it was the clutch, which allowed the drum inertia to freewheel when it was spinning and the gearbox changed down gear for a slower speed without back-feeding the gearbox at high speed. It was a large coil spring slid over the drum shaft which gripped the shaft when driven by the gearbox, but relaxed grip if the drum was turning faster than the gearbox output. (The machine could not reverse the direction of the drum.) The spring broke after around 12 years, but a replacement was obtained and fitted by my father. We had a Hotpoint Liberator about 15 years later, we must have had it for 10 years until the bearings gave up, and I replaced it with an identical machine from my parents-in law cellar that had little use. The first front lording automatic I ever saw was at my next door neighbours when I was a kid. A Bendix. I was very impressed. -- Graham. %Profound_observation% |
Microwave repair
On 13/03/2018 11:39, Brian Reay wrote:
On 12/03/18 11:39, Andy Burns wrote: Andy Burns wrote: That said I expect to be able to get at the turntable motor/gearbox without going near the "active" end ... any other gotchas? Oh, and how universal are the "so called" universal motors? They tend to be the larger motors sometimes used in washing machines. The motors used to drive turn tables in uwaves (and water pumps in washing machines and dishwashers) are small, AC, motors. Synchronous? Is that why the turntable on my Daewoo sometimes goes one way; sometimes the other? (And no, it's not a fault.) Electric clocks sometimes had a mechanism to ensure they went the right way. My Grandmother had a clock built in to a large mirror perminently screwed onto the lounge wall. There was no accesable connector, but it was wired to its own fuse in the massive metal fuse-box. The clock was self-starting, but it was 50/50 if it went in the right direction. As it didn't have a second hand, if there was a power interruption, you had to wait until you could perceeve some movement of the second hand and pull the fuse breifly if it was going backwards. -- Graham. %Profound_observation% |
Microwave repair
Andrew Gabriel wrote:
In article , (Roger Hayter) writes: Johnny B Good wrote: I can imagine the need for a 10A rated 240v supply which would require a 400VA auto transformer in this case (40v difference at 10A) which could easily weigh some 16 to 20 Lbs. Just as you described, not a lightweight item. :-) My knowledge of transformer theory was never very clear, but why is it not rated for the total output, which might well be something like 10A at 200v, 2000VA? An auto-transformer has just one tapped winding. The core only has to cope with the VA of the voltage difference. The common part of the transformer winding can be thinner too, although that depends on the no-load inductance and the harmonic component of the load. Thanks. I must make the effort to read a fuller explanation some time so I understand it. But the point is noted. -- Roger Hayter |
Microwave repair
On Sat, 17 Mar 2018 12:44:53 +0000, Roger Hayter wrote:
Johnny B Good wrote: ====snip==== I can imagine the need for a 10A rated 240v supply which would require a 400VA auto transformer in this case (40v difference at 10A) which could easily weigh some 16 to 20 Lbs. Just as you described, not a lightweight item. :-) My knowledge of transformer theory was never very clear, but why is it not rated for the total output, which might well be something like 10A at 200v, 2000VA? The main advantage of an auto-transformer over a conventional one with isolated primary and secondary windings is that you only need to rate it for the VA difference between input and output voltages. The easiest way to explain this is to consider the equivalent derived from, in this case, a 40v 10A rated secondary output 240v mains transformer where the secondary winding is wired in series opposing to the 240v live connection (voltage buck configuration) so as to provide the required 200vac. Since the 40v 10A secondary is merely handling its rated current and the mains live connection can handle whatever a 13A fused outlet can supply from a ring main socket, the 240v primary is only handling the 400VA load it is already rated for (its secondary winding is only handling an opposing 40v at 10A leaving the mains to directly supply a 240v 10A loading). A purpose designed auto-transformer in this case would consist of a single winding designed with appropriate tapping points of a common neutral (0v reference end), 200v and a 240v tapping points (with possibly other tap voltages such as 210, 220, 230 and 250 volts). Normal practice when winding such auto-transformers is to use appropriate gauges of wire between each tapping point to ensure that whichever way such a transformer is used, no more copper than is actually required at the maximum VA rating is used. In the case of Andrew's 240v to 200v autotransformer (assumed to have a 400VA rating), the section between the hot end of the 200v winding (200v tap) and the 240v tap (the mains input side) will have thicker gauge wire designed for the 10A load (less the portion of current supplied by the 200v winding section to the load) whilst the 0 to 200 volt winding will be specified to handle a maximum current calculated from the sum voltages of the 40v winding and itself which works out at a mere 1.67A which means the 200 to 240v section only has to handle a mere 8.33A. If we use the same auto-transformer to step up a 200v supply to 240v at the same 400VA load, those current ratings remain unchanged and this remains true even if we use the "240v tap" for the neutral connection so that we can provide a non-isolated 40v at 10A from the "200v tap" with the "0v tap" connected to the incoming 240v mains live. Another example of this principle is to take a 120VA split primary 240/120v mains transformer with any arbitrary low voltage secondary winding(s) which will remain unused in this case and use it as a 240VA auto-transformer to step up a 120v supply to 240v or to step down from 240 to 120v by simply connecting the split primaries in series phase aiding as per the requirement to provide the secondary voltages from a 240v supply. The connection between the split primaries becomes our 120v tapping point which can be used either as the input or the output, depending on whether we're stepping the voltage up or down respectively. In this example case, the 240VA auto-transformer rating arises out of the fact that each of the 120v windings is supplying 1A each to the load when used to step down the voltage. When used to step up the voltage, the required 2A at 120v is now split equally between the two windings, 1A to supply the 0 to 120v winding[1] and the remaining 1A becoming the load current via the other 120 to 240v winding to supply the load with 1A at 240v (240VA total output). The difference between a conventional fully isolated voltage transformer and and an autotransformer is that the VA rating in the former case has to be at least that of the load whilst that of the latter merely has to handle the VA difference between the input and output voltages. If you only had to step up to 240v at 10A from a 230v supply, the VA rating required of the auto-transformer would only need to be 100VA rather than the former case of stepping 200v to 240v at 10A which requires a rating of 400VA. A fully isolated transformer would, in this case, need to be rated at the full 2.4KVA rating of the load. [1] The reason for this portion of the winding requiring 1A is that the 1A load on the other winding is simply the result of a one to one voltage transformation to a secondary that happens to be connected series aiding to the incoming 120v mains so as to supply a 240v 1A load. -- Johnny B Good |
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