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From: Arfa Daily on 18 May 2010 08:03 "Meat Plow" <mhywatt(a)yahoo.com> wrote in message news:pan.2010.05.18.11.48.35(a)gmail.com... > On Tue, 18 May 2010 10:40:49 +0100, N_Cook wrote: > >> Arfa Daily <arfa.daily(a)ntlworld.com> wrote in message >> news:FfsIn.24657$Lg1.16488(a)newsfe17.ams2... >>> >>> "DaveD" <marday(a)ihug.co.nz> wrote in message >>> news:hstcbg$lgv$1(a)lust.ihug.co.nz... >>> > Arfa Daily wrote: >>> >> "Geo" <hw9j-s5hw(a)dea.spamcon.org> wrote in message >>> >> news:t7v2v5tt1gdnhv1k1pdmb3ntajhinru5rm(a)4ax.com... >>> >>> On Mon, 17 May 2010 17:28:20 +0100, "Arfa Daily" >>> >>> <arfa.daily(a)ntlworld.com> >>> >>> wrote: >>> >>> >>> >>> >>> >>>> It definitely says "Rega Planar 3" at the top front right corner, >>> >>>> although >>> >>>> it's hard to see as the letters are just black 'shininess' within >>> >>>> the black >>> >>>> satin anodised finish of the cabinet. Underneath, directly under >>> >>>> the motor, >>> >>>> is a cover secured by two screws, When this is removed, the motor >>> >>>> and >> a >>> >>>> small PCB are revealed. The PCB has just two components on it - >>> >>>> the burnt up >>> >>>> R, which is a large 'film' type, I guess something like about 5mm >>> >>>> diameter >>> >>>> and 20mm or so long, and the 0.22u 400v cap, which is one of those >>> >>>> green MKT >>> >>>> monobloc types. These two components are mounted 'on the slant' on >> the >>> >>>> board. The mains comes in, and the neutral is joined immediately >>> >>>> to >> two >>> >>>> grey >>> >>>> wires from the motor. The live leaves the board again on a white >>> >>>> wire which >>> >>>> goes to the on / off switch at the front top left of the deck. >>> >>>> Live returns >>> >>>> to the board on another white, and goes to the motor red lead via >>> >>>> the burnt >>> >>>> up resistor. The cap is between the red lead and the remaining >>> >>>> blue lead. >>> >>>> Doesn't sound much like the example that you're looking at, eh ? >>> >>> How about this version from mine - looks like a 15k 5% (old 2-5w >>> >>> carbon?) >>> >>> http://www.8zero.co.uk/planar.jpg >>> >>> >>> >>> >>> >>> -- >>> >>> Geo >>> >> >>> >> Yes, that's closer - although still not quite the same >>> >> configuration. It's actually a different motor in yours, but the >>> >> supply still goes to the red via the resistor, and the cap still >>> >> appears to be between red >> and >>> >> blue, and the same value, although a different type. Based on that, >>> >> I think I'm going to start with 15k now, and see if the motor runs, >>> >> and >> if >>> >> it does, if it has enough torque to drive the platter. >>> >> >>> >> Thanks very much for taking the trouble to post me the piccy. >>> >> Appreciated. >>> >> >>> >> Arfa >>> > Hi Arfa >>> > Further info. The data I supplied earlier was from the Planar 3 >>> > upgrade motor assembly. >>> > I have just pulled out the old motor and PCB. It has only 2 >>> > components on it. >>> > 1 x 220nf 250v ac X rated cap manufactured by Rifa. 1 x 12k 2-3 watt >>> > resistor, 8.5mm dia x 25mm long. The resistor is a mid brown body >>> > colour and the bands are quite hard to read but measurement confirms >>> > 12k 5% (as in brown red orange gold) The brown and orange are hard to >>> > differentiate The motor is a Philips 110v 50hz 250 rpm (12NC >>> > 990411131613) date of manufacture 1985 with the same colour leads I >>> > would suggest going with what you have in the 12 - 15k ~ 5 watt >>> > resistor. Check that the voltage to the motor is in the region of >>> > 110v under load and it should be good to go Cheers >>> > DaveD >>> >>> Many thanks Dave. That's it exactly. I just had a look, and I haven't >>> got >> a >>> high power 12 or 15k in stock, but I have got some 47k 2 watt film >>> resistors, so to save time and get the item back to the customer (he's >>> already put up with me being away on holiday for 2 weeks !), I'm going >>> to put three of those in parallel as there's plenty of room. Thanks >>> again, >> all. >>> >>> Arfa >>> >>> >>> >> Is there a fuseable resistor function to the original ? ie 2 watts of >> dissipation from stalled motor and the R blows rather than the motor. >> Would not some 1/2 watt resistors together giving 12K be better? > > He has a point. I wouldn't have said that there was an 'implicit' fusible function to the resistor, but I suppose that you could argue it as a secondary function. The plate on the bottom of the deck claims that the power requirement is 4 watts, so given that the primary function of the resistor is that of a dropper for the 110v motor, you would have to say that this equates to around 2 watts dissipation in the motor, and the other two in the resistor. As the original resistor is rated at around 4 watts, that would sort of indicate that it had been dimensioned to be able to stand up to its job without burning out. I'm not actually sure what happens to the current that a synchronous motor draws if you stall it, but I wouldn't think that it ramps in anything like the same way as that of a DC motor, or any kind of brushgear AC motor ?? Arfa
From: Meat Plow on 18 May 2010 08:14 On Tue, 18 May 2010 13:03:20 +0100, Arfa Daily wrote: > "Meat Plow" <mhywatt(a)yahoo.com> wrote in message > news:pan.2010.05.18.11.48.35(a)gmail.com... >> On Tue, 18 May 2010 10:40:49 +0100, N_Cook wrote: >> >>> Arfa Daily <arfa.daily(a)ntlworld.com> wrote in message >>> news:FfsIn.24657$Lg1.16488(a)newsfe17.ams2... >>>> >>>> "DaveD" <marday(a)ihug.co.nz> wrote in message >>>> news:hstcbg$lgv$1(a)lust.ihug.co.nz... >>>> > Arfa Daily wrote: >>>> >> "Geo" <hw9j-s5hw(a)dea.spamcon.org> wrote in message >>>> >> news:t7v2v5tt1gdnhv1k1pdmb3ntajhinru5rm(a)4ax.com... >>>> >>> On Mon, 17 May 2010 17:28:20 +0100, "Arfa Daily" >>>> >>> <arfa.daily(a)ntlworld.com> >>>> >>> wrote: >>>> >>> >>>> >>> >>>> >>>> It definitely says "Rega Planar 3" at the top front right >>>> >>>> corner, although >>>> >>>> it's hard to see as the letters are just black 'shininess' >>>> >>>> within the black >>>> >>>> satin anodised finish of the cabinet. Underneath, directly under >>>> >>>> the motor, >>>> >>>> is a cover secured by two screws, When this is removed, the >>>> >>>> motor and >>> a >>>> >>>> small PCB are revealed. The PCB has just two components on it - >>>> >>>> the burnt up >>>> >>>> R, which is a large 'film' type, I guess something like about >>>> >>>> 5mm diameter >>>> >>>> and 20mm or so long, and the 0.22u 400v cap, which is one of >>>> >>>> those green MKT >>>> >>>> monobloc types. These two components are mounted 'on the slant' >>>> >>>> on >>> the >>>> >>>> board. The mains comes in, and the neutral is joined immediately >>>> >>>> to >>> two >>>> >>>> grey >>>> >>>> wires from the motor. The live leaves the board again on a white >>>> >>>> wire which >>>> >>>> goes to the on / off switch at the front top left of the deck. >>>> >>>> Live returns >>>> >>>> to the board on another white, and goes to the motor red lead >>>> >>>> via the burnt >>>> >>>> up resistor. The cap is between the red lead and the remaining >>>> >>>> blue lead. >>>> >>>> Doesn't sound much like the example that you're looking at, eh ? >>>> >>> How about this version from mine - looks like a 15k 5% (old 2-5w >>>> >>> carbon?) >>>> >>> http://www.8zero.co.uk/planar.jpg >>>> >>> >>>> >>> >>>> >>> -- >>>> >>> Geo >>>> >> >>>> >> Yes, that's closer - although still not quite the same >>>> >> configuration. It's actually a different motor in yours, but the >>>> >> supply still goes to the red via the resistor, and the cap still >>>> >> appears to be between red >>> and >>>> >> blue, and the same value, although a different type. Based on >>>> >> that, I think I'm going to start with 15k now, and see if the >>>> >> motor runs, and >>> if >>>> >> it does, if it has enough torque to drive the platter. >>>> >> >>>> >> Thanks very much for taking the trouble to post me the piccy. >>>> >> Appreciated. >>>> >> >>>> >> Arfa >>>> > Hi Arfa >>>> > Further info. The data I supplied earlier was from the Planar 3 >>>> > upgrade motor assembly. >>>> > I have just pulled out the old motor and PCB. It has only 2 >>>> > components on it. >>>> > 1 x 220nf 250v ac X rated cap manufactured by Rifa. 1 x 12k 2-3 >>>> > watt resistor, 8.5mm dia x 25mm long. The resistor is a mid brown >>>> > body colour and the bands are quite hard to read but measurement >>>> > confirms 12k 5% (as in brown red orange gold) The brown and orange >>>> > are hard to differentiate The motor is a Philips 110v 50hz 250 rpm >>>> > (12NC 990411131613) date of manufacture 1985 with the same colour >>>> > leads I would suggest going with what you have in the 12 - 15k ~ 5 >>>> > watt resistor. Check that the voltage to the motor is in the region >>>> > of 110v under load and it should be good to go Cheers DaveD >>>> >>>> Many thanks Dave. That's it exactly. I just had a look, and I haven't >>>> got >>> a >>>> high power 12 or 15k in stock, but I have got some 47k 2 watt film >>>> resistors, so to save time and get the item back to the customer >>>> (he's already put up with me being away on holiday for 2 weeks !), >>>> I'm going to put three of those in parallel as there's plenty of >>>> room. Thanks again, >>> all. >>>> >>>> Arfa >>>> >>>> >>>> >>> Is there a fuseable resistor function to the original ? ie 2 watts of >>> dissipation from stalled motor and the R blows rather than the motor. >>> Would not some 1/2 watt resistors together giving 12K be better? >> >> He has a point. > > I wouldn't have said that there was an 'implicit' fusible function to > the resistor, but I suppose that you could argue it as a secondary > function. The plate on the bottom of the deck claims that the power > requirement is 4 watts, so given that the primary function of the > resistor is that of a dropper for the 110v motor, you would have to say > that this equates to around 2 watts dissipation in the motor, and the > other two in the resistor. As the original resistor is rated at around 4 > watts, that would sort of indicate that it had been dimensioned to be > able to stand up to its job without burning out. I'm not actually sure > what happens to the current that a synchronous motor draws if you stall > it, but I wouldn't think that it ramps in anything like the same way as > that of a DC motor, or any kind of brushgear AC motor ?? > I thought you should cover all bases as Cook did. Not really knowing what the pwr supply capability was I thought it at least worth looking into. Have you an idea why the original failed?
From: DaveD on 18 May 2010 10:06 Meat Plow wrote: > On Tue, 18 May 2010 13:03:20 +0100, Arfa Daily wrote: > >> "Meat Plow" <mhywatt(a)yahoo.com> wrote in message >> news:pan.2010.05.18.11.48.35(a)gmail.com... >>> On Tue, 18 May 2010 10:40:49 +0100, N_Cook wrote: >>> >>>> Arfa Daily <arfa.daily(a)ntlworld.com> wrote in message >>>> news:FfsIn.24657$Lg1.16488(a)newsfe17.ams2... >>>>> "DaveD" <marday(a)ihug.co.nz> wrote in message >>>>> news:hstcbg$lgv$1(a)lust.ihug.co.nz... >>>>>> Arfa Daily wrote: >>>>>>> "Geo" <hw9j-s5hw(a)dea.spamcon.org> wrote in message >>>>>>> news:t7v2v5tt1gdnhv1k1pdmb3ntajhinru5rm(a)4ax.com... >>>>>>>> On Mon, 17 May 2010 17:28:20 +0100, "Arfa Daily" >>>>>>>> <arfa.daily(a)ntlworld.com> >>>>>>>> wrote: >>>>>>>> >>>>>>>> >>>>>>>>> It definitely says "Rega Planar 3" at the top front right >>>>>>>>> corner, although >>>>>>>>> it's hard to see as the letters are just black 'shininess' >>>>>>>>> within the black >>>>>>>>> satin anodised finish of the cabinet. Underneath, directly under >>>>>>>>> the motor, >>>>>>>>> is a cover secured by two screws, When this is removed, the >>>>>>>>> motor and >>>> a >>>>>>>>> small PCB are revealed. The PCB has just two components on it - >>>>>>>>> the burnt up >>>>>>>>> R, which is a large 'film' type, I guess something like about >>>>>>>>> 5mm diameter >>>>>>>>> and 20mm or so long, and the 0.22u 400v cap, which is one of >>>>>>>>> those green MKT >>>>>>>>> monobloc types. These two components are mounted 'on the slant' >>>>>>>>> on >>>> the >>>>>>>>> board. The mains comes in, and the neutral is joined immediately >>>>>>>>> to >>>> two >>>>>>>>> grey >>>>>>>>> wires from the motor. The live leaves the board again on a white >>>>>>>>> wire which >>>>>>>>> goes to the on / off switch at the front top left of the deck. >>>>>>>>> Live returns >>>>>>>>> to the board on another white, and goes to the motor red lead >>>>>>>>> via the burnt >>>>>>>>> up resistor. The cap is between the red lead and the remaining >>>>>>>>> blue lead. >>>>>>>>> Doesn't sound much like the example that you're looking at, eh ? >>>>>>>> How about this version from mine - looks like a 15k 5% (old 2-5w >>>>>>>> carbon?) >>>>>>>> http://www.8zero.co.uk/planar.jpg >>>>>>>> >>>>>>>> >>>>>>>> -- >>>>>>>> Geo >>>>>>> Yes, that's closer - although still not quite the same >>>>>>> configuration. It's actually a different motor in yours, but the >>>>>>> supply still goes to the red via the resistor, and the cap still >>>>>>> appears to be between red >>>> and >>>>>>> blue, and the same value, although a different type. Based on >>>>>>> that, I think I'm going to start with 15k now, and see if the >>>>>>> motor runs, and >>>> if >>>>>>> it does, if it has enough torque to drive the platter. >>>>>>> >>>>>>> Thanks very much for taking the trouble to post me the piccy. >>>>>>> Appreciated. >>>>>>> >>>>>>> Arfa >>>>>> Hi Arfa >>>>>> Further info. The data I supplied earlier was from the Planar 3 >>>>>> upgrade motor assembly. >>>>>> I have just pulled out the old motor and PCB. It has only 2 >>>>>> components on it. >>>>>> 1 x 220nf 250v ac X rated cap manufactured by Rifa. 1 x 12k 2-3 >>>>>> watt resistor, 8.5mm dia x 25mm long. The resistor is a mid brown >>>>>> body colour and the bands are quite hard to read but measurement >>>>>> confirms 12k 5% (as in brown red orange gold) The brown and orange >>>>>> are hard to differentiate The motor is a Philips 110v 50hz 250 rpm >>>>>> (12NC 990411131613) date of manufacture 1985 with the same colour >>>>>> leads I would suggest going with what you have in the 12 - 15k ~ 5 >>>>>> watt resistor. Check that the voltage to the motor is in the region >>>>>> of 110v under load and it should be good to go Cheers DaveD >>>>> Many thanks Dave. That's it exactly. I just had a look, and I haven't >>>>> got >>>> a >>>>> high power 12 or 15k in stock, but I have got some 47k 2 watt film >>>>> resistors, so to save time and get the item back to the customer >>>>> (he's already put up with me being away on holiday for 2 weeks !), >>>>> I'm going to put three of those in parallel as there's plenty of >>>>> room. Thanks again, >>>> all. >>>>> Arfa >>>>> >>>>> >>>>> >>>> Is there a fuseable resistor function to the original ? ie 2 watts of >>>> dissipation from stalled motor and the R blows rather than the motor. >>>> Would not some 1/2 watt resistors together giving 12K be better? >>> He has a point. >> I wouldn't have said that there was an 'implicit' fusible function to >> the resistor, but I suppose that you could argue it as a secondary >> function. The plate on the bottom of the deck claims that the power >> requirement is 4 watts, so given that the primary function of the >> resistor is that of a dropper for the 110v motor, you would have to say >> that this equates to around 2 watts dissipation in the motor, and the >> other two in the resistor. As the original resistor is rated at around 4 >> watts, that would sort of indicate that it had been dimensioned to be >> able to stand up to its job without burning out. I'm not actually sure >> what happens to the current that a synchronous motor draws if you stall >> it, but I wouldn't think that it ramps in anything like the same way as >> that of a DC motor, or any kind of brushgear AC motor ?? >> > > I thought you should cover all bases as Cook did. Not really knowing > what the pwr supply capability was I thought it at least worth looking > into. Have you an idea why the original failed? Just another bit of info for what it is worth. The DC resistance of the motor windings are grey to red = 4k49 grey to blue = 4k49 red to blue = 8k99 grey to motor case greater than 20Meg as read on my oldish dvm The 220nf cap should be o/c also Now I am curious as to what you find. If it is the motor, it might be worth your customer getting the motor upgrade kit if it still available. http://www.rega.co.uk/html/upgrade_kits.htm Cheers DaveD
From: Arfa Daily on 18 May 2010 11:50 <snip> > > Just another bit of info for what it is worth. > The DC resistance of the motor windings are > grey to red = 4k49 > grey to blue = 4k49 > red to blue = 8k99 > grey to motor case greater than 20Meg > as read on my oldish dvm > The 220nf cap should be o/c also > > Now I am curious as to what you find. If it is the motor, it might be > worth your customer getting the motor upgrade kit if it still available. > http://www.rega.co.uk/html/upgrade_kits.htm > Cheers > DaveD Thanks for the link Dave. Do you know what the reasoning was behind the 'upgrade' ? Did they have a lot of trouble with motors failing ? I would say that this is the original motor, coming up on 25 years old. I fitted the 3 x 47k combination, and the motor runs normally. It has plenty enough torque to shift the heavy glass platter, and according to my strobe disc, the speed is spot on. Voltage across the motor measured at 98v, which would seem right, given that the 47k combo comes to 15.6k against the original value of 12k. In the circumstances, I'm prepared to call 98v on a 110v nominal motor, a draw. I s'pose it wouldn't be a bad idea to just check the winding resistances before it goes back, but I don't think I'll be expecting to find a problem, as it does run correctly, without anything catching fire. As to why the original resistor failed, anyone's guess. About 1 1/4 turns of the spiral element have charred, right in the middle. The resistor looks as though it has been pretty warm over its lifetime, but again, it is nearly 25 years old, so has worked hard. Could just be that it had started to go high and suffered a cumulative cascade failure. Might have been a voltage thing. Some of these resistors, particularly considering its age, are not rated especially well, working voltage-wise. I suppose that over it's lifetime, it's had around 130v RMS across it all the time that the motor was running. Could have been a slight manufacturing defect such as the spiral being 'nicked', that has degraded down the years, to the point where it became a failure. Endless possibilities ... Arfa
From: Meat Plow on 18 May 2010 12:07
On Tue, 18 May 2010 16:50:28 +0100, Arfa Daily wrote: > <snip> > > > >> Just another bit of info for what it is worth. The DC resistance of the >> motor windings are grey to red = 4k49 >> grey to blue = 4k49 >> red to blue = 8k99 >> grey to motor case greater than 20Meg as read on my oldish dvm >> The 220nf cap should be o/c also >> >> Now I am curious as to what you find. If it is the motor, it might be >> worth your customer getting the motor upgrade kit if it still >> available. http://www.rega.co.uk/html/upgrade_kits.htm Cheers >> DaveD > > > Thanks for the link Dave. Do you know what the reasoning was behind the > 'upgrade' ? Did they have a lot of trouble with motors failing ? I would > say that this is the original motor, coming up on 25 years old. I fitted > the 3 x 47k combination, and the motor runs normally. It has plenty > enough torque to shift the heavy glass platter, and according to my > strobe disc, the speed is spot on. Voltage across the motor measured at > 98v, which would seem right, given that the 47k combo comes to 15.6k > against the original value of 12k. In the circumstances, I'm prepared to > call 98v on a 110v nominal motor, a draw. > > I s'pose it wouldn't be a bad idea to just check the winding resistances > before it goes back, but I don't think I'll be expecting to find a > problem, as it does run correctly, without anything catching fire. > > As to why the original resistor failed, anyone's guess. About 1 1/4 > turns of the spiral element have charred, right in the middle. The > resistor looks as though it has been pretty warm over its lifetime, but > again, it is nearly 25 years old, so has worked hard. Could just be that > it had started to go high and suffered a cumulative cascade failure. > Might have been a voltage thing. Some of these resistors, particularly > considering its age, are not rated especially well, working > voltage-wise. I suppose that over it's lifetime, it's had around 130v > RMS across it all the time that the motor was running. Could have been a > slight manufacturing defect such as the spiral being 'nicked', that has > degraded down the years, to the point where it became a failure. Endless > possibilities ... > I hate endless possibilities. :) |