Should this be happening?

[soundman2]

HELLO ALL

My Rotel RP850 TT motor seems to be getting quite warm after an hour or so. The brass pulley starts to get hot and the chrome belt guide does too. I have lubed the motor and the bearing but it still happens even with no platter or belt on.

My concern is that the heat may have an effect on the belt so with that in mind can anyone offer me some advice on this. Does any other Rotel RP850 owners have the same "problem", or is this supposed to happen to get rid of heat from the motor?:scratch2:

 

[radioman76]

I don't own one, but in my travels I have not heard of this happening. Could be a problem with the motor coil. If it spins steadily and at the correct speed, then its not a problem with any bearings. Hope that helps.

 

[voltcontrol]

"Should this be happening?"
No.. it sounds like the beginning of a nasty failure, I'd have the turntable serviced...

 

[soundman2]

Thanks for your replies!

Yes, I thought this was not a good sign and I really don't know where to go from here. The deck did not cost me much and that is not an issue, but, like I said in my first post, I AM concerned that it could do things to the belt and ironically I have just sent for a new belt. DAMMIT!

ADVICE IS NEEDED HERE!:yes:

 

[steerpike2]

I don't know the motor design, but if it is a dual-coil-and-capacitor type, then a failing phase shift capacitor could cause the motor to overheat. A burned out motor is much more of a worry than a ruined belt.

If required, a new capacitor is a cheap item, and easily replaced.

 

[catman]

Capacitors.

G'day all, yes capacitors (especially electrolytic capacitors), are an often necessary electronic component, yet throughout the entire history of electronics, the most unreliable one and when they fail they often 'take out' other associated components.

As I mentioned in another thread recently, when any localised heating is involved the lifetime of capacitors in general terms, is drastically reduced. Yes a failing capacitor can cause many circuit problems. :yes: Regards, Felix aka catman.

 

[soundman2]

Thanks for the replies. According to vinylengine (downloaded the service manual) there is a capacitor near the motor, so I'll have take this thing apart and find out (I have loads of electrolytics etc) which I stockpiled a few years back.

I did call a hifi place about 30 miles from where I live and they said that obviously a motor IS going to produce heat which I already know but they thought what is happening is not quite right. May be worth changing ANY caps that are associated with the motor. Good article on electrolytics, Felix, (downloaded that too).:thmbsp:

 

[soundman2]

OK!

I have had a look at the schematic for the Rotel RP850 and the only caps I can see is probably a ceramic cap across the switch to stop noise at switch on and another what I think what is a polyester type. NO ELECTROLYTICS!

Even though the pulley gets "hot" it does not burn to the touch so I just don't know! The deck shows no speed variation and as far as I know it could be a normal thing.:scratch2:

I may place an e-mail to Rotel as I'm sure they will have a better idea as they made the deck.

 

[steerpike2]

The motor phase shift capacitor will be a non-electrolytic, of around 3uF to 8uF in value, rated at 350V or so. Often it's a chassis mounted 'can' type.

*IF* it fails completely it can cause the motor to run in the wrong direction, or worse, stall.

 

[soundman2]

Thanks for that! Very interesting!:thmbsp:

 

[catman]

G'day all, yes all capacitor types are subject to early failure and not just electrolytic capacitor types.

Years ago one of my turntables developed a fault caused by a dried out 'non electrolytic' capacitor. Regards, Felix aka catman.

 

[soundman2]

HI FELIX!

There was I thinking that only electrolytics were the bad guys! Thank you for that!:yes: