Turntable - voltage selector missing

[drspangle]

Hello kind strangers

I have bought an old turntable (Record player) that I planned to use in Canada, but then take back to New Zealand with me. My readings indicated that it had a switch to select between 110 and 220v and the direct drive motor is adjustable to allow compensation for 50/60hz differences.

After lugging it home, the first thing I did was open up the hatch where the switch was supposed to be, but it was empty, so I opened it up.

That black box (Resistor??) at the top is where the switch was supposed to be. This table has had some modifications, I'm wondering if the switching has been removed.

(click for full size)


Some useful info:

• The grey and brown leads from the top centre connect to the on off switch centre left
• The transformer appears to be very much a black box with wires leading to/from it internally. I didn't see any screws/levers to open it up, but it may be possible. There was no writing on it besides what is in the picture.
• I can provide details on anything else, including photos

I'm really just trying to determine if it's even possible that this was ever designed to accommodate 220v. And I'd really like to know what that black box is doing.

Thanks for your interest

 

[Reloadron]

My best guess is the black box is a line filter capacitor. That possibly this model wasn't designed for dual voltage operation. The transformer is in fact just a sealed unit with the larger orange & white being the primary side. Should that be true the transformer looks to have a single primary winding and not designed with a dual voltage primary. With the unit powered I would measure the voltage across the orange and white I suspect is the primary and if you have 120 VAC that is for sure the primary. Next I would measure across the small blue and orange pairs and see what voltages you get. Finally if I wanted to run the unit off 220 VAC I would just place a step down transformer in front of it. While living in Italy such transformers were common. Most 120 VAC appliances ran fine on 50 Hz.

Ron

 

[alec_t]

I agree with Ron. The top black box is clearly marked 'AC125V', which would seem to rule out the deck being dual voltage.

 

[drspangle]

As I suspected, sad!

I'll have to decide in a few months if it's worth keeping/shipping back/trying to run on a step down.

Thanks for your thoughts!

 

[JimB]

If you like the turntable, there is an easy modification that you could do to run it on 240v mains, use an auto transformer.

There appears to be plenty of room inside the base of the unit, all you need is a transformer of similar size to that which is already installed.
The secondary windings of the extra transformer are not critical, in fact they will not be used. The primary however MUST be centre tapped for 230/115 volt use.
All that you have to do is to connect the incoming mains supply across the whole of the primary of the new transformer and then connect the primary of the existing transformer across half of the primary of the new transformer.

That is what I would do.

JimB

 

[rumpfy]

Its a bit hard to see, but the 'black box' looks VERY much like a 0.01 uF capacitor in series with the mains transformer.
It looks like there are 3 speeds with separate adjustments for each speed; presumably 78, 45, 33 rpm.
The two capacitors at the bottom left are said to be AC types, and for me this is a bit of a puzzle but not a problem.
Would be nice to know what brand the TT is. It looks like a nice unit.
Jim B is right though; the problem to get it going on a 230 volt supply is mickey mouse.

 

[drspangle]

If you like the turntable, there is an easy modification that you could do to run it on 240v mains, use an auto transformer.

There appears to be plenty of room inside the base of the unit, all you need is a transformer of similar size to that which is already installed.
The secondary windings of the extra transformer are not critical, in fact they will not be used. The primary however MUST be centre tapped for 230/115 volt use.
All that you have to do is to connect the incoming mains supply across the whole of the primary of the new transformer and then connect the primary of the existing transformer across half of the primary of the new transformer.

That is what I would do.

JimB

It's been a while, so please be patient with my dumb questions

So if I get a transformer that can handle 240v/~12W (thats the spec of the table) center tap it and have this as the new input to the original transformer?

Do transformers have pins for tapping off the primary coil ? I've never dealt with them physically, only at uni, on paper, ~6 years ago

Its a bit hard to see, but the 'black box' looks VERY much like a 0.01 uF capacitor in series with the mains transformer.
It looks like there are 3 speeds with separate adjustments for each speed; presumably 78, 45, 33 rpm.
The two capacitors at the bottom left are said to be AC types, and for me this is a bit of a puzzle but not a problem.
Would be nice to know what brand the TT is. It looks like a nice unit.
Jim B is right though; the problem to get it going on a 230 volt supply is mickey mouse.

What would that capacitor be doing? I assumed it first it was a cap but it seemed odd for it to be across the inputs/switch.

It's a 2 speed table with adjustable speeds for each (hopefully enough to account for the ~10hz difference)

The motor is an AC servo so it makes sense that everything is AC.

It's a Taya DP-500 aka Marlux MX-86 aka Akai something something. It's touted as a rebrand online, but the Marlux claims 17watts while the sticker on mine (from memory) was 12 watts, might be wrong there.

https://goo.gl/8pLzR8

 

[KeepItSimpleStupid]

Th cap is marked 103 M and across the switch. Not uncommon at all. You would have to replace this with a safety cap (XorY) forget which. It's would be a 10 000 pf capacitor or 0.1 uf, but you would need 250 VAC. The cap is used to protect the switch contacts. The "voltage across a capacitor cannot change instantaneously".

This guy https://www.allelectronics.com/make-a-store/item/tc-100/100w-up/down-transformer/1.html is too big. I piked up a nice 120/240 xformer with a switch from a surplus outfit which I plan to use for a project

Then you have these toroidal ones. https://www.mouser.com/ProductDetail/Triad-Magnetics/VPT230-110

You can get switches and/or power entry modules which have the 120/240 switches in them. Torroidal transformers are expected to have the primaries in series or parallel. Other types of transformers are wired in the 0-120-240 tap kind of positions.

Notes of caution:
1) It might be wise to measure the secondaries for future use.
2) Transformer windings can be paralleled if IDENTICAL. If they are placed in series, they can ADD or SUBRACT.

Suppose you had two 120:120 V identical transformers and you wanted to make a 120/240 xformer at 2x the current. You would initially connect the primaries to a source <= 120 V and measure the outputs to confirm they are working. Mark the primary side connected to hot. Now connect the secondaries in series. measure the series connected voltage. Re-arrange, if needed, so the voltage adds. Assume a polarity, the black probe of your meter then mark as (-)wwww(+)(-)WWWW(+)
wwwww and WWWW stand for windings. the () are the polarities that you discovered. One side needs to be annotated. So, mark the hot in, and the two (+) for the phase markings.

Usually toroidal transformers come with the mounting hardware which is usually a large rubber washer and a large round washer.

So, if the secondaries are equal and they are placed in series, you will get either 2x their rating or nearly zero. Connecting two identical windings in parallel not phased properly, you might get smoke.

Here is an example of a series/parallel switch. https://www.mouser.com/ProductDetail/Schurter/00334503

I have a piece of audio equipment which there are two versions. From the front they are identical. The later model contains the 120/240 selector switch. Internally, they are vastly different.

 

[KeepItSimpleStupid]

The motor is an AC servo so it makes sense that everything is AC.

This is an invalid assumption anymore. Turntables were once synchronous motors and later they incorporated speed control. You adjusted the local oscillator for the motor and the motor could well have been a brushless DC motor. later they were only 45/33 and you had multiple strobe bands around the platter. The strobe being the line frequency and multiple bands to accommodate 50 and 60 Hz references.

Later, I believe, they removed the adjustability. Very early turntables had 16 3/4 (I think), 33 1/3, 45 and 78 RPM. Speed was done by steps on a shaft. These could not be operated on another frequency,

FWIW, 50 Hz stuff has a better chance of operating at 60 Hz. 50 Hz requires "more iron" than a 60 Hz transformer. You will commonly see 50/60 Hz on some transformers.

 

[drspangle]

Th cap is marked 103 M and across the switch. Not uncommon at all. You would have to replace this with a safety cap (XorY) forget which. It's would be a 10 000 pf capacitor or 0.1 uf, but you would need 250 VAC. The cap is used to protect the switch contacts. The "voltage across a capacitor cannot change instantaneously".

This guy https://www.allelectronics.com/make-a-store/item/tc-100/100w-up/down-transformer/1.html is too big. I piked up a nice 120/240 xformer with a switch from a surplus outfit which I plan to use for a project

Then you have these toroidal ones. https://www.mouser.com/ProductDetail/Triad-Magnetics/VPT230-110

You can get switches and/or power entry modules which have the 120/240 switches in them. Torroidal transformers are expected to have the primaries in series or parallel. Other types of transformers are wired in the 0-120-240 tap kind of positions.

Notes of caution:
1) It might be wise to measure the secondaries for future use.
2) Transformer windings can be paralleled if IDENTICAL. If they are placed in series, they can ADD or SUBRACT.

Suppose you had two 120:120 V identical transformers and you wanted to make a 120/240 xformer at 2x the current. You would initially connect the primaries to a source <= 120 V and measure the outputs to confirm they are working. Mark the primary side connected to hot. Now connect the secondaries in series. measure the series connected voltage. Re-arrange, if needed, so the voltage adds. Assume a polarity, the black probe of your meter then mark as (-)wwww(+)(-)WWWW(+)
wwwww and WWWW stand for windings. the () are the polarities that you discovered. One side needs to be annotated. So, mark the hot in, and the two (+) for the phase markings.

Usually toroidal transformers come with the mounting hardware which is usually a large rubber washer and a large round washer.

So, if the secondaries are equal and they are placed in series, you will get either 2x their rating or nearly zero. Connecting two identical windings in parallel not phased properly, you might get smoke.

Here is an example of a series/parallel switch. https://www.mouser.com/ProductDetail/Schurter/00334503

I have a piece of audio equipment which there are two versions. From the front they are identical. The later model contains the 120/240 selector switch. Internally, they are vastly different.

Thanks for the info on the switch protection, and the rest. I'm likely to go with an external transformer and just push 120v into it as it's expecting. Rather than set myself on fire - I don't like AC (which is why I dropped my EE papers and did Computer Engineering instead ). I don't want to bring any unknown equipment near the sensitive pickups anyway...

I've never heard of transformers being used in series, thanks for the info!

This is an invalid assumption anymore. Turntables were once synchronous motors and later they incorporated speed control. You adjusted the local oscillator for the motor and the motor could well have been a brushless DC motor. later they were only 45/33 and you had multiple strobe bands around the platter. The strobe being the line frequency and multiple bands to accommodate 50 and 60 Hz references.

Later, I believe, they removed the adjustability. Very early turntables had 16 3/4 (I think), 33 1/3, 45 and 78 RPM. Speed was done by steps on a shaft. These could not be operated on another frequency,

FWIW, 50 Hz stuff has a better chance of operating at 60 Hz. 50 Hz requires "more iron" than a 60 Hz transformer. You will commonly see 50/60 Hz on some transformers.

I don't know how else to check, the motor has no markings and I don't have a multimeter in Canada (was supposed to be keeping it simple, yet here I am ).

The table is from ~1977, 45/33rpm and indeed has multiple strobe bands for 50 and 60hz as reference.

 

[Nigel Goodwin]

I don't know how else to check, the motor has no markings and I don't have a multimeter in Canada (was supposed to be keeping it simple, yet here I am

There's nothing to check, it's a DC motor so mains frequency doesn't make any difference (apart from the strobe lines - which is why you have 50 and 60Hz ones).

The 50Hz 'requiring more iron' is also basically a myth, and certainly wouldn't apply to a small motor (if it was AC, but it isn't anyway) nor a small transformer.

 

[drspangle]

There's nothing to check, it's a DC motor so mains frequency doesn't make any difference (apart from the strobe lines - which is why you have 50 and 60Hz ones).

The 50Hz 'requiring more iron' is also basically a myth, and certainly wouldn't apply to a small motor (if it was AC, but it isn't anyway) nor a small transformer.

That's good news then. Excuse my ignorance here, but how are you certain it's DC? I guess the diodes are a clue...

/Edit

And it's just dawned on me how the strobe light works and how it relates to the markings, I feel a bit dim

 

[Nigel Goodwin]

That's good news then. Excuse my ignorance here, but how are you certain it's DC? I guess the diodes are a clue...

The design and shape of the motor, plus the fact there's electronics in there, plus that there are speed adjustments, and not to mention that the motor isn't connected to the mains - AC motors in TT's are connected directly across the mains, and no electronics is involved - speed change is done by stepped (or tapered) pulleys.

 

[drspangle]

The design and shape of the motor, plus the fact there's electronics in there, plus that there are speed adjustments, and not to mention that the motor isn't connected to the mains - AC motors in TT's are connected directly across the mains, and no electronics is involved - speed change is done by stepped (or tapered) pulleys.

Fair enough - that's really the best news I've heard about all this. Thanks for your thoughts!

 

[Nigel Goodwin]

Fair enough - that's really the best news I've heard about all this. Thanks for your thoughts!

I've repaired hundreds of turntables other the years, although not for a long time now of course as vinyl is long since dead - although there is currently a minor resurgence, presumably for nostalgia?

 

[drspangle]

I've repaired hundreds of turntables other the years, although not for a long time now of course as vinyl is long since dead - although there is currently a minor resurgence, presumably for nostalgia?

Not as dead as you think!