Classic Hifi Care

This little Columbia briefcase AC/DC power record player has
a DC motor.

1.From my searches, the motor should not require lubrication
or cleaning.

Is that correct ?

2. The rotor when spun by hand spins, but
not freely like an AC motor.

Is that normal for DC motors ?

Thanks.

The D/C motors I'm familiar with all have brushes which would add friction to the armature and not allow freewheeling like in a A/C record player motor. Having said that, the D/C motors I'm familiar with are all industrial big boys.

Bill

DC motors act like there is a "catch" in them as they rotate. Like Bill said, there are brushes that drag on the armature which has slots cut in it. That motor looks like it is staked together, so probably would be difficult to come apart then go back together again. They make brushless DC motors, but I've never messed with one or had one apart. Good luck.

Did you put the two black marks on the motor housing? Looks like somebody may have had it apart previously, or was getting ready to take it apart, and marked it so they could get it back right. There is a stake mark under the blue dot. Is that a guide, or is it a real staking point?

electra225 wrote: ↑Wed Apr 05, 2023 9:06 pm DC motors act like there is a "catch" in them as they rotate. Like Bill said, there are brushes that drag on the armature which has slots cut in it. That motor looks like it is staked together, so probably would be difficult to come apart then go back together again. They make brushless DC motors, but I've never messed with one or had one apart. Good luck.

Did you put the two black marks on the motor housing? Looks like somebody may have had it apart previously, or was getting ready to take it apart, and marked it so they could get it back right. There is a stake mark under the blue dot. Is that a guide, or is it a real staking point?

The reference marks are my own, before I started reading up on
DC phono motors.

That is a formed indention in the motor housing.

What is a stake point ?

The motor is pulling at the correct speed, and I have a new idler ordered.

The old idler won't pull through cycle completely, but speed is right on when
I assist the platter on through.

I think the motor is fine.
I had no experience, and now I know a lot more.

See that dent under the blue dot? That is what I call a stake point. They used a "stake" to hold two parts together, usually just long enough to bolt or otherwise secure the joint. They also used a stake to "clock" or orient the pieces so they could be put back together correctly. A common use of a stake was in carburetors. The metering rods in a Quadrajet carburetor were held in by the gasket, essentially. In order to retain the metering rods assembly then get the top back on the carburetor, I'd stake, or dent, the edge of the carburetor body just enough to hold the metering rods down so I could put the top on and not bend the metering rods. My guess is that motor was never intended to still be in use 50 years after it was produced. Probably not designed to be taken apart and serviced. It works until it breaks, kind of thing. It will probably run another 50 years, considering the light use it will likely see. Good luck.....

Don't some DC motors also present turning resistance from internal magnets? I recall rotating some by hand that cog along.

Chris Campbell

It certainly looks different from any other DC I have seen ... Is the motor really that tall, or is that a cover ? if it is that tall ,it must have a heavy duty armature setup... take that away and the fact it has the stepped pulley, and it looks like any crosley DC motor... does it state the RPM's it runs at ? most are in the 3-3600 range. you will have resistance in spinning a DC motor from the magnets ...

Well, new idler installed, and it appears this
DC motor is a bit tired.

It won't pull the changer through cycle still.

And the motor is inducing quite a bit of noise
into the amplifier.

Plan B ( because I'm stubborn at times), is to see
if I can fit a spare BSR AC motor and switch onto
the changer base.

I'll have to do a bit of re-wiring to the transformer that
drops 120 VAC to 12 volts DC for the amp & old DC motor.

I'm also going to remove the internal battery case, and cover
the hole underneath with some leftover fiber board from
and old record player.

As Greg says, sometimes these little gals can take
as much time as larger units.

It's a cute little briefcase that Don Draper
might like.

I firmly believe the little ones are MORE work than the bigger ones. It is amazing how many details they can build into a small unit. If they look simple, watch out!

The parts for little ones cost as much or more than for the bigger ones, too.

Somebody may have gotten that Masterwork record player as a freebie with their Columbia Record Club subscription....

Greg,
I'm going to post a tangent topic over in chat
about record clubs.

It certainly looks like the mounts for a AC motor are there , covered up by the DC motor plate

hermitcrab wrote: ↑Sat Apr 08, 2023 2:17 pm It certainly looks like the mounts for a AC motor are there , covered up by the DC motor plate

Yes, the other BSR has the same motor plate.

The replacement motor has different size speed turrets on
the rotor, and I think the platter turntable diameter
is smaller than other BSRs.

Then there is the RPM motor speed possible difference.

If some of those variables are true, the motor change may not work.

But, it's easy enough to put in the motor and try.

I put in the BSR AC motor and it fits and works well.

As I suspected, the speed selector choices now are
altered.

BUT, the good news is that 16 RPM = 33 1/3 RPM,
and 33 1/3 RPM = 45 RPM with the new set-up.

I will leave the AC re-wiring project for later, after I
finish with the Zenith HFY 17E console.

As my friend like to kid me..."It's ALMOST fixed !" Ha ha !

Getting some things ready for a large radio club
auction south of me, I remembered this project wasn't completed.

I permanently wired in the replacement BSR AC motor.
I had to adjust the idler wheel height for the speeds
to match the new motor's spindle configuration.

I had already cleaned the changer mech.

I removed the battery holder, which was broken and
its contacts/wiring all oxidized to rust.

I glued in the loose wood blocks that the motor board and
changer attach to in the "brief-case".

It has a new flip over dual tip stylus and sounds OK for
the little SS amp and 3 x 5 inch speaker.

The original 1968 owner's manual is there
with the 45 RPM adapter, too.

Good job salvaging a nice small device and making it available to somebody to discover analog....

Chris Campbell