Troubleshooting a 1970 Sears SS Record Player

[Hi-Fi-Mogul]

Hello all,
I received this little player and have the BSR
mini-changer all nice and functional.

When I put it back in the plastic cabinet, no
sound at all at the speaker.
I had already checked the cartridge which is good.

The changer is receiving power, so I think I should
check the silicon rectifier voltage first.

Question: to check the voltage, I will place red
meter lead right after the rectifier, and
then the black lead at one of the negative
sides of the electrolytic caps ?

2. There is an extra coil on the motor.
Does it function to supply a discrete
voltage for B+ ?

A bit of brain fog today (due to excessive
heat/humidity for weeks here).

Thank you !

[electra225]

To measure rectifier cathode voltage, what you said was right. Place the red lead of your meter on the output of the rectifier, the black lead on the negative of the filter caps. The motor has an extra winding for the power supply, maybe a choke? I can't read the value, but I THINK it says 3 ohms. Whatever it is, you can also measure voltage at the positive of the input filter cap to see if you have voltage there. If that winding were to open, that would kill B+. You only have 14 volts, so you shouldn't get electrocuted in any case. Good luck.

I believe, if it was me, I'd jump across that extra winding on the motor, if it is open, then add a resistor the value of the winding, maybe two watts or so, between it and the rectifier to take the place of the open winding.

[Hi-Fi-Mogul]

Thanks so much for the information, Greg.

I'll set up the amp tomorrow AM, and check
per your instruction.

I appreciate knowing there's a solution if that
winding is open.

I'll report back. [ : )

[TC Chris]

Hey, the ONLY connection to power for the amp is via that winding on the motor, so I think it's a transformer winding. It's supplying 11.6 VAC. Interesting way to go (saves an extra transformer).

Chris Campbell

[hermitcrab]

or you could wire in a old 12vac wall wort to replace the bad winding if that is the problem ...

[electra225]

The coil is drawn as a choke, not a transformer.

[Hi-Fi-Mogul]

The problem turned out to be simple.

My jukebox friend asked if I had tested
the speaker. I had not.

Test result: speaker is bad.
Good sound using an 8 ohm test speaker.

Now the problem is finding a replacement
2 x 6 inch 16 ohm speaker.

What are your thoughts on adding an 8 ohm
resistor in series to an 8 ohm speaker ?

It may be easier finding a 2 x 6 eight
ohm speaker.

[hermitcrab]

I did that on a portale player from monkey wards that was missing the speakers .... they called for 16 ohms as well.... I used a pair of 8 ohm 6x9's with a convenient 2 pack of the 8 ohm sand resistors that I bought a million years ago from radio shack before they went out of biz...it works ...I hear using too small of ohm speakers will overdrive the amplifier and possibly damage it.

[TC Chris]

Now the problem is finding a replacement
2 x 6 inch 16 ohm speaker.

What are your thoughts on adding an 8 ohm
resistor in series to an 8 ohm speaker ?

It may be easier finding a 2 x 6 eight
ohm speaker.

Instead of a resistor, which just eats up power, why not put two small speakers in series? It's easy to make a mall mounting board that would hold two little ones in the space made for one larger one.

Chris Campbell

[Hi-Fi-Mogul]

I've been entertaining Chris' idea of mounting
2 small 8 ohm speakers, if I can find the right size.

There's a very finite space to use for
any type of speaker(s).

In the meantime, I think I'll series wire a couple
of loose 8 ohm speakers, to get an idea of
how this record player sounds.

The amp is quiet as a mouse, and the
mono EV cart is strong.

[electra225]

I have two of those little 3 1/2" speakers they put in the dashboard of Cadillacs back in the 1970's. They are 8 ohm and the voice coils are almost as big as the speakers. I have new Radio Shack and I may have a pair of reconed ones, still, I think. Would those help you?

[Hi-Fi-Mogul]

I have two of those little 3 1/2" speakers they put in the dashboard of Cadillacs back in the 1970's. They are 8 ohm and the voice coils are almost as big as the speakers. I have new Radio Shack and I may have a pair of reconed ones, still, I think. Would those help you?

Hi Greg,
Those would be just a bit too wide.

Here's a photo of the speaker before removal.

Thanks for all the responses !

[Hi-Fi-Mogul]

Dave1138 had two 12 ohm television speakers someone
gave him, and brought them by.

Amazingly the speaker fits exactly on the plastic
mounting posts inside the plastic cabinet.

I tested it out, and the sound is VERY good.

I'm ordering a 4.7 ohm resistor to add onto
the output transformer lead, as the original
speaker was 16 ohms.

[electra225]

You were fortunate to find a semi-correct speaker. Glad you got it sorted.....

[Hi-Fi-Mogul]

Today I received some 4.7 ohm 1/2 watt resistors
to solder onto the OP transformer lead to the new
12 ohm speaker.

Then I realized, I had no idea of the amount of power
going to the speaker.

Is there a way with this schematic to calculate the
power, so I don't put in too small a wattage resistor ?

I realize the amp is low power, but here's
and opportunity for me to learn something.

Thanks !

[TC Chris]

I don't think so, or at least I can't. But I will offer the thought that most music listening is done at very low average power. Your little record player ain't gonna be shakin' the floor, either. And your new speaker is probably more efficient than the old one. So the power output is going to usually be pretty low, unless you get annoyed by the neighbors and want to annoy them back with your flea-power device.

And then consider that whatever the voltage drop across a 16 ohm speaker is, 3/4 of that will be dropped now by the 12 ohm speaker and only 1/4 by the new resistor in series.

What's the worst that can happen--your burn up one resistor? Apparently your amp can handle a no-load condition, because the old open speaker vice coil didn't kill it.

Chris Campbell

[Hi-Fi-Mogul]

Chris,
That all makes good sense.

Especially your point about the
dead old speaker.

I'll put in the resistor, and let the player
run, and see how hot the resistor gets,
or if it fails.

[Hi-Fi-Mogul]

Added in the resistor and played the
record player for a couple of hours.

Unplugged it and moved the changer out
to feel the resistor.
Resistor was cool to the touch.

I imagine the output of this player is
maybe 0.5 to 1 watt.

New stylus from Gary at V of M on the way, then
it's all back together lookin' for a home.

[William]

Nice job, Mr. Mogul. It sure is a cute little player.

Bill

[TC Chris]

And how does it sound?

Chris Campbell