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Realistic Lab 400 Speed Issue

PooreBoy

PooreBoy

Active Member
I recently purchased a Realistic Lab 400 that has a strange speed control issue. The platter only spins at one speed that is close to 78rpm. (definitely faster than 45rpm) The speed selector has no effect...neither do the speed adjustment pots.
The micro switch that’s supposed to change the speed seems to be working...it clicks whenever 33 or 45rpm is selected.
I’ve never encountered a problem like this before so I’m stumped. Could the micro switch go bad and cause this behavior? I appreciate any and all suggestions.
Thanks in advance.
 
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Could be a bad switch, I assumed you clean the trim pots inside. If so, it could be the switch itself. Might be something else along the circuitry as well.
 
Yes, all of the pots were cleaned with deoxit. When they're turned the speed isn't affected in the slightest.
I wonder if there is a speed control board mounted to the motor that could be bad?
 
PooreBoy said:
I wonder if there is a speed control board mounted to the motor that could be bad?
Click to expand...
All of the speed control electronics are in the motor, other than the external speed adjust pots and the power supply ...

vGQEQsy.png
 
The Slider said:
All of the speed control electronics are in the motor, other than the external speed adjust pots and the power supply ...

vGQEQsy.png
Click to expand...
That’s what I was thinking as well. So if it’s not the micro switch, then I guess the motor will need to be replaced as that board doesn’t appear to be serviceable.
Thanks for the replies.
 
The Slider said:
Well, at least parts are cheap and plentiful, though ya never know if the replacements are problem free until buying and doing the work to take it apart and put it back together :)

https://www.ebay.com/itm/REALISTIC-...871433?hash=item4da95c2a49:g:P2oAAOSwZ91edjxs
Click to expand...
I’ve actually been tempted to buy this pack o parts...but I also found a micro switch on the organ donor website for $15.
The cosmetics of the table are excellent. There’s no chipping, peeling, or scratches on the plinth. Even the original mat is in excellent shape. The dustcover would have been as well if it had been packed properly. They left it attached to the table when packing. This resulted in a huge crack along one of the back corners with a small piece broken off.
After I told the seller about the top he admitted that he has had some bad luck with dustcovers arriving damaged. :rolleyes:
I was going to simply send it back but instead opted for a partial refund thinking it would be a simple fix...which still maybe the case. I’m really hoping a parts table will pop up.
Thanks again for the suggestions.
 
Just thought I'd give you an update on this issue. It turns out that it was indeed the motor. I picked one up of off the bay, and dropped it in...problem solved. It now runs at both 33 and 45rpm as expected. There is a little speed drift but nothing a few more sprays of deoxit won't cure. ;)
 
PooreBoy said:
Just thought I'd give you an update on this issue. It turns out that it was indeed the motor. I picked one up of off the bay, and dropped it in...problem solved. It now runs at both 33 and 45rpm as expected. There is a little speed drift but nothing a few more sprays of deoxit won't cure. ;)
Click to expand...
Good to hear. I bought one awhile back for my son. The platter was wobbly and I just bought a motor on ebay from a parts unit. But while waiting I popped the old motor out, should have done that first, and found the screws on the bottom of the motor were loose. So he now has an extra motor if needed. I can't remember, but isn't the board inside the motor removable by unsoldering it?
 
Lavane said:
Good to hear. I bought one awhile back for my son. The platter was wobbly and I just bought a motor on ebay from a parts unit. But while waiting I popped the old motor out, should have done that first, and found the screws on the bottom of the motor were loose. So he now has an extra motor if needed. I can't remember, but isn't the board inside the motor removable by unsoldering it?
Click to expand...
Yes, it is removable in this way. I did so myself when I recapped that board.
 
Lavane said:
It's just 4 or more 90° connecting pins isn't it?
Click to expand...
Yeah. I don't remember the exact number. It's more like 8 or so. Almost everything on that board is pretty commonly available. The only part that would give you a hard time is the IC chip that has all the speed control circuitry on it. I'm guessing it's a custom made chip that would be nearly impossible to find on its own at this point in time, so getting an entire replacement motor (as the OP did) is the way to go if that chip is faulty.
 
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