Sony SL-3000 schematic
 

Hello,

I have a Sony SL-3000 betamax i want to repair.When i plug in the power supply and without any key pressed the drum starts rotating very fast and it doesn't tajke a cassette.

It was working fine before i put it on storage in 2008.
the heads are almost new( changed in 1988 and almost unused since then). My father is the frst owner.

¿Anyone have the service manualor the schematic?

Google sam's photofact, go to their site, search the model and make of your beta deck on their site. It will give you a folder number (Probably VCR#). If there is a large library (like one in a major city or state capital) near you they may have it and let you photo copy it cheaper than what Sam's website will charge you for a print out.

Thanks, i got the service manual online.

Now the fun begins.

i suppose i should start troubleshooting the servo circuit.

Also i remembered an annoying issue it had before i put it on storage. it did not stay in play mode unless i keep the play button pressed with my finger.
otherwise it was working fine it tracked very well, recorded fine and ff and rwd worked before i put it on storage.

Any ideas where to start?

Check the power supply voltages, any of the circuit protectors "CP"s on the boards and that the microprocessor reset is working when first plugged in. Since it spins the drum, may not be doing a full initial reset, where it will spin the drum briefly and check mechanism state when plugged in, before it goes to standby ready to go.

If there is a surface mount electrolytic capacitor on the capstan motor board, then you should probably replace it.

The capstan on the SL-3000 is driven by a small DC motor, coupled to the capstan with a belt, much like an old 8-track.

I was thinking of a different Sony anyway, along the lines of a SL-2300 slimline front-loader. I see now this is a portable. In the words of Emily Litella... "never mind".

Great news.
After cleaning the power supply ( ac-300c) it powers up and try to load the tape.
Now i have a belt problem.

The power supply was plenty of dust inside,and very wet.
i cleaned and dried it, also i cleanesd all the connectors.
Don't know if it is normal, but without the SL-3000 connected it delivers 15.4volts, and it should be 12volts

May be the 15.4V is battery charging voltage when it's off, 12V regulated when On. Your manual should explain.

i put a little rubber rejuvenator on the belts and now it loads the casste an ffwd and rew work ok.
when i put ffd or ew drum turns as it should

play doesnt work, when i press play nothing happens. play stays for less than a second and then it goes to stop mode. nothing moves. if i maintain the play button pressed nothing happens.

i think this is related to the issue it has when i put in on storage, but back then if i keeped my finger in the play button it played fine.

there is a pot to adjust voltage on the ac-300c i will check that

Check the capstan belt and motor. If that is bad it won't advance the tape in play mode which will cause it to sense a problem and shut down.

the capstan belt is stretched

I ordered a belt kit, but idon't want to wait so i will try to get the capstan belt locally.

A redneck solution is a normal rubber band. If too big slice a section out of it and super glue the ends together, if too long get another to extend it.

I have a Toshiba HiFi unit that uses a belt exactly the size of a dime store rubber band....The store bought rubber bands do rot in a few months, but it is so easy to swap it (two screws to open it's bottom access hatch) that I've never seen the need for a longer term fix...

I changed the belt and still the capstan doens't move.
the capstan and the motor move free and smooth when i move them by hand