ITT RC500/A Automatic Radio Cassette Checkout

[DMcMahon]

Early 1970's mono radio (3 wavebands) cassette player/recorder.

Was sold as "untested due to no mains lead", I did ask if tested on batteries but got no reply. Was not sure but thought the mains connector on the unit most likely was a standard figure of 8. Could see on the schematic that it was switched type to isolate the batteries (when batteries fitted and mains lead plugged in).

Label on unit shows it was made in Taiwan.

Externally looks dirty, has white paint splatter marks and some scuff marks to the silver coloured areas, some of which should clean up.

Will concentrate trying to get the tape cassette side working, if that works then will have a look at the radio section (would start a new thread for that in the radio section).

Plugged in a figure of 8 mains cable and initially everything appeared dead, no tape movement and capstan not rotating. With volume at max and Play selected there is some low volume hiss, the tone control has some effect on the hiss frequency. So there is a little bit of life.

With radio selected there is no sound at all on all 3 wavebands. Occasionally when the waveband switch is switched there is a little bit of crackling. With difficulty removed the battery compartment lid, it was full with 5 batteries, all of which were badly corroded. Have done an initial clean up of the battery compartment.

Removed the rear cover, much dirty fluff and dust inside cleaned away. No sign of the drive belt from the motor pulley to the flywheel, there is some gooey remnants of the belt around the flywheel. The motor does not rotate at all when play or fast wind/rewind selected and when manually rotated the motor is very stiff.

Tried measuring the motor supply at the motor but got nothing. There are a bunch of wires around the motor, need to study the schematic more to identify the correct connections. So not looking very encouraging so far.

David

[paulsherwin]

As always, the switch contacts should be your first port of call. It's probably spent the last 30 years in a garage or shed.

Taiwanese ITT products of that era are usually good performers.

[Nickthedentist]

Possibly longer, Paul. Those batteries are about 40 years old!

[DMcMahon]

Yes I thought they looked ancient.

David

[DMcMahon]

After figuring out the motor drive output circuitry connections confirmed that there is no voltage to the motor.

A bit confusing at first because the components do not fully match the schematic.

1. Schematic shows 2 capacitor (1nF) leadthrough assemblies C502 & C503, these do not exist, but in their place are 2 resistive terminal post feedthroughs on a mounting bracket.
2. Schematic shows 3 chokes, L501, L502 & L503 but there is only 1 choke.
3. Schematic shows 10uF capacitor C505 across the motor, this does not exist.

Have removed the motor to externally test by PSU and try and free up the very stiff rotation.

David

[Restoration73]

I did one of these last year. Main problem was removing the belt goo from flywheel.

They look like ordinary feedthru's - what is the resistance ?

Mine works really well. The most difficult job was manufacturing the missing bottom cover

[DMcMahon]

Yes they are ordinary feedthru's, when I said "resistive" I meant not capacitive, ignoring the meter lead resistance they measure a small fraction of an Ohm.

Could not find a PSU to test the motor so tested it with a 9 volt PP9 battery and it spins up lovely, after a drop of oil to the motor shaft below the motor pulley, it also now is very easy to manually rotate the motor shaft, so the motor looks good.

Measured the main DC supply at the power supply board main 1,000uF capacitors C601/C602 at nearly 10V but still 0V at the output of the motor drive board.

While doing the above switched the radio switch to on and was surprised to hear a good signal when I touched the FM aerial connection pin on the main board (FM aerial has to be disconnected to get the rear cover off).

Will enlarge on the radio progress in this Radio Thread:-

https://www.vintage-radio.net/forum/...d.php?t=197396

David

[ben]

Follow the voltage via the motor leaf switch, I'd bet money on it being dirty.

[DMcMahon]

The switch checks out OK.

Getting a solid supply voltage arriving at the motor drive board, trying to fault find the tiny board, measuring voltages/checking components etc, physically not easy.

David