SONY SL-C30 Betamax - looping on eject

[ben]

Trying to rid this old workhorse of an annying fault. About one in ten times when eject is pressed, it will unlace and not wind the tape back into the cassette. I have observed it with cover off, and occasionally it will look as if it is going to loop, then the supply spool gets its act together and takes up the slack just in time.

I have inspected the tape thread circuit around IC601 /SS16 PCB. Resoldered several dodgy looking joints, plus R420 (3R3) and Q334, as suggested by a Beta site. No change. Not sure if the fault is electronic or mechanical at this stage. Worth considering lowering the value of R420? I have a service manual that looks like an old Mauritron copy but no full schematic.

Hoping someone has had this one before,

[dj_fivos_sak]

Check if the reel motor gets the correct voltage when unthreading. Also check the idler/pendulum assembly.

[8 Tracker]

These intermittant faults can be a right pain. Most of the time you're looking for a fault that isn't there. Here's the threading circuit operation and timing chart from the technical manual.

Is FF/Rew sluggish in any way? This may indicate poor reel motor operation. See the circuit and description below.

Nice machines, usually reliable, but a pain when they're not! Good luck.

Mark.

[John123]

Backtension/ brakes, maybe? Often there are felt pads that press against the spools to stop this from happening. Maybe they've worn out, perhaps?

[dj_fivos_sak]

To gain access to the tension band you need to take the reel chassis apart from the bottom of the machine.

[Sanbeta]

Hi
I had one sent to me with this issue.
It turned out to be the extended plastic end of the idler assembly needing to be snipped off. It seems to afflict the C30 and if you look at other designs of the same not all have this extra piece.
It fouls the spring only on ejection.
Hopefully it's the same with yours as it IS an easy fix

.....Kevin

[Studio263]

It's the idler gear. They distort and bend upwards with age, meaning that the bracket catches on the bottom of the cassette lift. Take it out any you'll see.

My fix is to gently apply the iron whilst pulling the bracket straight, once the plastic sets it will be as good as new if you do it right. I've never had to replace one.

[ben]

Great tips, many thanks. The idler assembly looks pretty well hidden, is this going to mean taking the deck and stripping it down?

[dj_fivos_sak]

https://www.youtube.com/watch?v=AfAcN6jG6tY

Here's a video showing how to sort these problems.

[ben]

I have just been working on this unit. Thanks for the suggestions. The bracket was a bit warped, so as suggested I gently heated it and straightened it as best I could. Following the advice in the video I removed and relubricated the idler assembly shaft, and the idler pulley itself, plus the spool tables. They were all very dry.

Have reassembled and tested and so far so good. I'm unwilling to count my chickens before they've hatched with these intermittent faults, so will keep testing it before final reassembly.

Bad patterning on the RF output solved by replacing c319 (22uF) in PSU

[Sanbeta]

Originally Posted by ben

Bad patterning on the RF output solved by replacing c319 (22uF) in PSU

That's another common issue with these too.For some reason mainly on the c30.
Did yours seem to have an extra lip on the end of the idler that goes near that spring.It's like a step.It serves no purpose either.

kev

[Sanbeta]

Actually ,thinking about it ,it was probably to stop the idler assembly angling upwards slightly with age.
Troube is the end then fouled that spring so cause the same issue

.................Kev

[ben]

Yes, it had that little stub. I left it there for now but if it acts up again I will get rid.

[Sanbeta]

Originally Posted by dj_fivos_sak

Here's a video showing how to sort these problems.

Good video but he's made a couple of mistakes.
You should make sure the two thin washers go back on the capstan shaft as they will be loose inside if not.
Also you don't remove the back tension band with the screw end. You squeeze together the two clips on the other end and release from there. Otherwise you have to use a gauge to set the back tension.
Advice and help is good but some fail to address some important areas, especially if you are a novice.

.....Kev