Early Sony Betamax help request

[TUD1]

I've got not one, but two early Beta machines that share the same exact issue. Jittery unstable picture with very poor tracking. I'm suspicious of capacitors on the capstan servo board, but just want to ask around before I attempt repairing that issue.

See video... https://www.facebook.com/share/p/s66...ibextid=oFDknk

[ARC Tech-109]

What model are you working with?

[TUD1]

SL-5400 and SL-5600.

[Ed in Tx]

Before you go too far with those, check the capstan motor first and see if it spins freely. Replaced many capstan motors that were nearly seized, back in the day.

[ARC Tech-109]

I second the capstan motors and do check the supply reel tension brake to see if the felt lining has come off, without this there will be no tape tension regulation.

[TUD1]

I evaluated the supply tension by playing a tape and moving the tension arm fore and aft and the picture did not improve. Based on careful observation, I found that the drum speed is varying slightly in a regular pattern and a change in picture quality can be observed that correlates to the speed change. I procured a Capacitor Wizard from a friend, I'm going to start checking the ESR of the small electrolytics on the main servo board.

[Tube TV]

When you dig into it with an ESR meter also retest the cap for dead shorts with a multimeter. Twice in the last 6 months I have found ones to look great on an ESR because they were dead shorted. I like to use an old analog meter for this.

Check any electrolytic that is close to a heat sink these get the worse cooking and have a high failure rate. Go over the power supply area thoroughly.

Dose the Servo motor have a Bronze bushing or is it a small ball bearing race? A bronze bushing is usually easy to relube. Just pop off the C clip and lube with lithium grease, or any other light grease will work.

[redk9258]

That's great advise about following the ESR meter with a regular meter. Not all caps fail with high ESR. But if it's high ESR in circuit, it's bad!