Tandberg 1641X small problem

[barretter]

I've just bought a Tandberg 1641X and am happy with it but it has a small problem (apart from the pong caused by an overheating Rifa RC network across the mains input, which was swiftly replaced) in that it doesn't seem able to fast forward a 7 inch tape. With 5 inch tapes fast forward and reverse work OK and reverse works with 7 inch tapes, though it does tend to slow down and stop when near the end of the rewind ; but it can't fast forward a 7inch tape at all. Do experienced Tandberg users think this would be cured by a new belt?

[ben]

In a word: yes. You won't believe the speed these things can wind at, with a belt in good nick.

[ricard]

Yes, the belts tend to deteriorate, and can slip and very commonly break (leading to no motion of the reel holders at all).

However, my experience with this generation of Tandbergs is that the felt clutches that couple the rotary motion from the pulleys driven by the motor to the actual reel table tend to slip with age.

My first course of action used to be to clean the clutches with isopropanol or similar to get any oil or grease off that may have migrated from the rest of the machine, but that often made the problem worse.

I've turned to smearing the felt pads with so-called 'damping grease', which is basically the type of compound you'd use in an optical lens to make the movement smooth. Looks like white lithium grease, but in fact increases friction between the surfaces, due to its very high viscosity. Problem is it's rather hard to get hold of in small quantities, I managed to get hold of a sample set from Nye Lubricants a couple of years ago which I still use.

I'm at a loss to explain why this is needed. I've talked with service folks who serviced these machines back when they were new (some are present in the forum) and they've never heard anything of any compound being applied in the clutch area. My not very scientific theory is that soap used in the felting process leaves the surface of the felt slightly sticky, so that it's fine when new, and that the soap over the years migrates out of the felt and evaporates, leaving the felt dry, with reduced friction; indeed, when I've attempted to clean the clutches, there's usually been a slightly greasy film, which is why I used to assume that the surfaces were contaminated and needed cleaning. Perhaps also the soap degenerates with time, otherwise the thin film found should be enough to keep the friction up.

[barretter]

Thanks Ben and Ricard. I think I'll try the belt solution first, as it's easier!

[ricard]

Yes, that's definitely the first step.

I should add that these days I never attempt to clean the clutches, as I now know from experience that it never increases the friction, only decreases it. If there's too much friction on one table compared to the other I may try to wipe the mylar surface of the clutch with the higher frction clean with a dry rag, to attempt to balance them friction-wise, but that's all.

[barretter]

It was the belt : the 16041X now rewinds like a bat out of hell and fast forward is...fast!. Now I'm bugged by the whooshing noise generated by the idler/flywheel interface. Never happy!