Rubber belts (late 70s-early 80s) turning into goo

[japlytic]

On a number of Japanese-origin audio equipment from the late-70s to the early-80s (possibly later), the rubber belts (including drive belts) turn into sticky goo after several years.
Did the manufacturer(s) of the belts stuff up with the rubber mixture and/or processing?

[Scenic]

Re: Rubber belts (late 70s-early 80s) turning into goo

Don't know what causes it, but it certainly isn't just japanese audio stuff. Grundig and Philips also had lots of problems with this.

The belts turn into a sticky goo, and if left long enough will harden up to the point where the remains are rock solid (it basically behaves like very viscous glue). If you try to scrape it off it'll basically turn into really stinky dust.
Getting that crap off of pulleys etc. is a nightmare
Even worse if it dripped down onto PCBs when it was in its gooey state..

[ben7]

Re: Rubber belts (late 70s-early 80s) turning into goo

Perhaps it has to do with the rubber the belts are made of, and the oil that is used to lube gears etc..? I too have seen (and touched...what a mess!) this happen.

-Ben

[999999999]

Re: Rubber belts (late 70s-early 80s) turning into goo

It's a trade-off. They could vulcanize them with for high flexibility and eventually have them break down into oil faster, or for heat resistance then they'd crack sooner.

Consider this stuff is now 30+ years old, what rubber products that flex a lot do you own that have held up for 30 years? Even today, when I open a remote control with a silicone rubber keypad, I expect to find oil between it and the PCB unless it was bagged and kept away from air, moisture, light, and high temperatures.

[momaka]

Re: Rubber belts (late 70s-early 80s) turning into goo

I've seen this happen with regular rubber bands too - some just turn into a goo and then dry out and become like glue. Very hard to clean those indeed. Others just become dry, loose elasticity, and eventually crack/tear.

[Hondaman]

Re: Rubber belts (late 70s-early 80s) turning into goo

I believe it's the nature of the beast -- that's just the way it is.

I thought I read on slashdot some years ago about a computer rehab. Someone was trying to restore a 1965 mainframe made by the French firm Groupe Bull (Bull Computer).

The rubber parts in the Bull's tape drive turned to goo. I don't know if they ever found suitable replacements. If they did, they were "one-off" custom-manufactured items.

[b700029]

Re: Rubber belts (late 70s-early 80s) turning into goo

Most equipment from that era drove the rubber belts via brushed permanent-magnet motors.

Brushed motors arc, even when not worn out.

Arcs create ozone.

Ozone attacks rubber.

[cadiman]

Re: Rubber belts (late 70s-early 80s) turning into goo

All belts do that.

The tape deck belts for the delco radios would last about 5 to 7 years then turn into goo. It seemed to be worse in the car radios because of the heat from the summer and the duct work for the heater and defroster.

[Hondaman]

Re: Rubber belts (late 70s-early 80s) turning into goo

Old VCRs and CD players have problems with belts too.

There are a couple of places on the web where you might get replacement parts. Maybe.

(I'd love to get belts for my old 1987 Fisher CD player -- it could handle index numbers that old classical discs have!)

[999999999]

Re: Rubber belts (late 70s-early 80s) turning into goo

There are some old school electronics repair shops that have over time, accumulated a lot of belts and contacts to acquire them, as well as large and small electronics vendors though you'd have to measure the old one for a generic replacement part. For example,
http://www.kenselectronics.com/lists/belts.htm

http://electronics.mcmelectronics.co...=belts&x=0&y=0

[japlytic]

Re: Rubber belts (late 70s-early 80s) turning into goo

Arcs create ozone.

Ozone attacks rubber.

I saw the anode cap on an old TV partially turn into goo, so this explanation seems to be correct.

[ratdude747]

Re: Rubber belts (late 70s-early 80s) turning into goo

Old VCRs and CD players have problems with belts too.

There are a couple of places on the web where you might get replacement parts. Maybe.

(I'd love to get belts for my old 1987 Fisher CD player -- it could handle index numbers that old classical discs have!)

Same for my old hitachi-made RCA S-VHS player... the drive belt is wasted... and only one place has a replacement online...

[japlytic]

Re: Rubber belts (late 70s-early 80s) turning into goo

I forgot to say, in cassette recorders (and certain other equipment, especially without fans) which have rubber belts, the ozone cannot readily escape and then attacks the rubber belts over time.

[ben7]

Re: Rubber belts (late 70s-early 80s) turning into goo

I forgot to say, in cassette recorders (and certain other equipment, especially without fans) which have rubber belts, the ozone cannot readily escape and then attacks the rubber belts over time.

In cassette players/recorders if there are any DC brushed motors, there will be some ozone made by the motor's brushes arcing. How much ozone is made depends on how long the motor has been running, and how much air exchange there is from the air inside the unit to the air outside the unit.

[xsony30]

Re: Rubber belts (late 70s-early 80s) turning into goo

Acetone is a good solvent to remove the goo, but be careful around plastic surfaces. Also don't get any goo on your clothes, it is very difficult to remove.

[999999999]

Re: Rubber belts (late 70s-early 80s) turning into goo

^ Sometimes the goo will clean with strong detergent solution and other times any petroleum solvent like lestoil, goo-gone, gasoline, kerosene is less likely to damage nearby plastics.