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Old 18th Aug 2012, 4:31 pm   #1
6110c37
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Default A3300 back from the dead

A very sad Teac A3300 came my way looking fit for the dump. I like Teacs so decided to have a look. It was fitted with an IEC plug and the pinch roller was from something else entirely, being a 5mm alloy disc with a thin strip of rubber glued to it. Never having owned one of this series I decided to "have a go". First thing was to check out the electronics and the rest of the mechanics which appeared to be reasonable. Other than the pinch roller the other major problem was a jammed take-off guide.
When it was apparent that it was repairable the major clean up commenced, obtaining a service manual confirmed that all was within reason but no help re. the pinch roller. All I had was the sketch from the SM and various photos from the internet. So first was to acquire the Neoprene then off to the workshop to make a new pinch roller. This was turned out of ally bar then the Neoprene was vulcanized to it, then the complete assembly was mounted in the lathe and a home made grinder was used to true up the outside of the roller so it was concentric.
Not having any Phos-bronze bearings to hand I fitted (very sorry but I did) two ball races. When mounted on the machine the result was awful, about half speed and wow would have been around 80% (luckily my meter was not connected, it only goes up to 10%).
Rather than keep dismounting the roller and re-grinding, the choice was to adjust the pinch roller tension which was adjusted (bit fiddly) until the Wow was in limits and the long term speed was steady. The bearings played havoc with the flutter figures until the pre-load on the bearings was adjusted then hey-presto it came out well within the original specs.
Last job was to re-label the front panel which though not perfect came out okay. I'm happy with the result but SWMBO wants it out of the lounge so it may well end up in the workshop.
Cheers
Martin
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Old 18th Aug 2012, 9:54 pm   #2
reelguy
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Default Re: A3300 back from the dead

Hello Martin,
Thanks for the interesting write up on your Teac A3300.
Like you I am quite fond of Teac's.
Can you tell me where you obtained the Neoprene you mentioned and was it a particular shore hardness? Was it in sheet form or block form ?
I have a couple of recorders in need of pinch wheels but it wouldn't be economical to have them professionally rebuilt. So I would like to have a go at making them the way you suggested.
Peter W.....Reelguy.
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Old 19th Aug 2012, 10:23 am   #3
6110c37
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Default Re: A3300 back from the dead

Hi Peter,

The material was neoprene tubing, so no joints. The bore is very smooth but the external face not so much. Not a problem as this needs grinding to concentricity anyway. The tubing is for use in peristaltic pumps so is tough but flexible. (Shore A is D2240 and TS is 27.6 Mpa).
This stuff is not cheap if you have to purchase it from a supplier but off cuts are sometimes available at reasonable prices.
The tubing comes in a variety of sizes and wall thicknesses. I used 25mm bore with 4.8mm wall thickness for the Teac, which is one of the bigger sizes.
A cheaper tubing would be "Santoprene" which is a beige coloured neoprene based tubing with a better life than pure noeprene.
Hope this helps
Martin
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Old 21st Aug 2012, 7:46 pm   #4
reelguy
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Default Re: A3300 back from the dead

Thanks Martin,
I have tried cutting rubber bungs as used in Labs, down to size but it didn't work very well.
The material is ok but its difficult to cut accurately.
I shall try to obtain some of the neoprene you mention.
Regards Peter W....Reelguy
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Old 22nd Aug 2012, 2:28 pm   #5
6110c37
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Default Re: A3300 back from the dead

Hi Peter,
If you get stuck I have the following sizes:
Neoprene 25mm ID x 35mm OD, 6mm ID x 8mm OD.
Santoprene 9mm ID x 13mm OD, 6mm ID x 11 OD.

Plenty of the small stuff but only 300mm of the large size.

regards
Martin
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Old 24th Aug 2012, 7:06 pm   #6
reelguy
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Default Re: A3300 back from the dead

Thanks for the offer Martin, but I think I have something possibly suitable .
I was given some plastic { ?} tubing some time ago. It is 25mm ID x 35mm same size as yours. Black, Red and also some White.
I say plastic because I'm not sure what material it is really.
I need to see if I can fashion some pinch wheels for some old Ferrograph series sevens as well as the Teac A3300 I have. But Teac pinch wheels are a similar size.
By the way, my Teac A3300 takes 10 1/2 inch reels which is handy.
Good luck with your Teac.
Cheers Peter W......Reelguy
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