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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 21st May 2020, 9:47 pm   #1
Michael Maurice
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Default Repairing tape counters

I have 3 tape recorders with the normal counter where you push a button to zero it. Only on all three of them, it doesn't.

Everything appears to move freely but the digits dont move to zero.

They try to, but just cant get there.

Has anyone repaired these before and if so what normally causes it.
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Old 21st May 2020, 10:04 pm   #2
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Default Re: Repairing tape counters

I assume we are talking reel to reel.

Look between the number segments, you will usually see an eccentric cam on the side of each. Get a flat bladed jewellers screwdriver, and use it to apply a little light grease to the cams. Move them around a bit, reset a few times, and job done.

In the worst case scenario, in some designs, the thin springy plastic bars that apply pressure to the cams to return them to zero break off. No idea how one would repair those - I have one Tandberg in that bad way!
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Old 22nd May 2020, 3:56 pm   #3
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Default Re: Repairing tape counters

I have a few with the thin springy plastic bars (some broken) where I think even if only 1 breaks, it stops all the counter segments from being resettable. Sometime need to see if any way of doing a fix.
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Old 23rd May 2020, 4:25 am   #4
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Default Re: Repairing tape counters

I have (or had, not sure if I sold it or not) a Tandberg whose counter reset failed because some of the thin blades that press on the cams had cracked and fallen off (I think because the heat generated by the pilot lamp illuminating the counter had caused the plasticizer in the plastic to evaporate, leaving the material brittle).

I fixed this by drilling small holes in the bar which the blades emanate from and supergluing piano wire into the holes. This fixed the problem, but I'm not sure how long it will last, because the bar surely has suffered the same drying-out fate as the blades, and is now subjected to fairly large point forces where the piano wire enters the bar.

As can be seen in the picture, getting the holes in the right position was tricky and I didn't completely succeed, but on the whole the operation was a success.

(In the pictures, the first one shows the reset mechanism at rest, the second one shows it in operation, pressing against the cams.)

BTW, it has always struck me as interesting that the 'push-to-zero' mechanism didn't appear until the mid 1960s or so, before then, the counter reset mechanism on many machines at least used a thumbwheel mechanism which pulls all the digit wheels around until they reach 000 or 0000. I suppose everyone thought that was good enough until someone came around and invented the pushbutton reset. The thumbwheel reset seems more robust; I can't think of a single machine I've had where it's failed, whereas sticking pushbutton reset mechanisms are common.
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Old 23rd May 2020, 9:28 am   #5
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Default Re: Repairing tape counters

Hi Ricard,

That looks like a really good inventive solution, I will give that a go.

David
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Old 23rd May 2020, 10:36 am   #6
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Default Re: Repairing tape counters

A bead of high temperature epoxy along the bar would be a sure way of beefing up the plastic bar and the remaining plastic finger.
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Old 24th May 2020, 10:31 am   #7
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Default Re: Repairing tape counters

Quote:
Originally Posted by ricard View Post
I have (or had, not sure if I sold it or not) a Tandberg whose counter reset failed because some of the thin blades that press on the cams had cracked and fallen off (I think because the heat generated by the pilot lamp illuminating the counter had caused the plasticizer in the plastic to evaporate, leaving the material brittle).

I fixed this by drilling small holes in the bar which the blades emanate from and supergluing piano wire into the holes. This fixed the problem, but I'm not sure how long it will last, because the bar surely has suffered the same drying-out fate as the blades, and is now subjected to fairly large point forces where the piano wire enters the bar.

As can be seen in the picture, getting the holes in the right position was tricky and I didn't completely succeed, but on the whole the operation was a success.

(In the pictures, the first one shows the reset mechanism at rest, the second one shows it in operation, pressing against the cams.)

BTW, it has always struck me as interesting that the 'push-to-zero' mechanism didn't appear until the mid 1960s or so, before then, the counter reset mechanism on many machines at least used a thumbwheel mechanism which pulls all the digit wheels around until they reach 000 or 0000. I suppose everyone thought that was good enough until someone came around and invented the pushbutton reset. The thumbwheel reset seems more robust; I can't think of a single machine I've had where it's failed, whereas sticking pushbutton reset mechanisms are common.
Hi Ricard,

I am not really familiar with piano wire, I know one can get it in different diameters, what sort of diameter did you use, is it easy to cut ? does it naturally straighten ?

Looking at my Telefunken counter there is hardly enough material to drill even a tiny hole, in this case would just try just supergluing the wire direct to the counter.

David
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Old 24th May 2020, 12:16 pm   #8
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Default Re: Repairing tape counters

I'd be inclined to heat the wire, holding with pliers, and just push it into the plastic. Drilling sdomethign that tiny looks to be nigh on impossible to me.
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Old 24th May 2020, 1:49 pm   #9
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Default Re: Repairing tape counters

I would expect it to be a bit bigger than a compact cassette counter.
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Old 24th May 2020, 2:10 pm   #10
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Default Re: Repairing tape counters

Thanks guys, Ben’s tip on using grease worked a treat.
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Old 24th May 2020, 8:39 pm   #11
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Default Re: Repairing tape counters

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Originally Posted by Refugee View Post
I would expect it to be a bit bigger than a compact cassette counter.
Depending upon the diameter of the wire and required hole size there would not be much spare material on my Telefunken but I think on a couple of my Uhers that also have lost their plastic reset bits there is more material, so drilling might be more practical.
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Old 24th May 2020, 8:41 pm   #12
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Default Re: Repairing tape counters

Quote:
Originally Posted by ben View Post
I'd be inclined to heat the wire, holding with pliers, and just push it into the plastic. Drilling sdomethign that tiny looks to be nigh on impossible to me.
Sounds practical, getting the wire in the correct place (either with drilling or heated wire) so that the wire reliably resets the cams could be interesting.
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Old 25th May 2020, 10:49 pm   #13
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Default Re: Repairing tape counters

Quote:
Originally Posted by DMcMahon View Post
I am not really familiar with piano wire, I know one can get it in different diameters, what sort of diameter did you use, is it easy to cut ? does it naturally straighten ?
I can't remember the exact diameter, I think in this case as small as possible without it being too springy to do its job properly. Something like 0.1 or 0.2 mm I guess.

It's very hard and springy, so tends to straighten out, unless bent sharply, in which case it stays bent. It needs to be cut with hardened pliers, not the ones one uses to cut copper wire with.

Regarding Ben's question above, I have a small hand held drill originally intended for drilling holes when making PCBs. I think the diameter in this case was around 0.1 mm. It's not hard to drill with, what is hard is keeping the drill straight (as can be seen in the pictures) and in the right place. I should have used some form of mini vice to keep the counter in place while working on it.

Personally I'd be wary of heating the wire and just pushing it in. I think either the force would have to be quite large as the plastic will cool the metal, or if the wire is hot enough the hole will be rather large and/or the hot metal will warp the plastic.
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Old 26th May 2020, 9:36 pm   #14
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Default Re: Repairing tape counters

Thank you Ricard for your replies.

Fairly recently I helped my wife renew her broken "A" string on her Cello, this is a steel cored string, not sure what the external material is, looks like metal. I was going to throw the old string away, but at the time thought it might come in handy for an R2R repair.

So am considering trying this string, it possibly may not be stiff enough though.
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