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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 27th Jul 2017, 10:20 pm   #1
barretter
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Default Uher 4000 Report Monitor speed change problem

I've been working on one of these for the past few days. It's ex-University of Newcastle and it came without the top plate between the reels and the inside of the machine. I have managed to get it working again by replacing the Frako capacitor on the power supply board, which was a dead short and a little mechanical tweaking, but the major problem I have is that the speed selector switch doesn't change the speed. At first the speed-changing mechanism was stuck on 7.5ips and turning the speed selector did nothing at. I managed to move the speed-changing mechanism over to 3.75ips and then turning the speed selector moved the speed-changing mechanism up and down but not sideways.
In addition the vertical rod with the screw-driver slot in it which is situated between the speed selector and the speed-changing mechanism is very loose and is attached to a rectangular piece of ribbed white plastic which is also very loose whereas in a 4400 Report monitor which I have this vertical rod is firm and not apparently attached to a plastic sheet (though that might be invisible).
Can anybody help?
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Old 28th Jul 2017, 12:08 pm   #2
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Default Re: Uher 4000 Report Monitor speed change problem

Check to see if the red skeleton micro switches on the speed selector cam are working,
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Old 28th Jul 2017, 1:20 pm   #3
Welsh Anorak
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Default Re: Uher 4000 Report Monitor speed change problem

The belt's diameter is very critical in this model - maybe someone has changed it for one that's too small which is preventing the east-west movement of the mechanism?
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Old 28th Jul 2017, 7:15 pm   #4
barretter
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Default Re: Uher 4000 Report Monitor speed change problem

I don't think it's anything to do with the belt which fits perfectly and couldn't prevent sideways motion of the speed-change mechanism, I think. The microswitches in the 4000 operate the same as those in the 4400 I have.
I am now convinced it's something to do with the plastic sheet under the speed change cam. You can see it in my terrible photo in the bottom right-hand corner. There is also a white plastic sheet in the 4400 but shifted 90 degrees to the left so that it is completely under the cam and only visible with the aid of a bright light. This sheet is also attached to the vertical rod with the screwdriver slot but it is anchored in place whereas the one in the 4000 is loose.
Does anybody know how this works to shift the speed change mechanism?
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Old 5th Oct 2017, 3:01 pm   #5
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Default Re: Uher 4000 Report Monitor speed change problem

I'm afraid your machine has been dropped. When changing tape speed the cam at the rear of the speed change mechanism pushes the long brass arm holding the brass capstan in its cradle down while a rack and pinion under the mechanism is supposed to shift the vertical pin with a screwdriver slot along taking the long arm with it. As the cam releases the long arm returns to allow the brass capstan to engage once more with the rubber-rimmed flywheel at the new speed selected.
If you remove the speed change mechanism (it's like matrimony, not to be entered into lightly!) I think you will find a broken tooth on either the rack or the gear with which it engages.
A new speed change mechanism is the only solution.
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Old 6th Oct 2017, 4:08 pm   #6
barretter
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Default Re: Uher 4000 Report Monitor speed change problem

Thanks for that. It's, as I thought, the plastic sheet ("rack and pinion") which is the problem. I'm torn between leaving it as it is, since the speed change can be done by hand but necessitates opening the machine up, and taking it apart to find out what happened. As I have, in the meantime, obtained another, working, example of the machine, I incline towards the latter course of action. Do you have any advice on the best way to dismantle the speed-change mechanism? As far as I can see it's not currently possible to buy a replacement mechanism.
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Old 9th Oct 2017, 4:56 pm   #7
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Default Re: Uher 4000 Report Monitor speed change problem

As far as I recall the procedure is:
remove the three larger knobs retained by set screws,
remove the three smaller knobs which just pull off.
remove escutcheon (6 Philips head screws),
open up the PCB for access,
remove the two screws which attach the PCB hinges to the chassis (one is a nut and bolt and the other has a captive nut) and carefully lift the PCB upwards and outwards as far as the wiring permits to allow better access.
remove the two screws which hold the main speed mechanism in place to the chassis,
hold the long brass piece down while carefully withdrawing the speed mechanism in a kind of rotating way towards the rear of the machine.
You will find the rack with its post with the screwdriver slot sitting below in its guide.
Further to my earlier answer it's possible that just the rack is damaged and not any teeth on the main unit.
I'm away at present but may have some spares at home which will help.
I've not done this for many years and my apologies if my memory has failed me!
Good luck!
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Old 10th Oct 2017, 9:21 pm   #8
barretter
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Default Re: Uher 4000 Report Monitor speed change problem

Thanks for that. I'll give it a go in the near future.
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Old 17th Oct 2017, 1:20 pm   #9
barretter
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Default Re: Uher 4000 Report Monitor speed change problem

Well I did try last night and this morning and I succeded. What I did was to undo the screws holding the speed change mechanism in place and the screws holding the toothed speed change gate which I removed. This allowed me to fish out the ridged plastic plate which was flopping about in the bottom of the machine. I then replaced the plate into its proper position under a plastic cogwheel and replaced all the parts. Now I can change between the four speeds.
All this was much more fiddly than it sounds and in the process I seem to have lost the eccentric nylon screw which facilitates minor speed adjustment.
Does anybody have any ideas about its replacement?
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Old 18th Oct 2017, 6:44 am   #10
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Default Re: Uher 4000 Report Monitor speed change problem

Sadly, there was no need to separate the end of the brass strip from the plate with the speed gate! However, the eccentric nylon screw is used only to adjust the three lower speeds slightly once the top speed has been set with the two securing screws slackened off. The speed can still be adjusted and the two screws tightened to enable satisfactory running.
Before reassembly check that the black plastic runner on which the nylon slider (with the brass rod which has the screwdriver slot) engages is not damaged. I have known such damage and could be the cause of the speed change problem in the first place.
A spot of Vaseline on the slider aids operation.
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Old 18th Oct 2017, 5:37 pm   #11
barretter
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Default Re: Uher 4000 Report Monitor speed change problem

The problem was that the nylon slider was loose and nowhere near where it should be. Once I had managed to remove it from the bottom of the machine which necessitated removing the toothed gate I could see, by shining a very bright light into the Uher, the black groove where it had to sit, which I did not know before carrying out the first two operations. Had I known what had to be done I could, presumably, have wiggled the nylon slider back into place.
Having thought about it, I am not sure that the eccentric nylon screw was there in the first place. When I bought the machine it was in a sorry state, with no top plate and not working at all. It was stamped "Property of the University of Newcastle" and I suspect that somebody had had a go at it and that was probably why the nylon slider plate was so badly misplaced.
Now it will play at all four speeds and is useful for listening to all those World Record Club half-track mono tapes of which I have quite a few. And it plays them very well.
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Old 21st Oct 2017, 6:43 am   #12
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Default Re: Uher 4000 Report Monitor speed change problem

Glad it had a happy ending! Pleased to have been of help.
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