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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 25th Jul 2022, 2:10 pm   #1
jascha
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Default Uher CR240 disconnected wire help please

Hi everyone,

I just about finished restoration on a Uher CR240, replaced belts, and an IC on the Dolby card that was causing lots of interference on the left channel.

Upon testing it I discovered that the VU meter lights are not working. Upon further investigation I noticed that a grey wire that is soldered on the bottom board has come undone. It’s a grey thin wire that is supposed to be connected somewhere close to the troubling area with the VU lights. There is no voltage present on the VU lamps and am suspecting that this grey cable has something to do with it.

Could someone be so kind to help me where I should resolder this wire to please as I cannot seem to find any traces of where it came off from.
I attach photos of the wire which I point out with a pencil.

Kind regards and thanks
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Old 25th Jul 2022, 2:34 pm   #2
Uncle Bulgaria
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Default Re: Uher CR240 disconnected wire help please

Well done on getting so far. I find those little solid-core wires so frustrating - they always seem to break just as the main work is done!

I believe your wire has come off the location in the photograph - where the other grey one goes to that comes out of the hole.

Edit: looking at it, that contact is marked 709, which is a link to the Accessory socket. The VU lights are only fed from 1010; the ribbon cable contact from board 1000. I don't see a direct connection between your grey wire and those lamps. Are you sure they're not just blown? I have had to replace all mine with small LEDs.
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Old 25th Jul 2022, 3:01 pm   #3
jascha
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Default Re: Uher CR240 disconnected wire help please

Thanks so much for clarifying where that wire came out from. I was not quite sure although I could see a tiny trace of the broken wire sticking out. I still don't have any vu meter lights working however as there is hardly any voltage on the lights' terminals. Any ideas please?

Also the light that illuminates the counter is out but I have not checked the bulb itself if it's burnt out. Do you know what voltage rating are these bulbs rated at please?

Cheers
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Old 25th Jul 2022, 3:13 pm   #4
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Default Re: Uher CR240 disconnected wire help please

The lights are continuously on when the unit is plugged in. On battery they will only light if you press the button on the front panel.

Do you have +9.5V at 1014?
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Old 25th Jul 2022, 4:12 pm   #5
DMcMahon
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Default Re: Uher CR240 disconnected wire help please

Quote:
Originally Posted by jascha View Post

Also the light that illuminates the counter is out but I have not checked the bulb itself if it's burnt out. Do you know what voltage rating are these bulbs rated at please?

Cheers
As shown on the schematic section provided by Uncle Bulgaria, the bulbs are listed as 3V 30mA.

David
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Old 25th Jul 2022, 4:16 pm   #6
jascha
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Default Re: Uher CR240 disconnected wire help please

Hi,
Thanks to you both for your help. I do have around 9.5v DC on 1014.
When I measured the voltage across the bulbs however I just get a few millivolts. I have not taken the unit apart around where the VU meters are as I thought first I try to find the issue before I tackle it.
Am I thinking right now that it could be the transistor in the vicinity?
Everything is awkward to reach for testing purposes without dismantling it which is quite a pain.

Cheers
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Old 25th Jul 2022, 4:19 pm   #7
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Default Re: Uher CR240 disconnected wire help please

Is: I just measured over 5v across the right channel VU meter bulb but nothing across the left. By chance are these bulbs connected in series? This reminds of a Revox B77 I had to fix and it would not go into record as the red recording bulb is in series with the recording circuit. I wonder now if this is the case here as well?

Cheers
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Old 25th Jul 2022, 4:35 pm   #8
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Default Re: Uher CR240 disconnected wire help please

Yes if the TR 10 transistor was dead/not switching then there would be little if any voltage going to the bulbs.

As shown on the schematic the two VU meter bulbs are in series with each other and the other two bulbs are in series with each other and in parallel with the VU meter bulbs.

Try checking for resistance across each separate bulb.

David
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Old 25th Jul 2022, 4:58 pm   #9
jascha
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Default Re: Uher CR240 disconnected wire help please

And there was light .
Well I soldered in a 6v rather GOW bulb and bingo the left VU bulb lighted up but the right one hardly lights up as it’s the wrong rating. Now I know what I have to do… get a few 3v ones to finish the job .

Cheers again guys
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Old 25th Jul 2022, 5:06 pm   #10
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Default Re: Uher CR240 disconnected wire help please

Good progress, if you source correct bulbs that work OK then post the details.

David
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Old 25th Jul 2022, 5:11 pm   #11
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Default Re: Uher CR240 disconnected wire help please

Well done. I searched for a long time without success, but forum members came up with some options with higher current in this thread. In the end I decided to use LEDs as I wanted to minimise current draw.
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Old 27th Jul 2022, 8:23 pm   #12
jascha
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Default Re: Uher CR240 disconnected wire help please

Hi,
I almost finished successfully restoring the Uher and have used at the end 6v GOW lamps and connected them in parallel.

Unfortunately I have now ran into a problem that when I press the record button the machine shuts down completely as if there is a short. The record button is causing a short clearly, the lights all go off and the machine goes dead.
I have disconnected all the boards and still the problem persists. Is this a known problem?

Thanks
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Old 27th Jul 2022, 8:34 pm   #13
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Default Re: Uher CR240 disconnected wire help please

It sorted itself out it seems. I have no idea what I touched but clearly it worked… and sadly have not learnt anything from it. Hmmm
Thanks again guys
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Old 27th Jul 2022, 11:51 pm   #14
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Default Re: Uher CR240 disconnected wire help please

Not a known problem as far as I know, does sound like it was shorting something down, lucky that it has resolved itself.

David
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Old 28th Jul 2022, 10:53 am   #15
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Default Re: Uher CR240 disconnected wire help please

The record button can only be operated in 'stop' mode (which raises the gate that prevents the button being depressed), and will turn the machine off if you try to activate it with a cassette that is record protected.

Alternatively, your record switch wafer is broken and not aligning its contacts properly with the fingers in the switch housing. In that case, you would likely be able to get the machine to shut down by wiggling the record switch even though 'stop' is not engaged. I have had to manufacture a new record switch wafer for this reason.
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