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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 22nd Jul 2020, 12:17 pm   #1
DMcMahon
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Default Uher CR 240 AV Cassette Recorder

As a bit of light relief from a long list of ongoing (very slow) R2R refurbishments, I decided I would stray into the cassette arena and purchased a late 70's 4 track Uher CR 240 AV stereo portable cassette recorder.

It was sold as not working & requiring drive belts.

Powers up OK from supplied Uher Z 131 power adapter (24 volts) but no sign of life from the tape transport. Virtually impossible to see the drive belts properly but looks like at least 1 is gone/missing.

Appears to be a problem (am not familiar with how it should work) with the mechanical loading of the cassette. After the cassette is manually pushed into the cassette carrier mechanism, attempts to push the cassette done into the operating position by pushing down on the cassette lever (up to eject) fails because the open side of the cassette hits/fouls the 2 heads.

The heads assembly is spring loaded and it appears that the heads assembly is fully forward, maybe in the Play position, presumably there is a mechanism that should retract the heads assembly so that cassette can be loaded, but without a strip down impossible to see.

With no cassette fitted and simulating a cassette by pushing back a little cassette detection latch I can push the cassette carrier mechanism down and the motor can then be heard to run (can also get motor to run by just pressing the little associated microswitch that is actuated when mechanism is pushed down).

With cassette carrier down, selecting Play results in a little relay energising and Play/Forward led lighting but only for about 1 second, there is no movement of the flywheels.

Selecting FWD or RWD results in the motor spinning faster (by its sound, cannot see the motor) for about 2 seconds, once again no sign of the flywheels moving.

Next step is to strip down for belt inspection/replacement as required, hopefully then will be able to see what controls the position of the heads assembly.

David
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Old 22nd Jul 2020, 8:54 pm   #2
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Default Re: Uher CR 240 AV Cassette Recorder

Stripped down and found all 4 belts still fitted. All are square profile so possibly originals.

The 2 belts from the 2 flywheels to the 2 spools holders look OK but will replace all the belts as I have a new set (round section). The tape counter belt was stretched and starting to crack. The motor pulley belt to one of the flywheels was well stretched, quite badly cracked and stiff, I think it was so loose it would have just been slipping.

One of the 3 securing screws (designated G) for the Flywheel/Head Mount Plate with Deck drive Electronics was well seized, took some effort to remove, WD40 eventually helped.

Before starting to strip it down I read the instructions in the Service manual and half way down Step 5.9 it says "In re-installing the cassette lift, it should be stuck onto guide belt "H", while slide "I" is simultaneously pressed down (with a screwdriver) all the way to the battery compartment. Only then can the cassette lift glide unimpeded past pawl "K" on to the floor of the machine".

The reference to "guide belt" appears erroneous, probably should say "guide pin/post".

The reference to slide "I" when comparing the actual physical operation and drawing, did not appear to make 100% sense. When I removed the cassette lift I could then see by operation, that the slide is what operates via other linkage the retraction of the heads assembly. So I think that the cassette lift had previously at some stage been removed and refitted incorrectly so that the slide did not retract the heads assembly, that is why the cassette would not go down on loading.

So just need to re-assemble and get the slide working correctly. There is a metal tab/arm on the cassette lift that is somewhat bent, which I think may interface with the slide operation so need to work out if the bent tab needs to be straightened.
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Old 23rd Jul 2020, 5:38 pm   #3
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Default Re: Uher CR 240 AV Cassette Recorder

New drive belts fitted and everything re-assembled (not easy).

But now it will not switch on, that is a real nuisance. The DC adapter is still good and 24 volts is getting to the input of the Power supply board. The schematic is very busy and when enlarged some of it is difficult to read, have yet to see the On/Off switch or the "On" status LED in the schematic.

David
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Old 23rd Jul 2020, 10:37 pm   #4
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Default Re: Uher CR 240 AV Cassette Recorder

Located the On/Off switch on the schematic, it is called "Ein ausschalten" which translates as "A switch", not the most helpful designation.

No power to the switch, so am looking at the power supply board, very difficult to access/monitor it, so have partially removed it, but to power it up will need to fit a temporary heatsink to the power transistor on the back of the board.

Also with board partially removed cannot fit the power adaptor, either need to make up a D type cable to connect the adapter to the Auto/Radio power D type on the power supply board or connect up a PSU to the board.

Just noticed that the +24V wire from adaptor connector block has come loose/out of the board (black wire) but do not think that is the root cause of no power.
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Old 24th Jul 2020, 5:29 pm   #5
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Default Re: Uher CR 240 AV Cassette Recorder

I don't know German, but I've seen the terms 'Ein' for 'On' and 'Aus' for 'Off' in German service manuals. So a better translation might be 'On switch'.

My experience from reparing the (simpler) CR210 is that the PCB tracks break if you look t them wrongly... I would check that sort of thing first, particularly around the connectors on the plug-in PCBs and the backplane pins.
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Old 24th Jul 2020, 6:55 pm   #6
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Default Re: Uher CR 240 AV Cassette Recorder

Ein aus schalten = "switch on off" in Google translate.

Lawrence.
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Old 24th Jul 2020, 8:12 pm   #7
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Default Re: Uher CR 240 AV Cassette Recorder

Are you sure it's not "Ein- und Ausschalter" which means on/off switch. It might be an abbreviation for that.
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Old 24th Jul 2020, 8:34 pm   #8
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Default Re: Uher CR 240 AV Cassette Recorder

The quality of the schematic is poor, but it definitely looks like "Ein ausshalter" (i.e. no space between aus and shalter" which from Google auto translate = "A switch", as Lawrence states Google translate for Ein aus shalter" = on off switch.

As Tony says Ein and Aus can be On and Off, which I should know/do know, so I take it all back, the switch designation is correct and I fall on my sword

David

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Old 24th Jul 2020, 8:47 pm   #9
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Default Re: Uher CR 240 AV Cassette Recorder

Quote:
Originally Posted by TonyDuell View Post

My experience from reparing the (simpler) CR210 is that the PCB tracks break if you look t them wrongly... I would check that sort of thing first, particularly around the connectors on the plug-in PCBs and the backplane pins.
Closely examining the rest of the 6 core ribbon cable (from power adapter connector block) connections to the power supply board, shows that the 5 remaining connections are also loose.

So I will resolder all 6 connections. The numerous ribbon cable connections at the power supply board to the main board (motherboard) look OK.

Hopefully this will get it working but I will probably connect the power supply board to external PSU for initial switch on tests, so that if still a problem I can monitor the board easier with it partially out.

David
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Old 24th Jul 2020, 8:59 pm   #10
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Default Re: Uher CR 240 AV Cassette Recorder

The schematic I have is also a bit fuzzy, just for info contacts I to VII de- fuzzed.....so far as I can make out:

Contacts I&II make as do contacts IV&I/II when mains unit Z131 is fitted.

Contact III is battery -ve and Z131 (mains unit) -ve.

Contact V is battery +ve.

Contacts IV&VI make when battery unit (Z215) is fitted.

Contact VII is Z131 (mains unit) +ve.

Lawrence.
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Old 24th Jul 2020, 9:23 pm   #11
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Default Re: Uher CR 240 AV Cassette Recorder

Thank you very much for that Lawrence, very helpful. I have at least 4 different versions of the schematic with varying degrees of fuzziness (maybe it is my eyes ) I can just about make them out, really struggle with VII though.

I have ordered proper schematic/service notes/User manual from SDS.

David
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Old 24th Jul 2020, 9:59 pm   #12
barretter
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Default Re: Uher CR 240 AV Cassette Recorder

Quote:
Originally Posted by DMcMahon View Post
The quality of the schematic is poor, but it definitely looks like "Ein ausshalter" (i.e. no space between aus and shalter" which from Google auto translate = "A switch", as Lawrence states Google translate for Ein aus shalter" = on off switch.

As Tony says Ein and Aus can be On and Off, which I should know/do know, so I take it all back, the switch designation is correct and I fall on my sword

David
It actually reads "Ein-Ausschalter" which means on-off switch. "Ausschalter" is a noun, which is why it has a capital letter, even though it is not the first word in the phrase whereas "ausschalten" is a verb which means "switch off". Thus endeth the German lesson.
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Old 24th Jul 2020, 10:11 pm   #13
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Default Re: Uher CR 240 AV Cassette Recorder

Looks like a dot to me (on my schematics) not a hyphen, not that it makes any difference, both versions in Google translate = On Off switch

Can see it is a hyphen in your attachment.
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Old 25th Jul 2020, 10:44 am   #14
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Default Re: Uher CR 240 AV Cassette Recorder

Either way it's clear that it's the on/off switch due to its circuit position.

Lawrence.
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Old 25th Jul 2020, 10:46 am   #15
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Default Re: Uher CR 240 AV Cassette Recorder

Yes totally agree, still to spot the "On" LED though.

David
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Old 25th Jul 2020, 10:49 am   #16
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Default Re: Uher CR 240 AV Cassette Recorder

Quote:
Originally Posted by barretter View Post
Quote:
Originally Posted by DMcMahon View Post

David
It actually reads "Ein-Ausschalter" which means on-off switch. "Ausschalter" is a noun, which is why it has a capital letter, even though it is not the first word in the phrase whereas "ausschalten" is a verb which means "switch off". Thus endeth the German lesson.
How did you get such a clear image, was it taken from an original drawing ?

David
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Old 25th Jul 2020, 11:12 am   #17
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Default Re: Uher CR 240 AV Cassette Recorder

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Originally Posted by DMcMahon View Post
Yes totally agree, still to spot the "On" LED though.
D103....100 Board.

Lawrence.
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Old 25th Jul 2020, 11:24 am   #18
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Default Re: Uher CR 240 AV Cassette Recorder

Thank you Lawrence, I knew you would find it

Can see it now, but on the fuzzy schematic difficult to read D103 but D103 very clear on the 100 board layout.

David
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Old 25th Jul 2020, 1:54 pm   #19
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Default Re: Uher CR 240 AV Cassette Recorder

Resoldered the bad 6 connections at the ribbon cable. Checked for shorts between adjacent tracks and found a dead short between the orange (wire 623) and the yellow wire (wire 624).

Initially could not see where short was coming from and thought I had a fault but after looking at the schematic properly, can see it is correct. These connections go back to a slide switch contacts 14 and 15 (switch is not designated) and the schematic shows the switch with contacts 14 and 15 made.

There is a dotted line from the switch going back to the DC 12-24V AutoRadio 8 pin DIN connector, meaning I think that the slide switch is actuated/switched when DIN plug is inserted.

I fitted an 8 pin DIN (extremely tight) and this removes the short, operationally this disconnects the internal batteries from the voltage output connection, that goes out to the On/Off switch.
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Old 25th Jul 2020, 2:20 pm   #20
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Default Re: Uher CR 240 AV Cassette Recorder

Let me know if you need any pictures of a working CR240. If there's a delay for the diagrams to arrive, I can help with that too as I have the originals sent from SDS and it makes a world of difference not working with a blurry PDF!

With some major help (particularly Lawrence) mine is now working. It does look like your cassette loading part is bent. Compare this one - the yellowish passivated part shouldn't interfere with the cassette.
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