Uher CR 240 AV Cassette Recorder

[DMcMahon]

Thank you for the updates, I will retry the contact arm with its latch piece on the RHS (as viewed from the front).

No problem at all, in fact my Post # 45 exactly supported your previous information. I also saw a Post in the DIYAudio (or similar name) Forum that had very similar information, so similar in fact it I think it most likely was you.

I would say the first contact is on the lower/bottom side (viewed from either side) when the contact arm is fitted with its latch piece on the RHS as per photo 5. What I am calling a contact is the first short (around 4mm) strip of copper on the left side without a hole in it, the middle section of copper and the uppermost section of copper directly above have holes in them.

Last night I removed the Joystick assembly (Photo 3) good condition and its sprung loaded mechanisms work OK and I think I can see how the RWD/FFD operating lever would operate the joystick mechanism to release the latched record switch.

Photo 1 shows the Joystick assembly fitted.

Photo 2 shows a piece of solder touching the left hand vertical edge of the little brass sprung loaded piece that will engage and lock the record switch contact arm latch piece.

Photo 4 shows the bottom side view of the joystick assembly where its brass leg that is sticking out left locks (from moving) the little brass piece when Joystick position is moved down from the Stop position.

David

[Uncle Bulgaria]

Now that is fascinating - I remember noting specifically the contact arrangement, fearing lest I put the whole thing in upside-down having epoxied the knob back on. I might have got it wrong in the fuss of extracting the switch, but mine certainly (now) has the initial contact uppermost - the opposite of your photo 5. Luckily, this doesn't seem as crucial as I feared, as it functions upside-down as I may well have it!

That piece you have the solder against is the bit you need to pull away from the switch as you push it in, so that the switch can be fully inserted ready for the locking pin.

The joystick mechanism is a joyous marvel.

I think you could well have found me on DIY Audio - I do lurk there too and they've been helpful with more general audio topics that fall outside the remit here a bit (designing valve amps and so on). I found so little information about servicing the CR 240, and certainly nothing about repairing this switch, that I now have the zeal of the convert and must spread the Uher love around the Internet for other lost souls to stumble across in the future.

Are your bulbs all right in the tape counter, under-cassette illumination and level meters? Mine were mostly shot, so I replaced them with LEDs. You might as well do this while it's all in pieces if you have to!

[DMcMahon]

In an attempt to find the missing record contact arm retaining pin, turned unit upside and gave it a shake, no sign of the pin and the shaking only broke off the 3 wires from Joystick board (had not refitted the board at that stage) !

Reconnected wires and refitted the board.

The record switch now mechanically latches but only if the cassette is in place and lowered (this sounds correct according the Operating instructions).

But the Record LED does not illuminate when Record is selected, in fact it illuminates when the unit is powered up and goes out when cassette is lowered. Also now have no control of the tape transport (Play/FFD/RWD) so 1 step forward and 2 steps back ! So a real nuisance, more fault finding required.

Have not really checked out the bulbs yet.

[Uncle Bulgaria]

Classic! Those solid wires are a real pain - I had so many that had to be resoldered painstakingly with all the unplugging and replugging I was doing. Particularly the ones on the motor drive board socket which are particularly tiny and close together!

A straightforward way to see if the record switch contacts are OK is to check for continuity in both positions between two of the three contacts on the tunnel available to each wide contact strip. In my photo on post #31 you can see how I did this. I had a big crack across the motherboard so had to jumper a few of the record tunnel contacts. For each group of three contacts on the tunnel, the middle and rear have continuity for 'record' and the middle and front for 'not record'.

Is the cassette you're using recordable - is the tab record-lock removed? I remember some complexity in getting it to engage 'record' without a cassette in as well. There's a little tab that has to be engaged in the cassette loading mechanism otherwise it switches off.

[DMcMahon]

Yes cassette is recordable, I tried a couple of others to be sure with no change.

I have not disturbed the Motor Drive board but have now inspected the wires going to the header plug that plugs into the socket on the board, all looks good.

Not yet had time to measure the record/play switch contacts, but your sketch from Post 31 will be very helpful when I get there.

[Uncle Bulgaria]

Is it just the record LED that goes out or does the whole thing shut down?

If the latter, check switch K4 - the rearmost on the right hand side looking from the front, next to the battery cover. There's a spring-loaded swinging gate that presses this down (so it's open) when record is disabled and a cassette is inserted, as it engages with the tab or lack thereof on the cassette. I had to adjust mine as it wasn't latching properly. You can test operation by running without a cassette inserted. You'll see that trying to engage 'record' with K3 open will fail. Letting the switch close again will see the unit spring back into life.

[DMcMahon]

Thank you Uncle Bulgaria. Yes the whole unit shuts down, I did not realise that at the time (obvious now after you suggested it), so hence no transport operation.

By just pressing the K4 (or is it K3) it also shuts down. When the cassette goes down the swinging gate lines up directly above the switch and actuates it, so shuts down.

Seems strange as I thought several days ago it was actuating the switch but then not shutting down and tape transport then worked OK.

By putting in the cassette and moving the swinging gate when cassette lowered so that K4 not actuated the cassette transport all works.

So need to check operation of K4 out more.

Still a problem with the Record LED, now (with power on all the time) it is lit all the time, so need to check out the Record/Play switch.

May not get much more done for a few days due to visiting family so may go quiet for a while.

David

[Uncle Bulgaria]

Yes, it's K4! I checked it so many times that I ended up writing the wrong one second time around. K3 deals with the motor starting up.

When you next have a look, try just pulling and pushing the record switch a little. If the light goes out, it's likely you'll have to check the continuity as a couple of the contacts are probably bridged. When making my switch I had to keep taking it out to scrape a little more metal off certain contacts as I was getting the same issue with the light coming on. I don't think record was actually engaged, but there was current flowing in the wrong section when the button was disengaged.

[DMcMahon]

Yes later saw it was K4 on the Servicing Instruction sheet (reason I had queried it was because you had referenced K3 as well as K4). Had a quick look at the swinging gate and found it was quite stiff on its little spring and was not fully being pushed back when it made contact with the record lug on the cassette and so then making contact with K4 actuator.

After fiddling with the spring mechanism it freed up and now the swinging gate correctly moves back when recordable cassette inserted and no longer actuates K4.

With a non recordable cassette K4 is actuated which I guess is the intention. I see on the schematic that K4 is bypassed in Playback mode so K4 would only remove the power in Record mode. Seems a little over the top to remove power if attempting to record a non recordable cassette but effective.

I have tried pushing and pulling the Record switch but the Record LED always stays lit, will try removing the retaining pin to get a larger movement of the contact arm to see if the Record LED ever goes out. Still also to check out the Record/Play contacts continuity.

VU meter lamps work, counter and cassette lamps do not work. The cassette lamp is on the little Pulse Generator board, I assume it is just on the board because the board is in the cassette area rather than being anything to do with the Pulse Generator circuit operation.

[Uncle Bulgaria]

Yes - I realised I'd confused myself and written both! I'll have to think more about the LED always being lit. You could check to see whether record is actually being engaged by testing with a blank cassette and the internal mic.

The cassette lamp is just a nice touch to enable you to see how much tape is left by shining up through the cassette and the transparent removable cover. I couldn't find any wire-ended lamps of the right voltage and current after lengthy searching, so ended up replacing them all with small LEDs. I still have a number so if you need a couple I can send them over. Now that I've got it on top of the EG 740 I can see that they are a lot brighter than the VU lamps on the tuner, so could be dimmed further if I wanted them to match.

[ms660]

So far as I can make out the extinguishing of the Record LED depends on D4 being connected across it via switch contacts 46 & 47 on the Rec/PB switch (S1)

Might be worth checking that part of the circuit.

Lawrence.

[DMcMahon]

Thank you Lawrence.

David

[DMcMahon]

Originally Posted by Uncle Bulgaria

Yes - I realised I'd confused myself and written both! I'll have to think more about the LED always being lit. You could check to see whether record is actually being engaged by testing with a blank cassette and the internal mic.

The cassette lamp is just a nice touch to enable you to see how much tape is left by shining up through the cassette and the transparent removable cover. I couldn't find any wire-ended lamps of the right voltage and current after lengthy searching, so ended up replacing them all with small LEDs. I still have a number so if you need a couple I can send them over. Now that I've got it on top of the EG 740 I can see that they are a lot brighter than the VU lamps on the tuner, so could be dimmed further if I wanted them to match.

Have some little LEDs that I have used before for VU meters, so should be OK, thank you for your offer. Out of interest what voltage rating did you find the lamps are ?

I did try previously playing a music cassette but got no sound from the speaker or headphones so possibly that indicates that the unit is in Record mode.

Yes I should check with microphone to see if get a record signal on the VU meter etc.

David

[DMcMahon]

Now see that the lamps are 3V.

[Uncle Bulgaria]

Yes, 3V 30mA. If you find any I'd be glad to hear of it! Some of those mini LEDs (the cylinder on a rectangular parallelipiped type) with the cylinder snapped off do sterling service as diffuse sources, and are small enough that they and their resistor fit in the same space.

Do you have any transparent window over the tape counter? It looks like there ought to be something there but mine hasn't got anything. Perhaps I should endeavour to replace it.

[DMcMahon]

Yes does have a plastic removable window as per photos.

[Uncle Bulgaria]

Crossed wires: I have that one, but not anything over the tape counter below the equalisation slider. The rotating dials are exposed to touch on the front.

[DMcMahon]

Sorry, my one also does not have anything over the tape counter opening in the front panel.

[DMcMahon]

Quickly checked several of the Record switch contacts in both Record and Play but could not get any sensible switch readings at all.

Need to spend more time doing a deeper investigation.

[DMcMahon]

No record signal seen on VU meters when using the internal microphone.