Uher SG 561 Royal Reel to Reel Checkout

[DMcMahon]

Late 1970's 4 track, solid state, 4 speed stereo recorder with internal power amps and speakers.

Brought this quite a while back and at the time briefly powered it up but it was non functional but could not remember what was not working.

Externally pretty good looking condition and quite an attractive recorder. As pointed out by untune87 in his SG 561 Thread the control knobs for the speed selector and the Pause/Start selector are not the original knobs, looks like they have come from another Uher Royal model.

The carrying handle/stand and the Perspex lid are currently missing but I have them somewhere.

Powered it up today and the motor is heard to be running (when any one of the 4 speeds is selected) and both VU meters illuminate.

But when Start, Fast Forward or Rewind is selected there is no tape movement at all. With the head block assembly removed can see that the capstan runs when Start is selected and the pinch wheel makes good contact with the capstan but the pinch wheel does not rotate so no tape movement.

By first winding off some loose tape from the supply spool the tape will run through the capstan (pinch wheel then rotating) but there is no take up from the take up spool, but as soon as the loose tape is taken up the pinch wheel then stops rotating.

Need to go inside to have a better look to investigate further.

David

[untune87]

Hi David,

You might already know this but refer to the video I linked in my thread https://www.youtube.com/watch?v=waKLb-GXc_U for a few visual tips as to dismantling, it's best to flip the machine up onto the VU side once you've undone the bottom two screws on the face, then it will swing out like you're opening a book, just be wary that the face isn't flush with the edge and there's some weight to it—I folded some scrap card in a teatowel and sat the edge of the face on that to keep it square. The hinges can also become unlatched so be careful of that too! it's a very tight fit with some of the cables.

Also, I'm certain another thread on the board referred to this—upon opening for the first time, a small rectangular piece of paxolin board fell out. I've no idea where this went, and I haven't noticed anywhere it appears to have been mounted to. Worth bearing in mind!

Cheers!
Lee

[DMcMahon]

Thank you Lee, I had watched the video clip. Had quite a struggle getting to open first time and when hinging it open as you say some of the wires are very tight to clear the case.

Also had the problem of the bottom hinge keep coming out, a real nuisance when it does.

I posted a Thread quite a while back about the Paxolin board falling out, still have not found a home for it.

David

[DMcMahon]

Replaced the 2 pin continental mains plug with a UK 3 pin plug with 1A fuse fitted.

I may later replace the 2 core mains cable with 3 core so as to earth the metalwork, would do it now if had more time but not a 5 minute job getting the existing cable out of the strain relief grommet and replacement fitted.

Think I have found the cause of the tape transport not working.

The main drive belt from the motor pulley to the main idler wheel is broken, initially could not see it but after a good shake of the chassis it fell out.

Struggling to find a suitable replacement, may have to borrow one from another Uher.

David

[DMcMahon]

As a temporary measure super glued the broken drive belt, even if the glue repair lasts I do not think that the belt may last that long because when stretched could see lots of deep nasty cracks around some sections of the belt.

Playback mechanically works OK on all 4 speeds. Playback sound tested with old 3 3/4 ips recordings from tape that may have come with the 561, sound is reasonable but not good, some very strong bass particularly on the right channel, If the bass control (Tiefen) is turned up high together with high volume setting get quite a bass boom from the right channel.

Left and right VU meters working for both channels during playback.

Selector switch for the various stereo/mono settings appears to be working correctly.

Fast forward and rewind work but quite sluggish at times and often after a few seconds the control resets to its middle position, maybe the magnetic clutch needs tweaking.

Tape counter is not working, need to check its belt.

David

[DMcMahon]

Removed top panel to check out the tape counter belt and found the belt is broken.

I think I have a suitable spare, on previous Uher Royals have found the tape counter belt very difficult to fit due to difficult access to the rear of the Supply reel table.

David

[DMcMahon]

Found a suitable replacement belt for the tape counter and after quite a long struggle replaced the belt.

Thought the belt groove was somewhere in the lower section of the reel table but could see no groove using an inspection mirror so had to strip down the rear of the reel table but no groove to be seen anywhere.

Then realised that the groove was in the top part of the reel table on the spool carrier, in retrospect probably should have realised that at the start especially as I have changed the counter belt a couple of times before (quite a while ago) on other Royal models.

Getting the belt into the groove and staying there and stretching it across to the tape counter drive wheel was quite a challenge, one of those jobs where you need 3 pairs of hands.

David

[DMcMahon]

Tape counter now working fine.

Tried a quick test recording into the Phono I (low level DIN input) DIN input, using a Uher K557 cable which drops the phono line signals level down (via 470k resistors) into the DIN connector to avoid overloading the DIN input.

Good strong record signal peaking at 0dB on VU meters at record level 3 and sounded very good when monitored by the internal speakers when switched to Source.

Playback of the recording was poor/strange. It sounds like the original recording is not being erased, the original recording is also at a different speed from the new recording so the 2 together sounds strange. So need to check out why erase is not working.

Pause operation (was working fine) has developed a problem, now when pause is selected the tape takes off as if it is in Fast Forward wind. Think I have experienced this before on another Uher but canot remember the specific reason but something to do with the Pause mechanism mechanical set-up.

One or both of the VU meters illumination bulbs keep going on and off, like a bad connection.

David

[DMcMahon]

Tried another recording test, this time the old recording was erased but there was no new recording so that is confusing when comparing to first recording attempt.

Been looking at why selecting Pause makes the tape drive like Fast Forward was selected but nothing obvious seen yet.

David

[DMcMahon]

Tried another recording using the Phono II DIN input (less sensitive high impedance input) but still no sound on Playback, erase and playback of old recordings are still working.

Looked at the VU illumination issue. Resoldered a few suspect soldered joints at the PCB that is fitted to the rear of the 2 VU meters but no change. From resistance and voltage readings it looks like the problem is internal to the VU meters.

Does not look easy to get inside the VU meters so will come back to this sometime later.

Spent quite some time trying to work out why when pause is selected the tape drives forward at a similar speed to Fast Forward. Can see that the drive idler wheel that drives the Take Up spool when Play is selected is also driving the Take Up spool when Pause is selected, although cannot work out why the Take Up spool is driving so fast in Pause

I think I will need to have a comparison with another of my Uher Royals to hopefully see what the fault is.

David