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Kaidanovsky 19th February 2011 02:53 AM

Uher 4000 Report-L Repairs
 
Hullo all,
I've just got a Uher 4000 Report-L from my Grandfather and various cables. It had a horrible squeal and a start button that wasn't sticking. I've fixed the start button and checked the belts, it plays, changes speed, fast forwards and rewinds. However it still has an intermittent squeal which I think has something to do with the drive wheels. I've taken some of the rubber pieces off the forward/rewind 'see-saw' and they're still squishy and black. I can't see cracks and overall it doesn't give the sense of being dried out and perished. However when rewinding it sometimes finds it hard to get over the tape's resistance and makes a noise like the wheel's not entirely round and is gripping at one stage of the rotation but not the other. Should I replace the rubber bits, try 'rejuvenating' all of them or go over it all with some kind of cleaner? I've adjusted the see-saw with the aid of a service manual but something's still not quite right. Good enough for one evening though! I wondered if any of you had experience with these no doubt common issues for a machine of this age and had some tips 'n' tricks...

I've heard bad things about the capacitors too. Do they blow (I can't see any that have) or are there more insidious faults that require replacement? If so, what are their symptoms and what should I replace them with? The boards don't seem to have any dry joints.

As it's almost working it seems a shame to send it off to a repairman when I'm rather keen to do it myself, so DIY suggestions please!

In anticipation...

indianajo 20th February 2011 04:59 PM

I think you are talking about a tape player or recorder, as Uher doesn't sell in my area. Old tape players are difficult to repair because the rubber dries out and acts differently, even if it doesn't crack. The supply of replacement rubber parts is either a black art or something, except someone suggested one of the semi-pro Teac recorders was still supported. I've got three really nice sony's waiting to be worked over. Besides the rubber, the electrolytic caps dry out and affect sound and volume. My Sony TC250 I was using as a preamp for the turntable got strange, and has about 100 electrolytic caps in it at $.50 each average, so I worked over a disco mixer instead.
I learned a lot about modern electronics from a community college text I found at the charity resale shop, Thomas Floyd, "Electronic Devices, the electron flow version". They may have different useful texts at the community colleges near you. Sixties transistor texts have a lot of calculations in them nobody does much anymore. I already knew about tube circuit repair from "Electronics for XXXDogsXXX Scientists" a 1968 text I received in a college lab. Next time you see Wallace or Grommet, ask whether Electronics for Dogs is really that good. Before working on tube circuits, read the "HV safety for newbies" thread at the top of the tube forum here-. Voltages over 25 VDC can kill you, and should be safely discharged before you touch any metal.

Sorscha 24th February 2011 11:15 PM

Hello,
Rubber normally doesn't go bad in these machines as long as you do not use cleaner, solvents. Also never use oil with these machines on any place else then the capstan bearings (these are rotating, in copper covered, use just one tiny drop from a needle)
I expect you have replaced the belts ? Two on the motor, one on the counter, right ?
The horrible noise: Power on the machine at the highest speed without any reels loaded.
I assume the horrible noise is not there when you power on, machine is in stop position.
Also I assume that you have checked the pinch roller.
press play. If the noise is horrible... stop the right reel drum with your fingers. If the noise doesn't stop, there is a little roller on the left (which is actually the brake and tension in one) move it towards the heads. The left drum should stop (brake is on).
It is also possible that your counter is making this horrible noise: remove the belt.
If the noise is still not gone: Open her up and remove the flywheel plate. If I'm right you only have to remove two screws but it could be possible that the capstan plate is holding another little board that needs support: unscrew it. Remove the capstan and put the machine on its back side. power on again and check functions.
If the noise didn't go away ... touch the brass flywheel when the motor is running if the horrible noise changes .. I hope it's not your motor that needs lubrication ....
On the other hand, if it is one of the reel drums, it is quite an operation to reach them.

I have completely rebuild (and changed in certain stages) the 4200 report monitor. A cd-player should be ashamed of itself. The quality at 7,5ips is quite remarkable with 18hz to almost 26khz quite respectable to say. Test recordings are superb. I did not know that the 4200 report monitor is capable of producing an almost holographic image. I'm still playing with the record-amplifier but oh my goodness :)

Capacitors: Well .. you are lucky in a way as there are not so many cans in there.
But there are lot tantalums. Some can be an issue, as some transistors can.
But Let's hope it's just your counter, as it is very frequent: a troublemaker.
Check these things first please.
Cleaning the rubber: Use your t-shirt. Remove the dust afterwards with your fingers(dry fingers please), you can easily roll it off.

Cheers!
Johan

Kaidanovsky 25th February 2011 07:48 PM

Indianajo: It is a tape-recorder - I'm sorry I didn't make that clear! Those texts sound really rather interesting. Most of my electrical knowledge comes from poking around and A-Level Physics. I've made a few amplifiers (there're some threads on here about my trials and tribulations trying to get a headphone amp to work, and ridding my S.E. 300B of hum) and only have Morgan Jones's "Building Valve Amplifiers" and some 1950s amateur electrical magazines for more audio-related stuff. When I'm with my Grandfather his electrical engineering knowledge comes into play but we're at different ends of England so this can be tricky.

I didn't know the rubber could be so sneaky as to start failing without making it obvious - I've seen enough perished rubber to know when it's definitely gone, but it all looks almost new, though of course it isn't.

Sorscha: I haven't replaced the belts because I took them off and stretched them about (they've got springiness) when I stripped it down to fix the action of the buttons, which as you know are right under all those amazingly designed bits of metal and the excellent hinged circuit board! (I hope it's the same on the Monitor as the way they've managed to fit so much into so little space is phenomenal, while still making it pretty accessible).

Lack of knowledge alert: - what is a 'pinch roller'? This is my first experience with a reel-to-reel and having read up on many different brands this component comes up a lot.

I suppose you can take from that I haven't checked it! :-P

Thank you for the thorough 'trouble-shooting' tips - they've been very helpful.

I've been doing some further digging and it turns out that the noise seems to be located in the fast-forward/rewind see-saw. It happened before I adjusted it so I don't think I've exacerbated it. From prodding around it may be that the bearings that take the axle through the metal plate are dry, meaning they squeal and drag the washers around against the metal angle. I attach a photo in case it's different in the 'Monitor'.

I'm wary of lubricating it as in my student lodgings I haven't any oil to hand that would be suitable, only bicycle grease! I also wondered if they were some of the 'sintered bearings' mentioned in the service manual, which seem not to need lubricating. I'm unsure as to how this method of manufacture allows continuous lubrication from the metal, but I expect the engineers knew what they were doing!

If you think they need oiling then what sort of lubricant should I use? I shan't put anything on there without clearing it here first as the service manual is adamant on that point...

I've cleaned the rubber with the t-shirt, cotton bud and finger method. I had read bad things about lubricants and the rubber in these tape machines, so hadn't put any on and am certain it hasn't had any on in the past as I know its history.

Many thanks for both your replies!

I'll clean the tape heads now as per the instructions in the service manual as they're full of dust...

Sorscha 25th February 2011 08:35 PM

A pinch roller ...
In order to get the tape moving into play mode you have the flywheel, which is also the capstan. It is this parts that determines the tape speed.
Now, in order to get the tape moving the same speed as the capstan there is a rubber wheel that can be controlled on or off by the pause button. If you remove the metal plate above the function keys you'll see what I mean. It is this part that goes bad often due to cleaning or bad use, or bad storage.
But most Uhers are fine as these are high quality machines. Hey hey, if you think that there's little space left, you should see a Nagra or Stellavox :)
All by all I think it is fine. The only rubber thing that could go bad is the rubber on the flywheel. (it hardens). You will notice that by the noise it makes when engaging play mode. If you hear your capstan, replace it, or have the rubber replaced by Terry's rubber rollers. Your machine may cosmetic not miss beautiful, but the sound is, as every Uher is a kind of masterpiece. Build to last if you are good to it.
Capacitors: When a recording played back sounds exactly the same as the source it is fine. If it's not, it either needs cleaning or adjustment. Btw, clean the heads and tape path after each tape ! If the sound is not as expected, first check the heads, clean them and check again. Renew the cans (electrolyts) anyway. First of all the power supplies. Then the main amplifier. Please stay away from the record an playback amplifiers.
I think your machine isn't in a bad shape. With some care you will have a fine little machine.

Kaidanovsky 25th February 2011 09:47 PM

Well, I did have a photo but can't find it now. Always the way. Thanks for that introduction to pinch rollers - I took off the cover and can see it. Any particular things I should be looking for to see if it's dead? It looks very round and there're no signs of gooiness, which I assume is a good sign! Thanks also for that Terry's Rollers site - what a resource! If all goes to pot I know where to go. I was considering casting some more rollers myself if they turned out to be the problem, but I'll try and fix the bearings first and see if that gets rid of the noise. What lubricants have you used on your rebuilds? I expect even sintered bearings lose their lubrication after 50 years, so any suggestions on special oils will be much appreciated.
I haven't cleaned the heads yet as I can't find any isopropyl alcohol, so I'll have to try and buy some tomorrow.

indianajo 26th February 2011 09:59 AM

When you go to the drugstore (UK=chemist) for the isoprophyl alcohol, pick up a pint of mineral oil laxative. It is a straight chain parefin oil with no additive except tocopherol which is Vitamen E oil. I'm using it in my Hammond organ for lubrication in place of the mythical (after bankrupcy) "hammond oil". You also might want some cotton tip sticks for lubricating, "Q-tips" in the US. Sintered bearings are copper etc powder all melted together, porous as a result and traps oil. After 40 years, though it might need a drop. Watch no oil on any rubber parts or felt clutch/brake parts.

Kaidanovsky 26th February 2011 05:49 PM

Cheers indianajo - that sounds just the ticket. I'll see what I can find. It seems even Isopropyl is becoming difficult to find here as the 'nanny state' thinks we might drink it because it's got alcohol in the name and hurt ourselves. Sigh.

Kaidanovsky 13th March 2011 04:36 AM

Right, got the isopropanol and the mineral oil. With a dab or two on those sintered bearings the noise seems to have vanished and everything sounds much smoother, so many thanks for that tip.

Now it seems the trouble of forward/rewind not working properly hasn't been fixed. It seems like there just isn't enough friction and during my test today I discovered that while the motor was spinning all right, it wasn't driving the belt. I assume this was because the friction between the driving forward/rewind roller was too great for the brass wheel on the motor to grip the belt. Is this an indication that the belt's gone and I ought to get another or could it be an underlying problem? Is this something you've had happen with a Monitor?

techueu 26th March 2011 04:00 PM

Hi All!
I'm new to the forum but not to Uhers. I have several in my collection, so I'm familiar with most of the typical problems, you folks have been talking about. The main problem with Uhers is simply aging of the rubber components, becoming dry and glazed. The first part of any restoration should be a new set of belts and then go from there. If you have wheel problems I can also recommend Terry's Wheels web site, excellent job at reasonable prices. But just my two cents!


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