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Old 11th Jan 2020, 1:21 pm   #21
ms660
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Default Re: Uher 4000 Report Monitor Noisy

Here's an online converter:

http://www.sengpielaudio.com/ConvForce.htm

That site is good for other stuff too.

Lawrence.
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Old 11th Jan 2020, 2:37 pm   #22
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Default Re: Uher 4000 Report Monitor Noisy

Interesting input. I know Pond as Dutch for pound (weight) the same as Pfund in German.

To me this is the same as p / ilf and therefore by my conversion calculations 75 -85 are far too large.

in the Service manuals looks like p is always given for the units in the English, French & German text sections.

I had to look up kilopond (kp) and see it is the same as kilogram-force (kgf) which I am familiar with, it being just over 2.2 pounds force, so a kilopond cannot be 1,000 Dutch pounds.

Maybe there is another Pond unit, i.e. 1/1,000th of a kilopond, yet to easily find it.
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Old 11th Jan 2020, 2:45 pm   #23
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Default Re: Uher 4000 Report Monitor Noisy

Yes excellent converter ! this indicates that a pond (p) is the same as gram force (gf) so starting to make sense now (of course the big clue which I missed initially was that kilogram-force is the same as kilopond).

Struggling at the moment to find my spring balances to measure it.
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Old 11th Jan 2020, 2:49 pm   #24
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Default Re: Uher 4000 Report Monitor Noisy

At Sony I used to have two spring balances a low tension one for back and take up tension and a higher tension one for pinch rollers, brakes etc.

Lawrence.
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Old 11th Jan 2020, 5:33 pm   #25
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Default Re: Uher 4000 Report Monitor Noisy

Quote:
Originally Posted by DMcMahon View Post
Thank you for those inputs. Unfortunately my friend who owns the 4000 likes to do a lot of microphone recording and from a couple of microphone recording tests I have done, the recorded noise is noticeable.

I have not yet had a chance to do any more investigations, but having just done a quick conversion calculation from ibf to Newtons, realise that something is incorrect, as the average of 76 - 85 ibf is around 360 Newtons which is far too high (I thought 75 - 85 ibf sounded high) ?

It is certainly sounding like a NOS Drive Wheel may be the only way forward to improve the noise level. There are some second hand ones on eBay.de where they say they are good condition, but that is probably a large risk.
I should have said that the noise when recorded on microphone can be heard on the 4000, if listening on headphones or if the tape is played back on another machine, but when recording is played back on the 4000 when not listening on headphones, then the noise on the recording is drowned out by the real time playback noise from the mechanical drive.
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Old 11th Jan 2020, 6:23 pm   #26
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Default Re: Uher 4000 Report Monitor Noisy

After more flap C tweaking, now getting all 4 speeds operating consistently and also all 4 speeds only driving when Start pressed.

No idea what gap there is, as have not found any practical way to measure.

Tried tweaking the spring tension but could not improve the noise level, still cannot find my spring balances, so cannot attempt measuring the pressure of the flywheel onto the Drive Wheel.

The noise level remains bad on top speed (19 cm/s), noise is also present but at much lower level on speed 9.5cm/s.

I will double check that recording and playback are still good, then hand the 4000 back to my friend, and advise if he is not happy with the mechanical noise level, that I then advise that the Drive Wheel be replaced by an NOS part (I see on eBay Switzerland also sell them).

I will tell him that he if wants to save money he could try a second hand part from eBay, but at quite large risk that old replacement part may not be much better than existing part.

Knowing him, he may cut his loses and sell it on for small profit, if he is not looking for too much profit, I may be interested in buying it as I do quite like it (would prefer a stereo one though).
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Old 11th Jan 2020, 9:51 pm   #27
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Default Re: Uher 4000 Report Monitor Noisy

A working 4200 Report Monitor is going to be expensive. You can pick up BBC "modified" ones more cheaply but "modified" means really badly mangled and very hard to return to its intended state. 4400s are cheaper but quite thin on the ground at the moment.
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Old 11th Jan 2020, 10:35 pm   #28
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Default Re: Uher 4000 Report Monitor Noisy

Thanks for that, I do not like the sound of badly mangled, even though they have some quite nice engineering they are rather delicate, so I would guess that they would not take a lot of abuse before being troublesome.

I asked SDS if they were selling any NOS 4200/4400s and they said all sold, just the 4000 Remote Monitor AVs left.
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Old 12th Jan 2020, 1:17 pm   #29
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Default Re: Uher 4000 Report Monitor Noisy

Why are the 4400's cheaper, are they deemed not to be as good ?
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Old 12th Jan 2020, 1:24 pm   #30
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Default Re: Uher 4000 Report Monitor Noisy

Did you try what I mentioned earlier - putting a rubber band around the wheel and seeing if that makes a difference to the noise? If the softer interface makes a dramatic change, you know that a new, softer wheel will be worth the cost.

Can one of the rubber-roller people (like Terry in the US) repair these? I wonder what the process is. I thought it strange there weren't more people doing it, as my impression of Terry's is that he is doing it as a semi-hobby rather than on some giant expensive machine so it might be possible to DIY.
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Old 12th Jan 2020, 3:22 pm   #31
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Default Re: Uher 4000 Report Monitor Noisy

No not yet as such. I did try some soft insulating tape which made the noise worse.

As I see it the contact between the rubber bonding on the Drive Wheel to the flywheel metals treads is the rubber on the back of the Drive wheel not the top (wider) section of rubber around the wheel. So if a rubber band is put around the wheel, to me it appears that the Drive Wheel treads will make little if any contact with the band (unless the band overlaps the edge of the Drive Wheel), let me know if I am looking at this incorrectly somehow.

I am also planing to temporarily put on (somehow) some self- amalgamating rubber tape to see if the noise level changes.

When I have previously looked at Terry for other R2R rubber repairs the cost looked very expensive (for what it was) but maybe need to look again and ask for a price quote for the 4000.

Have now found (literally now) my spring balances so will be able to do the pressure check of the Flywheel onto the Drive Wheel.
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Old 12th Jan 2020, 5:30 pm   #32
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Default Re: Uher 4000 Report Monitor Noisy

Quote:
Originally Posted by DMcMahon View Post
Why are the 4400's cheaper, are they deemed not to be as good ?
I think it's just preference for half-track over quarter track recording. Certainly for playback a 4400 makes more sense as there are very few pre-recorded half-track tapes on 5" reels out there ; and all those twin track World Record Club mono reel-to-reels can be played on the 4000 as the heads are actually half-track rather than full-track like a Nagra 3.
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Old 12th Jan 2020, 6:24 pm   #33
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Default Re: Uher 4000 Report Monitor Noisy

Thank you, that makes sense.
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Old 12th Jan 2020, 7:57 pm   #34
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Default Re: Uher 4000 Report Monitor Noisy

Tested flywheel pressure onto drive wheel using spring balance. Had to first unscrew the 2 screws that hold the amplifier board hinge brackets to get access to point (E) as per Service manual 3.1.7.2

With board pulled out of the way, then quite easy to hook spring balance to point E area. As expected not easy and somewhat subjective to determine the point at which the drive wheel is not driven by the flywheel and note the spring balance reading at that time.

After lots of attempts, happy that got in the right ballpark and adjusted tension spring for a final value of nominal 80 grms ((80p (pont) as per manual)).

I tried a range of pressures around 70 gms (could not really get much lower than that) up to to around 140 gms, but no matter what pressure was set by the tension spring, the noise from the drive at 19.5cms never detectably changed, i.e. always loud.

I had read on one of the German forums, that if application of rubber restorer does not help that a second application of rubber restorer may be beneficial. So I tried a second application and no noticeably change (as really expected).

Next am going to try separately, rubber band & self-amalgamating tape to see if noise level changes.
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Old 12th Jan 2020, 8:04 pm   #35
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Default Re: Uher 4000 Report Monitor Noisy

A 2-track machine spreads the recording across more of the width of the tape than a 4-track machine. This means more individual oxide molecules are used to record each moment in the signal; and this in turn means the effect of one or two rogue ones will be lessened, as each molecule now represents a smaller proportion of the signal. But a 4-track stereo machine can play 2-track stereo tapes (although it will ruin them if you try to record new programme material over them, since you will only be erasing and replacing half of the original recording; single-sided recordings made onto bulk-erased tape will be playable, but with a worse signal-to-noise ratio due to the unrecorded width, on a 2-track machine).

The small maximum spool size means economy of tape becomes a more important consideration. I'd guess, if I had to, that reducing the track width has less overall impact on recording quality than reducing the speed. Reducing the speed limits the maximum recordable frequency depending on the head gap (which is fixed); a narrower track is just more vulnerable to noise and drop-outs due to uneven oxide particle distribution in cheaply-made tape (and you can really pay your money and take your choice with tape formulations). I'd expect the 4400 at 19cm/s. not to have quite as good a signal-to-noise ratio as the 4200 at 19cm/s., but it probably has a better HF response than the 4200 at 9.5cm/s. when using good-quality tape.

A stereo cassette squeezes 4 tracks into a tape width of just 3.8mm. as opposed to 6.3mm., so the four-track Uher has an extra 0.6mm. available per track, even if we end up using some of that space to give a wider guard band between recorded tracks and so reduce crosstalk. And cassette has a standard speed of 4.75cm/s., whereas your Uher will go all the way up to 19.
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Old 12th Jan 2020, 8:48 pm   #36
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Default Re: Uher 4000 Report Monitor Noisy

Thank you for the expert information.

So are you advising, do not buy a cassette deck
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Old 12th Jan 2020, 10:48 pm   #37
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Default Re: Uher 4000 Report Monitor Noisy

Tried a rubber band around the top of the Drive Wheel, no change but there is no contact between the rubber band and the flywheel metal treads.

Tried to position the rubber band so that it overlapped the edge of the drive wheel, so that the flywheel could make some contact with it, but due to the narrow width of the rubber band, every time I tried to get it to overlap all around the circumference, the band would come off (tried numerous times, most frustrating), before it could be tested.

Gave up with the rubber band until I find a wider band to try.

Wrapped some self-amalgamating rubber tape around the outside circumference of the Drive Wheel, so that there was an overlap that sort of wrapped over the edge, not easy as the tape is not naturally sticky, although if pulled tightly, the tape will sort of stick to itself.

With the self-amalgamating tape fitted the noise was noticeably worse, more of a knocking sound then, I got similar results days ago when I used soft insulating tape.

So results either way not really conclusive, will try again when I find suitable size rubber band and would like to try the amalgamating tape again with a cleaner/tidier adhesion.
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Old 20th Jan 2020, 11:53 pm   #38
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Default Re: Uher 4000 Report Monitor Noisy

Today got a bag of miscellaneous rubber bands, if I can get one to temporarily fit on to the Drive Wheel, I will have another look at the noisy drive later tomorrow..
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Old 22nd Jan 2020, 6:42 pm   #39
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Default Re: Uher 4000 Report Monitor Noisy

Tried 2 different rubber bands around the circumference of the Drive Wheel, so that there was an overlap, but no improvement to noise level, however even though the bands were quite a tight fit, the overlap still got pushed back during rotation, so that the Drive Wheel hard rubber was still making contact with the Flywheel tread.

So unfortunately not a conclusive test either way. Tried again with self-amalgamating rubber tape but once again inconclusive results.

Gut feeling is that most of the noise is due to the Drive Wheel hard rubber.
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Old 13th Feb 2020, 10:28 am   #40
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Default Re: Uher 4000 Report Monitor Noisy

After handing back to owner he appears to be happy with the mechanical noise level.
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