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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 3rd Jul 2020, 8:06 am   #41
DMcMahon
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Default Re: Uher 4000 Report Monitor Purchase

The speed change mechanism and control knob arrived from SDS several days back.

I am not going to try fitting the new parts until I sort out the issue with FWD & RWD, do not want to create potentially new problems which could muddy the diagnostics.

So far cannot see a mechanical problem with FWD/RWD, think it is fairly unlikely it could be the motor itself. Will try & have a look at the motor drive electronics, although not sure if I would recognize good from bad.

David
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Old 28th Jul 2020, 3:42 pm   #42
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Default Re: Uher 4000 Report Monitor Purchase

Borrowed my friends 4000 Remote Monitor and am doing a barrage of mechanical and electrical comparisons tests to try and determine why my 4000 is struggling with fast winding.

So far nothing significant found.

As I remembered from when I did lots of work on my friends 4000 a while back, the 4000 motor is not overly powerful and even on his 4000, FWD and RWD struggle somewhat towards the end of fast winding. I think this most likely is a feature of the 4000 design.

My 4000 is definitely worse particularly on FFD winding.

To save battery life and also to be able to easily monitor current drain, I am using my old PSU which is only rated at 500mA.

When my 4000 really struggles the PSU current increases and limits around 670mA and then there is quite a voltage drop.

One small difference I have found (do not really think it is significant) is that my Supply Reel Table is stiffer (with metal cord brake released) compared to his. Stiffer is not the best description but it is less free to rotate, e.g. With empty spool fitted and spun by finger, my one rotates for about 2 seconds, his one for about 5 seconds.

So I have just removed the table to clean up its shaft and lubricate it. Had a bit of a struggle getting it apart due to difficulty disconnecting one end of the brake cord, had to completely loosen the fixings for associated left clutch tensioning mechanism so will have to set that up after refitting the table back.
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Old 28th Jul 2020, 10:37 pm   #43
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Default Re: Uher 4000 Report Monitor Purchase

After cleaning and lubricating, refitted the Supply Reel Table and set the clutch to some nominal setting.

Was not really expecting any change/improvement, so was pleasantly surprised to see that both FFD & RWD are noticeably better, maybe better than my friends 4000.

Whether it was cleaning/lubing the table shaft, the clutch disturbance or something else that made the difference have no idea but great that something did
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Old 29th Jul 2020, 11:48 am   #44
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Default Re: Uher 4000 Report Monitor Purchase

Often making a few small improvements adds up to one big change - for the better. Well done.
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Old 29th Jul 2020, 8:26 pm   #45
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Default Re: Uher 4000 Report Monitor Purchase

I would change that Frako capacitor if I were you.
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Old 29th Jul 2020, 9:00 pm   #46
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Default Re: Uher 4000 Report Monitor Purchase

That is a co-incidence, I measured it last night and its capacitance was really high (even allowing for normal % tolerance), ESR was OK though and I thought (probably due to the fact it was a Frako) that maybe I should change it, to be on the safe side.

It is C4 on the power supply board on the main DC output.

David
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Old 29th Jul 2020, 11:39 pm   #47
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Default Re: Uher 4000 Report Monitor Purchase

New C4 fitted.
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Old 30th Jul 2020, 11:36 am   #48
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Default Re: Uher 4000 Report Monitor Purchase

Well done, David! I'm following this with interest as I have two 4000 Report-Ls to be repaired. One is almost entirely disassembled as my plan is to repaint it, so all the nuts and bolts have to come off. I've resisted doing anything with the other so I have some reference!

I didn't know Frakos were a likely candidate for going off. It's a pity they're so appealing looking compared to the modern equivalents. Sometimes I have an inkling of why people spend £50 on a single capacitor from a boutique supplier - the appeal of the object is too strong!
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Old 30th Jul 2020, 11:41 am   #49
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Default Re: Uher 4000 Report Monitor Purchase

Yes Frako (amongst other names) do sometimes get bad press, I think much if it aimed at the older valve vintage gear both paper and electrolytics.

David
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Old 30th Jul 2020, 2:15 pm   #50
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Default Re: Uher 4000 Report Monitor Purchase

I've repaired a few Uhers (all solid-state) and quite a lot of the Frako electrolytics in them were defective. It's not surprising as they are quite old by now.
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Old 30th Jul 2020, 9:47 pm   #51
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Quote:
Originally Posted by Uncle Bulgaria View Post

I didn't know Frakos were a likely candidate for going off. It's a pity they're so appealing looking compared to the modern equivalents. Sometimes I have an inkling of why people spend £50 on a single capacitor from a boutique supplier - the appeal of the object is too strong!
Yes the Gold Frakos do look attractive.

David
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Old 30th Jul 2020, 9:48 pm   #52
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New C4 fitted.
For good measure also replaced C4 on my friends 4000. Checked 2 other Frakos but measured good and looked good so did not replace.
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Old 30th Jul 2020, 9:58 pm   #53
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Default Re: Uher 4000 Report Monitor Purchase

My brown all leather case looks rather worn and battered compared to my friends black leather composite.
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Old 30th Jul 2020, 10:12 pm   #54
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Default Re: Uher 4000 Report Monitor Purchase

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Quote:
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New C4 fitted.
For good measure also replaced C4 on my friends 4000.
While doing this found a very bad soldered/dry joint at C2, a 22uF Tantalum on the +4.9V supply output.
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Old 31st Jul 2020, 4:46 pm   #55
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It is C4 on the power supply board on the main DC output.

David
Update - On the +5.3 - 7.8V output, not directly on the regulated +4.9V output.
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Old 16th Aug 2020, 12:01 pm   #56
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Default Re: Uher 4000 Report Monitor Purchase

Just making a start at undoing the BBC single speed modification, i.e. go back to normal 4 speeds. Have been unable to find any specific information on required wiring changes.

Have seen that the K4 Start switch and the K7 rewind switch are duplicated (2 of each) so will disconnect the duplicated switches and check that the wiring connections of the remining switches agrees with the schematic.

There is a vague reference in an older Forum thread about wiring changes at the speed changeover mechanism but I cannot see anything obvious so far but will fully check out all the wiring to it after refitting new assembly.
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Old 16th Aug 2020, 9:12 pm   #57
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Default Re: Uher 4000 Report Monitor Purchase

Fitted new tape speed selector switch assembly but having a real struggle getting the wiring connections sorted out, some of the wiring connections are quite different to the schematic, it is not just a simple case of disconnecting the duplicated switches as I had hoped.

Physically difficult to trace where some of the wires connect out to. Not going to be a quick job but I will get there eventually.
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Old 17th Aug 2020, 5:36 pm   #58
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Default Re: Uher 4000 Report Monitor Purchase

After much double checking got all the wiring sorted out and removed the 2 extra switches.

It was looking hopeful, motor powers up when each speed is selected as it should but then found that the Play button would not press down. By removing the speed change mechanism can see that the "widget" part has rotated 180 degrees from its correct position for some reason.

Cannot see how this relates to the Play button not moving. Looks like a big strip down required to investigate further, which does not look easy at all.
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Old 17th Aug 2020, 8:29 pm   #59
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In lots of bits but really struggling to determine why the Play key will not press down, trouble is loads of connected mechanisms and some bits cannot really see.

Everything else mechanically RWD/FFD/Pause/Stop all work OK.

Contemplating trying to remove the keys assembly but looks very difficult so will keep looking elsewhere.
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Old 18th Aug 2020, 8:58 am   #60
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Default Re: Uher 4000 Report Monitor Purchase

Have just found out why the Play/Start key will not move.

When the unit originally had the BBC fixed speed modification done, the machine screws for securing the K4 and K7 switches must have been too short to secure/fix down the additional K4 and K7 (additional switches fit on top of the original switches) so longer screws were fitted.

Yesterday when I removed the additional K4 & K7 (as no longer required) I could see that the screws were long but I could not easily find suitable shorter screws so just refitted the long screws.

I can now see that the screws for K4 must have been screwing down onto/fouling a metal lever that is part of the Play linkage and stopping the Play key from being pressed.

Cannot actually see the end of the K4 screws/that section of the Play lever but by measurement it is obvious this is what was occurring, surprising that I was able to screw the 2 screws for K4 fully down without obvious resistance.

Still cannot find suitable shorter screws, so I will refit the removed K4 switch (unwired) just to take up the excess screw length. Looks impossible to see if the K7 screws would have been fouling on anything but to be on the safe side will also refit the other K7 switch.

Then will re-assemble everything. Need to pay careful attention (in light of finding the widget rotated 180 degrees) to the widget, ensuring that it sits correctly in the channel that it runs along and that the widget driving gear on the speed change assembly meshes OK with the widget teeth, so that the widget moves correctly when speed is changed.

There is no fixed lateral position for the widget, so it is possible to install it in slightly different positions resulting in a different widget tooth meshing with the driving gear wheel. So it may take several iterations of fitting it to achieve correct lateral alignment so that flywheel is in correct contact with the driving wheel for correct operation.

This subsequently may well require adjustments to the "Tab C" on the sliding control member, my previous experiences of Tab C adjustments on my friends 4000 demonstrated that it is a difficult/subjective adjustment.
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