UHER 4000 Report Monitor

[Charles Norton]

I've got a UHER 4000 Report Monitor and the power board (the one under the battery compartment) is essentially knackered. The power transistors had a habit of blowing after a few months, so you have to de-solder them, put new ones in and re-solder. Except, it's now been done so many times, that the heat-damage has burnt off the tracks on the circuit board, so there's nothing left to solder to.

Where might I find a replacement circuit board? I notice there's some relatively inexpensive UHER 4200 machines on ebay. However, those are very different to my machines, the 4200 machines appear to all have that strange gear-stick type speed control. Mine has the twist knob and it an ex-BBC machine. Might it be worth me buying one of the cheaper 4200 machines from ebay, so I can cannibalise the board from there? Or are the machines just to different for that to work?

I would just buy a new UHER 4000, but the prices appear to have gone up a lot recently.

[Charles Norton]

I notice there's also a very cheap UHER 4000 Report IC. Might that work as a donor machine.

This is the part I'm looking to replace:

https://www.vintage-radio.net/forum/...5&d=1596194042

[Uncle Bulgaria]

(Some) new parts are available from Johann Gruber at uher-service.de and the chaps at SDS-Consult.de. I've used both for spares and have had excellent service.

I would be concerned as to why the transistors were blowing, as that ought not to be the case. Have you checked the power supply conditions, as (though I have no personal experience with the Report Monitor) if they're at all similar to the 4000 Report-L or the CR cassette series I would expect them to see only some nice DC from the mains adaptor, C-cells or 12V car input lead.

[Charles Norton]

Thank you for the links. I will have a look at those. The transistors didn't so much go bang or anything dramatic. The power would just stop working after a while. You'd change the transistor and it would work again. There's two of them in there. One for the mains supply and one for the battery. I think the battery one tended to go more often. In fact, I'd sometimes just swap them over, if I didn't have a spare transistor to hand. The board is properly wrecked now though, as the traces have gone. After soldering and de-soldering that many times over so many years, I suppose it was inevitable.

[DMcMahon]

Seems strange the repeated transistor failures.

Not experienced this on my 4000 Report Monitor or 2 other 4000 Report Monitors that I have worked on, also have not heard similar so think it is not a common problem.

Pretty sure that the Power Supply Regulator PCB (Uher # 021560) used on the 4000 Report Monitor is identical to the board used on the 4200 & 4400 Report Monitors.

The power supply board used on the Report IC is a simpler board, do not know if it could be used on Report Monitor. I think the Report L does not have a separate power supply board but just has power supply components mounted on the back of the battery box.

David

[DMcMahon]

As believed not to be a known/common fault, then can only assume that the reason for the transistors repeatably failing is either 1. a fault on the regulator board or 2. external fault within the 4000 that is causing excess loading.

If the fault is due to scenario 2 then a replacement power regulator board may suffer from the same problem.

David

[Uncle Bulgaria]

I concur. Unless the old board is completely shot, I would make up some wire links for the bust tracks and measure what's going on in use. These are very reliable, professional machines that no-one would have been using if there were regular failures of a simple part of the power supply.

If a new or donor board is not available, I don't suppose it's so complicated that you couldn't make a new one or draw one out to get it made?

[Charles Norton]

Thanks for the advice. I notice that SDS UHER do have a replacement board for sale, but I've not had a reply to my inquiry to them yet. The fact that I've had issues with both battery and mains power do at least suggest something on the board itself.

[DMcMahon]

It did not cause any obvious operational problem at the time but I did have to replace the 2,200uF capacitor C4 on the regulator board because electrolyte was leaking out. It was rated at 10V (shown as 8V on schematic), I replaced it with a 25V

So if you do manage to repair the board it would be prudent to check out C4 and the other electrolytics.

SDS normally are very good at communicating. When I referenced the board number I did not realise that SDS listed it on their price list.

David

[DMcMahon]

Forgot to say that to visually check out C4 without lifting the board up, you have to remove the Supply spool table.

David

[Charles Norton]

Thanks. The machine is getting on a bit now, so I suppose it might be reaching a point where the electrolytics start going past their sell-by dates.

[DMcMahon]

Originally Posted by DMcMahon

Forgot to say that to visually check out C4 without lifting the board up, you have to remove the Supply spool table.

David

This is rubbish, to see C4 just have to remove the top panel.

David

[chartz2]

The real issue with these machines is the capstan rubber wheel. It gets noisy and in my case a NOS wheel was no cure.
Would this expensive wheel work?

https://www.uher-service.com/online-...rad-p309075043

[Nickthedentist]

I think that’s a re-rubbering service being offered.

[TIMTAPE]

I guess yes if it is manufactured with newly vulcanised rubber to the original specs. There must be many of these machines with this same problem. I never tried it but had the idea of having the alloy wheel modded with a machined circular groove to accept a standard industrial O ring in place of the now hardened rubber ring. My only concern would be matching the profile closely enough to the original for trouble free operation.

[DMcMahon]

My 4000 is noisy, particularly at 7.5 ips and my friends 4000 is noisier still.

Sometimes have thought of trying the replacement part sold by SDS, they say they have been refurbised with new rubber to improved spec, but expensive especially if it does not help improve the noise level.

David

[TIMTAPE]

Well if it's been made correctly it should fix both problems: restore the capstan drive reliability without risk of slowing due to slippage, and reduce the noise to original quietness.

[DMcMahon]

Yes agreed. SDS describe the Drive Wheel as "New Production" but I guess an existing Drive Wheel that has had the old rubber removed and the new improved spec rubber fitted.

It is 79 Euro + VAT + packaging + shipping. I might bite the bullet one day and get one.

David