Trying to fix a Uher Report Monitor 4000
 

I recently got a Report Monitor 4000 and it's not powering on. It apparently worked before it was shipped to me but once it arrived it didn't.
I opened it up and discovered the power supply got damaged, the voltage selector popped off. I put in some batteries hoping it would work but it still didn't turn on.
Anyway, I took out my multi-meter to start taking measurements trying to pinpoint where the issue was. I measured the voltage in TP1 which is supposed to be 4,9 V but it read 0 V. I'll attach a picture of the board to make sure i'm measuring from the right spot.
At this point I don't know how to proceed since I don't have a schematic of that board and i'm not really experienced in fixing these kind of electronics (I've repaired guitar electronics and pedals)
Could someone point me in the right direction?
I want to try and fix it myself but if that fails I'll probably try finding someone to fix it.

Referencing the image: power from the batteries gets to the board fine, I'm measuring the voltage coming out of the terminal with the red and white cables for the positive and the terminal with the black cables as negative. I'm quite sure I'm doing it right but please let me know if I'm not.

Re: Trying to fix a Uher Report Monitor 4000
 

If you take the top plate off you will see on the other side of the board in your picture a 2200uF capacitor which is the main reservoir capacitor for the machine - that may be the source of your problems. If not there is presumably something amiss in the regulator circuit which it feeds.

Re: Trying to fix a Uher Report Monitor 4000
 

I just checked the capacitor and it is shorted, I checked the one in the mains adaptor and it is blown as well. I saw another one in the main board (that one seams to be fine). Should I just go ahead and replace all of these capacitors to be safe? are there any more caps I should look out for?
Thanks

Re: Trying to fix a Uher Report Monitor 4000
 

Not sure what you mean by "voltage selector popped off" are you talking about the power adapter (probably a Uher 124A) do you think it has blown up ? Was the adaptor fitted in the battery compartment or was it connected by D type cable connection to the 4000 ?

Attached is PDF section of the 4000 power supply circuitry. The 2,200uF capacitor barrreter references is C4, photo of it is attached (the Gold Frako capacitor), measuring across the capacitor you should see a voltage higher than the +4.9V

Re: Trying to fix a Uher Report Monitor 4000
 

If they are also Frako capacitors then they do have a somewhat general bad reputation on old units. I personally would only change if they measure or look bad, some people would recommend to change all Frako for future reliability/peace of mind, it is up to you really.

Frako are often Gold coloured or other bright colours.


David

Re: Trying to fix a Uher Report Monitor 4000
 

I have never had a problem with them, but Tantalum capacitors often get a bad name, there are many in the 4000 (not Frako) would be worth checking C2 (22uF) & C1 (47uF) on the +4.9V output.

David

Re: Trying to fix a Uher Report Monitor 4000
 

Yes, replace them. The easiest way with the one inside the machine is to snip off the leads very close to the body of the capacitor and solder the leads of the new capacitor to them. Make sure that you get the polarity right. A perfectionist would unsolder the capacitor leads from the board. In the outboard power supply you may be able to fit a slightly larger value of capaciitor if you want to. You may also find that the little regulating circuit has self-destructed. The Z124s often turn up on eBay for not a lot.

Re: Trying to fix a Uher Report Monitor 4000
 

By the voltage selector I mean the little wheel that lets you select between 110 and 220 V in the 124 A. I don't know what happened to it but it was a fairly easy fix. Once I reattached it there was still no power coming out of the unit. I checked the capacitor, one of those Frako 2200uF you mentioned and it was shorted so I'll have to replace it. The power adaptor was fitted in the battery compartment.
Anyways, thank you for the information, I'll probably just replace the ones that are not measuring right.

Re: Trying to fix a Uher Report Monitor 4000
 

Yes, I should have said just the two that are short circuits.

Re: Trying to fix a Uher Report Monitor 4000
 

Looking at the Z 124A schematic, I guess it is C4 which shows as 2,000uF, 16/18V. In my Z 124A it like yours is 2,200uF rated at 16V (an Elko not a Frako).

Power supply schematic shows its C4 rated at 8V, I have just replaced one of these C4's due to its capacitance being very high (actual rating 10V) with a 25V rating.

Make sure for the Z 124A C4 you do not use too low a voltage rating, i.e. if you have 12 volt 2,000/2,200uF, would be OK for the 4000 Power Supply board but no good for the Z 124A.

David

Re: Trying to fix a Uher Report Monitor 4000
 

Based upon your experience of C4 going short circuit in the your Z 124A, I thought it would be good PM (Preventative Maintenance) practice to replace my C4.

Of course while getting to it, 3 of those small solid core wires broke off at various places >:(

Even before the wires broke, I could see a wiring difference to the schematic. The schematic shows the +ve output connecting to pin 2 of the 5 pin D type Bu 1.

In my Z 124A the +ve output connects to either pin 4 or 5 of the D type, this seems incorrect.

I was planning to wire up a cable to connect the Z 124A D type to the 4000 Accessory Input DIN for when not using the Z 124A in the battery compartment. So need to double check all the wiring now and get it correct.

David

Re: Trying to fix a Uher Report Monitor 4000
 

The bridge rectifier in your picture is actually selenium which must mean that your Z124 is a pretty old one. I have a Z124 and a Z125 and they both have a B40C1500 bridge rectifier made by Herrmann. These are still available on the internet at a very reasonable price. As far as the DIN socket (I presume your "D type" means this rather than the 1955 Le Mans winning Jaguar!) is concerned they are both wired as per the Uher circuit diagram. The capacitor, by the way, is C1 even though the diagram on the internet makes it look like C4.

Re: Trying to fix a Uher Report Monitor 4000
 

Hi barretta,

Yes thought it was Selenium, it is a Herrmann B 30 C700. Good to know your adapters are wired as per the schematic.

Seems strange mine is mis-wired (hard to believe), still to double check all the wiring.

Silly of me calling DIN connectors D type, maybe another senior moment or maybe a very old memory from when I worked on warships and majority of equipment I worked on used D type connectors.

On the Z 124A schematic I have, the capacitor is clearly shown as C4, C1 is shown as a 200uF, how do you know it is actually C1 ?

David

Re: Trying to fix a Uher Report Monitor 4000
 

Well, this the diagram I have : there is only one capacitor in the Z124A1..

Re: Trying to fix a Uher Report Monitor 4000
 

Ah, I've just found a diagram for the Z124 which does contain more capacitors than the Z124A1 but it looks to me that your photo is of a Z124A1. Is that the case?

Re: Trying to fix a Uher Report Monitor 4000
 

While I can't shed any more light on the Z124 as mine is inaccessible at present, it appears the Z131 (the CR 240 PSU) is similar in having more capacitors than the diagram suggests. I replaced the large 25V/2200µF across the output, but there are a couple more visible in the photograph which are not there in the diagram.

The Z124 does appear altogether more complex than the Z131.

Re: Trying to fix a Uher Report Monitor 4000
 

I've now found a picture of the inside of a Z124 and it does look like David's whereas mine is the later A1 version which definitely only has the one capacitor and mostly silicon rather than the germanium transistors in the original Z124.

Re: Trying to fix a Uher Report Monitor 4000
 

I think that's only a part of the circuit diagram for the Z131.

Re: Trying to fix a Uher Report Monitor 4000
 

It would seem so, but the next board to the left is 600, which is inside the CR 240. The entirety of the dotted line marked 'Z131' is the snippet I attached.

Anyhow, I won't drag this off topic from the 4000 Report Monitor. Interesting though! It could be that the Z131 underwent changes (I think this is likely, as this moment I've checked my CR 240 printed diagram from SDS, not PDF, and each of the bridge diodes are bypassed by 47nF capacitors. That would explain my picture)!

Re: Trying to fix a Uher Report Monitor 4000
 

Yes my circuit I have is Z 124A1, I cannot attach due to copyright (radiomuseum.org)

Obviously have been a few revisions of the Z 124A, my drawing shows 4 capacitors with your C1 being my C4 on the drawing. Without removing my little board (which looks difficult) I do not know if my Z 124A has 1 or 4 capacitors, if only one then it would be C1 as you indicated.

David