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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 2nd Aug 2020, 5:32 pm   #21
DMcMahon
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Default Re: Trying to fix a Uher Report Monitor 4000

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Originally Posted by DMcMahon View Post
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
Fitted new C4 (or maybe C1) 2,200uf 25V.

After unravelling the tight wiring and double checking all the connections, found that the +ve output does correctly connect to pin 2 of the DIN connector (i.e. C4 +ve connection). But one of the connections to -ve side of C4 connects back via a red wire to the little lamp on the PCB, this is totally different to the schematic. The schematic shows the lamp connecting to pin 4 of the DIN connector but pin 4 connects elsewhere on the PCB (without a difficult strip down to view the PCB components better, impossible to determine where exactly).

As this is how it is wired decided not to try and change anything. Have never seen the lamp light, I assume this is because it in on the charging circuit, rather than being a power on indicator. Re-assembled and fixed broken wires, a really tight fit making everything go back in correctly

Wired a DIN cable and tested it out on my 4000 all OK.
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Old 2nd Aug 2020, 7:35 pm   #22
barretter
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Default Re: Trying to fix a Uher Report Monitor 4000

I think the supply you have is halfway between the original Z124 and the Z124A1, which I have and which does not have a lamp nor the AC176 transistor. Mine also has an all black plastic case with no metal inserts for the retaining screws. The Radio-Museum circuit diagram shows only one capacitor in the Z124A.
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Old 3rd Aug 2020, 8:31 am   #23
DMcMahon
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Default Re: Trying to fix a Uher Report Monitor 4000

I think mine may be the Z124 A1 version (even though identified as Z124 A) but a little different to your A1. Is yours actually identified as Z124 A1 ?

Until you said you had the A1 version I did not really realize there was an A1 version.

My schematic says Z124 A1 at the top of the page and Z124 at the bottom. When I originally downloaded it a couple of months ago I thought I was on the Z124 A web page but now when revisiting see that Z124 A gives the single capacitor schematic version (similar to Z 124 version) and Z 124 A1 gives the 4 capacitor schematic version.

From what little I could see of the PCB components it possibly looked like it had 3 capacitors (making 4 in total including the 2,200UF C4). I say possibly because they could have been Germanium transistors but it looked like there also were 3 Silicon transistors.

One of the possible capacitors had C1 stamped on it, obviously the circuit component number designation would not normally be stamped on the capacitor body, so the C1 could have been some other designation.

The underside of mine has been butchered (and very roughly glue repaired) where someone must have smashed it open to gain internal access, not realizing at the time that the top cover can easily be removed by removing the 4 screws (I guess then the screws would have been covered/hidden by the stuck on label).
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Old 3rd Aug 2020, 11:45 am   #24
barretter
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Default Re: Trying to fix a Uher Report Monitor 4000

I posted the circuit diagram of the Z124A1 higher up in this thread and it only has the one capacitor. It is the Z124 which has 4 capacitors. The Z124A also only has one capacitor - look at the diagram on Radio-Museum. I think the C1 you are seeing is part of the designation of the AC176 germanium transistor which is in the Z124A supply but not in the Z124A1
I append a picture of my 2 supplies. I can't see any difference between them but the Uher book (in German only) which I have on a DVD designates the Z125 as "Amerika".
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Old 3rd Aug 2020, 12:43 pm   #25
DMcMahon
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Default Re: Trying to fix a Uher Report Monitor 4000

Yes I agree the C1 probably is part of the AC176 designation. Some time when I have some spare time (not for a while) I will have a proper look at the board to correctly identify its components.

There must be 2 different different Radiomuseum links for either the Z124A or Z124A1, because the drawing I downloaded a while back which shows 4 capacitors and says Z124 A1 at top and Z124 at the bottom I saw it again yesterday but currently cannot find it.

But anyway I think we have done this to death. If I find anything more of interest to update will start a new Thread so as not take this Thread more off topic.
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Old 3rd Aug 2020, 8:04 pm   #26
AC/HL
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Default Re: Trying to fix a Uher Report Monitor 4000

Radiomuseum schematics can be downloaded on a guest basis if you're not a member.
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Old 4th Aug 2020, 1:33 am   #27
Uncle Bulgaria
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Default Re: Trying to fix a Uher Report Monitor 4000

It's a bit rich as they don't own them and it's not their copyright. I don't think Uher Munchen are going to kick up much of a fuss!
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