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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 7th Jan 2020, 6:44 pm   #41
DMcMahon
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

I have never sent a PM before before on this Forum, so wondered if I was doing something incorrect, although it looks simple enough. The fact that you are also having a problem I guess means that there is another problem.
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Old 7th Jan 2020, 7:19 pm   #42
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

Well my email is d3a[valve with five elements]@gmail.com.
You have to replace the part in square brackets with a single word, not a triode, not a hexode.
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Old 7th Jan 2020, 7:59 pm   #43
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

Picking up on the PM points, is there a general problem with PMs on the forum at the moment? I have sent several PMs in the past week, and I know that one didn't arrive, and I've had no reply to the second one (which may mean that it didn't either).

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Old 7th Jan 2020, 10:55 pm   #44
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

Sorry for delay, have just sent email.
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Old 7th Jan 2020, 11:03 pm   #45
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

The email failed on delivery. Is the correct email address d3a followed by the single word ?

I also see one can send an email message from the Forum without entering the email address by selecting your Forum User name and choosing "send email", I will try that now.
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Old 7th Jan 2020, 11:06 pm   #46
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

Ah, that doesn't seem to have worked either. I shouldn't be so cryptic about my email address. I don't like spam.

Last edited by barretter; 7th Jan 2020 at 11:09 pm. Reason: Don't want to divulge my email publicly
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Old 7th Jan 2020, 11:11 pm   #47
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

Ironically the email has just arrived - in my spam folder!
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Old 7th Jan 2020, 11:16 pm   #48
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

Just tried again, the first attempt from my email system was my stupid fault, I had Heptode (5 grids) in my mind for some reason (I think because it says Heptode under your user name), I grew up with valves so should not get Pentode and Heptode mixed up ! I blame it on my age
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Old 7th Jan 2020, 11:49 pm   #49
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

Just for reference, SDS confirmed that K2, K4 & K7 are identical switches.
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Old 8th Jan 2020, 11:10 am   #50
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

After the circuit disturbance of the Logic board and K4 wiring etc, rechecked that recording (from Phono DIN) still works, which it does.
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Old 9th Jan 2020, 5:16 pm   #51
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

Today received the new Playback switch (K4) in the post (many thanks to barretter for providing the switch). See photo image for comparison of the switches, on the right is the new switch where you can see the curved sprung metal piece that is missing on the original switch on the left.

After fitting the new switch, now have normal playback and record, the first time I have heard playback sound on this machine that lasts more than a couple of seconds, quality sounds very good indeed !

So a big step forward at long last. Now need to get back to the frustrating noise and speed issues covered in another post.
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Old 13th Jan 2020, 6:24 pm   #52
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

While still trying to find a suitable rubber band to do more mechanical noise diagnostics, rechecked Playback and Record, all still all OK. But after some playing I noticed that a previous issue has resurfaced, this being the Monitor switch, where in both Source & Tape positions there is no operational difference.

This issue was fixed or at least appeared to be fixed previously when the new Playback switch was fitted (there was also a capacitor replacement at the same time).

At the time I was also suspicious of the 2 FET transistors on the amplifier board that control the Source/Tape switching in the electronics, so will look at them next.

I am still awaiting delivery from Germany of the 4000 circuit diagram and component layout drawing. As it is very difficult (for me at least) to work on the amplifier board (in terms of locating the correct components) without the component layout drawing, I will wait until the drawing arrives (which hopefully will be very soon) before trying to progress this issue.

Last edited by DMcMahon; 13th Jan 2020 at 6:25 pm. Reason: Typo
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Old 15th Jan 2020, 8:10 pm   #53
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

I am still awaiting documentation delivery from Germany, so no more progress yet.
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Old 17th Jan 2020, 10:17 am   #54
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

Documentation just arrived, so now (later) will be able to look at the Source/Tape monitoring fault.
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Old 19th Jan 2020, 12:22 am   #55
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

Had a fresh look at the Source/Tape monitoring fault, using the documentation obtained form Germany, which was a big help.

A little confusing at times because the component layout, views the components from the artwork side of the board, so when working on the component side of the board you have to remember that left becomes right and top becomes bottom etc.

Not 100% conclusive yet, but all tests indicate that both of the E176 FET transistors (T19 & T20) have failed, as previously thought.
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Old 19th Jan 2020, 12:28 am   #56
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

That sounds helpful, and a cheap fix!

Do the documents not show both sides? With the documentation for the CR 240, all the boards are drawn about 1:1 with separate sheets for each board side.
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Old 19th Jan 2020, 12:53 am   #57
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

Just double checked the sheet now (in case I have missed anything), it is a large A2 double sided document, the artwork / component layout section is quite small, just under 1:1 (maybe A5), it shows the artwork side with the components superimposed onto the artwork side.

A proper double sided component layout would have been more helpful, but beggars cannot be choosers
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Old 19th Jan 2020, 9:35 am   #58
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

A pair of FETs have been ordered.
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Old 2nd Feb 2020, 3:13 pm   #59
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

Brief update. Currently have hit a temporary brick wall due to my confusion about the correct pin out for the replacement FETs.

I ordered and received the correct Siliconix E176, but these have a flat on one side and the originals do not, that in itself is no problem.

Currently cannot find a Siliconix E176 data sheet,but found out that the E176 is the same as the J176.

Found a Philips data sheet for the J176, this shows the flat but shows the 3 pins in a straight line, not the triangular arrangement of the new and original E716. My interpretation of the Philips data sheet indicates that the source and drain pins are physically transposed over, therefore to fit would have to bend the source and drain legs over, which in this case does not seem correct.

The Philips data sheet indicates that the Source & Drain are symmetrical p-channel junctions and are interchangeable. This may well be correct, but I would be happier to connect source to source and drain to drain without having to bend the legs the wrong way, especially as FETs potentially are more sensitive to abuse/wrong connections.

So I just need to find a Silconix data sheet for confirmation of connections.
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Old 2nd Feb 2020, 3:32 pm   #60
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Default Re: Uher 4000 Report Monitor Amplifier Component Layout

Siliconix J176 Datasheet.

The Datasheet Archive doesn't list any Siliconix products under 'E'. Have you consulted the place you got them from?
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