Any UHER buffs out there? Need help with Report Monitor sound

[Dale_Cooper]

HI all,
I have a UHER 4000 Report Monitor and for a while everything was working nicely, then suddenly it has started to sound really bad - i.e. muffled and rather quiet. I also have another the same model and in comparing the two I find this to be distinctly apparent.

I have unscrewed the tape head casing and given the heads a clean. Still nothing. Am stumped why this problem has suddenly come on as I hadn't messed around with anything.
Would anyone have any ideas as to what I should do or what the problem might be?
Thanks if someone can help!! I really want to get this lovely machine sounding good again!

cheers
Coop

[julie_m]

Does the fault affect only playback (including record monitoring with the switch set to "T"ape) or does it also affect what videoistas would call "E-E" (record monitoring with the switch set to "S"ource)? In the latter case, the signal isn't touching oxide, suggesting an electronic fault. Almost certainly capacitors.

Otherwise, if the fault is only apparent when playback is involved, suspect the heads. The rule for cleaning tape heads is: Clean them until they are as clean as you think you can get them, and then clean them some more anyway for luck. Methylated spirits and cotton buds were good enough for the BBC.

How does a tape recorded on the "bad" Uher sound on a good machine? That will indicate whether the problem is with recording or playback.

Listen to a (sacrificial) section of tape on a good machine. Play it about 20 times on the affected machine and try it again on the good machine. If it has deteriorated in quality, that is a sign that the heads need demagnetising.

Good luck with fixing it. These are cracking little machines when they are working well.

[Dale_Cooper]

Cool thanks -
I have just tried recording on the bad machine and playing it on the good machine. It does sound better in the good machine, while playing it back on the bad machine was REALLY bad as i suspected.
So..I guess this is a problem with playback? I have cleaned the heads twice now but I guess I can clean some more. I have been using isopropyl and a lint free cloth. Jeez, they should be clean by now!

To be honest I have been having trouble with this machine since I bought it. When I record into the line in (from stereo outs) and also using the mic input on the front I have been experiencing some low level distortion or 'fuzz',
This has annoyed me greatly - to the point where I could not tell if it was my imagination or not.
I tried recording my friends guitar playing - using a mic and it just sounded...garbage. The technician at my university where I was studying also could hear the distortion and was baffled like me.
So...with this 'newer' problem of a now extremely pronounced distortion and loss of sound coupled with what you said I think it might be the capacitors.

Get this:
The good machine also DOES have some distortion during recording which led me to believe this was normal or I just was not using these machines correctly. Nevermind, if I can get this first machine fixed ..that will be enough. I would really like to try this new capacitors thing though
Do you know the logistics of new capacitors?
I have once been to Geoff Kremer in Bexhill (I am in Brighton) so perhaps he is the man to ask? Else I am open to suggstions.

Many thanks for your help and suggestions ajs!!

Coop

[Refugee]

If it does only sound better when its recording is played on the good machine as opposed to being as good as it is likely to be a part of the amplifier that is common to both record and play.
It sounds like a scope needs to be used to find it.

[julie_m]

It's a three-head machine, so there are separate record and playback amplifiers. What happens if you record a source, but set the monitoring switch to "S"ource instead of "T"ape? This reroutes the playback amp input from the play head, to the output of the record preamp (which goes on to the record head). So, you will be listening through the playback amplifier, but missing out the record head drive amplifier, the recording head, the play head, and the play preamp. If the tapes play OK on another machine, then the fault lies in the play head or something downstream of there. If monitoring from source is fine, then the fault must lie between the play head and the monitor switch. If monitoring from source is affected as playback (or monitoring from tape), then the fault must lie downstream of the monitor switch.

When you get distorted recordings, are you using automatic or manual level control? Setting 1 is for speech, 2 for music. Older tape formulations, or very strong signal sources may need the level set by hand. Pin 3 of the "RADIO / PHONO" input has a lower sensitivity than pin 1. Pin 3 of the front MIC socket is active. Pin 5 is tied to ground in case you are using a balanced, dynamic mic, but I prefer an electret mic.

Service data is definitely available, you may have to pay for it in English but it's available for free in German if you search hard.

[Dale_Cooper]

Ok - this is great. I am too busy today but I will go through these tests at the weekend and get back to you all
thanks for the input folks!!

[Welsh Anorak]

Hi
Having had a couple of these machines I was disappointed with the performance compared with the older Reports - there's certainly some distortion, especially via its internal speaker.
I'd be inclined to remove the head block to the extent of its wires and give the heads a really good polish and inspection. Common circuitry such as the bias oscillator can be ruled out as it appears to affect both recording and playback.
Reading through AJS's suggestions above I thnik you'll soon find the problem.
Glyn

[camtechman]

Have you tried playing the machine from the output socket into a separate amplifier?

If so, does the distortion remain the same?

Although unlikely, and I have this with two Uhers, the speaker has been known to cause the problem, more so at low volume.

[Dale_Cooper]

Originally Posted by ajs_derby

It's a three-head machine, so there are separate record and playback amplifiers. What happens if you record a source, but set the monitoring switch to "S"ource instead of "T"ape? This reroutes the playback amp input from the play head, to the output of the record preamp (which goes on to the record head). So, you will be listening through the playback amplifier, but missing out the record head drive amplifier, the recording head, the play head, and the play preamp. If the tapes play OK on another machine, then the fault lies in the play head or something downstream of there. If monitoring from source is fine, then the fault must lie between the play head and the monitor switch. If monitoring from source is affected as playback (or monitoring from tape), then the fault must lie downstream of the monitor switch.

Hi - thanks ajs derby, only just had the time to have another go at finding out this problem.

On the bad machine with record/pause/play set downand listening to the line in from audio interface - Set to 'S'ource I have to turn the Rec volume all the way up to 9 for the needle to get to the middle. Switching the ALC from 1, 0 or 2 does nothing different- no change in sound.
Switched to 'T'ape there is also nothing. Where on the 'good' machine there is still a quieter level on 'T'ape, on the bad machine there is nothing.

Playing back the recording on the bad machine is the same. really quiet, muffled like its underwater. On the 'good' machine it still sounds quiet but not so awful like on the other one.

Also, on BOTH machines is still this soft distortion more audible at low volumes - a problem since the beginning i would really like to clear up

Really crazy!

camtechman - thanks for the suggestion - tried another amp but still no change in sound

I might try Geoff Kremer in Bexhill - see if he can help fix it
thanks guys - any other ideas greatly appreciated!
DC

[julie_m]

With the tape paused and the monitor switch on "T", you shouldn't get anything at all coming through; since the tape on which you have just recorded a signal hasn't gone past the play head yet. (You may get a very faint signal, due to unwanted coupling.)

With the tape moving, you should get a good, strong signal delayed by a few centimetres' worth of tape (speed dependent; the delay will be longer at the low speeds) and (unless you are using extremely good tape!) you should be able to take this into audible distortion by turning up the recording level (with ALC off, obviously).

But even with the tape paused, you should get a signal coming through with the monitor switch on "S" and the recording level turned up (or the ALC set to "1" or "2"). The fact that you aren't getting that on one machine, suggests a connection fault.

Assuming that you used exactly the same cables with the "good" machine, then suspect the input socket of the "bad" machine. Hopefully it will be nothing more serious than a dry solder joint.

I suspect that there are two issues here. Firstly, there is the above-mentioned connection problem. Until you fix that, you won't be able to get a decent recording out of that machine. And secondly, the playback head of the "bad" machine has become magnetised. This is a common problem with three-head recorders -- the play head never sees the recording bias current, so it doesn't get self-demagnetised during recording.

What does a tape recorded on the "good" machine sound like when played on the "bad" machine?

[Dale_Cooper]

Originally Posted by ajs_derby

With the tape moving, you should get a good, strong signal delayed by a few centimetres' worth of tape (speed dependent; the delay will be longer at the low speeds) and (unless you are using extremely good tape!) you should be able to take this into audible distortion by turning up the recording level (with ALC off, obviously).

But even with the tape paused, you should get a signal coming through with the monitor switch on "S" and the recording level turned up (or the ALC set to "1" or "2"). The fact that you aren't getting that on one machine, suggests a connection fault.

Just tried this again on the bad machine - with the tape paused, set to 'S' I am getting signal both with the recording level up and on the ALC set to 1 and 2 - so i guess not the connection fault

Originally Posted by ajs_derby

What does a tape recorded on the "good" machine sound like when played on the "bad" machine?

Really bad. Any tape sounds awful on the bad machine

Can I get a demagnetizer somewhere like Maplins? Like the ones used for screwdrivers?
ta

[Dale_Cooper]

Need to bump this - would anyone know about demagnetizing the heads?
Thanks - DC