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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 5th Sep 2021, 12:28 pm   #1
KevinT2081
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Default Uher 4200 Report monitor, recording problem

Hi All. I have a Uher 4200 Report monitor on hand, it is a 3 heads version with 2 round VU metres. Currently, playback is OK, but recording does not work. I can clearly near source sound through the radio/phono socket with both VU metres working when switch to "S", but no sound on "T", and no moving of VU metres. When I turn the recording level and input volume to maximum, very very tiny sound can be recorded on the tape. The input is my ipod6, using 3.5mm to 5 pin din (1,2,4), don't have a microphone. I have changed most of the capacitors on the mainboard. Both channels have the problem. Really don't know what to do next. only have a multimetre on hand. Maybe something wrong with the recording amplifyer? or the unit 800 on the schematic? Please give some advice, many thanks. Kevin
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Old 5th Sep 2021, 12:51 pm   #2
Restoration73
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Default Re: Uher 4200 Report monitor, recording problem

Sounds like the bias/erase oscillator is not functioning.

Can you erase a previously recorded tape when set to record ?
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Old 5th Sep 2021, 1:12 pm   #3
KevinT2081
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Default Re: Uher 4200 Report monitor, recording problem

Yes, it can be erased
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Old 5th Sep 2021, 10:51 pm   #4
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Default Re: Uher 4200 Report monitor, recording problem

Has this arrangement with the Ipod worked previously?
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Old 6th Sep 2021, 1:55 am   #5
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Default Re: Uher 4200 Report monitor, recording problem

It is the first time. I tried from my computer and cellphone, but the same problem.

Now I can hear sound and VU moving both on"T" and "S" when pressing the record button only, but still cannot record when pressing the play + record buttons, the recording sound is very very weak, only can be heard under maximum volume. Maybe a bad recording head?
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Old 6th Sep 2021, 11:54 am   #6
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Default Re: Uher 4200 Report monitor, recording problem

What does the very weak recording sound like? Good but just low in volume? Muffled? Distorted? Tinny? How would you describe it compared to the input signal?
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Old 6th Sep 2021, 12:17 pm   #7
KevinT2081
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Default Re: Uher 4200 Report monitor, recording problem

as same as the input, but very very low in volume, with the VU metres no moving. Already turned the input and recording level to maximum.
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Old 6th Sep 2021, 3:09 pm   #8
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Default Re: Uher 4200 Report monitor, recording problem

Is this off tape while recording or just in playback mode?
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Old 7th Sep 2021, 1:12 am   #9
KevinT2081
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Default Re: Uher 4200 Report monitor, recording problem

The weak sound is in playback, off tape is normal as input. Seems something wrong with the recording amplifier? Can both channels break at the same time?
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Old 7th Sep 2021, 10:21 am   #10
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Default Re: Uher 4200 Report monitor, recording problem

I suspect that you are picking up the wrong pins on the DIN socket rather than there being any defect in the recorder.
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Old 7th Sep 2021, 10:34 am   #11
KevinT2081
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Default Re: Uher 4200 Report monitor, recording problem

I tried 1,4,2 and 3,5,2 but neither is working.
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Old 7th Sep 2021, 10:39 am   #12
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Default Re: Uher 4200 Report monitor, recording problem

The meters should move on both record and playback - this is a three-head machine. Obvious things first - give the heads a very thorough clean - you'll need to remove the small cover (two timy screws) first. See if that improves matters. The middle head's the record head, the right one's for playback.
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Old 7th Sep 2021, 12:42 pm   #13
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Default Re: Uher 4200 Report monitor, recording problem

Is playback of a known good recording good both in quality and volume ?

Is the record issue the same with automatic (ALC) recording ?

As well as the heads also would be worthwhile giving the record switch contacts a clean.

It is not impossible but not that likely to have a hard failure with both left and right channels either components or Record head.

David
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Old 7th Sep 2021, 3:36 pm   #14
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Default Re: Uher 4200 Report monitor, recording problem

Agreed - does it play a prerecorded tape well?
This doesn't have ALC as it's a stereo model.
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Old 7th Sep 2021, 4:07 pm   #15
KevinT2081
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Default Re: Uher 4200 Report monitor, recording problem

thank you all for your reply. it indeed plays prerecorded tape normally. Only recording issues. I have cleaned the heads and adjusted the azimuth, but seem helpless. The contact should be ok, because the red light is on when pressing down the record button. Are the L and R channels totally separated? Could be a unit or components that control both recording channels?
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Old 7th Sep 2021, 9:26 pm   #16
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Default Re: Uher 4200 Report monitor, recording problem

Quote:
Originally Posted by Welsh Anorak View Post
This doesn't have ALC as it's a stereo model.
Yes was incorrectly thinking that the stereo 4200/4400 had ALC like my mono 4000 Report Monitor.

David
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Old 8th Sep 2021, 9:32 am   #17
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Default Re: Uher 4200 Report monitor, recording problem

Quote:
Originally Posted by KevinT2081 View Post
Are the L and R channels totally separated? Could be a unit or components that control both recording channels?
The Bias Oscillator circuitry is one obvious area which was suggested in Post 2 and you confirmed in Post 3 that Erase works OK.

The Bias Oscillator produces the Bias signal for recording and the Erase signal for erasing. The fact that Erase is working Ok would normally also mean that the Bias signal for recording should also be good. But to 100% prove it, the relevant signals would need to be monitored on an oscilloscope.

Could also be monitored (but to my mind less effectively) using a volt meter capable of reading the high frequency bias oscillator signals (most ordinary digital multimeters and analogue AVO type meters will not measure the high frequency signals).

What is the history of the unit, was it purchased recently with unknown recording status or have you had it for some time and recording previously was working ?

David
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Old 8th Sep 2021, 2:26 pm   #18
KevinT2081
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Default Re: Uher 4200 Report monitor, recording problem

Many thanks, David. I will check the HF generator first and report back later. the recorder is a new purchase with unknown recording function history, and some resoldering signs in the recording amplifier and related area.
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Old 9th Sep 2021, 11:05 am   #19
Welsh Anorak
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Default Re: Uher 4200 Report monitor, recording problem

This is probably a very trivial suggestion, but are you sure the tape's the right way round? I speak from experience!
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Old 9th Sep 2021, 1:26 pm   #20
KevinT2081
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Default Re: Uher 4200 Report monitor, recording problem

Quote:
Originally Posted by Welsh Anorak View Post
This is probably a very trivial suggestion, but are you sure the tape's the right way round? I speak from experience!
That is a good question. Please forgive my limited knowledge, there is some music previously recorded on the tape which I don't know by this recorder or others. I can hear that under the speed of 19cm/s. The side of the tape facing heads is in a darker colour than the other side. I tried to record on every four speeds, as well as swapped the reels in another running direction, but all failed. I once suspected it was a read-only tape, but have not got any info regarding this. Is it possible the tape has expired and only can be read but not recorded?
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