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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 29th Mar 2020, 2:19 pm   #41
ms660
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Default Re: Uher 724L

Voltmeter.

Lawrence.
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Old 29th Mar 2020, 2:50 pm   #42
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The fact that the power on indicator is not working, could just be its lamp/bulb being defective.

Depending upon it accessibility you could monitor the 2 connections on the back of the power on lamp holder, it will be an AC voltage, do not know its level, probably greater than 20 volts (but less than 30) I would guess. This supply comes from the secondary winding of the combined motor/mains transformer and will be live with the unit switched on and both internal fuses not blown.
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Old 29th Mar 2020, 2:51 pm   #43
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Don't have one. Not really wanting to mess about with this, not qualified to do circuits. Thanks though : )
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Old 29th Mar 2020, 3:02 pm   #44
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No, there appears to be no power indicator light on this. Maybe the bulb is dead too but there would still be sound if everything else worked?
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Old 29th Mar 2020, 3:49 pm   #45
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Default Re: Uher 724L

Fair enough, understood.

What is the red button/indicator on lower right of top panel as shown in photo 3 in Post # 8 ? Record On/Off button ?
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Old 29th Mar 2020, 3:53 pm   #46
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Hello. Its the record button, you hold it down while engaging play (and pause, I think).
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Old 29th Mar 2020, 3:57 pm   #47
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I am guessing but the power on indicator maybe (effectively) the VU meter illumination lamp because the schematic does not appear to show a separate lamp for the VU meter.
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Old 29th Mar 2020, 4:37 pm   #48
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Yes, think so. When the top plate was off, there was a bulb adjacent to the VU
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Old 29th Mar 2020, 5:26 pm   #49
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Looking at the electrical schematic more, I believe there are at least 6 fusible resistors in the electronics. Fusible resistors are fast acting safety fuses but in resistor form.

I say believe because the schematic is difficult to read clearly due to poor quality.

There are 2 on the power supply board, one feeds a voltage supply to the bias oscillator, so if fused then the Erase & Record heads would not work, it also powers the VU meter circuitry. The second one if fused would remove power from the Record and Playback amplifier circuitry.

The other 4 are used on the left and right channel output stages of the Playback power amplifiers (2 per channel) any single one fusing would result in that channel having no sound to the respective speaker.

Note however that the power on/VU meter lamp should still light even if 1 or more fusible resistors have failed.
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Old 29th Mar 2020, 6:19 pm   #50
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Default Re: Uher 724L

For Rewind not working could be due to a number of mechanical issues:-

1. Drive belt G slipping on motor pulley A or slipping on friction wheel H due to belt being loose/stretched.
2. Friction (idler) wheel H slipping on left hand clutch disk (reel table) due to hard rubber, worn rubber, friction wheel not levering over correctly etc.
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File Type: pdf 724 Rewind.pdf (248.8 KB, 37 views)
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Old 29th Mar 2020, 7:48 pm   #51
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There's possibly a missing belt, can only see three

I think it's all repairable, assuming the parts are still available (assuming it's just components).
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Old 29th Mar 2020, 8:02 pm   #52
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Default Re: Uher 724L

If it goes into FF and play then rewind should work, if it doesn't then as David says it could be a slipping clutch nut more likely is that the pulley H is not moving to the left enough if it is at all due to hardened grease.

If you're missing any belts than most likely its the counter belt.
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Old 29th Mar 2020, 8:02 pm   #53
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Default Re: Uher 724L

Well spotted BUT I extracted the wrong figure out of the manual ! correct figure showing 3 belts now attached.

Yes should all be repairable.
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File Type: pdf 724 Rewind Correct Drawing.pdf (194.6 KB, 25 views)
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Old 29th Mar 2020, 8:04 pm   #54
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As you can see, the counter belt is still there, took this pic when I got the top plate off
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Old 30th Mar 2020, 1:16 pm   #55
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Default Re: Uher 724L

The same still applies for rewind, FF and Play.

Only the capstan belt has been replaced with a pulley.
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Old 30th Mar 2020, 1:36 pm   #56
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Cool, didn't notice that
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Old 30th Mar 2020, 1:50 pm   #57
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Hopefully I can get it repaired as I really like the style of it, and it will be very handy for doing more tape loops and such stuff
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Old 30th Mar 2020, 3:43 pm   #58
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Yes you should be able to get it repaired, shame you do not live local to me, I would be willing to have a look at it.
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Old 30th Mar 2020, 3:47 pm   #59
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Yes, that is a pity. A local fellow has offered to have a look, so I'll hopefully get some news in a few days
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Old 31st Mar 2020, 2:50 pm   #60
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Hello Dave, did you email me the service manual?
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