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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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Thread Tools |
29th Mar 2020, 2:19 pm | #41 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Uher 724L
Voltmeter.
Lawrence. |
29th Mar 2020, 2:50 pm | #42 |
Dekatron
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,604
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Re: Uher 724L
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. |
29th Mar 2020, 2:51 pm | #43 |
Tetrode
Join Date: Dec 2016
Location: Glasgow, Scotland, UK.
Posts: 83
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Re: Uher 724L
Don't have one. Not really wanting to mess about with this, not qualified to do circuits. Thanks though : )
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29th Mar 2020, 3:02 pm | #44 |
Tetrode
Join Date: Dec 2016
Location: Glasgow, Scotland, UK.
Posts: 83
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Re: Uher 724L
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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29th Mar 2020, 3:49 pm | #45 |
Dekatron
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,604
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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 ? |
29th Mar 2020, 3:53 pm | #46 |
Tetrode
Join Date: Dec 2016
Location: Glasgow, Scotland, UK.
Posts: 83
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Re: Uher 724L
Hello. Its the record button, you hold it down while engaging play (and pause, I think).
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29th Mar 2020, 3:57 pm | #47 |
Dekatron
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,604
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Re: Uher 724L
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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29th Mar 2020, 4:37 pm | #48 |
Tetrode
Join Date: Dec 2016
Location: Glasgow, Scotland, UK.
Posts: 83
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Re: Uher 724L
Yes, think so. When the top plate was off, there was a bulb adjacent to the VU
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29th Mar 2020, 5:26 pm | #49 |
Dekatron
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,604
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Re: Uher 724L
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. |
29th Mar 2020, 6:19 pm | #50 |
Dekatron
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,604
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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. |
29th Mar 2020, 7:48 pm | #51 |
Tetrode
Join Date: Dec 2016
Location: Glasgow, Scotland, UK.
Posts: 83
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Re: Uher 724L
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). |
29th Mar 2020, 8:02 pm | #52 |
Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,225
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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. |
29th Mar 2020, 8:02 pm | #53 |
Dekatron
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,604
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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. |
29th Mar 2020, 8:04 pm | #54 |
Tetrode
Join Date: Dec 2016
Location: Glasgow, Scotland, UK.
Posts: 83
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Re: Uher 724L
As you can see, the counter belt is still there, took this pic when I got the top plate off
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30th Mar 2020, 1:16 pm | #55 |
Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,225
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Re: Uher 724L
The same still applies for rewind, FF and Play.
Only the capstan belt has been replaced with a pulley. |
30th Mar 2020, 1:36 pm | #56 |
Tetrode
Join Date: Dec 2016
Location: Glasgow, Scotland, UK.
Posts: 83
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Re: Uher 724L
Cool, didn't notice that
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30th Mar 2020, 1:50 pm | #57 |
Tetrode
Join Date: Dec 2016
Location: Glasgow, Scotland, UK.
Posts: 83
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Re: Uher 724L
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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30th Mar 2020, 3:43 pm | #58 |
Dekatron
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,604
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Re: Uher 724L
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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30th Mar 2020, 3:47 pm | #59 |
Tetrode
Join Date: Dec 2016
Location: Glasgow, Scotland, UK.
Posts: 83
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Re: Uher 724L
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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31st Mar 2020, 2:50 pm | #60 |
Tetrode
Join Date: Dec 2016
Location: Glasgow, Scotland, UK.
Posts: 83
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Re: Uher 724L
Hello Dave, did you email me the service manual?
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