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Author Topic: Analogue VU meter repair?  (Read 159 times)

Ken Webster

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Analogue VU meter repair?
« on: October 13, 2019, 03:33:13 am »

Hi,

I had thought that a stuck VU meter was a dead meter and the only option was to replace.  Then I saw this: https://www.youtube.com/watch?v=CVN94wbQIRI

This surprised me so I tried it on some old parts.  My impression is that the heat simply melts the screw locker and readjusting the screw (it moves by wriggling the iron) simply releases pressure on the pin bearings.  The meters are now free but I am still dubious whether this is a real repair that restores meaningful and reliable measurement (response speed etc).  I have not been able to install and test the meters for accuracy.

All previous advice has been that such meters are toast, so it seems too good to be true.
So, what's the opinion here, valid repair or fluff?

Ken

« Last Edit: October 16, 2019, 04:29:03 pm by Ken Webster »
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Ken Webster

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Re: Analogue VU meter repair?
« Reply #1 on: October 14, 2019, 03:44:58 am »

OK, No replies but an update might be of interest to some.

Although I have spare meters from a 2nd hand console for such repairs, I decided I really have nothing to loose and tried the heat method to adjust the bearing screw.  This freed all three stuck meters on our 16 ch console. One of them was the left ch main out.  Then I ran a 1kHz test tone and both main outputs measure the same, within a gnat's whisker.  However, the group meters all measure differently from each other and have trimmer pots.  So I used some Deoxit spray on the trimmers which brought the groups within to +/- 5dB.  So, to calibrate, I set the group and main faders to zero dB and assigned one input to one group at a time and brought the test tone level up to zero VU on the main meters and trimmed that group's meter to zero VU.  Repeating this for all groups now makes all the metering consistent.

Maybe not correct though.  I will give it a rest overnight and then check all the meters against my digital multimeter to ensure the calibration is correct.

So, it seems to have worked OK for now at least.  Worth a try for an old mixer I thought but time will tell.

Ken
« Last Edit: October 16, 2019, 04:38:01 pm by Ken Webster »
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Re: Analogue VU meter repair?
« Reply #1 on: October 14, 2019, 03:44:58 am »


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