VU BUFFER & PEAK LED KIT BUILD THREAD

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Joe Malone
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Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Post by Joe Malone »

bigboy wrote:
Sun Sep 19, 2021 12:44 am
I think the issue is I am sharing the power supply from the amplifier to power the buffer but don’t fully understand the wiring needed. I use a dc-dc buck converter to reduce the +35v amplifier rail to 12v which powers the buffer. I connect the amplifier input audio rca V+ to the V+ Of the buffer board and the rca V- to the V- of the buffer board. The 0v on the buffer is not connected to anything. Is this the correct wiring ? A sketch would help greatly.

Richard
Do you mean +in and -in for audio in ? As +V is power in? Best to attach some photos of the pcb buffer wiring to see if I can see the problem. As long as 0v from power supply is linked to the shield of the input it should be ok. The unused -in should also be wired to 0v.
Joe :-)
JLM Audio
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bigboy
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Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Post by bigboy »

Hi Joe

Omg, I have spent 3 days trying to sort this out. One buffer board has fried an opamp, 2 1uf caps and a diode. I decided to desolder the lot and rebuild it and it seemed to fix the issue.... it seemed. Then the same meter stopped working all of a sudden. It turned out to be the solder connection at the rca input at the back of the amp. Joys of a hobbyist builder. Anyway it's working now, both VU meters are responding. Sorry to be a serial pest.

I ordered a prebuilt meter prior to finding the poor solder joint about 2 hrs ago. I don't suppose you could provide a refund as I won't need it anymore.

Regards

Richard

bigboy
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Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Post by bigboy »

The saga continues :)

Fired up the amplifier this morning and there is no response from either VU meter. I must be wiring something incorrectly. I have attached my wiring diagram. Its as though the meters need to be "charged" or "awakened" some how. Any suggestions on the wiring appreciated.
Amp.png
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Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Post by Joe Malone »

bigboy wrote:
Thu Sep 23, 2021 12:32 pm
The saga continues :)

Fired up the amplifier this morning and there is no response from either VU meter. I must be wiring something incorrectly. I have attached my wiring diagram. Its as though the meters need to be "charged" or "awakened" some how. Any suggestions on the wiring appreciated.
Amp.png
From your diagram, you have the 12v dc going directly to the meter terminals which will kill the meters and buffer instantly if the meters are wired there as well???

You do not show any vu meter wiring at all?

Also the green and black wires are reversed on the input wiring.
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Joe :-)
JLM Audio
Capturing Audio without Injury

bigboy
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Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Post by bigboy »

Sorry, I have the 12V wired to the VU globe and not the meters, sketch was wrong.

So based on your sketch I just need to swap the black and green around ? I thought I had already tried that but I will give it a go and report back.

Final wiring as attached.
vu.png
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bigboy
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Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Post by bigboy »

Ok

Rewired as above

Adjusted meters and they do work...... but

After turning the amp off and on again they only way I can get them going again is to quickly wake them up by turning the volume up to almost 100% for a brief moment ? Progress I guess.

Richard

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Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Post by Joe Malone »

bigboy wrote:
Fri Sep 24, 2021 7:33 pm
Ok

Rewired as above

Adjusted meters and they do work...... but

After turning the amp off and on again they only way I can get them going again is to quickly wake them up by turning the volume up to almost 100% for a brief moment ? Progress I guess.

Richard
Have you checked the 12v voltages. What does it read on a dc volts meter?
Check to see how many ac millivolts noise it has on it if an 12v SMPS?
In an amp setup normally I would run from the output of the amp so buffer uses a lot less gain.
The buffer can actually run directly from the 35v rail also. The 12v could be used for the lamps only.
Best to attach actual photos of the buffer and wiring and top and bottom pcb photos so I can check them.
Maybe worth trying another TL072 encase this one has been damaged.
Joe :-)
JLM Audio
Capturing Audio without Injury

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