Stereo VU meter kit BUILD THREAD

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Re: Stereo VU meter kit BUILD THREAD

Post by Joe Malone »

Ekz wrote:
Mon Apr 27, 2020 1:15 am
I am not entirely sure what I did wrong, but when I turned the VU meter on, smoke started coming out of the unit. I found out that the bottom right resistor is burned. I checked my solder. They are all fine. Please advise how can I fix this, if it can at all.

https://www.dropbox.com/h?preview=IMG_2 ... 539766.jpg

P.S. Sorry, for some reason, I cannot seem to upload any photo because it keeps failing.
Your dropbox is not offering me the download button. It want me to sign in and I do not have a dropbox account.

Are you not able to add the photos as attachments to your post?
Joe :-)
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Ekz
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Re: Stereo VU meter kit BUILD THREAD

Post by Ekz »

Joe Malone wrote:
Mon Apr 27, 2020 10:36 pm

Your dropbox is not offering me the download button. It want me to sign in and I do not have a dropbox account.

Are you not able to add the photos as attachments to your post?
Hopefully this upload works.

I just realised that there are 2 images of the PCB, and I think I was going by the older one. The one I was supposed to do had no diodes and a 680ohm resistor on the bottom left and right, correct?

Would this have damaged the VU meters themselves? Do I have to buy replacement parts for them? I reordered the VU2 buffer kit to replace the one I messed up.
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Re: Stereo VU meter kit BUILD THREAD

Post by Joe Malone »

Ekz wrote:
Tue Apr 28, 2020 4:17 pm
Joe Malone wrote:
Mon Apr 27, 2020 10:36 pm

Your dropbox is not offering me the download button. It want me to sign in and I do not have a dropbox account.

Are you not able to add the photos as attachments to your post?
Hopefully this upload works.

I just realised that there are 2 images of the PCB, and I think I was going by the older one. The one I was supposed to do had no diodes and a 680ohm resistor on the bottom left and right, correct?

Would this have damaged the VU meters themselves? Do I have to buy replacement parts for them? I reordered the VU2 buffer kit to replace the one I messed up.
All that should be needed is to change the 10R to the correct Rload of 680R and replace the 2 x white high bright 5mm led in each meters backlight box by unscrewing the 2 small philip head screws.

If you remove the 2 x Rlamp 10R for now you can test and align the meters without the backlights.

The actual VU meter will be fine. Since you left the diodes in the meter will just be out of cal a bit below 0VU.
Joe :-)
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Ekz
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Re: Stereo VU meter kit BUILD THREAD

Post by Ekz »

Joe Malone wrote:
Tue Apr 28, 2020 5:38 pm
All that should be needed is to change the 10R to the correct Rload of 680R and replace the 2 x white high bright 5mm led in each meters backlight box by unscrewing the 2 small philip head screws.

If you remove the 2 x Rlamp 10R for now you can test and align the meters without the backlights.

The actual VU meter will be fine. Since you left the diodes in the meter will just be out of cal a bit below 0VU.
I did have some problems trying to desolder the resistor and diodes (there may have been some angry yelling at inanimate objects involved), so at this point I would feel more confident redoing everything from scratch. If the LED in the backlight box doesn't work, where can I get the replacements for them? How do I test that the LED's are still functional?

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Re: Stereo VU meter kit BUILD THREAD

Post by Joe Malone »

Ekz wrote:
Tue Apr 28, 2020 5:50 pm
Joe Malone wrote:
Tue Apr 28, 2020 5:38 pm
All that should be needed is to change the 10R to the correct Rload of 680R and replace the 2 x white high bright 5mm led in each meters backlight box by unscrewing the 2 small philip head screws.

If you remove the 2 x Rlamp 10R for now you can test and align the meters without the backlights.

The actual VU meter will be fine. Since you left the diodes in the meter will just be out of cal a bit below 0VU.
I did have some problems trying to desolder the resistor and diodes (there may have been some angry yelling at inanimate objects involved), so at this point I would feel more confident redoing everything from scratch. If the LED in the backlight box doesn't work, where can I get the replacements for them? How do I test that the LED's are still functional?
When the new VU2 pcb is built with the Rlamps of 680R it will be safe to plug into the meters and see if the leds light or not.
Joe :-)
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Ekz
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Re: Stereo VU meter kit BUILD THREAD

Post by Ekz »

I've since rebuilt the VU buffer kit, and replace the LED's in the VU meter. The VU meter works fine and has been calibrated, but the LED's don't work, even after desoldering and replacing the burnt ones with new 5mm white LED's.

I don't know how to troubleshoot from here. Please advise.

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Re: Stereo VU meter kit BUILD THREAD

Post by Joe Malone »

Ekz wrote:
Thu May 07, 2020 11:11 pm
I've since rebuilt the VU buffer kit, and replace the LED's in the VU meter. The VU meter works fine and has been calibrated, but the LED's don't work, even after desoldering and replacing the burnt ones with new 5mm white LED's.

I don't know how to troubleshoot from here. Please advise.
Ok do you understand that the leds need to be the correct polarity to work.

So +L goes to long leg of first led then short leg of that led links to the long leg of the next led. Then the last short leg no used goes to -L. If one or both leds are backwards they will not light up.
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Ekz
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Re: Stereo VU meter kit BUILD THREAD

Post by Ekz »

Joe Malone wrote:
Fri May 08, 2020 10:32 am
Ok do you understand that the leds need to be the correct polarity to work.

So +L goes to long leg of first led then short leg of that led links to the long leg of the next led. Then the last short leg no used goes to -L. If one or both leds are backwards they will not light up.
I'm sure I got the polarity correct, since I copied the position of the LED before soldering, but I will double check just in case.

Ekz
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Re: Stereo VU meter kit BUILD THREAD

Post by Ekz »

Here are the photos from the LED's I put in. Hopefully you're able to see. Both polarity should be correct.
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Re: Stereo VU meter kit BUILD THREAD

Post by Joe Malone »

Ekz wrote:
Fri May 08, 2020 12:05 pm
Joe Malone wrote:
Fri May 08, 2020 10:32 am
Ok do you understand that the leds need to be the correct polarity to work.

So +L goes to long leg of first led then short leg of that led links to the long leg of the next led. Then the last short leg no used goes to -L. If one or both leds are backwards they will not light up.
I'm sure I got the polarity correct, since I copied the position of the LED before soldering, but I will double check just in case.
Yes they are backwards. Just reverse the red and black wires and make sure you have RLamp resistors 680R fitted and it should work.
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Ekz
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Re: Stereo VU meter kit BUILD THREAD

Post by Ekz »

Joe Malone wrote:
Fri May 08, 2020 12:54 pm
Yes they are backwards. Just reverse the red and black wires and make sure you have RLamp resistors 680R fitted and it should work.
Wow, alright thanks. I copied what was in the photos and what was on the previous circuit exactly. Glad that's sorted out. Sorry for being really new at this.

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Re: Stereo VU meter kit BUILD THREAD

Post by fpvga »

Hi there. Just finished my kit, nicely packaged! I’m thinking of changing a few things, perhaps with another stereo board, and have a few questions:

1: if I want to wire in a front panel pot, all I need is a 5K single turn linear pot, and to wire it to the trim pot pads? Are there any other pads on the board I can use?

2: if I want to do rca jacks in, and pass through rca jacks out, are there any other pads I can use or would I just do this on a new board? Asking for the main board and also the input accessory board.

3: if I’m putting this buffer inside an amp housing, I gather I’d just wire the inputs in parallel with the amp? No decoupling or anything needed?

Thanks again..

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Re: Stereo VU meter kit BUILD THREAD

Post by Joe Malone »

fpvga wrote:
Mon Feb 08, 2021 10:43 am
Hi there. Just finished my kit, nicely packaged! I’m thinking of changing a few things, perhaps with another stereo board, and have a few questions:

1: if I want to wire in a front panel pot, all I need is a 5K single turn linear pot, and to wire it to the trim pot pads? Are there any other pads on the board I can use?
Not a good idea as you need the 25turns to get good fine adjustment and also any stereo pot will be 20% so the left and right will never match. Best to wire 4 wires out to a 2 x 6 rotary switch that switch 5k trimpots so you can set up to 6 perfect reference points in stereo.
2: if I want to do rca jacks in, and pass through rca jacks out, are there any other pads I can use or would I just do this on a new board? Asking for the main board and also the input accessory board.
For RCA we use RCA to XLR and or TRS jack adaptors but you can wire rca in and out as a wired loop and then to the buffer as unbalanced either as tip to +in and Shield to -in and you depending on power setup -in may need to be connected to 0v.

3: if I’m putting this buffer inside an amp housing, I gather I’d just wire the inputs in parallel with the amp? No decoupling or anything needed?
Correct. If you do not want to adjust the meter level all the time just make sure it is wired pre volume control to something like a old tape loop out point.
Joe :-)
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fpvga
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Re: Stereo VU meter kit BUILD THREAD

Post by fpvga »

Thanks a ton. On the pot setup... I’m a little confused why that’s 4 wires. Can you explain that one more time? Is it the first and third pin from each channel, then the wiper from the other side of the little trim pot array?

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Re: Stereo VU meter kit BUILD THREAD

Post by Joe Malone »

fpvga wrote:
Mon Feb 08, 2021 11:34 am
Thanks a ton. On the pot setup... I’m a little confused why that’s 4 wires. Can you explain that one more time? Is it the first and third pin from each channel, then the wiper from the other side of the little trim pot array?
HI Will The trimpots are wired as variable resistors if you look at the schematic. So wiper is shorted to one end of the trim pot. So you would need 2 wires from the 1st and third pins from each trimpot wired to the switch
Joe :-)
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