Bloo LA2A VU Meter Bulbs
« on: June 09, 2019, 03:12:02 AM »
Hi All,
I got a Bloo LA2A recently, and I've been trying to figure out how (if ever) the VU meter was illuminated.

When I  open it up, I can't see any signs of a VU meter having ever been in there at all - but I might be missing something.

Here's a few pics of the meter assembly - any ideas on how I could get this lit up ?

https://i.ibb.co/4tnzYyL/20190530-123040.jpg
https://i.ibb.co/jHvz6WL/20190530-123046.jpg
https://i.ibb.co/LQVJM2M/20190530-123055.jpg
https://i.ibb.co/xFjvD8j/20190530-123324.jpg




Re: Bloo LA2A VU Meter Bulbs
« Reply #1 on: September 15, 2019, 06:31:57 AM »
Hi Guys !

Anyone got any ideas on how to light up this VU on this puppy ?

moamps

Re: Bloo LA2A VU Meter Bulbs
« Reply #2 on: September 15, 2019, 12:37:55 PM »
From the top outside?

Re: Bloo LA2A VU Meter Bulbs
« Reply #3 on: September 15, 2019, 12:57:23 PM »
yes indeed

mjrippe

Re: Bloo LA2A VU Meter Bulbs
« Reply #4 on: September 16, 2019, 05:51:30 PM »
I like warm white LEDs.  If they are clear, scuff the outer surface of the LED with 150 grit sandpaper for diffusion.  And yes, mount above the meter.

Re: Bloo LA2A VU Meter Bulbs
« Reply #5 on: September 16, 2019, 09:22:56 PM »
I like warm white LEDs.  If they are clear, scuff the outer surface of the LED with 150 grit sandpaper for diffusion.  And yes, mount above the meter.

Any suggestions on where to tap the signal for that - i'm a bit apprehensive of working with this thing given the voltages floating around in there ?

mjrippe

Re: Bloo LA2A VU Meter Bulbs
« Reply #6 on: September 16, 2019, 10:37:17 PM »
Any suggestions on where to tap the signal for that - i'm a bit apprehensive of working with this thing given the voltages floating around in there ?

Off the 6.3V filament voltage supply.  You will need a diode if they are not DC heaters in that design.  And you will need a current limiting resistor.

Phrazemaster

Re: Bloo LA2A VU Meter Bulbs
« Reply #7 on: September 17, 2019, 11:14:00 PM »
Off the 6.3V filament voltage supply.  You will need a diode if they are not DC heaters in that design.  And you will need a current limiting resistor.
With just a diode wouldn’t it flash at 60hz?
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** * Kablooie!

mjrippe

Re: Bloo LA2A VU Meter Bulbs
« Reply #8 on: September 19, 2019, 01:18:45 AM »
With just a diode wouldn’t it flash at 60hz?

If it does, you won't see it.  Persistence of vision.

Phrazemaster

Re: Bloo LA2A VU Meter Bulbs
« Reply #9 on: September 19, 2019, 04:08:20 AM »
If it does, you won't see it.  Persistence of vision.
OK...it’s just I read a post on another site about this very thing and they said you can see the flashing. But maybe you’re right.

I’m doing a project right now and will need to solve this very thing; I was going to use a diode bridge but maybe that’s overkill.

Thx!

Mike
***********************
*********************
******************
***************
************
********
*****
** * Kablooie!


mjrippe

Re: Bloo LA2A VU Meter Bulbs
« Reply #10 on: September 19, 2019, 11:39:44 AM »
OK...it’s just I read a post on another site about this very thing and they said you can see the flashing. But maybe you’re right.

I’m doing a project right now and will need to solve this very thing; I was going to use a diode bridge but maybe that’s overkill.

Thx!

Mike

Hmmm, it would probably flicker on video but I have used this method and never noticed any flashing.

Phrazemaster

Re: Bloo LA2A VU Meter Bulbs
« Reply #11 on: September 19, 2019, 12:16:41 PM »
Hmmm, it would probably flicker on video but I have used this method and never noticed any flashing.
I’ll take your real world experience over some random post.

Thank you!

Mike
***********************
*********************
******************
***************
************
********
*****
** * Kablooie!


 

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