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I have a fully functioning PL400, that has meters that don't move. The lights on the meters work but the needles don't budge. Looking for a pair of functioning meters to replace the broken meters. Thanks

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Hello JesterRace, and welcome to thecarversite.com. We're glad you're hear. ;) There is a lot of information here, much technical know how, and a pretty good bunch of folks that are happy to help. @Bonzoro is one of the Phase Linear gurus that frequents this site, and there are others that may be able to hook you up. @Nahash5150 has repaired meters before. He may also be able help you out.


Please consider uploading some pics of your gear in the Members Systems area. We all like pics of all kinds of audio gear.


In the meantime, kick your shoes off, turn up the music, and welcome aboard.

 

giphy.gif

 

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I took it to a repair guy when I got it, because one channel was out. After fixing the modded volume pot on the front and tightening the inputs on the back the thing sounds great.  The repair guy looked at the meters and said it looks like they need to be replaced.

 

I replace lights in gear and fix belts on cassette decks and cd players. Other than that I'm not competent on advanced repairs. 

 

What steps need to be taken to troubleshoot and fix the meters?  Thanks

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19 hours ago, JesterRace said:

I have a fully functioning PL400, that has meters that don't move. The lights on the meters work but the needles don't budge. Looking for a pair of functioning meters to replace the broken meters. Thanks

Is it a series 1 or 2? I’m assuming series 1.

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If you want to verify if the meters are at fault you can do this. 

 

WARNING - Do this at your own risk.  There is a chance if you wire this up wrong or the voltage is to high you could burn up a perfectly good meter movement.  

 

You will need a 1.5V battery,  a couple of resistors from 5Kohm to 20Kohm.  Wire the battery negative in series with a resistor to the meter negative.  Start with a 20Kohm resistor.  Momentarily connect the battery positive to the meter positive.  If the meter deflects left disconnect quickly.  Reverse the battery polarity and try again.  You should see some deflection.  If the meter pegs full scale disconnect and find a larger resistor.  If the deflection is between 0 and full scale your meter is likely good.  You can also try a 10Kohm resistor.  This time the meter deflection should be greater than what the 20Kohm provided.  

 

IMG_0347.JPG

Note: my drawing is wrong.  Wire battery negative to meter negative.

 

Here is a bit more complex test method.  Wire the test setup as shown in the drawing below.  Make sure the pot is at maximum resistance.  When connected you should get a small amount of meter deflection.  Turn the pot until the meter is at full scale.  Read the current.  This will tell you what the meter is rated for at full scale.  

 

 

IMG_0342.JPG

Note: my drawing is wrong.  Wire battery negative to meter negative.

 

In the video I am testing a Carver M500 meter.  This meter is showing 500mA at full scale.  This is a good meter.

 

 

 

Music:  Roxy Music "In Every Dream Home A Heartache"

Edited by dennismiller55
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It's probably the light board where the meter inputs run through it. I doubt that both meters went bad. They are pretty reliable. If somebody has been dorking around inside, that's probably it.

Look at the schematic, probably an easy fix. Don't disassemble the meters or "Blow" on them or use canned air on them.

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Could be the ground going to the meters, or, there are a couple resistors and a couple diodes which are on the light board.  These boards are USUALLY in pretty rough shape after 40 years. White Oak Audio Design has all the items to get that amp back into safe operable condition. The rest of the amp is probably in need of some updating ie....   DC Protection circuit, new bulk caps, new back planes, new control board.....   They basically are ticking time bombs unless updated. They weren't made to last forever for sure. And when they fail......   Better have some eye protection on. Maybe a cup too      :)

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Here is a shot of the 400's big brother. Custom chassis, lighting etc.etc etc.....  Show's what you can do to your 400 (And dig another 100 wpc out of it). Just finished this one for a gent an hour ago....

 

 

IMG_5850rs (2208 x 1656).jpg

IMG_5855rs (2208 x 1656).jpg

IMG_5854rs (2208 x 1656).jpg

IMG_5851rs (2208 x 1656).jpg

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