Can't adjust the voltage to what it needs to be at

pixeltarian · **Joined:** Mon Sep 08, 2008 1:17 pm **Posts:** 49

I get a reading of about 58v at it's lowest for the phantom power. it won't go down any further... and also LED 2 doesn't come on. just LED 1. what do I do now?

the positive and negative voltage adjustment went just fine.

owel · **Posted:** Wed Sep 24, 2008 9:28 pm

Quote:

>the positive and negative voltage adjustment went just fine

That's good!

Quote:

> LED 2 doesn't come on. just LED 1.

Possible causes
A) You inserted LED 2 backwards
B) You fried LED2 while soldering it

It doesn't really do much except serve as a visual indicator on the PCB, that power is ON.

Can you check with a multimeter if the LED is working or not? If it doesn't lit up, then it's fried. If it lits up in one direction, then you inserted the LED backwards. (wrong polarity)

Quote:

I get a reading of about 58v at it's lowest for the phantom power. it won't go down any further...

It means the regulator chip is not regulating.

Possible causes... You fried the LM317 regulator, maybe due to a short, or soldering it too long.

The LM317 Regulator will need to be replaced.

pixeltarian · **Joined:** Mon Sep 08, 2008 1:17 pm **Posts:** 49

is this what I need to get?

http://www.alliedelec.com/Search/ProductDetail.aspx?SKU=2880479&MPN=LM317T%2fNOPB&R=2880479&SEARCH=2880479&DESC=LM317T%2fNOPB

and it does adjust, it just will not go any less then like 60v. I can adjust it to go higher... still a broken regulator?

owel · **Posted:** Thu Sep 25, 2008 3:23 pm

Yes, that part will work.

Quote:

it just will not go any less then like 60v. I can adjust it to go higher... still a broken regulator?

Yes. Should go down way lower than that.

Okay... one question... are all resistors in their correct places?

Curran · **Joined:** Sun Nov 15, 2009 7:08 pm **Posts:** 16

I cannot get the 5k trim pots to adjust these settings at all. and to the 5k trim pots bottom out or do they turn for infinity? if not i may have "cracked" the trim pots on thos two the +20volt calibrated just fine

Curran · **Joined:** Sun Nov 15, 2009 7:08 pm **Posts:** 16

it just started a bit ago, and bow when I fired it up again to just double check the burning smell is really nice and string!

Curran · **Joined:** Sun Nov 15, 2009 7:08 pm **Posts:** 16

my voltage regulators in in backwards!!!! and one of the resistors is blackened.!!!!! what has been damaged from this goof up in my part?!?!?! do I need to replace all three voltage regulators and obviously this resistor? it is the 3k57. or do I need an entire power supply replacement?!?!? DAMN!!!!

owel · **Posted:** Thu Nov 19, 2009 7:52 pm

Quote:

my voltage regulators in in backwards!!!! and one of the resistors is blackened.!!!!! what has been damaged from this goof up in my part?!?!?! do I need to replace all three voltage regulators and obviously this resistor? it is the 3k57. or do I need an entire power supply replacement?!?!? DAMN!!!!

There's a 317 part, and a 337 part. Don't confuse the two and insert them backwards.

You just need to replace the 2 voltage regulators, and the resistor.

If you don't have the right desoldering tool, this may be difficult to remove from the board.

Do you want to send it in? I'll replace the parts and complete testing. Just pay for shipping both ways.

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Can't adjust the voltage to what it needs to be at

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