[fyleow]

I'm currently half way done, at the part where it's supposed to be 24V. I'm assuming that you're supposed to mess with the variable resistor until you get 24V DC right?

So I hook it up to my Fluke DMM and I got 38 V DC the first time. I adjusted the pot a little and now I am at 29V. Problem is it keeps rising by 0.02 V every second or so. I think it will stop eventually but I'm still waiting.

How precise do I have to be? Does it really need to be exactly 24 V or what?

 

[antness]

it does not have to be exactly 24V, as in the second stage of regulation you are multiplying by 5V.

But you want the + and - sides to be consistently the same.

Please tell us exactly the pot you are using to adjust the voltage

 

[fyleow]

I am using the Vishay Spectrol knob I got from Mouser.

Mouser part number 594-63P203T7

 

[antness]

you should be using a pot with multiple turns to adjust the voltage. single turn isn't precise enough.

 

[fyleow]

Thanks for the help antness but I think I'm just going to purchase the board from you when they are available. I cannot find the problem, one side is 36V (Ground to V+) and the other is 24.2 (Ground to V-). I have double checked my connections several times and I still can't see the problem. I have also checked the resistance for cold solder joints, no luck either.

 

[braillediver]

 

[fyleow]

It is not the same voltage supplied to the bridge rectifier because it is DC and not AC. The 36 V does not vary.

As I said one side is 24V and the other is 36V. I've checked it several times and I still can't find the problem. I've also set both sides to the same resistance value ( on the pot). I don't think it's a pot problem as the voltage stays the same no matter which way I turn the dial.

My best guess is it's a grounding problem, something is reaching ground and it's not going through the pot and that's the cause of the 36V. I don't see it though, and I've been trying for the past 3 hours.

Don't worry I will finish the amp someday, I've already spent a lot of money....

 

[transducer]

What is the voltage you get after the rectifiers but before the LM317? It sounds like the regulator is not regulating, either it is blown or you have a wiring problem. Check the wiring against the 337, since it is working properly. The pot is for fine tuning only. You must get both sides tracking identically.

Ron