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March 06, 2021, 01:05:55 AM

Author Topic: Help. Can’t get past the power supply test. [mostly resolved]  (Read 199 times)

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Offline last lemming

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Help. Can’t get past the power supply test. [mostly resolved]
« on: February 22, 2021, 03:00:20 PM »
I’ve double checked everything and my solder joints and direction of all components look correct. My test on the power transformer came up correct, but when I test the +6.3v and -6.3v I get 13.2v. What do I do?
« Last Edit: February 23, 2021, 02:19:41 PM by Paul Birkeland »

Offline Paul Birkeland

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Re: Help. Can’t get past the power supply test.
« Reply #1 on: February 22, 2021, 03:06:32 PM »
Can you post some photos of the top and bottom of the power supply board?  I would be willing to bet you have some cold solder joints and the regulator isn't doing any regulating.
Paul "PB" Birkeland

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Offline last lemming

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Re: Help. Can’t get past the power supply test.
« Reply #2 on: February 22, 2021, 03:29:22 PM »
this is where I am so far

Offline Paul Birkeland

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Re: Help. Can’t get past the power supply test.
« Reply #3 on: February 22, 2021, 03:38:25 PM »
Those are teeny, is there any way to get something a bit bigger?
Paul "PB" Birkeland

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Offline last lemming

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Re: Help. Can’t get past the power supply test.
« Reply #4 on: February 22, 2021, 03:56:05 PM »
hope these are better

Offline Paul Birkeland

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Re: Help. Can’t get past the power supply test.
« Reply #5 on: February 22, 2021, 04:22:34 PM »
Can you confirm that there's a 1085 regulator on the PC board and not an MJE5731A?

You could certainly reheat all your solder joints, but they don't look like I would expect them to in order to end up with no regulation.
Paul "PB" Birkeland

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Offline last lemming

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Re: Help. Can’t get past the power supply test.
« Reply #6 on: February 22, 2021, 04:27:03 PM »
Are you talking about the two Cree 1060’s?

Offline Paul Birkeland

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Re: Help. Can’t get past the power supply test.
« Reply #7 on: February 22, 2021, 04:27:33 PM »
No, the three legged regulator that mounts to the heatsink.
Paul "PB" Birkeland

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Offline last lemming

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Re: Help. Can’t get past the power supply test.
« Reply #8 on: February 22, 2021, 04:29:29 PM »
Oh yeah. Yes that is what is on there

Offline last lemming

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Re: Help. Can’t get past the power supply test.
« Reply #9 on: February 22, 2021, 04:30:33 PM »
Would a bad connection at T7, T9 or T11 or T12 do this?

Offline Paul Birkeland

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Re: Help. Can’t get past the power supply test.
« Reply #10 on: February 22, 2021, 04:33:53 PM »
I would go ahead and reheat all of the solder joints on that PC board.  You are unlikely to damage anything on there from overheating. 

If you have 12V coming out of the 6.3V pads, you power transformer connections are unlikely to be a problem, but the 1085 regulator isn't doing its job.  This could occur due to soldering issues, an MJE5731A swapped in instead of the 1085, or possibly you have a meter that isn't working properly.  To rule out the meter, you can try measuring a 9V battery with it.
Paul "PB" Birkeland

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Offline last lemming

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Re: Help. Can’t get past the power supply test.
« Reply #11 on: February 22, 2021, 04:36:55 PM »
I pulled the power supply off and retested the transformer. I got 9.2
V on the first test and 144v on the second. I also reflowed the joints. I will try soldering the PS board back on and see what happens

Offline last lemming

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Re: Help. Can’t get past the power supply test.
« Reply #12 on: February 22, 2021, 04:54:14 PM »
Well not sure where to go from here. I’m still getting 13.2v. My meter is good, I reflowed all the joints, they didn’t look bad, but I reflowed them anyway. I also double check the transformer it checks out, so I’m not sure what to do now?

I don’t know enough to know how to trouble shoot.

Can the 1085 be over heated by the solder?  I didn’t really put too much heat on it. I did notice that on each leg on the top side of the board, I used a bit too much solder and each leg had a small ball of solder at the base.  I tried to remove after I tested but really couldn’t get the solder off.
« Last Edit: February 22, 2021, 05:17:04 PM by last lemming »

Offline Paul Birkeland

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Re: Help. Can’t get past the power supply test.
« Reply #13 on: February 22, 2021, 07:59:50 PM »
Can you post a photo or two looking at the 1085 and what you're seeing?
Paul "PB" Birkeland

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Offline last lemming

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Re: Help. Can’t get past the power supply test.
« Reply #14 on: February 23, 2021, 01:57:33 AM »
here you go