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No voltage at voltage regulator help


Bant_Panorama

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Recently picked up a non working Vader unit and it is using the PS I use for my modded and working 4S woody, Vader doesn’t have show any voltage at the regulator, I had extra new main cap and VR and changed those out for the heck of it and no change.  What’s the proper next diagnostic steps in terms of what to check with my meter?  Thanks!

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0E7FCB42-8E7A-421C-93A9-E92ECAC6C135.jpeg

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50 minutes ago, Bant_Panorama said:

Recently picked up a non working Vader unit and it is using the PS I use for my modded and working 4S woody, Vader doesn’t have show any voltage at the regulator, I had extra new main cap and VR and changed those out for the heck of it and no change.  What’s the proper next diagnostic steps in terms of what to check with my meter?  Thanks!

F37ED43E-AD8D-4D3E-88F4-15418B4695AE.jpeg

0E7FCB42-8E7A-421C-93A9-E92ECAC6C135.jpeg

The solder on the power jack looks kinda weak. Might want to add some solder (or remove all the old and replace) with flux to make it flow.

 

If you have zero volts at your voltage regulator, but the PSU is known to work, you have a bad connection to the board. Check voltage at the power jack. It may also be rusty.

 

image.thumb.png.18d13d6dd6cb6f5678fd63d5019b9a78.png

 

 

Also looks like that RF mod might be junk. It's pretty fugly at the base.

Edited by Dopy25
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Well if you are getting voltage at those two points then it is either a bas solder joint or an open circuit.

With the power switch in the op position are you getting voltage onw or both sides of the switch? If not then to one side only suggests a faulty power switch, to either suggest an open circuit between the 200uF Cap and the Switch.

If you get 9.3V to both sides of the switch but nothing on the left leg of the regulator that suggests a open circuit between the power switch and the voltage regulator.

 

The most common place for an open circuit to occur is where the PCB track joins the solder pad, rather than at a random point along the track. A close visual inspection may reveal that, alternatively you can carefully scrape off some of the solder resist around the mid point of the suspect section of power track (solder over to prevent the exposed copper tarnishing) and measure the resistance (power disconnected) along the suspect section of track to the component either side to narrow down to which side the fault lies.   

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Thanks for the thorough response.  I was able to semi consistently get 9 and 5V out of the regulator by changing out one of the green cap tabs under the main cap though it’s not reliably the right voltage at the regulator.  No picture or sound still, no booting at all.  Added a leftover AV mod kit to see if it changed anything and still won’t boot.

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On 12/15/2022 at 5:31 AM, WhyLee commotari.club said:

The regulator has an input pin and an output pin. What about the voltage on the input pin?

I’ve got that to more consistently give me 9.39 at the input side and 5.04 on the output.  I was poking around at the disc capacitors and found the one in the row of resistors near the RF only reads 1.4 VDC when unit powered on, all the others hover around 5 VDC, is there anything to that?

1A171534-563E-48C4-9F3C-F3D2D98CD85A.jpeg

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17 hours ago, Bant_Panorama said:

I’ve got that to more consistently give me 9.39 at the input side and 5.04 on the output.  I was poking around at the disc capacitors and found the one in the row of resistors near the RF only reads 1.4 VDC when unit powered on, all the others hover around 5 VDC, is there anything to that?

1A171534-563E-48C4-9F3C-F3D2D98CD85A.jpeg

That cap is part of the audio circuit and is for filtering. That wouldn't likely cause the issues you are having. 

 

BTW what happened to the interconnect PCB from the RF modulator to the mainboard?

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9 hours ago, -^CrossBow^- said:

That cap is part of the audio circuit and is for filtering. That wouldn't likely cause the issues you are having. 

 

BTW what happened to the interconnect PCB from the RF modulator to the mainboard?

Thanks for the response, I figured it was something like that but I wanted to ask since I’m not sure what direction to go in next.


I had a completed AV mod kit so I just installed it since the RF looked in terrible condition and I’ve installed enough of them that the I’m confident it won’t be an issue.

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