POWER PLANT BUILD THREAD

[RelevantOctopus]

Hi Joe, thanks for all the help with the email/server/forum/my obvious brain damage, etc. and getting touch with me thru different means, I really appreciate it.

OK, now on to my Power Plant that I unfortunately killed.

The short must have happened when that resistor unsoldered itself? I should have asked how to implement a pilot light for the 24v and 48v rails correctly before I did it.
I will go with the LED and resistor suggested by you on the 48v.
The 24v pilot light still works......but is there a better way to do it than I did? I used the same LED type as the 48v one, but I had the proper resistor for the 24v pilot LED. I think....

I am pulling out the 48v LM317 and will test the adjuster and resistors and let you know what I find.
Thanks again,
George

[RelevantOctopus]

Hi Joe,

Here is what I found:

With LM317 in or out of the circuit, the 3 parallel 120r resistors read 'OL' when the meter is set to ohms and .251m when meter is set to megohms - I think that means they are no good?

After a rather violent and disturbing de-soldering operation I was able to get the adjuster off the board and I was able to adjust it to 2.7k (I think 2.7k is how they come in the kit) with no problem, so I think that is OK.
Now, with the adjuster also out of the circuit, those resistors read .259megohms.

Please let me know what you think.

Thanks
George

[Joe Malone]

Hi Joe,

Here is what I found:

With LM317 in or out of the circuit, the 3 parallel 120r resistors read 'OL' when the meter is set to ohms and .251m when meter is set to megohms - I think that means they are no good?

Yes they are open circuit which is stopping the voltage getting to the LM317. Need to replace all 3 of them on the right side of the reg. the 4th one beside those 3 is for the 24v so will be ok.

After a rather violent and disturbing de-soldering operation I was able to get the adjuster off the board and I was able to adjust it to 2.7k (I think 2.7k is how they come in the kit) with no problem, so I think that is OK.
Now, with the adjuster also out of the circuit, those resistors read .259megohms.

OK if you do not turn the trim pot down when the reg is blown it will usually always be ok. You can test it when the reg is removed without having to unsolder it. But yes resetting it to roughly half its value is a good idea if it was removed.

Replacing the LM317 reg and any blown 120R and 10uF caps will bring the power rail back up and running and will still be set to 48v if trimpot not moved.

[RelevantOctopus]

Hi Joe,
I will replace these parts hopefully today, they arrived from Mouser yesterday.
I will post the results here for the perusal and edification of interested parties.

One further question, if I may, concerning LEDs...

I like to mount these power supplies in separate boxes, I also like to have LEDs on these boxes indicating the power rails are up, like on some mixer power supplies. No reason really, I just like it.

Previously you had mentioned to use high brightness type LEDs (which I didn't even know were a thing) with 100k 1/4w resistor on the 48V rail to keep from wasting power on a LED, and to presumably not blow it up so I bought them and will implement them as suggested.

My question is: If I use the same high brightness LED method on the 24V, what value resistor should I use? And, does it matter which side of the LED is 'resistored'?

Thanks again Joe, I really appreciate your help
George

[Joe Malone]

Hi Joe,
I will replace these parts hopefully today, they arrived from Mouser yesterday.
I will post the results here for the perusal and edification of interested parties.

One further question, if I may, concerning LEDs...

I like to mount these power supplies in separate boxes, I also like to have LEDs on these boxes indicating the power rails are up, like on some mixer power supplies. No reason really, I just like it.

Previously you had mentioned to use high brightness type LEDs (which I didn't even know were a thing) with 100k 1/4w resistor on the 48V rail to keep from wasting power on a LED, and to presumably not blow it up so I bought them and will implement them as suggested.

My question is: If I use the same high brightness LED method on the 24V, what value resistor should I use? And, does it matter which side of the LED is 'resistored'?

Thanks again Joe, I really appreciate your help
George

Yes you don’t want to waste a watt of power in a resistor just running a led as it will need to be very big and it will run very hot. Even with normal leds 10k on the 48v is as low as you should need to go and 4k7 on the 24v to get enough brightness. But with high brightness types you can go 10x higher value easily with 100k on 48v and 47k on 24v and basically waste no power or heat.

[RelevantOctopus]

Thanks again, Joe. I'll post all the fine results after I fix it. In a couple days or so.
George

[RelevantOctopus]

Hi Joe,
I was able to perform the prescribed surgery this morning and now my power plant has recovered from its accidental death and is working perfectly, just like it did before I killed it
Thank you VERY much for your quick responses to my questions and your further suggestions about the LEDs. All is good now.
Thank you for an excellent product and excellent support!!!
George

[Joe Malone]

Hi Joe,
I was able to perform the prescribed surgery this morning and now my power plant has recovered from its accidental death and is working perfectly, just like it did before I killed it
Thank you VERY much for your quick responses to my questions and your further suggestions about the LEDs. All is good now.
Thank you for an excellent product and excellent support!!!
George

HI George
Great to hear you got it up and running again

[RelevantOctopus]

Hi Joe
So these LEDs are very bright (using the suggested 10K and 4K7 on normal green LEDs).
Can I use higher value resistors to dim them? Like the blue LED on your switch kit, which is the perfect brightness, I would like to match that.
I thought I would ask how before I destroyed my Power Plant again
Thanks
George

[Joe Malone]

Hi Joe
So these LEDs are very bright (using the suggested 10K and 4K7 on normal green LEDs).
Can I use higher value resistors to dim them? Like the blue LED on your switch kit, which is the perfect brightness, I would like to match that.
I thought I would ask how before I destroyed my Power Plant again
Thanks
George

If using high bright leds usually at least 10 x those values like 100k on 48v and 47k on 24v. The blue leds we use 470k on 48v. Just make the resistor larger value until you get the brightness you want.

[RelevantOctopus]

Thanks again, Joe - that is exactly what I needed to know!
George