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Gb: F5 Pcb

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#962
Man I feel stupid, I know this is a small issue...
When I use the calculator:
24v source
20ma
3.4v forward voltage
The calculator recommends 1.2k 1watt for a resistor.

What am I not seeing here....😕
 
Last edited:
#963
you're not seeing the fact that 20ma is a huge amount of current for a led which is only used for indicating power on...
As I said, I use 33k - nice and dim light. Use 33k if you want dim light or 10k if you want something stronger. No big deal. 😉
 
#964
rtate said:
What am I not seeing here....😕
Click to expand...


You made a funny!

You are not missing anything, as I said it all depends on how bright you want the LEDs to be. Christian likes his at a soft glow level. The 1.2K level will produce the most light safely possible from the LED, BRIGHT!
Start with something around 2K and see if it's too bright. You could always add a small 5 - 10K pot and make them adjustable. Or put a switch on the amp and make daytime listening bright and nitetime soft glow. ie: 1.5K and 30k at night.
No dumb questions, unless it's the one you DON'T ask.

Ron
 
#965
Hey Christian,
As you know, I've done my best to kill any chances of making the F5 a working amp.
Here's what my Friend Steve has discovered I did wrong.
I built the rectifier boards correct but connected their output to the PS board wrong. I bulged all the negative rail caps, they look like roasted marshmallows, all puffy on top. 🙂 That in turn gave the + rail 50V and that killed several resistors and transistors. I could not troubleshoot it myself (lack of skills) because the caps were shorted and all my readings were off because of it.
New caps have been installed, but the - rail doesn't want to bias up past .5V on R12.......I think that's what Steve said..........I could be wrong.

Thanks,
Ron
 
#966
Renron said:
Hey Christian,
As you know, I've done my best to kill any chances of making the F5 a working amp.
Here's what my Friend Steve has discovered I did wrong.
I built the rectifier boards correct but connected their output to the PS board wrong. I bulged all the negative rail caps, they look like roasted marshmallows, all puffy on top. 🙂 That in turn gave the + rail 50V and that killed several resistors and transistors. I could not troubleshoot it myself (lack of skills) because the caps were shorted and all my readings were off because of it.
New caps have been installed, but the - rail doesn't want to bias up past .5V on R12.......I think that's what Steve said..........I could be wrong.

Thanks,
Ron
Click to expand...

Hi Ron,
It sounds like a massacre of burning parts...

Do you have all the burned components changed and still only .5V on R12? Silly question: have you tried adjust both pots on the board?
 
#967
Christian,
IT WAS A BARBECUE !!!
Yep. both pots. the P channel adjust to .6 but the neg. channel only goes to.5V
Any ideas? Low value resistor in // with the pot maybe?
Good Voltages from the PS now. +25.3V and -25.1V.
Thanks for the help CViller!

Ron
 
#968
lower pos rail to .5v. It will probably heat up to a higher amount.
I thought I read somewhere that low idss or unmatched JFets may cause this. But unsure.

Whenever I light an ampboard on fire, I throw it away. You dont know what kind of stuff happened, and how that will play outlong term.
 
#969
Thanks Tea Bag.
I agree,
New boards were purchased and all the transistors were replaced with new ones.
The Resistors were all checked prior to reinstalling them. New Caps were installed on the PS board. Will drop the P rail V. to .5 and see what happens.

Thanks so very much. I built a very nice case and am anxious to hear this Amp sing.

Ron
 
#972
PS Board question

I'm putting my PS board together and have a couple of questions...

The BOM that I am using has R9 and R10 as the 2.2K 3watt resistors used for
discharging the caps on power down.
Looking at a schematic I think that these resistors shoud be in the R1 and R4
locations.
R2,3,5,6,7,8,9 and 10 are the .47 ohm resistors, is this correct??


Also what are the T13,14,15,16 and T7, T18 conections for?

Thanks....
 
#976
rtate said:
I'm putting my PS board together and have a couple of questions...

The BOM that I am using has R9 and R10 as the 2.2K 3watt resistors used for
discharging the caps on power down.
Looking at a schematic I think that these resistors shoud be in the R1 and R4
locations.
R2,3,5,6,7,8,9 and 10 are the .47 ohm resistors, is this correct??


Also what are the T13,14,15,16 and T7, T18 conections for?

Thanks....
Click to expand...

They are used for extra power taps, as Christian has stated before he designed these boards to be used with / as other designs too. Good thinking!

Ron
 
#979
Thanks Ron, I do have a copy of that guide and should have checked there first.
Sometimes when these threads get long, some mis information(although good intentioned) slips in and I had made a copy of another BOM that had the bleed resistors in the wrong spot and I saw some photos over ar AK that also had the resistors in the wrong location....

Thanks again.
 
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