Gb: F5 Pcb

[cviller]

Originally Posted by rtate

when using the "calculator" what do I plug in as the "source voltage"
if the current is 20ma and the "forward voltage is 3.4v" ?

Source voltage is 24.

If your diodes are to be mounted on the front-plate, select anything in the 10-40k range. With 10k normal blue leds will be plenty bright, so don't worry too much about this.

[rtate]

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....

[cviller]

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.

[Renron]

Originally Posted by rtate

What am I not seeing here....

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

[Renron]

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

[cviller]

Originally Posted by Renron

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

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?

[Renron]

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

[Tea-Bag]

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.

[Renron]

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

[Steve Eddy]

Actually it's not even coming up to 0.5V.

I'm getting R3 up to 4.2V, but can't get any more than about 3.2V across R4. And even at that, not getting more than 10-20mV across R11 and R12.

The MOSFETs just aren't biasing up.

se