An illustrated guide to building an F5

6L6

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Joined 2010
Paid Member
merlin2069er said:
But my left is way out of wack. I'll attempt to look at the board closely to determine if I've mixed up any resistors, hopefully I can check these values with a meter.

Any suggestions?

Let's assume that you haven't mis-wired anything on the the left, as you are getting legitimate numbers. It still won't hurt to look, however!

On the left channel, what is the max bias can you attain with zero offset?
 
ok, this is what I've attempted...

I've adjusted my left channel to ~ .004v dc offset after an initial few minutes of tweaking.

I had to adjust the voltages @ 1.284 v dc & -1.279v dc (across the .47ohm 3 watt resistors)

It definitely heats up quicker... I'll check it again at 30 minutes and 1hr.

That's more that 2x the .59v dc the service manual suggest to bias the amp at.

Any suggestions, or is this fine?

-----
I've checked it at ~ 30 minutes, and the heatsink is quite hot. I can leave my hand on it for 5 seconds or so.
It's 2x as hot as the other heatsink...
-----
I've turned it off just after ~ 40 minutes...
 
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6L6

Moderator
Joined 2010
Paid Member
If everything is wired up correctly and you got that much bias, there is no doubt that you are well, well past the rated dissipation of the output devices. You have the 4U x 400mm heatsinks, right? You should be able to leave your hand on them indefinitely. It is more than enough heatsink. The fact that you could only do 5 sec means that something is wrong. Hopefully it's only a wrong bias adjustment.

Turn the pots all the way down until they click and start over.
 
ok, got it!

I reset the pots to 0hms, and powered it up.

adjusted each pot and looked at the offset. As you adjust one pot, the offset grows larger, by adjusting the other it takes it back down to ~ 0v.


So after a few minutes I got ~ -.005 v dc

.536 v dc & -.537 v dc.

I'll leave it on for another .5 hr before I get to bed...


:rolleyes: I melted my a pair probes on one of the resistors... at the higher bias.
 
two leds in parallel

Hi friends,

I'm building an F5 and I'm using parts methacrylate. I'm using the plates cviller 1.1. The PCB has holes to solder LEDs with cable or mounted on the plate.

I can use this pair of holes to mount two LEDs in parallel with its corresponding resistance? Will it affect the sound charge led PSU with a more?.

The LEDs are blue.

Thanks for your reply. Excuse my English.
 
Quote >Is anybody else currently building an F5? Please post anything relevant, especially pictures, in this thread.

Are you really sure about it?:D:D:D:smash::D:D:D

Funny Joke about wheater in Uk>Quote

reminds me of an experience I had last time I visited England...

After two weeks of rain in july I asked a young boy passing by :
- Don't you ever have nice weather here? ...
He said :
- How could I know, I am only 16 ...

Is it funny ?


Manu



Still got the giggles and as sunny today 3 bottles of Sol with lime to many sizling in the garden so no much work.
definetly back to 18 C and dull tomorw

So have a pre view.

New 2 transistors on off and soft start
Mounted on aux supply
In new PSU case with DC filter and shafner EMF duda
Big box today she saying what the Fluff is in that?
Usual answer>they blipping got not a clue about global warming such a big box and is full of packing paper. And a few new Caps.

http://www.diyaudio.com/forums/swap-meet/182480-holco-mfr-15ppm-2w-sale.html
 

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