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Old 5th January 2013, 11:54 PM   #791
nrg2009 is offline nrg2009  United States
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Any photos? Any progress on the heatsinks?
Is anyone building F5Tv2 prototype boards?
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Old 6th January 2013, 12:09 AM   #792
N Brock is offline N Brock  United States
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Default nrg, funny you should ask

Finished wiring up a V2 monoblock last night. I am in the process of powering up the first time right now. I'm kinda guessing that P3 gets set near the middle of its range.

Anyhow, here are some photos. New UKToecutter boards, diyA chassis.

The plan is to get it up and running (biased) by tonight.

I'll post more details a bit later when I've got a spare moment and the amp's done.

-Nelson
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Old 6th January 2013, 01:23 AM   #793
sts9fan is offline sts9fan  United States
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That's real pretty! I just got my case. Now I need the rest!
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Old 6th January 2013, 01:44 AM   #794
6L6 is offline 6L6  United States
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That looks sharp! Very nice.

What's the story behind the enormous caps?
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Old 6th January 2013, 01:51 AM   #795
N Brock is offline N Brock  United States
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Mondo caps came from a Burning Amp raffle. I figured I'd use them because they fit and they were otherwise just sitting on the shelf.

33,000uF 60v each.

Last edited by Variac; 8th January 2013 at 12:32 AM.
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Old 6th January 2013, 01:53 AM   #796
6L6 is offline 6L6  United States
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Cool.

I knew there was a story...
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Old 6th January 2013, 02:54 AM   #797
nrg2009 is offline nrg2009  United States
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Default awesome!!

N-Brock.
Looking good!!
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Old 6th January 2013, 07:44 AM   #798
N Brock is offline N Brock  United States
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I'm in a spot of trouble. Here's what I spent the evening doing.

While trying to bias the above F5t channel I noticed a few problems.

I tested the power supply, it works fine, unloaded voltage hovers right around 35v.

I set P1 and P2 all the way counter-clockwise and P3 somewhere in the middle.

Power on and nothing smokes which is a good sign.

I measure voltage across R11 and R12. R11 is at 930 mV, R12 is close to zero.

Uh oh.

Turning P1 doesn't affect the voltage across R11. P2 adjusts R12 just fine.

Offset at the output was quite high, between 180 and 230 mV.

I say screw it, attach a test load and source and I get music. Why did that work?

Now I'm sitting here scratching my head. Best thing I can come up with is a transistor is gone. Neither P-ch heatsink or N-ch got any warmer than ambient using an infrared gun.

Anyone have something for me to measure or try?

Best,
Nelson
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Old 6th January 2013, 08:40 AM   #799
sangram is offline sangram  India
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Reversed pot on one half?

Getting music out is possible even with a bit of bias. That's never the issue. The high offset is likewise normal indication because the adjustment process is about getting the bias and offset to hit a 'sweet spot'.
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Old 6th January 2013, 08:46 AM   #800
N Brock is offline N Brock  United States
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Quote:
Originally Posted by sangram View Post
Reversed pot on the half showing 0V?
That might be the case if the side showing zero was the one I'm worried about. It's t game e side at 930mV that isn't doing what it's supposed to. The pots are the correct orientation on the silk screen but I'll check the traces vs the schematic next.
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