F5 Turbo Builders Thread

THe F5 is a really tough design. I have been using the PSU to proto a J2 and once, when i hooked up the psu back to the F5T boards, I accidentally hooked up the positive wire to the output hole. Fried a fuse, nothing else, It is the perfect amp for first time builders. It just so happens, you get a phenominal amp. I can see the V3 competing against anything and have got a preliminary layout for a balanced version, to take advantage of excess current available at low rail voltages.
 
nrg. he did a bond on us. a Aston martin vanish:D
he left the job half done, i'll know. i was the one rectifing the smal faults that was on the boards. alldoh i use those prototype boards on my monoblocks. it was only marking errors.
i'm just crossing my fingers and hope there is nothing else:D i don't think there is. i have went thrue this curcuit and boards 100 times:D
 
Audiosan, you are on a large stage with many folks watching you and awaiting your results.
We need to keep our fingers crossed that it all works.. can you see any changes in layout at this point? I will read back in this thread and find the post with a photo of the boards.. i need to refresh my mind as to what they look like again..
 
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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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. :scratch: 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