Well done bru.
Check over your shoulder. I am on your heels. Must still get my speaker connectors. Drilled and tapped my heatsinks yesterday. Building in 4U/400 case cause it gets hot here. PSU and PCBs are done. Wiring next.
Good on ya Anand!
It all started here and then after that, a friendship commenced
! I was worried about member tbrooke's safety
and I noticed that he had been 'working' on this amp for several months 
. Jumping from an ACA build to an F6 build can be a big leap especially if it is the first time one is wiring up a linear power supply. To make a long story short, the primaries had been wired for 240V and a couple of JFETS got toasted during the bias procedure
.Once these oversights were rectified
, all was well. No biggie! It was a mutual learning experience for me 
, since I have an F6 in the build queue...to be tackled...someday !Best,
Anand.
Hello DIY community. I am getting closer to finishing an F6 project however, there is a question regarding the two amp circuit boards. There are 2 resistor positions showing that are not numbered and I can find no reference to them. Actually, it is 1 position on each circuit board. I have so far, considered these to be optional positions to be populated at each builders discretion but I have since decided that I really would like to know for sure what they may be for and suggested resistor values.
Sorry if this question has been previously visited, I did try searching but, well, here I am. Thank you for any assistance offered.
Sorry if this question has been previously visited, I did try searching but, well, here I am. Thank you for any assistance offered.
AudGuy,
They are not optional positions.
Look CAREFULLY at each board. Post#1 of this thread has pictures you can zoom in where you can verify what I have said below.
One board is labelled Channel B, the other is labelled Channel A.
On the Channel B board, the large power resistor, next to Q1 that is not labelled is actually R1.
On the Channel A board, the large power resistor, in between C2 and Q2 is actually R2.
The reason they are unlabelled is because of a layout labelling (silkscreen) error. You have to double check with the schematic to verify which is which.
R1 = 0.56 ohms (3 watt)
R2 = 0.47 ohms (3 watt)
If you didn't populate these resistors, the amp would not bias.
Hope that helps,
Anand.
They are not optional positions.
Look CAREFULLY at each board. Post#1 of this thread has pictures you can zoom in where you can verify what I have said below.
One board is labelled Channel B, the other is labelled Channel A.
On the Channel B board, the large power resistor, next to Q1 that is not labelled is actually R1.
On the Channel A board, the large power resistor, in between C2 and Q2 is actually R2.
The reason they are unlabelled is because of a layout labelling (silkscreen) error. You have to double check with the schematic to verify which is which.
R1 = 0.56 ohms (3 watt)
R2 = 0.47 ohms (3 watt)
If you didn't populate these resistors, the amp would not bias.
Hope that helps,
Anand.
Last edited:
Those are not optional positions. First, as an exercise, get your printed schematic and compare it to your boards. You should be able to determine which resistors they are. Set your DMM to check for continuity between adjoining parts and/or simply use the process of elimination to determine which parts did not have their designation silkscreened. You should find that the resistors will be different between the two boards.
Post your results. If you find that you can't determine which is which, of course, someone will give you the answer. However, being able to trace the circuit between the boards and the schematic is a very valuable skill to begin learning.
Have fun with the build!
Edit - Anand types faster than me.
Post your results. If you find that you can't determine which is which, of course, someone will give you the answer. However, being able to trace the circuit between the boards and the schematic is a very valuable skill to begin learning.
Have fun with the build!
Edit - Anand types faster than me.
This makes perfect sense now that I have been reminded of a few things. I wondered why I had a .47 and a .56 resistor left over and now I know why and where they go.
And, perhaps even more importantly was the reminder of the need to study things closely, use the meter and confirm that the board matches the schematic. I thought I was doing that, mostly, but I see that I wasn't really looking closely enough.
Thank you folks for your kind assistance.
And, perhaps even more importantly was the reminder of the need to study things closely, use the meter and confirm that the board matches the schematic. I thought I was doing that, mostly, but I see that I wasn't really looking closely enough.
Thank you folks for your kind assistance.
Oh, in another wonderful turn of events I managed to FUBAR a Toshiba 2SJ74BL last night.
I mounted it in the wrong position because on the one PCB Q4 is next to the transformer, and on the other PCB Q3 is next to the transformer. Silly me did not bother the verify the positions and I saw the error just after I solered it in. In a flurry of subsequent bugger-ups in trying to desolder it, I managed to kill it.
I have some 60 on the way from Punkydawgs, but when they ever will arrive here is another mystery as our postal service is renowned for their terrible service, if the package does not go AWOL in the process.
I feel like my Avatar today.
I mounted it in the wrong position because on the one PCB Q4 is next to the transformer, and on the other PCB Q3 is next to the transformer. Silly me did not bother the verify the positions and I saw the error just after I solered it in. In a flurry of subsequent bugger-ups in trying to desolder it, I managed to kill it.
I have some 60 on the way from Punkydawgs, but when they ever will arrive here is another mystery as our postal service is renowned for their terrible service, if the package does not go AWOL in the process.
I feel like my Avatar today.
Last edited: