Quick question - I am now just starting to put power to my F5 v3 (Cviller) boards.
First power-up was with light bulb inline which lit briefly before fading out.
Bulb was removed from the circuit when initiating to adjust bias.
(In either scenario the board LED did not light up btw, could be wrong polarity but it might give a clue)
P1 & P2 were both set to zero ohm prior to soldering them onto the board.
Power is applied to the F5 board. V=51,2VDC over V+ and V-. (PSU reach 26,2VDC per side at idle)
At start-up I measure at R9 and R11 = 0,51V for both.
Offset at the speaker output terminals read 0,2V
No heat is felt from either mosfet.
All three DVM´s are set to VDC 2000m
I have turned P1 & P2 one turn each about 10 times and the readings do not alter one bit.
I am apprehensive to continue to turn the pots in case I have bad readings or poor/wrongful setup.
Input greatly appreciated
First power-up was with light bulb inline which lit briefly before fading out.
Bulb was removed from the circuit when initiating to adjust bias.
(In either scenario the board LED did not light up btw, could be wrong polarity but it might give a clue)
P1 & P2 were both set to zero ohm prior to soldering them onto the board.
Power is applied to the F5 board. V=51,2VDC over V+ and V-. (PSU reach 26,2VDC per side at idle)
At start-up I measure at R9 and R11 = 0,51V for both.
Offset at the speaker output terminals read 0,2V
No heat is felt from either mosfet.
All three DVM´s are set to VDC 2000m
I have turned P1 & P2 one turn each about 10 times and the readings do not alter one bit.
I am apprehensive to continue to turn the pots in case I have bad readings or poor/wrongful setup.
Input greatly appreciated
Last edited:
Hi AudioSan,
Yes, the bulb light up making the room bright but still quite....
then something is drawing current when it should't. disconect everyting and start measuring from the main input and towords the amp PCB's.
Thank you for chiming in
I have populated my boards based on the schematics attached, so in other words DVM1 and DVM2 is placed incorrectly now and should go over R7/R8 instead? (The 0.47R 3W resistors at V+ and V- inputs)
So I adjust P1 and P2 to read 0ohm over R5 and R6?
Attachments
Last edited:
I can only adjust for 300mV over the 0.47 Resitors. Output DC is at 540mV
Somewhere in this thread someone had a similar problem, but I can't find his post anymore.
He changes some resistors to get the offset to the right values.
Has anyone give me an idea what to do?
Thank you again for your great support.
Somewhere in this thread someone had a similar problem, but I can't find his post anymore.
He changes some resistors to get the offset to the right values.
Has anyone give me an idea what to do?
Thank you again for your great support.
Trade DIY parts for F5 parts, where do I post?
A new disability forces me to use my inventory of parts to support my DIY audio addiction!!!
I have to blank F5 boards I want to populate, not the turbo. I have some speakers, 2 new BG neos, NOS One Focal TC 120 tweeter, the older original with metal face plate, LM3886 chips and parts, Sennheiser impedance meter, lots of speaker caps and inductors. NOS in box Leaf Tweeters, Realistic.
I have other stuff. If u have the parts to do two boards, let's talk.
A new disability forces me to use my inventory of parts to support my DIY audio addiction!!!
I have to blank F5 boards I want to populate, not the turbo. I have some speakers, 2 new BG neos, NOS One Focal TC 120 tweeter, the older original with metal face plate, LM3886 chips and parts, Sennheiser impedance meter, lots of speaker caps and inductors. NOS in box Leaf Tweeters, Realistic.
I have other stuff. If u have the parts to do two boards, let's talk.
Changed the parallel resistors to 4k7, this leads to max 550mV with zero offset. Amp sounds soft and clear with no distortion. Should I change the resistors to 5k6?
But to get to 550mV one poti is totally open, the other just one third. Will this lead to any problems? I'm new to fets, sorry for this noob question....
It seems "knowing what a resistor is" isn't enough.
I will measure Idss and drain load this evening.
But to get to 550mV one poti is totally open, the other just one third. Will this lead to any problems? I'm new to fets, sorry for this noob question....
It seems "knowing what a resistor is" isn't enough.
I will measure Idss and drain load this evening.
OK, we've made some progress in taming the hum, but not completely. We rotated the transformers which helped some. Then we changed the input wires to shielded twisted pairs (drain wire connected to chassis ground), which didn't seem to change anything.
There is no hum when the input cables are not connected.
There is no hum when the inputs are shorted.
There is no hum when the input cables are connected to the F5, but not to a source (this is a change from earlier attempts; rotating the transformers seems to have quieted the hum that was there with just the cables connected).
There IS a hum when the input cables are connected to a source (i.e., tube preamp), even if the source is not powered up or if the IEC connector is completely disconnected from the source.
We picked up a used oscilloscope, but don't know yet how to derive meaningful data from the squiggly lines. Once we've figured that out, I'll post what we find. In the meantime, does any of the above info suggest a possible cause/solution?
Thanks...
There is no hum when the input cables are not connected.
There is no hum when the inputs are shorted.
There is no hum when the input cables are connected to the F5, but not to a source (this is a change from earlier attempts; rotating the transformers seems to have quieted the hum that was there with just the cables connected).
There IS a hum when the input cables are connected to a source (i.e., tube preamp), even if the source is not powered up or if the IEC connector is completely disconnected from the source.
We picked up a used oscilloscope, but don't know yet how to derive meaningful data from the squiggly lines
. Once we've figured that out, I'll post what we find. In the meantime, does any of the above info suggest a possible cause/solution?Thanks...