Just for your info, the paralleled resistors in the PSU are there to help smooth out the residual ripple voltage after the first capacitors. Hence the name CRC filter. In that position you may actually want to use resistors with some inductance, such as regular wirewound resistors, to filter some higher frequency components. Non-inductive MILLS are pretty much a waste in that circuit position.
Ah, ok thanks for that! But why are there then so many people here using MILLS in that position? (So i saw a lot of pictures with MILLS...)
Would it be a good idea to add an inductive anywhere in the psu then?
A choked PS is always desirable but not always necessary. CRC PS works good for FW clones. The inductance of low value resistors as used here is negligible.
Yeah, CRC is a proven design for FW amps.
It's true that practically the resistors' inductance is entirely negligible here, which is why paying extra for non-inductive winding brings no real benefit.
It's true that practically the resistors' inductance is entirely negligible here, which is why paying extra for non-inductive winding brings no real benefit.
Hi! Can someone help me out? On the initial schematic extracted from Turbo article, this https://cdn.shopify.com/s/files/1/1006/5046/files/F5_Schematic_w-P3.jpg does not include a LED, however the available pcb for v3 has it... Is the PCB of a different design compared to this schematic or only the LED was added?
Second question: did someone try to make a point-to-point wiring (or using turret board)?
Thanx for your help in advance,
helsington
Second question: did someone try to make a point-to-point wiring (or using turret board)?
Thanx for your help in advance,
helsington
Hey everyone!
I need help 🙁 i thought everything works fine. I powered up my boards, everything worked good, so i was at 90% of Iq. As suggested I wanted to use it some days at this level.
Today i heared that on of the two channels has a buzz, furthermore i saw that the elkos, C3, of the softstart board looks like blowing up sooner or later... so i removed the softstart board and tried using the amp without. Again using a lightbulb tester i powered up and, yes, the bulb did shine a little bit brighter than it should have... during this process i think i destroyed something.
I put in the softstart board again and unpluged the amp boards. voltage rails look good.
I connect the boards -> PSU voltage drops down. So i turned back P1 and P2 to zero ohm -> PSU voltages look good.
Now, when I increased the values of the pots the voltage of the PSU breaks goes down.
So, the question is, which of the transistors did i just blew up? 🙁 🙁 🙁
I need help 🙁 i thought everything works fine. I powered up my boards, everything worked good, so i was at 90% of Iq. As suggested I wanted to use it some days at this level.
Today i heared that on of the two channels has a buzz, furthermore i saw that the elkos, C3, of the softstart board looks like blowing up sooner or later... so i removed the softstart board and tried using the amp without. Again using a lightbulb tester i powered up and, yes, the bulb did shine a little bit brighter than it should have... during this process i think i destroyed something.
I put in the softstart board again and unpluged the amp boards. voltage rails look good.
I connect the boards -> PSU voltage drops down. So i turned back P1 and P2 to zero ohm -> PSU voltages look good.
Now, when I increased the values of the pots the voltage of the PSU breaks goes down.
So, the question is, which of the transistors did i just blew up? 🙁 🙁 🙁
goes down to around 10V i think? I think this was the values when i measured before reducing P1 and P2 to zero ohms.
Now when i increase the values i stopped when the PSU voltage was at 18V because obviously there is something wrong now
Now when i increase the values i stopped when the PSU voltage was at 18V because obviously there is something wrong now
but it started when i first removed the soft start board? Actually i really don't know that went wrong when I removed it, I used a CL60 in one of the main lines and this blue X1 capacitor...
Yes, when pots are at zero ohms, Iq is zero, therefore no current is taken from psu, thats why I can measure +/- 24V due zo zero load.
Now when i increase pots Iq gets bigger and psu breaks down. Actually i think the IRF 9240 and 240 are burned?? That would mean i have a huge current only via source resistors and the psu cant handle it?
Now when i increase pots Iq gets bigger and psu breaks down. Actually i think the IRF 9240 and 240 are burned?? That would mean i have a huge current only via source resistors and the psu cant handle it?
Hey!
So i just checked it. I removed the softstart board, and tried to increase P1 and P2, same behaviour as before. So I must have destroyed something, the only question is what part, and furthermore how. I connected the transformer exactly as yesterday when I first removed the soft start. I should have returned to zero ohm at P1 and P2 yesterday, i think then nothing would have happend... I learned my lesson 🙁
So, at the moment the F5 transistor kit is sold out at the store 🙁 🙁 🙁 I still think the mosfets are the bad guys. Does somebody have matched IRFP9240 / IRFP240 lying around willing to sell me? For the moment I will buy not matched one and try to fire up the f5 again...
Or does somebody have a clue what i might have destroyed?
So i just checked it. I removed the softstart board, and tried to increase P1 and P2, same behaviour as before. So I must have destroyed something, the only question is what part, and furthermore how. I connected the transformer exactly as yesterday when I first removed the soft start. I should have returned to zero ohm at P1 and P2 yesterday, i think then nothing would have happend... I learned my lesson 🙁
So, at the moment the F5 transistor kit is sold out at the store 🙁 🙁 🙁 I still think the mosfets are the bad guys. Does somebody have matched IRFP9240 / IRFP240 lying around willing to sell me? For the moment I will buy not matched one and try to fire up the f5 again...
Or does somebody have a clue what i might have destroyed?
Did you measure the voltage drops across the 0.47 ohm source resistors when
the power supply starts sagging?
Thanks,
Dennis
the power supply starts sagging?
Thanks,
Dennis
So 100mV across the 0.47 ohm resistors? That only about 0.2A. A properly
functioning power supply for the F5 shouldn't drop like that on such a
small load.
Skipping the softstart, is there some way for you to test the power supply itself?
Do you have any big power resistors you can use as a 0.1 to 0.2A load on the PSU
itself and see if you get the same kind of voltage drop? Do you see any bulging
on the PS caps?
Is your PSU a CRC one? If so, what R do you have there and what voltage drop
across it do you get when the rails drop?
Thanks,
Dennis
functioning power supply for the F5 shouldn't drop like that on such a
small load.
Skipping the softstart, is there some way for you to test the power supply itself?
Do you have any big power resistors you can use as a 0.1 to 0.2A load on the PSU
itself and see if you get the same kind of voltage drop? Do you see any bulging
on the PS caps?
Is your PSU a CRC one? If so, what R do you have there and what voltage drop
across it do you get when the rails drop?
Thanks,
Dennis