Thank you!
Hopefully you building your F5 will be a wonderful journey as well. Please contact me if you have any questions with your build.
Hopefully you building your F5 will be a wonderful journey as well. Please contact me if you have any questions with your build.
i will be creating this build ...last time i soldered was around 14 years ago so this will be interesting...
6L6
Please, where did you get the aluminium brackets:
http://www.diyaudio.com/forums/pass-labs/188691-illustrated-guide-building-f5.html#post2566447
Nice job and thanks for sharing
JC
Please, where did you get the aluminium brackets:
http://www.diyaudio.com/forums/pass-labs/188691-illustrated-guide-building-f5.html#post2566447
Nice job and thanks for sharing
JC
Jose,
Hello! I am not sure which brackets you mean. Can you elaborate?
The entire chassis (box and heatsinks) was bought from modushop.biz Here is the link to the chassis with the thick front panel, I wish I bought that instead of the rack-mount front... modushop.biz
Good luck with your build and always feel free to ask any questions in this thread or the main F5 thread!
Jim
Hello! I am not sure which brackets you mean. Can you elaborate?
The entire chassis (box and heatsinks) was bought from modushop.biz Here is the link to the chassis with the thick front panel, I wish I bought that instead of the rack-mount front... modushop.biz
Good luck with your build and always feel free to ask any questions in this thread or the main F5 thread!
Jim
Hello Jim
Sorry, I mean those "L" aluminium brackets attached to the sinks wich also hold the whole case assembly (front, top and bottom plates). Modushop don´t show on its acessories list. I´m planning to assemble two uglish from scrap Borbely Audio monoblocs in one single 4U or 5U Dissipante case.
Thanks for your F5 pics and kind assistance.
Jose
Sorry, I mean those "L" aluminium brackets attached to the sinks wich also hold the whole case assembly (front, top and bottom plates). Modushop don´t show on its acessories list. I´m planning to assemble two uglish from scrap Borbely Audio monoblocs in one single 4U or 5U Dissipante case.
Thanks for your F5 pics and kind assistance.
Jose
I have tried to ask this before in another F5 threat, but didnt get a real usable answer.
I am one of the stupid guys who were so eager to fire up my F5, that I did it without the bulb thing, and setting the bias pots in the opposite direction.
When I fired up the amp, I got a little smoke, but both sides of the PS stille works.
My question then and now is: What will burn out in this situation, and will the Power FETS die.
The answers last time were that I could change all the transistors and all the power resistors - of course I can do all that, I could also build a completely new one.
But someone with at better understanding of this circuit than me, could with a high probability estimate what will burn out.
And how do I easily test if the Power FETS has died ?
I mostly build tube equipment, and when people hand me a schematic and a voltage scheme I can most of the time easily predict what is wrong. This is not the case with this amp.
By the way my amp looks very good with a 10 mm faceplate with logo and everything, and it has been sitting on the shelf for more than 6 month now.
Thanks in advance
Arthur.
I am one of the stupid guys who were so eager to fire up my F5, that I did it without the bulb thing, and setting the bias pots in the opposite direction.
When I fired up the amp, I got a little smoke, but both sides of the PS stille works.
My question then and now is: What will burn out in this situation, and will the Power FETS die.
The answers last time were that I could change all the transistors and all the power resistors - of course I can do all that, I could also build a completely new one.
But someone with at better understanding of this circuit than me, could with a high probability estimate what will burn out.
And how do I easily test if the Power FETS has died ?
I mostly build tube equipment, and when people hand me a schematic and a voltage scheme I can most of the time easily predict what is wrong. This is not the case with this amp.
By the way my amp looks very good with a 10 mm faceplate with logo and everything, and it has been sitting on the shelf for more than 6 month now.
Thanks in advance
Arthur.
If you start with the power fets turned off (bias potmeter turned to zero ohms), then there is no current (see the instructions).
I assume the fets are connected correctly.
Else, for instance: If the source and drain are connected wrongly then the unit does not die: there is a reverse diode inside the fet. Just the resistor is fried.
Other common mistake is the insertion of the limiting transistors the wrong way around.
So this answer depends on how well you placed components on the PCB. It can hardly go wrong.
I assume the fets are connected correctly.
Else, for instance: If the source and drain are connected wrongly then the unit does not die: there is a reverse diode inside the fet. Just the resistor is fried.
Other common mistake is the insertion of the limiting transistors the wrong way around.
So this answer depends on how well you placed components on the PCB. It can hardly go wrong.
Thank you for your answer 🙂
I am quite sure that the components are placed correctly, but the amp got full bias on startup, instead of no bias.
And I am also sure that something burned in the proces.
And what I would like to know is which components will burn, when applying too much bias, and if the the power FETs will burn, assumed that everything is assembled correctly.
Thanks
Arthur.
I am quite sure that the components are placed correctly, but the amp got full bias on startup, instead of no bias.
And I am also sure that something burned in the proces.
And what I would like to know is which components will burn, when applying too much bias, and if the the power FETs will burn, assumed that everything is assembled correctly.
Thanks
Arthur.
Hi AuthurDK,
TEST your parts ,mostly the FETS,the resistors ,and so on ,if it smoked,look for where it came from,I use a variac with a watt watcher(it measures amp,watts,voltage ) and a bulb,just a bulb at the least will save your circuit,
Tests are on the web with pictures for all of the above,all you need is a ohms meter , Double check next time ,I know you were excited,but ,,,,,
good luck
TEST your parts ,mostly the FETS,the resistors ,and so on ,if it smoked,look for where it came from,I use a variac with a watt watcher(it measures amp,watts,voltage ) and a bulb,just a bulb at the least will save your circuit,
Tests are on the web with pictures for all of the above,all you need is a ohms meter , Double check next time ,I know you were excited,but ,,,,,
good luck
Hi NoSmoke,
that was exactly NOT the answer I was looking for 🙂
Then I will have to disassemble the whole ting, because you cannot test components in circuit.
There must be somebody with better insight in this circuit than me, that is able to predict which components will burn, when the circuit gets full bias, and and if there is a high probability that the power FETs dies too.
I dont think that would be rocket science - I just cant do it myself.
that was exactly NOT the answer I was looking for 🙂
Then I will have to disassemble the whole ting, because you cannot test components in circuit.
There must be somebody with better insight in this circuit than me, that is able to predict which components will burn, when the circuit gets full bias, and and if there is a high probability that the power FETs dies too.
I dont think that would be rocket science - I just cant do it myself.
Gee AuthurDk,
Truth hurts sometimes,BUT good luck !!!! some 2 legged parts you can just lift one side,I would bet you cooked the output fets,check for shorts or burned open,
If you can't do that find a friend or a repair shop,I hope you get R done soon !!!
Truth hurts sometimes,BUT good luck !!!! some 2 legged parts you can just lift one side,I would bet you cooked the output fets,check for shorts or burned open,
If you can't do that find a friend or a repair shop,I hope you get R done soon !!!
AudioSan,
it went quite quick, and I dont think that the heat sinks are on the small side.
It is more than 6 month ago, so I dont remember exactly, just that the amp seamed dead, and that the power supply still worked.
Nothing got hot, so the amp did not draw much power afterwards.
NoSmoking,
thank you for your good wishes 🙂
it went quite quick, and I dont think that the heat sinks are on the small side.
It is more than 6 month ago, so I dont remember exactly, just that the amp seamed dead, and that the power supply still worked.
Nothing got hot, so the amp did not draw much power afterwards.
NoSmoking,
thank you for your good wishes 🙂
if the fets was isolated, my guess is that the source resistors was fried. and you can messure them in circuit.
Thank you 🙂 The FET were isolated from the heat sink. I did measure that before firing it up.
I will try to measure the resistors, but right now I am putting the last finish on some new OBL´s, which are the reason that the F5 is getting very interesting again. As I remember it were some resistors that got hot, but I just thought they would have taken a lot of other components with them to electric heaven.
The OBL´s are natural ash, treated with thick white soap. I am very kean to hear them, and will post them on a new threat later, when I find out how to attach pictures.
I will try to measure the resistors, but right now I am putting the last finish on some new OBL´s, which are the reason that the F5 is getting very interesting again. As I remember it were some resistors that got hot, but I just thought they would have taken a lot of other components with them to electric heaven.
The OBL´s are natural ash, treated with thick white soap. I am very kean to hear them, and will post them on a new threat later, when I find out how to attach pictures.
Hi Arthur, I think you got the right answer the first time you asked. Although we know the circuit, it is quite difficult to pinpoint what components have been burned in your amp. The pots could have been set asymmetrically, you could have had oscillations or something else - and with your selection of components, mounting etc, there are simply too many possibilities.
One of the F5's I built, I also fired it up with the pots in the wrong end of the scale, but I was quick to turn it off and nothing burned - I just had some smoke coming up from the resistors. If you put a bulb in the circuit, you can adjust the pots to zero ohm and start up the amp. Then you can start doing some voltage measurements - if you post those measurements on the board, people will be able to help you assess if you frontend is ok - then you can start adjusting the pots and check if the power fets are also ok.
One of the F5's I built, I also fired it up with the pots in the wrong end of the scale, but I was quick to turn it off and nothing burned - I just had some smoke coming up from the resistors. If you put a bulb in the circuit, you can adjust the pots to zero ohm and start up the amp. Then you can start doing some voltage measurements - if you post those measurements on the board, people will be able to help you assess if you frontend is ok - then you can start adjusting the pots and check if the power fets are also ok.