The circuit has to operate, there's nothing wrong with this circuit
You have construction errors Sunny, do not loose you time measuring and searching for voltages and deducing things, realising things or concluding things.
You gonna loose smaller time checking parts with multimeters, check base, emitter and colector , measure your resistance values, measure continuity, to see if you have conduction into copper line, check copper line.... goes painting red line into the schematic with lines checked and transistors tested...this will be faster than to be boiling your mind....when something goes wrong all circuit shows crazy voltages, hard to deduce, realise, conclude....go to the simple hard work man..this was proved, along years of repair and service in equipments that remotion of parts and continuity testings works better and faster.
Good to see you once again Sunny.... do you remember.
" Everybody loves sunrise"
regards,
Carlos
You have construction errors Sunny, do not loose you time measuring and searching for voltages and deducing things, realising things or concluding things.
You gonna loose smaller time checking parts with multimeters, check base, emitter and colector , measure your resistance values, measure continuity, to see if you have conduction into copper line, check copper line.... goes painting red line into the schematic with lines checked and transistors tested...this will be faster than to be boiling your mind....when something goes wrong all circuit shows crazy voltages, hard to deduce, realise, conclude....go to the simple hard work man..this was proved, along years of repair and service in equipments that remotion of parts and continuity testings works better and faster.
Good to see you once again Sunny.... do you remember.
" Everybody loves sunrise"
regards,
Carlos
Carlos - good to see you here... nice 
it seems to me that i will have to disasemble the whole bias/driver circuit, measure everything and connect somehow the right way.... the problem is that i have allready done that and found nothing... my other channel is behaving the same.... completely crazy thing.... i am very sad and nervous because everything seems to be working in simulator and here it is making problems........
maybe i will make the same thing but only i will use VBE multiplier instead of this crazy thing - everything strait from the VAS to the driver transistors and in between only vbe multiplier....
this has to start working soon..... i am slightly loosing my mind with it....
it seems to me that i will have to disasemble the whole bias/driver circuit, measure everything and connect somehow the right way.... the problem is that i have allready done that and found nothing... my other channel is behaving the same.... completely crazy thing.... i am very sad and nervous because everything seems to be working in simulator and here it is making problems........
maybe i will make the same thing but only i will use VBE multiplier instead of this crazy thing - everything strait from the VAS to the driver transistors and in between only vbe multiplier....
this has to start working soon..... i am slightly loosing my mind with it....
yes i know.... that is why i am so puzzled.-... it works on sim, it is producing sound here but no bias current and not offset at the output and not correct values at the Vbe..... oh my.... it seems that i will disasemble driver output circuit and check every part for errors.... i hope that it is not very bad....
i have to go to sleep - tommorow i will disasemlbe it and check...
if any other ideas please let me know.... i will be happy to try them.... this amp is very important to me as i do not know much about the design - i used this idea here and that idea there.... and it started to work nicely in the sim... i wanted to try it... it is a big step for me since i am mostly in tubes - this is solid state where i do not have to much experience...
i have to go to sleep - tommorow i will disasemlbe it and check...
if any other ideas please let me know.... i will be happy to try them.... this amp is very important to me as i do not know much about the design - i used this idea here and that idea there.... and it started to work nicely in the sim... i wanted to try it... it is a big step for me since i am mostly in tubes - this is solid state where i do not have to much experience...
Works into simulator, worked into your calculations and design
Transistor positions are correct, sub circuits correct, PNP is into the correct place...NPN also in correct place..
So.... something constructed is wrong related the design and simulator...go to the board, to the parts, hold the soldering iron my dear...do not loose your time.... catch your multimeter, remove parts, go measuring them out from the circuit...check if they are NPN and PNP and are assembled correctly...check continuity...measure those resistances, the 1 ohms can be a mistake, you can have 1 Megaohms there.... you have no conduction over the bias resistance..voltage was zero over it...so..not conducting... errors.
Errors.... building errors, absolutelly no doubt about that.
Voltages shows a mess..all unballanced...you gonna turn crazy testing by voltages..go to measure resistances.
regards,
Carlos
Transistor positions are correct, sub circuits correct, PNP is into the correct place...NPN also in correct place..
So.... something constructed is wrong related the design and simulator...go to the board, to the parts, hold the soldering iron my dear...do not loose your time.... catch your multimeter, remove parts, go measuring them out from the circuit...check if they are NPN and PNP and are assembled correctly...check continuity...measure those resistances, the 1 ohms can be a mistake, you can have 1 Megaohms there.... you have no conduction over the bias resistance..voltage was zero over it...so..not conducting... errors.
Errors.... building errors, absolutelly no doubt about that.
Voltages shows a mess..all unballanced...you gonna turn crazy testing by voltages..go to measure resistances.
regards,
Carlos
You have 15 miliamps, so calculate a single resistance for testing purposes
and put it in series with the bias trimpot you already have in circuit, disconect your diode-transistors and test the whole stuff with simple resistances.
163 ohms will be the resistance... 100 ohms trimpot in series with a 100 ohms resistance will work.
This will finish, will stop with suspections into the bias network.... if this do not works, for sure you gonna have errors before or after the bias network.
regards,
Carlos
and put it in series with the bias trimpot you already have in circuit, disconect your diode-transistors and test the whole stuff with simple resistances.
163 ohms will be the resistance... 100 ohms trimpot in series with a 100 ohms resistance will work.
This will finish, will stop with suspections into the bias network.... if this do not works, for sure you gonna have errors before or after the bias network.
regards,
Carlos
the bias circuitry that i have now is working - i have managed to make the voltage Vcd = 4V - this should be more than enough to trigger the current through the 80.6R resistor - but it is not doing that.... i am puzzled why because the pcb seems to be o.k. - pcb from the VAS and also PCB from the driver/bias/output... i have to check the positions of the parts and their values.... remove everything, measure everything, double check the position where to mount them again and them mount them.... than i have to put the pcb on the heatsink once again to check if it is working.... if not - i have to find a shotgun to shoot the damn board.....
i am realy confused related this one... i am at wokr so i am not able to work on the boards - have to wait until today evening....
arrrgggghhhhh!!!!
before doing that - i will put that 163ohm as you told me - to see if it is working - who knows - maybe it will
i am realy confused related this one... i am at wokr so i am not able to work on the boards - have to wait until today evening....
arrrgggghhhhh!!!!
before doing that - i will put that 163ohm as you told me - to see if it is working - who knows - maybe it will
Yes.... things really confused.... very strange
all that stuff..... also, between voltage amplifier emitters you should have voltage...and you have measured zero volts over the floating emitter resistance.... this tell us the voltage amplifier are underbiased into their base to emitter junctions....there you may need more than 550 milivolts to force some current over that floating resistance.... maybe not VAS ...maybe this can be a driver..well.... driver or Vas... need more than 550 milivolts from base to emitter to put them to conduct... check that.... i do not remember very well..but seems i have readed 430 milivolts, this means underbiased and non conducting...so...no voltage will be developed into emitter resistances...this will make output underbiased too.
The most crazy thing.... i do not understand that...you have conduction into your output... when you should not have that...you are measuring voltage over your emitter resistances into the output...is this real?... or you are reading bad multimeter showing 2 milivolts or something there.... are you sure your multimeter disconnected is measuring 0.000 volts?
Sorry some idiotic questions....but the defect, the trouble you have is very strange... seems also that things could have got some error of measurement too.
We are Humans.... we use to make hundreds of errors each day.
regards,
Carlos
all that stuff..... also, between voltage amplifier emitters you should have voltage...and you have measured zero volts over the floating emitter resistance.... this tell us the voltage amplifier are underbiased into their base to emitter junctions....there you may need more than 550 milivolts to force some current over that floating resistance.... maybe not VAS ...maybe this can be a driver..well.... driver or Vas... need more than 550 milivolts from base to emitter to put them to conduct... check that.... i do not remember very well..but seems i have readed 430 milivolts, this means underbiased and non conducting...so...no voltage will be developed into emitter resistances...this will make output underbiased too.
The most crazy thing.... i do not understand that...you have conduction into your output... when you should not have that...you are measuring voltage over your emitter resistances into the output...is this real?... or you are reading bad multimeter showing 2 milivolts or something there.... are you sure your multimeter disconnected is measuring 0.000 volts?
Sorry some idiotic questions....but the defect, the trouble you have is very strange... seems also that things could have got some error of measurement too.
We are Humans.... we use to make hundreds of errors each day.
regards,
Carlos
every measurement is above in the thread...
http://www.diyaudio.com/forums/showthread.php?postid=1491988#post1491988
(not to write it again)....
this is the pic i am refering to in this post...
http://www.diyaudio.com/forums/attachment.php?s=&postid=1491902&stamp=1208981468
indeed it is very confusing.... those 0.46V is on the resistor between emmiters of the driver and ground - not on the resistor - on that resistor i have 0V because there is no current flowing......
well, i will know more today at the evening - hopefully...
http://www.diyaudio.com/forums/showthread.php?postid=1491988#post1491988
(not to write it again)....
this is the pic i am refering to in this post...
http://www.diyaudio.com/forums/attachment.php?s=&postid=1491902&stamp=1208981468
indeed it is very confusing.... those 0.46V is on the resistor between emmiters of the driver and ground - not on the resistor - on that resistor i have 0V because there is no current flowing......
well, i will know more today at the evening - hopefully...
i do not have the board here at my work right now - bu i have bought the resistors at Farnell and before mounting in i checked them - they should be fine - i have to check them and everything else again..-... this is one completely crazy amp..... i can tell you that so far.... playing music and does not have the right values of votlages and currents....
crazy thing..
crazy thing..
i will check that - but i think that, between two bases of the driver transistors, i have 4V of difference - this will have to trigger the driver transistors to start conducting... and they are not - so i supose that the problem is somewhere between the emitter resistors of the driver transistors.... i will check that when i dismount the pcb today at the evening.....
when i have 4V it has to work ....
between emitter and emmiter of the drivers i have 0V and between the bases of the drivers i have 4V.... they should conduct - right? i think so but they are not ....
and the most interesting thing is that i have music comming out of that thing....... crazy...
when i have 4V it has to work ....
between emitter and emmiter of the drivers i have 0V and between the bases of the drivers i have 4V.... they should conduct - right? i think so
but they are not ....and the most interesting thing is that i have music comming out of that thing....... crazy...
Mooly said:
yes.... two blocks - one on each heatsink.....
both of them behave the same ... i was at my friends house and we checked the output waveform - apsolutelly correct... but no bias current.....
i have to dismount the board to check under the board.... to dismount the parts, measure them piece by piece and check the board again.... and than hopefully i will find the cause of the problem
Crazy indeed Recheck like I suggest, measure directly from base to base and emmiter to emmiter. 4Volt across bases, 0.7mv across emmiter, nah, not posible. Unless ! It could'nt possibly be oscillating at HF or UHF could it. That resistor in your zobel network is it all O.K. If it were oscillating a meter would read weird, a 'scope would show all. Just a thought.
Regards Karl
Recheck like I suggest, measure directly from base to base and emmiter to emmiter. 4Volt across bases, 0.7mv across emmiter, nah, not posible. Unless ! It could'nt possibly be oscillating at HF or UHF could it. That resistor in your zobel network is it all O.K. If it were oscillating a meter would read weird, a 'scope would show all. Just a thought.Regards Karl
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