Sounds very much like you have some scaling enabled on your printer or in the pdf-reader somewhere ("fit to page/paper" maybe)?
I checked this everytime i printed the template.
Maybe some other diy-ers can print and say if their print is the same size with real pcb
Maybe some other diy-ers can print and say if their print is the same size with real pcb
And Shaan Plz change schematic post 1 , post 397 is not on the first page of this tread....it's really confusing.
Printed 103% and is ok.
The problem is i made a stupid beginner mistake and i believe i distroyed first built channel, i powered up with wrong polarity of power supply, the 1R resistors (in series with power supply) went to fire.
Replaced the two resistors and i measure 26mV across R29/R30 47ohm and the biasing is not working not matter how much i turn VR3.
I hate myself ... 🙁
Where to start with troubleshooting?
The problem is i made a stupid beginner mistake and i believe i distroyed first built channel, i powered up with wrong polarity of power supply, the 1R resistors (in series with power supply) went to fire.
Replaced the two resistors and i measure 26mV across R29/R30 47ohm and the biasing is not working not matter how much i turn VR3.
I hate myself ... 🙁
Where to start with troubleshooting?
Post 166 has a correct BOM. This is linked in the first post.
I would if I could. But diyAudio doesn't seem to allow changing attachments of first post. Let me see if reporting to moderators helps this.
Yay!!! 🙂
a. Can you change R29/30 bias by turning VR1/2?
b. Does turning VR1/2 change output offset voltage?
It is possible that the MOSFETs died if the PSU have no fuses. To check whether the MOSFETs are alive or not try to do this without applying power:
Remove R23 and R24.
Set your multimeter to diode test.
To test Q11 connect red probe to its pin 3 and black probe to pin 2.
The meter should show a couple hundred ohm or lower value or even an open connection, doesn't matter.
Now take a small wire and short pin 3 and 1.
The meter should show very low resistance or a short connection.
If yes then it is alive.
To test Q12 do the same but reverse probe polarity i.e. red probe to pin 2 and black probe to pin 3.
If the meter continuously shows very high or very low resistance (i.e. open or short circuit) regardless of whether you connect the wire or not, then the MOSFETs are probably gone.
I have requested moderators for changing the attached schematic in the first post to a corrected version.
It is possible that the MOSFETs died if the PSU have no fuses. To check whether the MOSFETs are alive or not try to do this without applying power:
Remove R23 and R24.
Set your multimeter to diode test.
To test Q11 connect red probe to its pin 3 and black probe to pin 2.
The meter should show a couple hundred ohm or lower value or even an open connection, doesn't matter.
Now take a small wire and short pin 3 and 1.
The meter should show very low resistance or a short connection.
If yes then it is alive.
To test Q12 do the same but reverse probe polarity i.e. red probe to pin 2 and black probe to pin 3.
If the meter continuously shows very high or very low resistance (i.e. open or short circuit) regardless of whether you connect the wire or not, then the MOSFETs are probably gone.[/QUOTE]
Thanks for reply Shaan!
In place for 1R/2W that you recommend for bias adjust i had installed some 10R/0.4W metal film resistors and they acted like a very slow blow fuse i would say, they literally burned with open fire.
I tested only the mosfets and this are the results (i'm not familiar with mosfets)
Asuming 1=G, 2=S, 3=D for Q11 without wire measured 10R with wire 143R
and for Q12: without wire resitance was infinite and with wire bridge measured 660R.
I will try to see in the next days if adjusting Vr1/Vr2 shows some variations on DMM.
PS i have 2 dmm, in diode mode one shows resistence value and the other one (more advanced) shows a DC voltage wich i think is Vf of diode measured
Remove R23 and R24.
Set your multimeter to diode test.
To test Q11 connect red probe to its pin 3 and black probe to pin 2.
The meter should show a couple hundred ohm or lower value or even an open connection, doesn't matter.
Now take a small wire and short pin 3 and 1.
The meter should show very low resistance or a short connection.
If yes then it is alive.
To test Q12 do the same but reverse probe polarity i.e. red probe to pin 2 and black probe to pin 3.
If the meter continuously shows very high or very low resistance (i.e. open or short circuit) regardless of whether you connect the wire or not, then the MOSFETs are probably gone.[/QUOTE]
Thanks for reply Shaan!
In place for 1R/2W that you recommend for bias adjust i had installed some 10R/0.4W metal film resistors and they acted like a very slow blow fuse i would say, they literally burned with open fire.
I tested only the mosfets and this are the results (i'm not familiar with mosfets)
Asuming 1=G, 2=S, 3=D for Q11 without wire measured 10R with wire 143R
and for Q12: without wire resitance was infinite and with wire bridge measured 660R.
I will try to see in the next days if adjusting Vr1/Vr2 shows some variations on DMM.
PS i have 2 dmm, in diode mode one shows resistence value and the other one (more advanced) shows a DC voltage wich i think is Vf of diode measured
The MOSFET gates are responding to voltage, a good sign the MOSFETs may be okay.
Now probe between G-S and G-D for any resistance. This I suggest because usually the 1N4007 diodes in the rails protect the VAS+Input from reverse PSU polarity, but they are still connected to the MOSFET Gates via R23/24.
Now probe between G-S and G-D for any resistance. This I suggest because usually the 1N4007 diodes in the rails protect the VAS+Input from reverse PSU polarity, but they are still connected to the MOSFET Gates via R23/24.
GB2 Update:
Mdpae - 2 PCBS - DELIVERED
kartk - 2 PCBs - DELIVERED
Manoranjan - 2 PCBs - DELIVERED
lifewater - 2 PCBs - SHIPPED
NishantS - 4 PCBs - DELIVERED
muthumuthiah - 2 PCBs - DELIVERED
cganeshprabhu - 4 PCBs - DELIVERED
airkrishna2015 - 4 PCBs - DELIVERED
patriz - 4 PCBs - SHIPPED
cgraf - 2 PCBs - SHIPPED
potepuh - 4 PCBs - SHIPPED
andrewboyp - 10 boards - SHIPPED
mj777 - 2 PCBs - SHIPPED
arthur - 6 PCBs - SHIPPED
zebulo - 2 PCBs - SHIPPED
electrix - 2 PCBs - SHIPPED
HH - 2 PCBs - SHIPPED
phill094 - 4 PCBs - SHIPPED
ben123 - 4 PCBs - SHIPPED
vasillis - 4 PCBs - SHIPPED
rdobbis - 4 PCBs - SHIPPED
nikosokey - 4 PCBs - SHIPPED
JaredC79 - 4 PCBs - SHIPPED
CitizenKane - 2 PCBs - PAID
tome - 2 PCBs - PAID
dersucher - 4 PCBs - PAID
brookhart995 - 2 PCBs - PAID
Last shipment of GB2 consignments will be done on 13th September.
Notice: A third group buy will start as soon as anyone interested joins. 🙂
Thanks.
Mdpae - 2 PCBS - DELIVERED
kartk - 2 PCBs - DELIVERED
Manoranjan - 2 PCBs - DELIVERED
lifewater - 2 PCBs - SHIPPED
NishantS - 4 PCBs - DELIVERED
muthumuthiah - 2 PCBs - DELIVERED
cganeshprabhu - 4 PCBs - DELIVERED
airkrishna2015 - 4 PCBs - DELIVERED
patriz - 4 PCBs - SHIPPED
cgraf - 2 PCBs - SHIPPED
potepuh - 4 PCBs - SHIPPED
andrewboyp - 10 boards - SHIPPED
mj777 - 2 PCBs - SHIPPED
arthur - 6 PCBs - SHIPPED
zebulo - 2 PCBs - SHIPPED
electrix - 2 PCBs - SHIPPED
HH - 2 PCBs - SHIPPED
phill094 - 4 PCBs - SHIPPED
ben123 - 4 PCBs - SHIPPED
vasillis - 4 PCBs - SHIPPED
rdobbis - 4 PCBs - SHIPPED
nikosokey - 4 PCBs - SHIPPED
JaredC79 - 4 PCBs - SHIPPED
CitizenKane - 2 PCBs - PAID
tome - 2 PCBs - PAID
dersucher - 4 PCBs - PAID
brookhart995 - 2 PCBs - PAID
Last shipment of GB2 consignments will be done on 13th September.
Notice: A third group buy will start as soon as anyone interested joins. 🙂
Thanks.