Pulled all transitors
I pulled all of the transistors one by one checked them on a atlas dca55 all good!
I then double checked resistors all appear correct one in question is 220r , r25 when I powered it up after replacing it and checking transistors it immediately stared to burn again.
Checked again for shorts got nothing that jumps out,
Cannot keep it on long enough to check voltages on q3 q4q5 q6, if I remember when I built these I had this very issue with r25 quickly burning.
So I am once again stumped why it worked for over month then went down.
I pulled all of the transistors one by one checked them on a atlas dca55 all good!
I then double checked resistors all appear correct one in question is 220r , r25 when I powered it up after replacing it and checking transistors it immediately stared to burn again.
Checked again for shorts got nothing that jumps out,
Cannot keep it on long enough to check voltages on q3 q4q5 q6, if I remember when I built these I had this very issue with r25 quickly burning.
So I am once again stumped why it worked for over month then went down.
Can’t remember
For the life of me I can’t figure what I did last time, the bad about getting old!,,
I left out R25 220r. Now I can measure some voltages on the transistors .
Base of q7. -52.6v. Col. -10v. Em -53.7
Q8. Base -53.7. Col -53.7. Em -54.7
Base of q4 14.5v. Col. 53.7. Em. 13.9
Q3 14.5 base. 52.4 coll em 13.9
Q1. Em -.0947. Base -.333 col13.9
Q2 col. 13.9 Base -.435 col -1.043
Q5 base 53.3. Col 52.5 em53.98
Q6 base 53.5 col 53.3 em53.95
Q10 base53.2 col.992 em53.8
Q9. 52.51 base. Col53.1 em 53.2
Q11 -53.5 base. Col -52.9 em-54.8
Q12 -52.9base col-1.3 em-53.6
This is done with a current limit bulb and r25 left vacant
For the life of me I can’t figure what I did last time, the bad about getting old!,,
I left out R25 220r. Now I can measure some voltages on the transistors .
Base of q7. -52.6v. Col. -10v. Em -53.7
Q8. Base -53.7. Col -53.7. Em -54.7
Base of q4 14.5v. Col. 53.7. Em. 13.9
Q3 14.5 base. 52.4 coll em 13.9
Q1. Em -.0947. Base -.333 col13.9
Q2 col. 13.9 Base -.435 col -1.043
Q5 base 53.3. Col 52.5 em53.98
Q6 base 53.5 col 53.3 em53.95
Q10 base53.2 col.992 em53.8
Q9. 52.51 base. Col53.1 em 53.2
Q11 -53.5 base. Col -52.9 em-54.8
Q12 -52.9base col-1.3 em-53.6
This is done with a current limit bulb and r25 left vacant
after such episodes, you must again do two things, first is the output offset voltage chack and the other is the idle bias test...if these two items checks out, then you have a viable amp..
you do not even have to do a lot of voltage checks, just the two if your board has been done correctly...it will work the first time...
those two resistors in parallel with the fuses are meant for setting up, they can be omitted once the amp is up and running....and if you use the series lamp to setup, all the more unnecessary....
you do not even have to do a lot of voltage checks, just the two if your board has been done correctly...it will work the first time...
those two resistors in parallel with the fuses are meant for setting up, they can be omitted once the amp is up and running....and if you use the series lamp to setup, all the more unnecessary....
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Thank you for the response
I am not exactly sure I can get those checked when the r25 resistor goes up in smoke, can I check the offset without r25? Can you please advise on how to get to the result?
I am not exactly sure I can get those checked when the r25 resistor goes up in smoke, can I check the offset without r25? Can you please advise on how to get to the result?
r25, 220 ohm resistor going up in smoke tells me that the current mirrors opened so that q9 saturated, that is the only explanation i can think of or else you got some serious oscillations...r25 is some form of a clutch to protect q9, check that q9 survived...
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i will replace the to-92's with fresh ones and before you do check them with a component tester like this one...https://shopee.ph/Multi-Function-IR...ronic-Component-LCR-TC1-i.85777331.5415151252
Will replace them
I will replace the q9 Q6,5,4,3 tomorrow and report back thanks for directing me!
I will replace the q9 Q6,5,4,3 tomorrow and report back thanks for directing me!
Fixed, I found the root of what I believe to be the issue
Well it is alive and well, R26 was absolutely the issue it was a 10k value replaced it with the proper value of 100rand replaced the transistors q1,2. Q3,4 ,q5,6 fired up no burning has been stable at 24mv bias on both channels and with 0.007dc offset.
Damn that’s disappointing I made such a stupid error I have to run some music through it yet. Thank you for the guidance again I hope we’re good now!
Well it is alive and well, R26 was absolutely the issue it was a 10k value replaced it with the proper value of 100rand replaced the transistors q1,2. Q3,4 ,q5,6 fired up no burning has been stable at 24mv bias on both channels and with 0.007dc offset.
Damn that’s disappointing I made such a stupid error I have to run some music through it yet. Thank you for the guidance again I hope we’re good now!
Ha that’s what I thought too
Ha you are correct it does sound good unfortunately I blew one woofer on my good speakers so I have that to look forward to fixing!
Thanks again for you support!
Ha you are correct it does sound good unfortunately I blew one woofer on my good speakers so I have that to look forward to fixing!
Thanks again for you support!
not that one, the SOA protection circuit that Leach built into his amps......Leach Amp Protection Circuit
i hope someone will come up with such modifications...
i hope someone will come up with such modifications...
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Hey everyone. I'm about to order the parts for the power supply (I'm using 2 PSU boards from the diyaudio store) and I've selected these capacitors: https://gr.mouser.com/ProductDetail/598-380LX103M080A052/. They're 10kuF so with 4 in each rail I'll be able to reach the recommended 40000uF filtering capacitance per rail. But is the maximum voltage rating of 80V enough? It is certainly higher than the +-63V working supply voltage of the badger, but since I don't have any experience on linear power supplies, could you confirm that I won't have capacitors exploding in my face after I turn on the amp?
