Help with class AB amp

Thread Starter

CRY&PRAY

Joined Jan 6, 2014
84
I know that i keep asking the same thing, is that i'm scared.. if i burn the only one amp that works.. how will the speakers play the 15th? by screaming loud?

I just want to be sure 100%, today i've tried to attach the bases of the transistors to the push pull stage of my AB amp, ad it worked, but i was using that +-18v, i'm a bit scared to use 2 2sc5200 and 2 complementary PNP, with a freaking 1500 watt transformer.

it's simple i know, just wire all the resistors to the emitters then to the anti bump circquit, and 2 collectors to a rail, and the other 2 to the other, and connect the bases. But if a small drop of solder falls on the collector and then touches the heatsink? ever seen a 1500w spark? cuz i did....
 

tubeguy

Joined Nov 3, 2012
1,157
I know that i keep asking the same thing, is that i'm scared.. if i burn the only one amp that works.. how will the speakers play the 15th? by screaming loud?
.....
Exactly... So, don't do it. Sorry, but YOU shouldn't be trying stuff like this on equipment which you must have in working condition. I wouldn't do it myself....

For more power rent something as suggested.
 

bountyhunter

Joined Sep 7, 2009
2,512
I wasn't criticizig your response, just remembering the 20 years at national Semi that I spent answering similar questions. I think you nailed it. If you go back through the five pages of this thread, I and others have all been saying the same thing you did but you phrased it more concisely. This thread is kind of a prototype of how to waste five pages on something that is not feasible and absurd to even try for a variety of reasons. But harmless I guess.
 

bountyhunter

Joined Sep 7, 2009
2,512
I wasn't criticizing your response, just remembering the 20 years at national Semi that I spent answering similar questions. I think you nailed it. If you go back through the five pages of this thread, I and others have all been saying the same thing you did but you phrased it more concisely. This thread is kind of a prototype of how to waste five pages on something that is not feasible and absurd to even try for a variety of reasons. But harmless I guess. Nobody got electrocuted and no houses were burned down.
 

Thread Starter

CRY&PRAY

Joined Jan 6, 2014
84
I wasn't criticizing your response, just remembering the 20 years at national Semi that I spent answering similar questions. I think you nailed it. If you go back through the five pages of this thread, I and others have all been saying the same thing you did but you phrased it more concisely. This thread is kind of a prototype of how to waste five pages on something that is not feasible and absurd to even try for a variety of reasons. But harmless I guess. Nobody got electrocuted and no houses were burned down.
luckily no house were burned down :3, ho well i'll go with what i have, tomorrow i'll go to but the pieces to repair the omnitoric, i'll need help there on a particular resistor that i forgot the value, if you go to see the img it's the one with some numbers and question marks. That resistor bridge emitter and base of the d669a thru a pot, but i don't remeber the exact value, i think that were all 3 red strips so a 2k2, i'll buy all the 3 probalily types and start from the bigerg one :3 i'll post here the conclusion during the repairing
 
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Thread Starter

CRY&PRAY

Joined Jan 6, 2014
84
Let's wait until February 16th.:p
haahahahhaah, i'm not that crazy to wire stuff like i don't know how... and make my house burn with my freaking multimonitor and gaming pc that cost an eye of the head!! and a usual a freking 10 amp fast blow fuse for that amp until i got it working correctly, then it's own 10 amp slow blow fuse.
 

Thread Starter

CRY&PRAY

Joined Jan 6, 2014
84
One channel of the omnitronic is ALIVE!!!

just need a d699a transistor to set the bias correctly, now sounds like a fart at low volumes, but if i touch the collector and emitter of the d699a place where now is nothing it sounds well!!! i'll wait to get all the parts :3, as the other channel, just need to pray.... still using the famous bose psu +-18 v

 
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Thread Starter

CRY&PRAY

Joined Jan 6, 2014
84
I must applaud you ... you remind me of me...
Never give up... never surrender!!! :D
hahaha, happy to know that, i really like eletronics :3 it's like an advanced lego and i find awesome how freaking piece of Si can stop current. Today maybe i'll go out with a friend and go get some of the parts, but the shop is pretty far away, hope they have that D699A that's pretty rare and i'll post the results, as the other channel.... need a check to the pre-amp that's not driving the 2 transistor (the one in the photo that i've placed, but to the other side) and so these transistor are not giving anything on the bases of the Power amp.
 

Thread Starter

CRY&PRAY

Joined Jan 6, 2014
84
Guys need a help!, what does that transistor one the 1 img down left with his base to the ground and a diode to the -95 v? the amp does not sound or sounds really bad on both channels (they are specular, i've tried to see if was a burned transistor) i have to connect a 100kOhm pot between the collector and the emitter set at around 40-50 KOhm in order to get sound (powerfull and well).



 

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Thread Starter

CRY&PRAY

Joined Jan 6, 2014
84
Guys need a help!, what does that transistor one the 1 img down left with his base to the ground and a diode to the -95 v? the amp does not sound or sounds really bad on both channels (they are specular, i've tried to see if was a burned transistor) i have to connect a 100kOhm pot between the collector and the emitter set at around 40-50 KOhm in order to get sound (powerfull and well).



i've got today 60 euros of components :3 yay, all mounted and the amp is working well, still having that problem, now i've placed 2 resistors (one for channel) on the emitter and collector of these 2 transistor (the one who has the base grounded and kinda biased with a diode coming from the 95-)

The question now is... is sounding this bad cuz i'm powering it with a low voltage (+- 18v) and so the diode that has maybe been thought to work with higher voltages is not biasing that transistor.. or it's a bigger problem?

the resistors that i've placed are 2k2 Ohm
 

Veracohr

Joined Jan 3, 2011
772
I don't know, maybe. You might try downloading LTSpice and simulating the circuit before you try the "hit the switch and pray" method.
 
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