transistor amp not working after shorting output

[wg_ski]

The rest of us might be able to make sense of your readings if we knew how it was connected. And might be able to suggest resistor values for ones that are burnt beyond recognition.

 

[chrisng]

Have we even attempted to trace out a schematic yet? This thing looks pretty simple.

I tried making a schematic based on the image provided, but those wires from the 2N3055 are blocking the traces underneath it. It would help a lot if sg97 could take photos without these wires.

I also created an image of the board with no components populated.

sg97, please check if the copper trace is correct? Can you draw the components on it so we can make a schematic?
By the way, it looks like a 3D circuit combining P2P and PCB!

 

[sg97]

i will provide all info that you need 😀

 

[Netlist]

You only need 3 symbols. Resistors, capacitors and transistors. 🙂

https://www.diyaudio.com/community/...ing-after-shorting-output.406712/post-7556210

 

[sg97]

my only issue is as you can see some componenct like resistors are not in pcb directly its connect in unusual way and how can i draw it in there ?

 

[Netlist]

This is just an example, not the actual location of components.
Oh, and you'll need the diode symbol as well.

 

[sg97]

i will do my best in showing where components are but as i said i may not able to draw all because not all components are on board its stupid and not professional. if it was board from commercial product it would be easier for me

 

[Netlist]

I realize it's the end of the working week, but I'm sure you can do it. 😉

 

[Netlist]

As you can see I drew some 'floating' components. Not that hard...

 

[sg97]

as you can see there are some components outsire of board and also connected to eachother i will try to represent is as best as i can

 

[sg97]

i will add all components and label them as best as i can, btw for resistors caps and transistors i will use default symbols

 

[oscroft]

yes it does. so i measure like from 00.6 to 01 something

sg97, that multimeter you have will not measure such low resistances accurately - even much better meters have trouble too. You'd need a meter that can specifically measure milliohms, and they're not cheap.

 

[sg97]

here it is it took a lot of time but its here, i did not put resistor values but you can see it it second pic. btw orientation for transistors may not be 100% true. but their place is. let me know guys what you think

 

[gijser]

That is progress 🙂, but there are things that don''t make sense to me. I dont have much time right now, but to start:
the two diodes with the resistor in series, I think they are the bias parts. The driver transistors (the small ones that have one leg connected to the base of a 2n3055) should have their base connected to the bias string, one on either side. But I don't see that in your picture, so I am confused..

 

[sg97]

trust me all the parts except two resistors i changed are there even when it was working 2 years ago. i am not sure what can cause problems it looks really messy

 

[sg97]

for red resistors i marked 2n3055 i am 90% sure it is like that for small ones i am not really sure of e c and b but connection points are right

 

[Wakh]

Looks like it should be like this

 

[sg97]

btw that big cap there appears to be shorted with a wire ? it does not connect to anything now its shorted

 

[sg97]

i mean that pad is shorted cap is just sitting with no use at all xdd

 

[Wakh]