Stage Line 500W amp repair project

[bikemech]

Never mind. The first step is always the hardest.
Do you have any more veroboard and can you get the sockets off without damaging them?

I jave the other half of the veroboard i used, so yes there is plenty more to redo it, as for reusing the ic sockets, i can get some more there cheap enough and i have yet to order the box and leads, i may have to order some more 100k resistors though, tnere were only 4 in stock, all the others i ordered 10 of for this reason, i am thinking it may be a good idea to order a bread board so i can dry build things first to get placing and connections correct before soldering and wasting componants, will there be a way of testing this when complete ?

 

[WHONOES]

Plan it out on a piece of paper you can then have as many goes as you like until it looks right without wasting lots of components.

 

[WHONOES]

I can remember my first attempts at building circuit on Veroboard over 50 years ago. They were a bit of a disaster none of them worked. It takes a while to get your head around a good layout. That's why I suggest planning out on paper first.

 

[bikemech]

I can remember my first attempts at building circuit on Veroboard over 50 years ago. They were a bit of a disaster none of them worked. It takes a while to get your head around a good layout. That's why I suggest planning out on paper first.

I hate getting it wrong, but suppose its part of the learning curve, i now know how opamps, transostors NPN and PNP work, amongst other componants, i realise now VCC is the control input on these opamps thanks to you guys, i have always been interested in electronics but never had the time to studdy it propperly, kris was fantastic at explaining things with pictures which made it realy easy for me to understand, i am still learning and realy greatfull of everybodys help, maybe someday i will be in a position to guide someone else,

Pete

 

[bertus]

Hello,

If you do not want to use paper, you could use a piece of free software called PEBBLE.
It has all kinds of components and boards to "draw" your PCB.
https://picaxe.com/software/third-party/pebble/

Bertus

 

[bikemech]

Hello,

If you do not want to use paper, you could use a piece of free software called PEBBLE.
It has all kinds of components and boards to "draw" your PCB.
https://picaxe.com/software/third-party/pebble/

Bertus

unfortunately i cant seem to get that to work on my laptop :-(

 

[bertus]

Hello,

You have to unzip the file.
You will find the following files in the unzipped directory:

The software uses a browser as user interface.

Bertus

 

[bikemech]

here is what i have come up with, does it look right ?, assuming the copper strips run vertically,

Cheers

 

[bikemech]

just noticed i am missing the electrolytic cap on there

 

[bikemech]

 

[bertus]

Hello,

You can change the size of the electrolytic capacitor by using the right mouse button.
A menu will pop-up like this:


You can also change the board style with the two bars in the menu:


Bertus

 

[bikemech]

Hello,

You can change the size of the electrolytic capacitor by using the right mouse button.
A menu will pop-up like this:
View attachment 50676

You can also change the board style with the two bars in the menu:
View attachment 50677

Bertus

thank you, yes i know that, i was almost done by the time i noticed i could change the board

 

[bikemech]

how does this look ?

 

[bikemech]

For what i have spent on componants to build this buffer circuit i could have just bought a cheap scope and sig gen, but i suppose i have learned some more so its worth it, and will aid me in understanding how to diagnose and finish this amp

 

[bikemech]

Ordered some better veroboard along with some more IC sockets, BNC to crock leads and a set of probes, should be here in a couple of days,
Does anybody have any idea if my plan for the componants is right ?, i think it is,

Cheers

 

[bikemech]

Am i right in thinking X1 and X2 are 1 IC, AND X3 and X4 are the second IC ?,
Also is the ground the negative of 9v battery or is the groung supposed to be the 0V rail, if that is the case where does the negative go to ?

 

[WHONOES]

For some reason I haven't been receiving up to date posts for a few days.

You are correct in your assumption. X1 and X2 are indeed part of 1 I.C whilst X2 and X3 are part of a second I.C.

The battery connections go as shown for the 9V supply in the schematic. The 0V connection which is applicable to both input and output is at the output of X2 as on the schematic.

Because you have used two IC's rather than having all 4 amplifiers in one package, you will need a duplicate of C2, call it C3. These two items must go directly across the power supply pins for each IC package. They are to decouple the supply, at those points, from the wiring. They are essential as they stop X1 to X4 oscillating.

X1 forms what is termed a false or phantom 0V.

 

[bikemech]

Ok, on the drawing there is only a positive symbol for the battery, is the earth/ground symbol also negative and chassis earth?,

And C2 on the drawing connects to both opamps via the positive and ground/negative/earth

 

[bikemech]

For some reason I haven't been receiving up to date posts for a few days.

You are correct in your assumption. X1 and X2 are indeed part of 1 I.C whilst X2 and X3 are part of a second I.C.

The battery connections go as shown for the 9V supply in the schematic. The 0V connection which is applicable to both input and output is at the output of X2 as on the schematic.

Because you have used two IC's rather than having all 4 amplifiers in one package, you will need a duplicate of C2, call it C3. These two items must go directly across the power supply pins for each IC package. They are to decouple the supply, at those points, from the wiring. They are essential as they stop X1 to X4 oscillating.

X1 forms what is termed a false or phantom 0V.

Do you mean X3 and X4 are the second IC ?

 

[WHONOES]

It really doesn't matter how you configure them. You can organise them in any order to suit you.

I originally specified a TL034 which is 4 opamps in one IC package. The schematic was drawn using my Simulation software. The Sim' identifies each of the separate amplifiers in the IC with its own identifier hence X1, X2 etc.

The sim' requires a ground connection as shown on the schematic. Every voltage in the circuit is referenced to it. Without a ground, it simply will not simulate.

AS I said earlier, each IC will need its own "decoupling" capacitor to ensure stable operation hence the need for a second one.