Rats it wont work

[Kipper4]

i'll add some more info as i go if i can get my drop box to work again but hey here goes.
I built a VERO (my first vero) Original 80's Rat and ive probed it i get signal going to input on pin 3 of the LM308n but no out put at pin 6

heres the vero i did
http://www.aronnelson.com/gallery/main.php/v/cathexis/Veroboard+Layouts/ProCo+RAT/ProCo+RAT.JPG.html

[Kipper4]

heres some pics

https://www.dropbox.com/sh/7ma9n53c5jqdgsr/d-0TvwYXDL#f:Rat%20back%202.jpg

https://www.dropbox.com/sh/7ma9n53c5jqdgsr/d-0TvwYXDL#f:Rat%20back.jpg

https://www.dropbox.com/sh/7ma9n53c5jqdgsr/d-0TvwYXDL#f:Rat%20front%202.jpg

https://www.dropbox.com/sh/7ma9n53c5jqdgsr/d-0TvwYXDL#f:Rat%20front.jpg

[Kipper4]

no substitutions
voltages IC1
1   7.02
2   0.72
3   0
4   0.78
5   0.83
6   7.75
7   8.73
8   7.52



Q1
0.32
2.46
8.75

[Jopn]

So you've got signal at pin 3, but 0 voltage?

Something is fishy there...

[rousejeremy]

Can you post better pics of the bottom of the board? Those ones are a little too blurry and angled.

[Kipper4]

Thanks for the response JR
i'll take some more pics toute suite

https://www.dropbox.com/sh/7ma9n53c5jqdgsr/d-0TvwYXDL#f:Rat%20Back%202.jpg

[rousejeremy]

Did you cut that trace under R9?

[rousejeremy]

C13 looks backwards. The negative side should be going to Vol.3.

[Gurner]

Straight off the bat, assuming a 9V supply, Pin 3 should be sitting at 4.5V DC (give or take a hundred millivolts or so)...until it is, the circuit won't work properly.

I'm going goggle eyed, trying to map a schem from the vero layout in my head.... I googled for the schem but the component numbers don't seem to tie up...

[rousejeremy]

It also looks like the trace cut below C6 is misplaced. You have it on the fourth row down whereas the vero has it on the fifth.

[Kipper4]

thanks guys i'll investigate all the above when i get up.

[Kipper4]

Thats what it was thanks guys it works now though i built another using tonepads layout as the 80's version is very noisy.
I'm about to fire it up (V2) just got the off board wiring to complete.

[Kipper4]

~Once i ironed out a few bugs and got the transistor round the right way. The tonepad rat is way better than the vero (not my thing) version.
The vero has a lot of noise with it and not in a good way. its like it's loading down the amp somehow. Not that i know what im on about but thats how it feels to my ears.

[Kipper4]

I built a second rat tonight from Hollow earths perfboard layout and although i made a few mistakes and debugged it. it has nothing like the gain the tonepad one does although in theory they should be almost identical.

Heres the layout

http://www.hollow-earth.de/index.php?op=ViewAlbum&albumId=11&blogId=1#prettyPhoto[album]/2/

you can google the tonepad Rata for comparaison.

I dont understand why this is any ideas?


unless i fried something before debugging. Although i changed the ic and transistor just to see and it made no differance.
The pcb signal is lower than the bypassed, in the Hollow earth circuit.

[Kipper4]

I reckon I've made a booboo . I didn't have any 560r so I made one up from a 510 and a 4k7 oops . I'll fix it later and see if it work better.

[duck_arse]

the 560R is one of the gain setting parts. that is prolly where yr signal has gorn.

[rousejeremy]

The 560R is also part of the "Reutz Mod". Being able to switch it in and out of the circuit is a nice option.

[Kipper4]

i changed to a 560R then after 3 hours trouble shooting it works finally phew.
I created a solder bridge somehow between the 1m that joins to the 1uf electro cap and the 10nf cap that joins pin4.
its got so much gain, its like the other circuit now.