Marshall sim not working

[Rafa]

Hi:
Ive finished the lxh2 marshall simulator (without the cabinet), as I expected it doesnt work.
Ive cheked all the connections many times with an ohmeter, but everything seemes to be ok.
When I turn it on, thers no sound, If play rellay hard its turns on for a little while, so I thought that maybe Ive burned some opamps(I used sockets)??
The only mods I did where: 1n4148 instead of 1n914
                                        100 ohm resistor instead of 150, I couldnt find it.
                                        2,2k instead of 2,7K resistor
Anybody knows how to test opamps with an omheter?

Thankssssssssssssssssssssss

[Rafa]

Now testing I found out that if I connect the pins 11 and 12 of the tl084 it works, not the way it should, but the fault should be there

[bancika]

like with any other effect, audio probe is your friend. Just trace signal from start towards the end following signal path. Make someone play chords on guitar or connect pedal input to sound card output of your PC and play music there. Once you don't hear anything you've found the problem.

[petemoore]

  When I was messing with that I did one stage/test/next stage.
  I would get familiar with the Debugging page, and look for opamps +/- inputs and outputs that *aren't about 1/2v...or post OA pin voltages.

[MartyMart]

The LHX2 is a HUGE build, I made one this year, which works great, but I would not have
attempted that 2 years ago .... a little bit much for someone who has other more simple
builds that are not working ..... yet !!
You do know that it's a "two battery" +9/-9 v dual supply circuit ?
Sorry , dont mean to be rude but it is a very complex circuit @ 9 opamps !!
..... that's a LOT of degugging and voltage checking .....

MM.

[Rafa]

Thanks a lot Marty
I used this layout:

http://diy.prophecysound.com/DIYeffects/LHXampsim/layoutv1_1.pdf

I didnt understand the part of the two voltage supplies, I just used one as the schematic indicated

Thankssssss

[MartyMart]

OK, i see - wont work that way, here's a quick "how to"

Use 2 x battery snaps
Use stereo jack sockets for in and out of circuit.
First battery, connect red + to +9v on board, connect black - lead to
the "ring" on the jack socket. ( input jack )
Second battery, connect the black - lead to -9v on board, connect the
red + lead to the ring of the second jack socket ( output jack )
All grounds go to the "0" ground on board, so now you have a +9 and -9 v
connection, when both input and output lacks are inserted.
Remember to unplug "both" or one battery will drain down !!

Marty.

[Rafa]

Wow thats very helpful.
Thanksss
Hear there are some photos from my website (http://www.geocities.com/rafa23189) :

[Rafa]

ops the links didnt worked
Well if you want to take a look just enter my website the photos are at the main page.

[Rafa]

Can I use the same battery??. I guess the answer is no, and as I am using transformers Ill have to use two.
Furthermore if youconnect  + and - to each ring, then it all matches in the ground   
Thankssss

[petemoore]

  On the Right side of that layout, I see a trace...looks like it says V-, and that goes to pin 8 of the TL072 [wouldn't that be reverse polarizing it?...I'm sure I can't see or the layout is correct...but a schematic is made for reading, layouts are made to confuse the reader...
  Mine had 2 battery clips coming off it, I used 2 batteries to power it.

[donald stringer]

I used the +9 -9 maxim 1044 charge pump schem  its located in  geofex. I too wasnt even going to attempt it without making sure each part worked as Iwent.

[Rafa]

No Peter thats for the pin 4 the pin8 is indicated V+, the layout is a bit confusing.
Can you achieve clean sounds with yours or is it only for overdrives and distortion??

[Rafa]

I saw the ``+9V *and* -9V from one battery!´´ using max 1044 but I dont know whats that for, I think theres something I dont know about power supplies, where should I start reading??

[MartyMart]

I saw the ``+9V *and* -9V from one battery!´´ using max 1044 but I dont know whats that for, I think theres something I dont know about power supplies, where should I start reading??

GEOFEX above left

MM.

[Rafa]

  Thanksssssss

[Rafa]

               
Its working
Thanks Marty Thabksss a lot
ITs amazing I  really recommend it
It sounds just like one of my favourite guitarrist Walter Giardino from Rata Blanca
He uses a jcm800
Incredible very close to the original  as soon as I can Ill upload photos and soundclips.

[Yazoo]

I've just finished the Fender sim using the Frank'n'tone mods, and the standard Fender Cab simulator. I was disappointed because I wasn't getting anything like the sounds Frank did. I was using a 9 volt bipolar power supply. I searched around and came across the suggestion that it needed more than 9 volts. I redid the power supply to run at 12 volts and I am now getting much better results. I am getting a full range from clean to very overdriven.

By the way, again from what I have read, it doesn't make any difference which way around the two Zener diodes are connected, cathode to cathode or anode to anode. I noticed Frank had connected the diodes the opposite way around to the schematic and so I did as well.

Frank was very helpful and generous in sending all his files to me, so Frank, thanks again.

[AJS]

About the +-9v battery arrangement suggested by Marty Mart. Why use both input and output as switches for each of the batteries? I would assume that wiring black from one battery and red from the other together and then call this GND and solder GND to the ring of only one stereo jack would do just fine? The red and black left is then V+ and V-. But, maybe there is some smart reason for not to do this?-
--
AJS

[stm]

About the +-9v battery arrangement suggested by Marty Mart. Why use both input and output as switches for each of the batteries? I would assume that wiring black from one battery and red from the other together and then call this GND and solder GND to the ring of only one stereo jack would do just fine? The red and black left is then V+ and V-. But, maybe there is some smart reason for not to do this?-

Unfortunately there is. If you don't open at least one wire on EACH battery current will still flow into the circuit and drain the batteries.  This is because there will be 18V difference between the (+) of the upper battery and the (-) of the lower one, since they are still tied together in the middle.  Current will flow into the positive and negative supply pins of the opamps, since they don't care if there is an actual circuit ground or not, just if there is a positive voltage difference applied to their supply pins.

The arrangement you suggest will leave the ground of your circuit floating and you will probably get a bad sound or no sound at all.