Problem with Markm HAO rustdriver, please help

[stefcuypers]

Hello,

Build myself a Hao rustdriver from Markm's layout and having a hard time get it proper working. Build it on perf according to the schema. Problem is that there is a very loud singing tone all the time, sort of feedback but lower, oscillation probably is the best word to describe it.

The difference in components i used are:

1n4148 for the 1SS119,
R7 is R42k and not 47k,
R8 is 420k and not 470k
and C3 is 0,01uF and not 0,012uF.

Been debugging it the whole afternoon and can't find something wrong, checked it 3 times. I don't have more electronic knowledge than check the connections and measure the resistors and check the caps with the written values. If someone have a suggestion or tip would be great, really want to get it working! Thanks,

Stef

[jlullo]

Hey there!  Follow the sticky on "what to do when it doesn't work".  Post your readings and we'll try and figure it out!

[DougH]

A) There's no schematic of this circuit anywhere in the archives, layout gallery etc that I can find.

B) There are 2 caps on the layout that have leads that are apparently not connected to anything. Unless there is something about the layout I don't understand, was since modded or explained, these appear to be mistakes.

So....Sorry, I cannot help.

This is not your fault, but it underscores why I really hate layouts being posted without schematics.

The schematic's the thing... The schematic's the thing... Etc...

[Renegadrian]

Here's Markm layout


Starting from that, I made my own Vero


DAMN IT IS NOISY AS HELL!!! Gain pot doesn't work properly, and that insane hum!!! grrr...
Used 1n4148 as diodes, caps and res follow the first layout. I put in a Mill.2, but that shouldn't bring problems, as I always use that layout...

Some voltages...
dc jack from unreg. wall wart 10.20

LM358
1   5
2   5
3   4.80
4   0
5   4.80
6   5.10
7   5.10
8   10.20

--------------------------

Quick update - I tried to hook up a battery, this was meant to have dc jack only, but I wanted to try.
powered by a battery, it is very quiet, no hum at all!!!
Else, I tried with two different wall warts that both work good with other pedals I have. As soon as you connect one, you have TONS of hum...Also wit a 1000µF cap between + and -.
grrrrrrrrrrrrrrrr

[Renegadrian]

Case solved
I had some problems with my wall warts - tried at my friend's house, it sounded good with his ww

So my layout is working and verified, may you need to build this one...

[newfish]

Congrats on your build.

...where's the Tube though?   

[Renegadrian]

 

[Renegadrian]

Actually it never sounded that good...In fact I dismantled after a while, unsatisfied for what I didn't have from that pedal...
I discovered that there's a mistake in MarkM's layouts, that .012µF cap should be .0012µf like in all the other schems/layouts around. Maybe that was the reason my pedal did not have the right sound...