help Gary hurst MKI tagboard layout several issues.

Started by strassercaster, November 26, 2015, 02:35:08 PM

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strassercaster

well i am on build number 50. i have a lot of builds under my belt . ABout 6 rangemasters 4 vox tonebenders a couple fuzz faces as far as germaniums circuits go.. I took my time on these and although they arent mega builds like the boss ce-2 or small stones i did on vero they take jaut as much time.I had read that these MKI can be very tricky so i waited.i did the tagboard effects layout and its perfect as far as mistakes. i  spent several hours last night triple wuadrouple checking for mistakes. I even changed both electro caps in case of leakage .

the issues are a chirpping and squealling. it also cuts out as well. with the attack past noon it has a slight muddy delay.i started with a set of oc75 from Lic Pedal i got from Chris.the typical gains for q1 q2 and q3. its was insane squeall cut out chirp and squeal. i have about 13 sft363e in the 36hfe to about 86hfe , i have about 20 ac125 in the 75-122 hfe i have about 20 2n404 in the 70 to 156hfe range. i also have a few other pairs and leftovers totaling about 30 . i have tried over twent different combination. even when i use q1 60 hfe q2 78 hfe and q3 70 hfe i am still getting squeal chirpping cutting out and over stauration. the build i did has two trimmers in the layout. from what i have read you really want to keep them stock 8.2k. i set them to 8.19 and 8.25 k. .


http://3.bp.blogspot.com/_y7gcfRKQFgA/TToomaBly1I/AAAAAAAAAT4/fr2UqmbJJ1I/s1600/Gary%2BHurst%2BTonebender%2BMKI%2Bwith%2Btrimmers-713497.png

this is the layout i used. i know its all about the bias but after swaping transistors and even going to half the normal hfe on all three transistors i have the same issue. with the extremely low hfe transistors the problems isnt as insane but its still there. i have had many probably over half my builds that didnt work or sound good on the first try. out of the other 49 i only have one that i am not comepletely satisfied with.

What is the proper bias for these i have done several seaches and really have t seen any working bias figures. does this layout look right it is verified but several people had issues and never reposted.i have listened to dozens of shootouts and tonebender 1 2 2pro 3 fuzz faces and vox tonebenders. from the videos on you tube this would be my goldie lox tonebender/fuzz pedal.i am positive i dont have any bridges i have come back with fresh eyes twice now. i havent missed any solder points redid them all changed out the pots . only have a battery running it for now once i get it right ill hook up a charge pump.i have tried low gain low leakage high gain low leak age medium gam med leakage . . i havent done much woth my two trimmers i wanted to get it to work as designed and figured i had enough transistors to do so. man how could you mass produce these without biasing the germaniums were never that accurate or reliable.

the thing than bothers me on this layout is. the 1meg resistor is on the other side of the transistor idk why but when i modded it to the other side i .got nothing . i did read one guy had the chirpping and he put 4.7 n from input to ground. i did that and the chirp and squealch wasnt quite as bad but still prominent.
i always ramble to much for these posts sorry

in summary
pedal is 100 percent built right physically

it chirps squeall and cuts out.
when you turn the attack knob it has voltage static and make s noise
i tried extremely low hfe for all three transistors med and rgular gain

I really need to know what the working voltages are on all theree or at least ranges.

my last attempt for transistors was q1 54hfe q2 78 hfe and q3 60hfe all medium .2 to.3 leakage on my meter the premeasured on atlasdc are mixed leakage and i have tried twenty combinations.

its time to use those trimmers i put in but they do no good without knowing where i need to be ha ha.
also i used the layout with the 470k resistor should i try going down to the 180k or in between?

Thank You all in advanve and happy Thanksgiving

this is almost as hard as my first chorus build i had the dreaded tic but wventually got it to work right ha ha. at the moment it feels worse because it looks so easy and isnt a mojor bui
d but man is this the king of finicky or what ha ha

PRR

Squeal suggests layout. Output too close to input.
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strassercaster

Quote from: PRR on November 26, 2015, 09:07:07 PM
Squeal suggests layout. Output too close to input.
idk the output cones off the level pot and both input and output wires are shielded.hmmm

Electric Warrior

Quote from: strassercaster on November 26, 2015, 02:35:08 PM

I really need to know what the working voltages are on all theree or at least ranges.

my last attempt for transistors was q1 54hfe q2 78 hfe and q3 60hfe all medium .2 to.3 leakage on my meter the premeasured on atlasdc are mixed leakage and i have tried twenty combinations.

This worked for me:

Battery measures 9.04 V
Attack at 0:

Q1
C -8.89
B -1.09
E -1.31

Q2
C -8.78
B -0.04
E -0

Q3
C -8.19
B -0.03
E -0

Full Attack:

Q1
C -8.76
B -1.10
E -1.34

Q2
C -5.81
B -0.13
E -0

Q3
C -8.07
B -0.03
E -0

MKIs tend to do that chirping thing. I had to increase the resistor between Q2B and -9V from 180k to 470k (both are known stock values) to get rid of it. I didn't need any other tweaks. My transistors are pretty leaky, btw.

strassercaster

Quote from: Electric Warrior on November 27, 2015, 08:31:52 AM
Quote from: strassercaster on November 26, 2015, 02:35:08 PM

I really need to know what the working voltages are on all theree or at least ranges.

my last attempt for transistors was q1 54hfe q2 78 hfe and q3 60hfe all medium .2 to.3 leakage on my meter the premeasured on atlasdc are mixed leakage and i have tried twenty combinations.

This worked for me:

Battery measures 9.04 V
Attack at 0:

Q1
C -8.89
B -1.09
E -1.31

Q2
C -8.78
B -0.04
E -0

Q3
C -8.19
B -0.03
E -0

Full Attack:

Q1
C -8.76
B -1.10
E -1.34

Q2
C -5.81
B -0.13
E -0

Q3
C -8.07
B -0.03
E -0

MKIs tend to do that chirping thing. I had to increase the resistor between Q2B and -9V from 180k to 470k (both are known stock values) to get rid of it. I didn't need any other tweaks. My transistors are pretty leaky, btw.

thanks . i am already using the 470k i appreciate the voltages.i was old hat this layout i am using from tagboard has some issues .