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EVH Flanger problem

Started by foster, March 05, 2015, 03:10:57 PM

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foster

March 05, 2015, 03:10:57 PM
Hello everybody!
I've recently bought an used EVH Flanger that it sounds great but
in the higher and lower peaks of the sweep (EVH mode engaged or not) it produces some kind of a Hits..
My question is : is it something that I can fix just fine tuning one of the two internal trimpots that I see on the board ?
If yes, do you guys know which is the trimpot to adjust? (I know there are two more trimpots in the internal side of the pedal)

Thank you in advance!
Foster

P.S If needed I can send a short audio file where you can hear the "kind of a hits" I'm talking about..

Govmnt_Lacky

#1
March 05, 2015, 03:24:33 PM
If by "hits" you mean THUMPS at each end of the sweep then you can most likely trim those out. Just need to find the correct trimmer.

More than likely it is the BBD bias trimmer -OR- possibly the clock trimmer.

Whatever you do, MARK THE TRIMMER POSITIONS BEFORE TURNING. And only trim a tiny bit
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

foster

#2
March 05, 2015, 03:27:29 PM
Yes, the correct word is "Thumps" at each end of the sweep!

Can you please give me suggestions to individuate the BBD and the clock trimmers?

THX

Foster

Quote from: Govmnt_Lacky on March 05, 2015, 03:24:33 PM
If by "hits" you mean THUMPS at each end of the sweep then you can most likely trim those out. Just need to find the correct trimmer.

More than likely it is the BBD bias trimmer -OR- possibly the clock trimmer.

Govmnt_Lacky

#3
March 05, 2015, 03:51:35 PM
Quote from: foster on March 05, 2015, 03:27:29 PM
Can you please give me suggestions to individuate the BBD and the clock trimmers?

Can you provide some good pictures of the inside so we can see the PCB and the trimmers?
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

foster

#4
March 05, 2015, 04:12:49 PM
Quote from: Govmnt_Lacky on March 05, 2015, 03:51:35 PM
Quote from: foster on March 05, 2015, 03:27:29 PM
Can you please give me suggestions to individuate the BBD and the clock trimmers?

Can you provide some good pictures of the inside so we can see the PCB and the trimmers?
I don't know how to upload them here, I don't see any option "attach file", I'm using a Mac,

can you help me please?

THX

Foster

Ice-9

#5
March 05, 2015, 04:23:03 PM
Quote from: foster on March 05, 2015, 04:12:49 PM
Quote from: Govmnt_Lacky on March 05, 2015, 03:51:35 PM
Quote from: foster on March 05, 2015, 03:27:29 PM
Can you please give me suggestions to individuate the BBD and the clock trimmers?

Can you provide some good pictures of the inside so we can see the PCB and the trimmers?
I don't know how to upload them here, I don't see any option "attach file", I'm using a Mac,

can you help me please?

THX

Foster

The easiest way is to upload the pictures to something like photobucket and insert the links directly into the post. The forum admin I think prefer them uploaded to the forum site if I am correct as that way they don't get deleted as they would if you deleted them from photobucket they would disappear off this forum as well.
www.stanleyfx.co.uk

Sanity: doing the same thing over and over again and expecting the same result. Mick Taylor

Please at least have 1 forum post before sending me a PM demanding something.

foster

#6
March 05, 2015, 04:47:11 PM
Quote from: Ice-9 on March 05, 2015, 04:23:03 PM
Quote from: foster on March 05, 2015, 04:12:49 PM
Quote from: Govmnt_Lacky on March 05, 2015, 03:51:35 PM
Quote from: foster on March 05, 2015, 03:27:29 PM
Can you please give me suggestions to individuate the BBD and the clock trimmers?

Can you provide some good pictures of the inside so we can see the PCB and the trimmers?
I don't know how to upload them here, I don't see any option "attach file", I'm using a Mac,

can you help me please?

THX

Foster

The easiest way is to upload the pictures to something like photobucket and insert the links directly into the post. The forum admin I think prefer them uploaded to the forum site if I am correct as that way they don't get deleted as they would if you deleted them from photobucket they would disappear off this forum as well.

OK,  here it is..  http://s1303.photobucket.com/user/fosterdato/media/EVH%20Flanger%20inside/DSC08808_zpsmmcwdrhv.jpg.html

THX

Foster

Govmnt_Lacky

#7
March 05, 2015, 07:25:36 PM
Whole lot of trimmers on that board!  :icon_eek:

My best recommendation is to only try adjusting the larger trimmers. (You can see a few SMD trimmers hiding in there)

Start with the one closest to the BBD chip (Bias?). BE SURE TO MARK THE STARTING LOCATIONS FIRST!!!

Turn them ever so slowly until the thumping goes away. If small adjustments do not work on the trimmer you are adjusting after going a few millimeters, return it to the initial mark and try another.

Good Luck
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Fender3D

#8
March 06, 2015, 06:44:46 AM
Why unregulated Bias would provide "Thumps" at each end of the sweep?
Thumps usually are correlated with LFO....
sadly, no trimmer in there has to do with LFO.

I don't think EVH schematic differs too much from stock M117...
Then the usual Flangers' trimmers are: BBD's Bias, Regen trimmer, Level trimmer and clock trimmer.

Bias is easy to set watching BBD's output with an o-scope,
you'll easy realize if you set regen trimmer too high  :icon_lol:
level will do what's you may guess,
clock is really important, since it sets (usually) the start of the sweep. Check with a freq. meter what's the clock BEFORE messing with it...

EVH has a 572 maybe 1 trimmer sets its "distortion", and (maybe again) other trimmer(s) might have to do with VH preset.
"NOT FLAMMABLE" is not a challenge

foster

#9
March 06, 2015, 09:22:32 AM
Quote from: Govmnt_Lacky on March 05, 2015, 07:25:36 PM
Whole lot of trimmers on that board!  :icon_eek:

My best recommendation is to only try adjusting the larger trimmers. (You can see a few SMD trimmers hiding in there)

Start with the one closest to the BBD chip (Bias?). BE SURE TO MARK THE STARTING LOCATIONS FIRST!!!

Turn them ever so slowly until the thumping goes away. If small adjustments do not work on the trimmer you are adjusting after going a few millimeters, return it to the initial mark and try another.

Good Luck

Can you please help me individuate the BBD Bias related trimmer?

THX

Foster

foster

#10
March 07, 2015, 04:57:46 AM
Quote from: foster on March 06, 2015, 09:22:32 AM
Quote from: Govmnt_Lacky on March 05, 2015, 07:25:36 PM
Whole lot of trimmers on that board!  :icon_eek:

My best recommendation is to only try adjusting the larger trimmers. (You can see a few SMD trimmers hiding in there)

Start with the one closest to the BBD chip (Bias?). BE SURE TO MARK THE STARTING LOCATIONS FIRST!!!

Turn them ever so slowly until the thumping goes away. If small adjustments do not work on the trimmer you are adjusting after going a few millimeters, return it to the initial mark and try another.

Good Luck

Can you please help me individuate the BBD Bias related trimmer?

THX

Foster

Anyone knows where it is located??

THX

Foster

Govmnt_Lacky

#11
March 07, 2015, 08:50:21 AM
Quote from: foster on March 07, 2015, 04:57:46 AM
Anyone knows where it is located??

Since there are no readily available schematics then your best bet is to mark the trimmers and make small adjustments like
I mentioned before. Start with the trimmer closest to the BBD chip. I wouldn't mess with the SMD trimmers though...
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

foster

#12
March 07, 2015, 09:27:27 AM
Quote from: Govmnt_Lacky on March 07, 2015, 08:50:21 AM
Quote from: foster on March 07, 2015, 04:57:46 AM
Anyone knows where it is located??

Since there are no readily available schematics then your best bet is to mark the trimmers and make small adjustments like
I mentioned before. Start with the trimmer closest to the BBD chip. I wouldn't mess with the SMD trimmers though...

Yes, I 100% Agree!

But.. wich of the chips is the BBD's one? And wich trimmer do you consider the closest to it?

THX

Foster

Govmnt_Lacky

#13
March 07, 2015, 10:40:31 AM
The BBD (Bucket Brigade Device) is the only chip that is NOT soldered directly to the PCB. It is the one in a socket. The trimmer I was talking about is directly below it. Start with that one and move on if you hear no change in the thump.

REMEMBER TO MARK THE ORIGINAL POSITIONS OF ALL THE TRIMMERS SO YOU CAN GO BACK.
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

foster

#14
March 07, 2015, 07:19:19 PM
Quote from: Govmnt_Lacky on March 07, 2015, 10:40:31 AM
The BBD (Bucket Brigade Device) is the only chip that is NOT soldered directly to the PCB. It is the one in a socket. The trimmer I was talking about is directly below it. Start with that one and move on if you hear no change in the thump.

REMEMBER TO MARK THE ORIGINAL POSITIONS OF ALL THE TRIMMERS SO YOU CAN GO BACK.

OK,

now it's clear!

THX

Foster

Fender3D

#15
March 07, 2015, 09:52:32 PM
Quote from: Govmnt_Lacky on March 07, 2015, 10:40:31 AM
... The trimmer I was talking about is directly below it...

Nope, that's the "null" trimmer Greg...
"NOT FLAMMABLE" is not a challenge

Govmnt_Lacky

#16
March 08, 2015, 11:50:50 AM
Quote from: Fender3D on March 07, 2015, 09:52:32 PM
Quote from: Govmnt_Lacky on March 07, 2015, 10:40:31 AM
... The trimmer I was talking about is directly below it...

Nope, that's the "null" trimmer Greg...

OK. You probably know better than I which trimmer or trimmers to try an adjustment on. Please... do tell  ;D

I cannot find a schematic for this pedal. Do you happen to have one to share?
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Fender3D

#17
March 08, 2015, 06:48:34 PM Last Edit: March 08, 2015, 06:50:54 PM by Fender3D
Sadly I have not an EVH flanger schematic... but I found a PCB's tracks picture
And since I'm used to work on PCBs without a schematic, I usually follow the tracks comparing it all to similar schematics, first (tracks from that trimmer go to BBD's pins 7 and 8 ).
This is, actually, the only useful advice I can give...

I don't know whether foster is more interested in repairing his flanger or he's just in a frenzy of messing with its trimmers, but I'd learn how a flanger (and especially in this case, a BBD) works, first.

Marking trimmer position, is also useless.
Learn or find what the trimmer does, and measure its "job"...
"NOT FLAMMABLE" is not a challenge

Govmnt_Lacky

#18
March 08, 2015, 08:57:05 PM
Quote from: Fender3D on March 08, 2015, 06:48:34 PM
Sadly I have not an EVH flanger schematic... but I found a PCB's tracks picture

Please do tell... I looked for quite a while and came up with nothing.  :-\
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Fender3D

#19
March 09, 2015, 03:19:17 PM
I got this, I'd have sworn they were on the other site, but a quick search lead to nothing...  :icon_confused:



"NOT FLAMMABLE" is not a challenge
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