Boss GE-7 Mods

A forum devoted to mod, tips and suggestions for upgrading and rehousing your VERY CHEAP commercial stompbox to near boutique excellence.
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blackbunny
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Post by blackbunny »

Thanks Mortad, this is a great post. I think GE-7 (2) may be the schematic for the current production (Taiwanese) model, which I have never found anywhere on the 'net before.

This should correspond to the component values and numbers on your PCB. Could you compare the diagram to your PC board?

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mortad
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Post by mortad »

Hey...
I've trying to read that schem and I think it's the right schem for the GE7 Taiwan V2, though my hability to read electronic schems is very poor !
cheers :wink:

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mortad
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Post by mortad »

PEDAL FIXEEEEEEDDDD !!!!!.... [smilie=a_partyguy.gif]
There was NOTHING WRONG: I put the pcb back in the box and it works perfectly!
The contact with the metal case is the ground for the Output jack !
Thanks to all who replied to this post.
1000 Thanks to blackbunny [smilie=a_goodjob.gif] !!!!

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blackbunny
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Post by blackbunny »

Good news! And thank you for finding and posting the super-rare version 2 MIT schematic. Sometimes the solution is the simplest thing. :slap: :blackeye

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Post by rcustoms »

I have this on my hard drive ,long long time ago ,i dont know who did it ,I apologize for posting but thanks anyway.
ge7.jpg
http://www.rcustomspedals.blogspot.com
guitars,pedals and amps.
@zuleta.rafael(Instagram)

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Qatbyte
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Post by Qatbyte »

Dude, you rock! That photo was just what I needed to decipher all the tantalums and other caps that I'm gonna replace. All you guys -- going back through the years on this subject -- have been so generous and thus so helpful to me. I'm about to hit the "Place Order" button on my Mouser cart... hate to find I missed one damn 25¢ part, but seems like I do almost every time... you guys have helped me really nail down my parts list with the schematics and jpgs. Thanks to all of you in helping me decipher my vintage GE-7. And in case anyone else is out there scouring the web for answers... this post has everything you need for the GE-7. Go to Monte's and Mouser and order the parts and that's it. The piece that I labored on was the dang SIL HA12017. The schematic by Jon Halverson suggests upgrading this SIL to a OPA134 via a SIL to DIP adapter. But Monte doesn't do it... and if anyone could easily, it would be him b/c he has all the bits and the motivation... and he still doesn't mess with that SIL. No one does. I wish I could slap a OPA134 with a SIL->DIP, but I think that's stepping off the end of the plank. Any input on this would be most appreciated.

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Post by Qatbyte »

Here is my compiled list of changes that I've gleaned from the various postings for the VINTAGE Boss GE-7 with three TL022 opamps in a row. FWIW.

Replace the following capacitors with Panasonic ECQ-V stacked metal film poly caps unless noted.
C1 .047uF
C2 .039uF
C4 .1uF
C5 .15uF
C7 .33uF
C9 .68uF
C10 1.5uF
C11 1uF
C13 0.1uF (to give better base)
C16 10uF
C17 100uF
C18 47uF
C19 1uF
C21 47pF silver mica
C22 0.047 uF
C23 0.047 uF
C24 0.047 uF
C25 1 uF
C26 0.047 uF

Add silver mica 270 pF x R26

Replace the following resistors with 1/2 watt MF
R1 47R for greater opamp current with newer opamps or jumper instead.
R10 380R LED resistor
R14 1K
R24 3.3K
R25 3.3K
R26 10K
R27 10K
R30 10K
R33 4.7K

Diode
D1 replace with Schottky diode 1N5817 or similar. Or, jumper connection. Or, upgrade zener to 12v and change input power to 12v. I chose to keep it at 9v and thus will try 1N5817.

IC1,2,3 install DIP sockets then plug and play to your heart's content any of the following opamps: OPA2134PA, NE5532AP, RC4559, RC4558P, RC4558DD, TL072.

IC4 is JRC4558DD and is acceptable as is.
IC5 is a SIP that is not acceptable but is too much trouble to upgrade.



Check out as well:
https://www.diystompboxes.com/smfforum/ ... ic=63463.0
https://www.diystompboxes.com/smfforum/ ... ic=51583.0
http://www.freeinfosociety.com/electron ... ossge7.pdf
http://www.monteallums.com/images/GE7_Vin.jpg

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rudeez
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Post by rudeez »

Sorry to bring up a dead thread but.
I did the monte allums mod to my ge-7 a few years back, it's the new type, not the vintage.
It dosnt work anymore tho, the two OPA2134PA gets VERY warm, it's like you can't really put your fingers on them for more then 3 secs, i guess its a short somewhere?
It worked back then but stopped working and have since a year back collected dust.
Does anyone have some big clear pics of the back of the pcb? I think i know where it's shorting, just can't see really if it's supposed to be solderd togheter or not.
Ihave really bad knowledge in reading schematics, veros are ok tho :P
but im unsure on the C21 C22 C32, should they be +/-caps? if so, how do i know what side is +/-, i lost the instructions i got from monte allums before.
Could it be possible that the OPA2134PA are burnet out as well?
I dont even get sound from the pedal in bypass mode...

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Post by xelalien »

noob question: is it possible to add a frequency slider and turn it into an 8-band equalizer?
am planning to convert the LEVEL slider into a pot (will drill a hole on the side for it), then use the slider for the added frequency (9kHz or 10kHz)... :scratch:

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Post by gilmour_pugliese »

Hi guys, it's possible to replace the tantalum caps on top of PCB (.68uF, .33uF, .15uF, .1uF) with some film caps? This substitution will improve the sound?

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blackbunny
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Post by blackbunny »

You can definitely replace those tantalum caps with film caps. Will it improve the sound? Depends on your own ears....I do it just to get the tantalum caps out of the signal path, and I think film caps sound better to my ears. :horsey:

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Post by digitalzombie »

I ordered and performed the "Sniper Mod" a few years back before the guy who made it disappeared. Love it. Quiet as a mouse. I guess I'm not really contributing...

(runs back into the shadows)

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Post by gilmour_pugliese »

Just added a LT1054 voltage doubler on my 1987 MIJ... Other mods are the Monteallums mod (with 3 OPA2134 and 1 OPA2107) and a complete recapping with film caps (Panasonic, Orange Drops, WIMA, ERO axial... some caps are on the way from Banzaimusic)

Image

:thumbsup

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Post by abakuzam »

how can i make this mods on ge7b? same as ge7?

ic's are m5218 x4 , ha12017

thanks a lot
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ge7b-bass-equalizer-schematic.png

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blackbunny
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Post by blackbunny »

abakuzam wrote:how can i make this mods on ge7b? same as ge7?

ic's are m5218 x4 , ha12017
Which mods do you mean? You could do the LT1054 voltage doubling mod on your GE7B, as shown in Gilmour's post.

Changing the op amps will be more difficult on the GE7B because they are all SIP (inline) IC's, which severely limits your options for replacement op amps.
You could buy some inline-DIP adapter circuit boards from Monte Allums, but they can be very difficult to squeeze into the small spaces available on the component side of the board.

You can replace any tantalum or electrolytic (can) capacitors in the signal path with metal film or MKT types using the values on your schematic. For example, C4, C5, C7, C9, C10, C11, C19 and C25.

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Post by abakuzam »

blackbunny wrote:
abakuzam wrote:how can i make this mods on ge7b? same as ge7?

ic's are m5218 x4 , ha12017
Which mods do you mean? You could do the LT1054 voltage doubling mod on your GE7B, as shown in Gilmour's post.

Changing the op amps will be more difficult on the GE7B because they are all SIP (inline) IC's, which severely limits your options for replacement op amps.
You could buy some inline-DIP adapter circuit boards from Monte Allums, but they can be very difficult to squeeze into the small spaces available on the component side of the board.

You can replace any tantalum or electrolytic (can) capacitors in the signal path with metal film or MKT types using the values on your schematic. For example, C4, C5, C7, C9, C10, C11, C19 and C25.
how does effect the circuit? low noise? i read about noise problems, does ge7b have any noise problems?(in 1987 schematic)

thanks

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Post by blackbunny »

Replacing the electro or tantalum bead caps with film caps can reduce background hiss a little bit, but you will not hear a big improvement unless one or more of the original caps is leaky or noisy due to internal cracking (caused by mechanical stress or vibration), which sometimes happens as they get old.

The GE7B circuit is not too noisy anyway, so you would have to upgrade those caps and find some low noise replacements for the SIP op amps to hear much difference. If your GE7B doesn't sound noisy, then maybe you should leave it as it is.

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Post by abakuzam »

blackbunny wrote:Replacing the electro or tantalum bead caps with film caps can reduce background hiss a little bit, but you will not hear a big improvement unless one or more of the original caps is leaky or noisy due to internal cracking (caused by mechanical stress or vibration), which sometimes happens as they get old.

The GE7B circuit is not too noisy anyway, so you would have to upgrade those caps and find some low noise replacements for the SIP op amps to hear much difference. If your GE7B doesn't sound noisy, then maybe you should leave it as it is.

i will build ge7b clone by the way :D any suggestion for sip opamp i will use HA12017? is that proper for low noise op-amp?

thanks

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Post by abakuzam »

abakuzam wrote:
blackbunny wrote:Replacing the electro or tantalum bead caps with film caps can reduce background hiss a little bit, but you will not hear a big improvement unless one or more of the original caps is leaky or noisy due to internal cracking (caused by mechanical stress or vibration), which sometimes happens as they get old.

The GE7B circuit is not too noisy anyway, so you would have to upgrade those caps and find some low noise replacements for the SIP op amps to hear much difference. If your GE7B doesn't sound noisy, then maybe you should leave it as it is.

i will build ge7b clone by the way :D any suggestion for sip opamp i will use HA12017? is that proper for low noise op-amp? (i will build 4 dip opamp(m5218A) and 1 sip pre-amp(ha12017) version)

thanks

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Post by blackbunny »

The HA12017 version of the GE7 has a subtle high frequency pre-emphasis (boost) at the input stage to help reduce hiss, with de-emphasis near the output. This seems to work fairly well, as the HA12017 has pretty decent noise performance anyway, and the M5218A also has low noise specification.
Attachments
HA12017 (GE7).pdf
HA12017 datasheet
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