Boss GE-7 Mods

sinner · Post by **sinner** » 28 Jul 2010, 18:05

Finally I've menage to find a minute to play with my unit

roseblood11 wrote:The circuit is very similar to the newer versions. Try to do the mods that I described above - it´s really a great improvement!

Capacitor locations are not the same in vintage unit

roseblood11 wrote:
-replace capacitors:
C18,C25, C29, C30 : 0.047 µF
C21, C22, C32 : 1 µF
C13 : 0.1 µF
(use stacked metal film caps (MKT) for all positions!!! Panasonic ECQ-V series sounds very good here)

Corrections to fit in the vintage unit as fallows:

C22, C23, C24, C26 : .047uF
C11, C19, C25 (electrolytics) : 1uF
C13 : .1uF

All caps Panasonic ECQ-V all the way as you suggested and sounds great! Now time to play with tantalums and the filter caps - they just get bad/noisy with the age. I have some Sanyo Os-Con in the mail, so I'll use those for filtering, and Nichicons muse for the rest of electrolytics. Will see what does this changes

MartyM wrote: The problem was mostly the crap tantalum caps attached to each tone band.
Swopping them out for decent poly caps helps a LOT

I don't really get it. Are you talking about those tants marked on my photo?

ge7.jpg

Cheers
Pawel

sinner · Post by **sinner** » 28 Jul 2010, 18:10

I've forgot, D1 and R1 replaced with the jumpers. This way I can use it with standard 9VDC powering insteed of 12VDC/bossACA power supplies

sinner · Post by **sinner** » 28 Jul 2010, 18:54

One more shot!

I've replaced stock 3mm LED with hi-bright multicolor 5mm. Stock LED resistor was to big to drive the color change, so I've swapped it with 380R. On the vintage unit it is located at R10. You may swap it also to have brighter LED status

roseblood11 · Post by **roseblood11** » 01 Nov 2010, 19:40

As someone asked me for that, I´l attach a photo of my pedal again. See post #8 for details...

defec · Post by **defec** » 02 Dec 2010, 04:39

Thanks for posting the mods for the order version. I have a mid 80's japanese born pedal and I don't detect any of the excess noise others complain about. I'll forsure do the cap swaps though. Did I just get lucky or are the older units generally quieter?

Oh yeah how will the opamp swap effect battery life?

phatt · Post by **phatt** » 02 Dec 2010, 12:52

defec wrote:Thanks for posting the mods for the order version. I have a mid 80's japanese born pedal and I don't detect any of the excess noise others complain about. I'll forsure do the cap swaps though. Did I just get lucky or are the older units generally quieter?

Oh yeah how will the opamp swap effect battery life?

Hi defec,
Not sure of what changes where made to these units over time but I'm fairly certain that some have ***INSANE*** hiss so consider yourself lucky.

On the schematic that I found there is a *Pre Emphasis before EQ then a De emphasis after EQ setup.
Just what on earth they where thinking is beyond me as the De Emph does not actually De anything much at all and you are left with stupid high freq alteration of the tone curve.
A simulation of the basic circuit reveals most of it is way above the freq a guitar can produce but that translates into the dreaded hiss which makes it a pain to use.

Also note the oddball SIP chip in some is actually a *dedicated Phono preamp chip* designed to run from 40 or more Volt supply.
If you are the unlucky owner of a hissy unit then my guess is that you will fair a lot better if you can somehow bypass the filters front and back of the EQ which is otherwise probably quite useful.
The oddball Phono chip I don't know enough about but would be interesting to do an A/B test with other more common chips. This might effect battery life.

I personally use hifi type Graphic EQ as they are at least delivering a flat response to start off with so you do at least have a known refference point before you move any sliders.
Not pedal board friendly but works well in a rack.

Phil.

cctsim · Post by **cctsim** » 03 Dec 2010, 07:37

Sadly, the pre-emphasis and de-emphasis circuits are left on the signal path even in bypass mode.

I have removed them both from my unit by converting the first op-amp to a voltage follower and removing C27 and R33.
Also, R33 needs to be replaced by a short.

mortad · Post by **mortad** » 20 Feb 2011, 11:25

Hi everybody.

I did the complete "roseblood11" BOSS GE7 mod but had no success.

When plug in I only hear an awful constant noise, no guitar signal at all. When I press the switch you can hear the guitar passing trough (with no effect and no noise) , and when I stop pressing the switch, the noise starts again.

After that I took off the OPA and soldered again the NJM but the noise was the same.
The pictures are when I soldered again the NJM.

I have some questions:

- I replaced the 3 electrolytic capacitors (C21, C22, C32) with 3 Epcos MKT 1uF/63V.
My question is: Can I solder these 3 new caps in any position or there is only one position (as the electrolytic caps)?.

- I replaced NJM2068 at position IC3 with a OPA2134, and (as you said) I built an adapter using perfboard, but I´m not sure if I did it right (see the pic): how to solder the cable to the perfboard and to the socket at the same time?.

- In the NJM the 8 legs are in vertical order, 1 to 8 up-down, and in the OPA the legs are 4 in each side: 1 to 4 up-down, and 4 to 8 down-up. The 1 is in both IC where the circle is, right?.

- In another pic you can see the soldering of the 3 IC and the NJM: there are some solder joints that were togheter in the original soldering and I did the same soldering (pink squares). Is this OK?

Well, I hope to bring back to life to my GE7.

Sorry for so many questions. I´m just a beginner !!.

mysticwhiskey · Post by **mysticwhiskey** » 20 Feb 2011, 13:07

mortad wrote:I replaced the 3 electrolytic capacitors (C21, C22, C32) with 3 Epcos MKT 1uF/63V.
My question is: Can I solder these 3 new caps in any position or there is only one position (as the electrolytic caps)?.

Any orientation is fine for these caps.

mortad wrote:I replaced NJM2068 at position IC3 with a OPA2134, and (as you said) I built an adapter using perfboard, but I´m not sure if I did it right (see the pic)

Can't see much in the picture - too small, sorry.

mortad wrote:In the NJM the 8 legs are in vertical order, 1 to 8 up-down, and in the OPA the legs are 4 in each side: 1 to 4 up-down, and 4 to 8 down-up. The 1 is in both IC where the circle is, right?

You mean the circle on the actual chip? If so, yes that's pin 1 for both opamp types.

mortad wrote:In another pic you can see the soldering of the 3 IC and the NJM: there are some solder joints that were togheter in the original soldering and I did the same soldering (pink squares). Is this OK?

Again, picture is too small to really see anything.

In general, when doing these types of mods it's a good idea to test the pedal after each component change to make sure you've done everything correctly, and to easily identify when you've made a mistake.

Chances are you've inadvertently bridged a solder connection when replacing one or more components - maybe if you post a high-res picture of the PCB we might be able to spot something.

mortad · Post by **mortad** » 20 Feb 2011, 14:30

mortad · Post by **mortad** » 20 Feb 2011, 16:21

roseblood11 · Post by **roseblood11** » 20 Feb 2011, 19:30

That adapter looks horrible!!!
You should learn how to solder before you mod a pedal. Those Boss pcb are easily destroyed...

For the adapter, use a piece of veroboard an do it like this:

mortad · Post by **mortad** » 21 Feb 2011, 09:48

I´m not a solder wizard, that's for sure, specially when UNsoldering.
I had no confidence in that horrible adapter when I made it, so I decided to take it off the pcb and replace the original NJM... But the noise was the same.
The strange thing is that all the other componets that I replaced (CAPS, SOCKETS) I think that I soldered them right, with no bridges... I´ve been looking my solder joints with Magnifying glasses all the time.

Another strange thing is that when I plug in the pedal, and with power on, I touch with a screwdriver in the solder joint (circled in yellow), the LED turns ON, and then, when I press the switch, the guitar signal pass trough WITH EQ EFFECT.
When I stop pressing the switch, the Noise starts again.

(yes, I´m a bit rude !!)...

I'm not sure, but I think there is something wrong with the input, output or some wiring.
... And yes: the Boss pcb is starting to be destroyed... Oh my god, what I'm doing!

bye bye

mortad · Post by **mortad** » 21 Feb 2011, 19:43

any idea ?????

geegads · Post by **geegads** » 27 Mar 2011, 19:29

mortad wrote:Hi everybody.

I did the complete "roseblood11" BOSS GE7 mod but had no success.

When plug in I only hear an awful constant noise, no guitar signal at all. When I press the switch you can hear the guitar passing trough (with no effect and no noise) , and when I stop pressing the switch, the noise starts again.

After that I took off the OPA and soldered again the NJM but the noise was the same.
The pictures are when I soldered again the NJM.

I have some questions:

- I replaced the 3 electrolytic capacitors (C21, C22, C32) with 3 Epcos MKT 1uF/63V.
My question is: Can I solder these 3 new caps in any position or there is only one position (as the electrolytic caps)?.

- I replaced NJM2068 at position IC3 with a OPA2134, and (as you said) I built an adapter using perfboard, but I´m not sure if I did it right (see the pic): how to solder the cable to the perfboard and to the socket at the same time?.

- In the NJM the 8 legs are in vertical order, 1 to 8 up-down, and in the OPA the legs are 4 in each side: 1 to 4 up-down, and 4 to 8 down-up. The 1 is in both IC where the circle is, right?.

- In another pic you can see the soldering of the 3 IC and the NJM: there are some solder joints that were togheter in the original soldering and I did the same soldering (pink squares). Is this OK?

Well, I hope to bring back to life to my GE7.

Sorry for so many questions. I´m just a beginner !!.

About your noise problem. The input and output 1/4" sleves need to be grounded together if you remove everything from the box. And I would recomend that you do pull it all out. The other common problem is the grey wire likes to break so take special note of both ends where it attaches. Have a great day.

andyg_prs · Post by **andyg_prs** » 24 May 2011, 09:26

Hi there,

I have the old 4 op amp model http://www.monteallums.com/images/GE7_Vin.jpg

I see various instructions in this thread but I'm not clear what would refer to my pedal.

Could someone please confirm parts and instructions for the sniper mod?

Also, would changing out the 4 op amps sort out the noise or do I have to replace the caps and other stuff as well?

Thanks!
Andy

roseblood11 · Post by **roseblood11** » 24 May 2011, 09:48

The opamps are the most important part. Then you could replace all electrolytic caps in the audiosignal path with film caps (Panasonic SMF are small enough). If there are carbon resistors with higher values, replace them with metalfilm

andyg_prs · Post by **andyg_prs** » 24 May 2011, 10:52

Thanks, as I have no idea I was hoping to get a list somewhere of exactly which bits to place with what.....for my model of GE-7....

marmaliser · Post by **marmaliser** » 24 May 2011, 11:04

andyg_prs wrote:Thanks, as I have no idea I was hoping to get a list somewhere of exactly which bits to place with what.....for my model of GE-7....

From a post above

Corrections to fit in the vintage unit as fallows:

C22, C23, C24, C26 : .047uF
C11, C19, C25 (electrolytics) : 1uF
C13 : .1uF

andyg_prs · Post by **andyg_prs** » 24 May 2011, 11:49

Thanks - not clear on what the op amps are to be replaced with - mine has 3 of 1 type and 1 of another...