Marshall Shredmaster questions

[marcoharder]

Hi! I have a Marshall Shredmaster with me but is currently showing a problem. The effect is working in both effect and bypass modes, but the thing is that when I turn the pedal on to effect mode, the LED only lights up for a split second and goes off. However, the effect still remains and when I press it again, the effect is bypassed.

My worry about this is that in clubs with extremely bad acosutics or PA systems, I sometimes have a hard time determining whether the pedal is on since I cascade it with another pedal. What do you think is the problem here?

Thanks!

Marco

PS. I also am planning to make a Marshall Shredmaster clone. Any links to PCB patterns and parts layouts? Thanks

[km-r]

check the bypass switch...
i think it has true bypass...

btw, how does it sound? im intrigued by the schem...

[marcoharder]

Well it's a smooth distortion and a bit on the bassy side of things. What do I check for in the switch? How does it explain the momentary lighting of the LED?

[petemoore]

  If it's using 3pdt true bypass w/LED bypass wiring...
  It would be likely that the LED is seeing voltage for a split second, then none.
  This can be measured easily enough.
  probable causes include a wire that bouces to touch/connect...bluntly hit the pedal from different angles to see if you can make the wire touch/led light,
  or, a switch which momentarily contacts, a fairly common failing to mechanical switches, this can easily be tested, power off, connect DMM across the LED's switch lugs, a functioning switch will connect / not connect 'solidly' when activated.
  A possible Q 'n D fix for this would be test the other side of the switch to the LED center lug, if it solidly switches, move the LED over to that side, now it will light when the effect is off...
  If the effect bypassing is good, I'd be inclined to mete the last miles [there could be many good switchings left in the circuit's bypass Sw. mechanics] out of the switch and just know the LED lit means 'off'.
  or replace switch

[petemoore]

how does it sound? im intrigued by the schem...
  Great sounding pedal, kind of unique.
  quite versatile, the contour knob is a mid-scooper/mid-humper, which is interactive with the T/B/G/V knobs.
  does plenty boost, has 'voicey' stamp on the sound when on, OD, Dist.
  What makes it sound like a shredmaster IME is when the contour knob is scooping mids and the gain's turned up..thick heavy DIST. is fun to play.

[marcoharder]

I see. but it uses a DPDT switch. How's that?

Now I just discovered something after using it at a gig last night. When the effect is on, sometimes the LED would emit a faint light and at one point during the gig, I just noticed that the LED was lit brightly. When I turned the effect off and and switched it back on, the same thing happened: the light was gone, the effect is there.HELPPP!!

  If it's using 3pdt true bypass w/LED bypass wiring...
  It would be likely that the LED is seeing voltage for a split second, then none.
  This can be measured easily enough.
  probable causes include a wire that bouces to touch/connect...bluntly hit the pedal from different angles to see if you can make the wire touch/led light,
  or, a switch which momentarily contacts, a fairly common failing to mechanical switches, this can easily be tested, power off, connect DMM across the LED's switch lugs, a functioning switch will connect / not connect 'solidly' when activated.
  A possible Q 'n D fix for this would be test the other side of the switch to the LED center lug, if it solidly switches, move the LED over to that side, now it will light when the effect is off...
  If the effect bypassing is good, I'd be inclined to mete the last miles [there could be many good switchings left in the circuit's bypass Sw. mechanics] out of the switch and just know the LED lit means 'off'.
  or replace switch

[marcoharder]

Fixed!

Fiddled with the switch and apparently, some of the contacts inside the switch were not latching because of the clamping nuts. Just had to re-tighten them and adjust them to fix this. Thanks!

[chieljan]

Cool, I have a shredmaster too, hope it won't start doing that But, how does the bypass work then? With a DPDT and a LED it can't be true bypass, right? Something like the Millenium bypass or something?

Thnx!

[marcoharder]

Same thing I asked after fixing it.

Cool, I have a shredmaster too, hope it won't start doing that But, how does the bypass work then? With a DPDT and a LED it can't be true bypass, right? Something like the Millenium bypass or something?

Thnx!

[spud]

OLC has a kit for a clone of this pedal: 

http://www.olcircuits.com/olc_shredmeister.html

I might have the schematic - I'll look for it.  If I do, I'm not sure anymore where I found it...

Check out the clips on the OLC site - 

[spud]

I found a schematic in the schematics archive of this site.  I'm not sure if it is even accurate (I didn't look at it and wouldn't be able to judge anyway)    

So, as they say: YMMV

Later

SPUD

[MartyMart]

The Marshall pedals in this '90's series - Guv'nor/Shredmaster/Drivemaster and Bluesbreaker
are not wired as "true bypass".
They use a DPDT switch with one middle pole grounded and one outer pole connecting the LED, so in
bypass, you're alway's going through part of the circuit.
They dont sound "bad" because of it - they sound quite good to me !!
I wonder why we dont use a similar setup .......

[ubersam]

I found a schematic here: http://www.harpamps.com/schematics/shrdmstr.pdf - not sure if its official.

[km-r]

just try to measure the voltage on the across the leds...
dpdt?
then it might use the same technology that ive seen from the schematic drawings by patrick erikson...
uses a bjt to switch the led... somewhat... meh...

[SteveB]

The Marshall pedals in this '90's series - Guv'nor/Shredmaster/Drivemaster and Bluesbreaker
are not wired as "true bypass".
They use a DPDT switch with one middle pole grounded and one outer pole connecting the LED, so in
bypass, you're alway's going through part of the circuit.
They dont sound "bad" because of it - they sound quite good to me !!
I wonder why we dont use a similar setup .......

Not true bypass, but also not buffered bypass, correct? With a dead battery in it, I can still get sounds in the bypass mode, unlike buffered bypass pedals.

I agree, it has a very usable range of sounds from blues to heavy rock. I got it from a friend who found it at a pawn shop, & was very skeptical about it. But good sounds are fairly easy to dail in with minimal tweaking. Very "Marshall Amp-like" from a pedal.

Steve

[thisismunich]

Hi Guys,

I've had my shredmaster for a while now, it's been gigged and toured pretty heavily and taken a battering once in a while, but generally it's been on a board the whole time and safe.

Over the past few months it's been showing an intermittent fault where the pedal is switched on with full shredmaster roar coming out of the amp. But then the sound dies out (it fades to silence a bit like a loss in power) and stops making any sound. I switch it to bypass and back on again quickly and it works again back to full sound/power. Sometimes only to die out again maybe 5-15 seconds later. Throughout all of this the red light works perfectly when the pedal is on, it shows no sign of fatigue.

I have taken it to an electrician, but he says there is nothing wrong with it (obviously he is wrong).

Does anyone have any idea what this could be? I'm going to take the pedal to another electrician with the schematics, but i am starting to lose hope! I am in a touring band and i cant afford £150 to purchase another on ebay and i'm not the most educated chap in the field of circuit board electronics!

PLEASE HELP ME!!!
James