Bare Knuckle Pickups Forum

Forum Ringside => Tech => Topic started by: phlip on April 01, 2010, 10:32:19 AM

Title: MXR Overdrive Bypass issue?
Post by: phlip on April 01, 2010, 10:32:19 AM

Hi I recently got a good deal (I thought) on an MXR Zakk Wylde overdrive (Lets leave it's tonal abilities to one side please, it does what I need for pretty cheap  ).

It seems to have an intermittent fault, kick it on fine, kick it off, fine. Next time, Kick it on fine, kick it off and the bypass signal is 50% of what it should be, kick it on and off and all is well again.

I hate intermittent faults, the seller is from his other sales just a shifter of stuff, and probably not a guitarist, so a quick test will most likely have led him to believe it was 100% working fine. So I'm not holding any Malice here, you takes ya risks on ebay...

What do the pedal/tech experts of here think this fault could be, I know MXR aren't real true bypass, could this be a switch issue or something more sinister.

Title: Re: MXR Overdrive Bypass issue?
Post by: Twinfan on April 01, 2010, 10:39:14 AM

Sounds like the stomp switch isn't working properly.  An easy thing to replace, but fiddly to solder.....

Title: Re: MXR Overdrive Bypass issue?
Post by: HTH AMPS on April 01, 2010, 10:43:43 AM

(http://www.jimdunlop.com/files/1145727517_ZAKK_WYLDE_OVERDRIVE_ZW44_463x342.jpg)

The blurb on the MXR website states that it has a 'hardwire bypass', i.e. true bypass - this ties in with the schematic I have for it too.  Also, your description of 50% output when bypassed is consistent with footswitch faults I've seen LOTS of times.

Open it up, see whether it needs a DPDT switch or 3PDT (most likely the latter) and just replace the switch like for like - easy peasy.

Title: Re: MXR Overdrive Bypass issue?
Post by: phlip on April 01, 2010, 11:04:09 AM

Cheers Guys. My comment about the not being true bypass came from here http://www.stinkfoot.se/andreas/diy/articles/bypass.htm But hell I'm no expert I just believe what I read  :D

I take it these switches are fairly easy to get a hold of?

Title: Re: MXR Overdrive Bypass issue?
Post by: phlip on April 01, 2010, 08:17:03 PM

Could someone confirm from these pics if this is a standard DPDT switch?

If it is I guess maplin or ebay for the correct dimensions is my best bet?

Thanks again  :D

Title: Re: MXR Overdrive Bypass issue?
Post by: Twinfan on April 01, 2010, 09:52:37 PM

Looks like it to me, and an easy swap with the PCB there  :)

Title: Re: MXR Overdrive Bypass issue?
Post by: phlip on April 01, 2010, 10:05:45 PM

Thanks mate  :D
Daft Question am I right in assuming the switch operates the same regardless of which way up it is?
So replacement switch, solder sucker and remove  then replace without orientation issues?

Title: Re: MXR Overdrive Bypass issue?
Post by: Twinfan on April 01, 2010, 10:55:54 PM

Yep - it's the 3PDT ones with 9 poles you have to watch out for  ;)

Title: Re: MXR Overdrive Bypass issue?
Post by: HTH AMPS on April 01, 2010, 11:05:36 PM

yep, its just a DPDT footswitch - not sure where you're gonna get one with PCB-mounting connections though.  Good luck.

Title: Re: MXR Overdrive Bypass issue?
Post by: cerpintaxt on April 01, 2010, 11:24:36 PM

Probs best to have a gander on the BYOC (Build Your Own Clone) forum, they might know  :?

Title: Re: MXR Overdrive Bypass issue?
Post by: jpfamps on April 02, 2010, 05:07:29 PM

In the past I've got this type of switch either from Maplins or Rapid Electronics.

If you can't find a PCB mount switch, you can bend the solder terminals in using a pair of needle nose pliers, so that a chassis mount switch will fit on a PCB.

Title: Re: MXR Overdrive Bypass issue?
Post by: HTH AMPS on April 03, 2010, 04:23:48 PM

heres a PCB mount one on ebay...  http://cgi.ebay.co.uk/Latching-footswitch-DPDT-Long-Mounting-Bush_W0QQitemZ110493957515QQcmdZViewItemQQptZUK_BOI_Electrical_Components_Supplies_ET?hash=item19b9f3fd8b#ht_836wt_939

Title: Re: MXR Overdrive Bypass issue?
Post by: phlip on April 03, 2010, 09:01:34 PM

Thansk HTH, that seems to in the ballpark dimensions wise. I'll take a punt on that.

At the moment a good cleaning with Servisol has stopped the cutting out, but I don't know for how long.

Cheers for the help everyone.