blown up boss distortion

[pinkjimiphoton]

hey guys,
i'm going to be in pa for a couple days, and my friend nate fried his boss distortion..

he said he hooked up the wrong power supply to it, and it fried.

i said i'd take a look at it for him while i'm there.

i looked at the schematic, and got another in my endless series of dumb newb questions.

do you think the diode at the the power supply jack took the hit, or do these things usually get really cooked?

is it worth fixing?

thanks...just wanna have a slight clue what i may be up against..and wanna help the kid out.

peace

[Scruffie]

Depends on what power supply it was, wrong polarity, over voltage or AC instead of DC?

Wrong polarity will be the easy diode fix, the others may be more involved.

[pinkjimiphoton]

thanks scruffie,
i'll call him and ask. i'm hoping worst case it's just the power supply.

[runmikeyrun]

most likely the problem is with polarity protection diode and possibly power filtering cap if he exceeded its voltage rating.  If there is further damage suspect more sensitive items first like ICs, then stuff like transistors and caps.  Try to find out which supply he used that was wrong and how many volts it is.

[Mike Burgundy]

To the best of my knowledge BOSS always uses the reverse-diode polarity protection. If he reversed voltage, it all depends on what supply it was - if it was a "classic" one without any kind of protection the diode (shorts out the reversed supply) and supply are engaged in a battle to the death. If the diode fails first (which it probably has) it offers protection no more - you might be in for a bigger repair job. Depends on if it failed shorted, or open-circuit. The first means easy fix, the latter means trouble (since it is now as if the diode isn't there at all)

[pinkjimiphoton]

i just talked to him, he hit it with a 12v supply....says he opened it up, something in "the middle of the board" looks messed up.
we'll see....thanks guys

[runmikeyrun]

cool, let us know!  Now I'm curious as to what happened.  I think the polarity diode is near the edge of the board on most BOSSs.

[pinkjimiphoton]

i'll have my laptop with me, so i'll check in and let ya know what's up.

[O]

If it's in the middle-left side of the board (looking at the component side), it's definitely the diode and possibly the filter cap. I'd swap both (one at a time) and test the pedal after each swap. If it still doesn't turn on after the 2 part swap, then I'd look at the flip-flop transistors. Good luck!

[petemoore]

  12v probably wouldn't 'burn' anything, exception is if there are any components rated for less than the Measured voltage...assuming it Is DC...
   In the case of AC application, figure the resistors are still good, anything else is hit or miss.
  Reverse polarization would be stopped by, or burn the protection diode out, then proceed into the circuit where the caps would see inverted polarity [and would then be ready for the toss can], perhaps frying a chip along the way.
   Check/measure the diode with the DMM, see if power is making it's way into the pedal, then take some voltage measurements...
  "Is it worth it'' is another question with possible outcomes:
  No...not if it doesn't get working.
  Yes if it is really irreplacable [I haven't really found a basic/common distortion that is truly irreplacable].
  15 buxx gets really nice distortion, [maybe almost exactly the same thing?..slightly different?...maybe preferrable even..] [not the boss/metal case etc.], 30buxx gets two of them [spare].
  For all the messing about with a 'burnt' circuit, a new circuit is worth considering...if it's a simple matter of replacing the diode or similar then...weight the time/savings/preciousness of the unit to derive a ''worthy'' or ''unworthy'' moniker on the scenario.
  If it involves replacing all the polarized components [caps, chips etc.], not breaking any traces or creating new ones...just to test for success...maybe an alternative would have been worth considering.

[pinkjimiphoton]

i figure since the kid is pretty broke, i'll offer him 20 bux for the shell of the thing if i can't get it working for him...
he can get a new one for probably 30 bucks. that will get him most of the way there, and i don't mind rebuilding the whole circuit if i have to if it's for me...
i just don't think he wants to, or can afford to, put any money into it.

i'll check in when i see it...i'm gonna probably check out martin guitars tomorrow cuz i'm just outside of nazareth.

thanks guys
peace

jimi

[pinkjimiphoton]

well, i took a look at it for nate...the first filter cap, c43 i think, 100u was EXPLODED. so was the voltage protection diode...blown in half. replaced the 1n4001 and subbed a 47u for the 100u.

i can't get it to pass signal, the tone and volume controls work, the distortion just makes it hum bad. no sound in bypass, either, tho the led works.

ALL the voltages were WACK... where it should read 9, was reading almost 16v, the 4.5 was around 7 or 8...so i assume something is cooked, shorted, and drawing heavy current.

when the effect is on, it hums like a bear...so i figure blown diodes and caps at the least, thru most of the circuit. it's weird, the voltages are close, in terms of division etc, just about double what they should be...used a regulated roland 9v adapter.

so....any thoughts? advice? where would be a good place to start looking do you think?

i took a phone pic, will try and upload later..thanks guys

[Mike Burgundy]

Blowing up BOSS pedals makes them into DC multipliers? I'm stumped.
The devision voltage is made by two resistors which will still be ok, that's to be expected.
I can think of no way at all that a blown up simple circuit (what, DS-1?) can "magically" make a 9V supply churn out 16V. Less, yes, but not more, at least not more than it's unloaded voltage.. What is that supplies unloaded voltage? I think it's a very good idea to grill this guy until you're sure *what* he plugged into it, if only to satisfy our curiosity.
If the cap is blown and the protection diode is blown, without any other protection present whatever was stuck in there ran through the circuit. Depends on *what* it was that blew everything, but count on a full electrolytic cap and sillicon overhaul. Signal diodes should be ok.

[seedlings]

Makes me wonder if 'general modern practice' should be 'updated' to include a fuse before the diode.  Easy troubleshooting.

CHAD

[O]

I had one come in exactly like you describe. I ended up replacing all the electro caps and the 2 flip-flop transistors since it wouldn't turn on or off. If I remember correctly, I think I also swapped the opamp because it didn't sound right.

[pinkjimiphoton]

wow, so i guess it's cooked alright!! wondering...could any of the transistors if blown have acted like a diode bridge? that could maybe explain the voltage doubling?

i saw the adapter he used...it was a 12 vdc...that should not have blown the damn thing! it's only gonna draw 9volts!!

the can from the cap was literally rolling loose below the circuit board, and i had to de-fluff the whole area from all the crap from the capacitor.

good call on all the electros and diodes...a bad diode can inject a dc hum like that too.

i have the pedal, when i get a chance, i'll post specific voltages and what i find.

really weird!!

[Seven64]

what model pedal is it?

[pinkjimiphoton]

just a newer model (his mom got it for him for christmas a year or two ago, paid full retail, ouch!!! 30 bux is the most i'd go..lol)

plain, bone-stock orange boss ds1 distortion pedal.

[fatfoot51]

Hi~ I had a similar problem when my friend used a wrong polarity adapter on my boss ds-1 over the summer.. The protection diode blew open and the 100uf capacitor exploded... The pedal was switching on and off after the parts were replaced but there wasn't any distortion.. I wasn't sure about the exact chip replacement since I had the third version of the ds-1 which uses the M5223AL sip (system in package?) ic that is an in line shape.. That's probably the one you have.. When I desoldered the ic, there was a burn spot on the board where the chip had a crack... Not being up to the task of chasing down an exact match of the ic I ordered an alternative off of smallbear called the BA4560... That seemed to do the trick for a while until I had a problem with the board... Its one thing to deal with just the components...

[DavenPaget]

Hi~ I had a similar problem when my friend used a wrong polarity adapter on my boss ds-1 over the summer.. The protection diode blew open and the 100uf capacitor exploded... The pedal was switching on and off after the parts were replaced but there wasn't any distortion.. I wasn't sure about the exact chip replacement since I had the third version of the ds-1 which uses the M5223AL sip (system in package?) ic that is an in line shape.. That's probably the one you have.. When I desoldered the ic, there was a burn spot on the board where the chip had a crack... Not being up to the task of chasing down an exact match of the ic I ordered an alternative off of smallbear called the BA4560... That seemed to do the trick for a while until I had a problem with the board... Its one thing to deal with just the components...

That's the 4558's brother the 4560 .