exploded capacitors!

[no one ever]

friend of mine broke his ds-1, saying that he plugged in some weird adapter and it started smoking. recalling RG's reverse polarity protection articles and posts, i say i can fix it. i look inside... and one 100uf 16v cap had EXPLODED, leaving only its leads in their respective joints and the contents strewn about the case. the tin case of the cap was just rattling around in there. the reason for this? the 1n4002 diode apparently was overloaded and before actually cracking clean in half, decided to put some + where - is meant to be. so i replace the diode... and questions arise that i would love for some more intelligent people to answer:

does it matter what voltage rating my replacement 100uf cap has? i tried 32v, 24v, and 10v, but the circuit still doesn't work. is this the root of the problem?

what voltages should i check for on the mn chip? could this have failed as well?

is there something else i should be checking?

[petemoore]

does it matter what voltage rating my replacement 100uf cap has? i tried 32v, 24v, and 10v, but the circuit still doesn't work. is this the root of the problem?
  I guess it's possible that the blown cap[s [could be more than one?] could have seen high enough voltage to blow them. Repla...any caps should never see more voltage than their rating allows, if you're running off an adapter, measure it/use applicable caps.
what voltages should i check for on the mn chip? could this have failed as well?
  Sure, chips fail too, so that's a 'could be', replace all else that could be failing and take voltage measurements on the chip's pins. Sure fire way to check a chip is stick it in a circuit's socket...helps if you know the circuit is good though.
  Unless someone else has a magic eye...trial and fixing errors seems the most effective tool here...how many errors? trial may tell.

[no one ever]

oh, and the caps' contents (namely, the paper-like substance) have almost adhered themselves to anything within its blast radius. is this stuff conductive? do i need to painstakingly remove all of it?

[Vsat]

The pedal probably had the wrong polarity of adapter plugged in... this can also happen if you plug in an adapter that puts out AC instead of DC. Take a look at the DS-1 schematic (on the net) to find out what working voltage the electrolytic is rated for.

Oftentimes  a problem with  the power supply will damage chips further down the line. Have seen 4558 op amps fried this way, although have seen BBD chips survive a brief power supply reversal.

The pedal should be washed out with warm water and dried... with compressed air or by putting it in the sun... the liquid in the electrolytic is conductive.
Cheers, Mike

[no one ever]

thank you

where can i find the normal voltages on the pins of the mn chip?

i've searched long and hard for the ds-1 schem, but i ALWAYS end up with 403s or 404s! could someone email a copy to me please? aka.hector@gmail.com

[R.G.]

A reversed polarity DC supply or battery isn't usually that disastrous. What is absolute pedal killer is plugging in one of the few 9vAC supplies like the Line 6 one. There are a few others as well. They have the same style plug as DC pedals use. These adapters seem to be able to put enough power into a parallel-reversed protection diode to burn it out.  The diodes usually fail shorted, then open up, sometimes charring the PCB. Once the diode opens, the reversed polarity cycles then proceed to fry everything that's susceptible.

The advice you've already received is good.

If I were doing the repairs, I would remanufacture the pedal. I'd take good pictures and make good sketches about where everything is and how it's connected, then order replacements for every polarized capacitor, diode, and semiconductor on it. If some semi's are not available, or are simply too expensive, order the rest and hope.

Then wash the board, using a toothbrush and mild detergent. Dishwasher detergent is good. Rinse it well, then use compressed air an/or a hair dryer to get it dry. Clip off the bodies of the parts to be replaced, then remove the stubs of the leads by lifting them out with a soldering iron tip. Open the holes by heating the pad and poking a wooden toothpick end into the hole, leaving a nice solder ring around the pad for the replacement.

When you get the new parts, put them in the correct places with the correct orientation and solder. Rebuilding is a pain, but it's also incredibly frustrating to repair the same pedal eight times as successive things fail.

How well do you like this guy?

[gez]

Open the holes by heating the pad and poking a wooden toothpick end into the hole, leaving a nice solder ring around the pad for the replacement.

Tip of the week, thank you! 

[Vsat]

Agreed... wooden toothpick method a great one       Bamboo might also work.
Cheers, Mike

[Paul Perry (Frostwave)]

Agreed... wooden toothpick method a great one   :D    Bamboo might also work.

True, but I find a stainless steel dental pick better. It's sharp & solder won't stick to it (wiggle it a bit as the solder cools, though).
And I don't like your chances on fixing that box easily, obviously the power has been reversed (or AC applied) & if it was enough to explode the cap, I doubt many chips survived.

[petemoore]

  At the very least, whatever beast attacked the board [nasty trick putting AC on same type adapter IMO], probably left you with at least a board, the resistors, box switch etc.
  Taking your time, and with correct enough parts in hand, it shouldn't be all that bad, you have the 'poke a pick thru' trick to try out too !!
  I used to just 'ease' 'em in, heating all four pads on one side of an IC 'separatedly', one, the next, on down the line and back, never overheating and just getting that socket right in there quick and clean anyway don't try this at home without a wrist pad near the mounted iron.

[dosmun]

My advice would be to tell your friend to buy a new one.  They are only about $30 new.   Keep the old one to fix up or part out  but besides the learning experience it may be a lot of hassle for a $30 pedal.

[no one ever]

thanks, dosmun, but i'm doing this to gain experience... dead set on fixing it

so by "semiconductors", RG, you mean ICs too? becaause...

the chip reads "m5223AL"... but from what i've read, the ds-1 supposedly has a chip that starts with TA? i can't find any vendors that carry this chip that will sell me some of these for <500$.. i'm not one for bulk ordering.


there's no leaky stuff around the cap, in fact, no liquid-like residue anywhere on the board. the exploded cap was dry? and the rosin that oozes around a solder joint isn't conductive, right?

replacing the blown cap with a real 100uf 16v cap straight out of my useless psm-5. also using one of 2 jrc4558dd's harvested from that switch-a-ma-jigger for my ts9dx...

ceramic disc caps aren't polar, right?


oh, and i thought i might give you guys an example of how it doesn't work: does put out some sound that is in fact "ds-1"-like, but it is very low and slowly fades during use. perfectly fine in bypass mode, guess there's nothing wrong with the flip flop circuit.

[PenPen]

thanks, dosmun, but i'm doing this to gain experience... dead set on fixing it

so by "semiconductors", RG, you mean ICs too? becaause...

the chip reads "m5223AL"... but from what i've read, the ds-1 supposedly has a chip that starts with TA? i can't find any vendors that carry this chip that will sell me some of these for <500$.. i'm not one for bulk ordering.


there's no leaky stuff around the cap, in fact, no liquid-like residue anywhere on the board. the exploded cap was dry? and the rosin that oozes around a solder joint isn't conductive, right?

replacing the blown cap with a real 100uf 16v cap straight out of my useless psm-5. also using one of 2 jrc4558dd's harvested from that switch-a-ma-jigger for my ts9dx...

ceramic disc caps aren't polar, right?


oh, and i thought i might give you guys an example of how it doesn't work: does put out some sound that is in fact "ds-1"-like, but it is very low and slowly fades during use. perfectly fine in bypass mode, guess there's nothing wrong with the flip flop circuit.

Take what I say with a barrel of salt, since I'm still fairly new too, but what I could find on that chip is that its a dual opamp made by Mitsubishi. I can't find a datasheet for it that doesn't require me to pay for it, so I can't verify this chip. However, going by the tonepad layout, the dual opamp can be subbed with a TL072. DON'T SUB THIS CHIP IN YET! Can someone more knowledgable like RG vouch for the TL072 being a drop in replacement?

However, since you do get some sound from the thing, I suspect the existing chip COULD be ok, if you want to wait and replace all diodes and polar caps, then seeing if it works ok. If it still is dropping out, then I'd try to get a replacement. However, it is probably cheaper to get a drop in replacement (or three, get some spares just in case) for the chip when you order the other parts to save on shipping. If you don't end up needing them then at least you have a few dual opamps to play with.

And no, ceramic caps aren't polar. Tantalum and Electrolytic Alu caps are polar, the others are pretty much all non-polar.

[no one ever]

Take what I say with a barrel of salt, since I'm still fairly new too, but what I could find on that chip is that its a dual opamp made by Mitsubishi. I can't find a datasheet for it that doesn't require me to pay for it, so I can't verify this chip. However, going by the tonepad layout, the dual opamp can be subbed with a TL072. DON'T SUB THIS CHIP IN YET! Can someone more knowledgable like RG vouch for the TL072 being a drop in replacement?

However, since you do get some sound from the thing, I suspect the existing chip COULD be ok, if you want to wait and replace all diodes and polar caps, then seeing if it works ok. If it still is dropping out, then I'd try to get a replacement. However, it is probably cheaper to get a drop in replacement (or three, get some spares just in case) for the chip when you order the other parts to save on shipping. If you don't end up needing them then at least you have a few dual opamps to play with.

And no, ceramic caps aren't polar. Tantalum and Electrolytic Alu caps are polar, the others are pretty much all non-polar.

thanks for you help, fellow newbie , but i'm looking for an exact replacement because it would be a pain to replace (is the term 'linear ic'?) a chip whose pins are all on  one side with a (is the term 'dip IC'?) set of four pins on each side...

so the paper stuff from the popped cap isn't conductive enough to join leads of any components?

6 diodes... 4 electros... 8 trannies... steve, ship my desoldering braid quick!

[Paul Perry (Frostwave)]

i'm looking for an exact replacement because it would be a pain to replace (is the term 'linear ic'?) a chip whose pins are all on  one side with a (is the term 'dip IC'?) set of four pins on each side...

If you mean there is just one row of legs, sothe thing looks like a comb, I think the term is SIL for single inline package (as opposed to a 'normal' DIP or dual inline package chip).
I *think* Mouser or someone has the SIP version of a TL072, maybe others. The Japanese are keen on these SIP.

[no one ever]

i'm looking for an exact replacement because it would be a pain to replace (is the term 'linear ic'?) a chip whose pins are all on  one side with a (is the term 'dip IC'?) set of four pins on each side...

If you mean there is just one row of legs, sothe thing looks like a comb, I think the term is SIL for single inline package (as opposed to a 'normal' DIP or dual inline package chip).
I *think* Mouser or someone has the SIP version of a TL072, maybe others. The Japanese are keen on these SIP.

searching for tl072 sip yields nothing, and searching for tl072 yields too many results... how should i be searching for this? is there a specific manufacturer that produces SIP's?

[Paul Perry (Frostwave)]

It isn't a TL072, but it is a dual SIP op amp & mouser has it: NJM4580.
maybe the Fairchild KA4558 is worth a try too, at least it is low noise, SIP, and at mouser.
(under 50c).

[PenPen]

Paul knows more than I in this case. Keep in mind, though, that I have no idea what the pinout on that m5223 is, since I can't find a datasheet. The pinouts on the replacement ICs may not match. I'd recommend doing more research to find out the pinouts for the m5223 before you stick anything else in there.

[spudulike]

Datasheet
http://www.datasheetarchive.com/semiconductors/pdfdatasheet.php?Datasheet=1232026

The pdf contains pinouts for the sip and dip variants. The 5223 series is quite common (dialelec .com in the UK sell the "L" suffix for £0.92)

[no one ever]

this is a great learning process, i can already see a few naive statements in my topic post...

added njm4580d (513-njm4580) to my cart.

thank you for the service manual! very helpful.