battery burning up

[jlullo]

hey guys, i was just gathering the info for help on debugging my TS-808, and before i could get any measurements with the battery in clip, i felt the battery and it was unbelievably hot.  I disconnected it.  What should i do?

[jlullo]

for further backround info, i finished building, and then tested the pedal for the first time last night.  the led would flicker for a sec when i engaged the pedal, but no sound.  Today i bought a multimeter.  When i pulled out the battery everything felt fine, and i probed the battery terminals.  Then, i put the battery back in to start checking voltages, and i thought i heard a tiny pop a few minutes ago.  When i accidentally felt the battery it was unbelievably hot.  I pulled it out, and let it cool off... what should i do now?  what does this mean?

[littlegreiger]

Check all your traces and wires. It sounds like you have a short somewhere on the 9v line. Basically the power is going out the battery and right back in which is making it heat up.
Hope you find the problem.

[jlullo]

i just noticed that there may have been a tiny bridge between the left and middle poles of the middle row of the 3pdt swtich.  could this have been the problem?  Besides that there doesn't seem to be any bridges?

[mdh]

Depends on how you have it wired... if one of those lugs is connected to +9V and the other to ground, then yeah, could be the problem. I also noticed in the pictures that you posted of this build (I believe I'm thinking of the right one) that you had your board solder side out in the enclosure. If this problem is occurring with the lid on, it's possible that +9V and ground are shorting out by contact of the solder side of the board with the lid. If that's the case, you should put something nonconductive between the board and the lid before you close it up. I believe a lot of folks around here use neoprene sheet that you can buy in a crafts store. I've used a sheet of rubber cut from an old bicycle tube for the same purpose.

If that's not the problem, there's probably still a short somewhere between +9V and ground. To verify that, remove the battery (as well as any AC adapter you may have plugged into the pedal), plug a cable into the input jack, and test for continuity between the +9V and ground connections. If there is anything less than infinite resistance, you've got to track down what's causing that and fix it.

EDIT: actually, come to think of it, the resistance between +9V and ground should not be infinite because there's a voltage divider across the supply for Vref, but anyway, it should be something like 20k or greater, certainly not a dead short.

[jlullo]

i had lined the inside of the lid with the fuzzy side of velco.  Would this not work well?

how do i test for continuity between the +9V and ground connections?  Sorry, i'm very much a newbie (as i'm sure you can tell  )

[rockgardenlove]

Just measure the resistance from the batteries (+) terminal to ground, or (-) terminal.

[jlullo]

i'm getting a reading of zero.  what does this mean? 

  i'm also wondering if i burned out my led, because it's not even flickering anymore

[sfr]

A reading of zero means no resistance at all - so you've got a short between the + 9V and ground.

things to check - first make sure that the +9V is going the right place - to the +9V connection on the board.  You probably have another wire running to the resistor connected to the LED as well.  But make sure the +9V isn't running anywhere else and isn't accidently connected to a ground pad on the board by accident!

Do you have a jack for a power adaptor?  Is it the plastic, isolated type?  If it's got a metal body, and the body of that jack is connected to the 9V instead of ground, there's your problem.

Next thing to do is look for shorts - probable places are at the power jack (if you have one) as well the wiring going to the LED.  (Especially if you've got uncovered LED or resistor legs legs hanging there.)  Check around the pad for the 9V connection - a solder short between there and any adjacent ground connectiong can be the culprit.  And follow the 9V line around from it's offboard connection and make sure there aren't any solder bridges. 

I'd make that measurement again with everything outside of the enclosure as well - sometimes if you don't plan things well enough, stuffing everything in the box can short something out, like the LED's legs or the back of the pots against something.  Or a jack looks like it clears until you insert a cable and it shorts against something next to it. 

[mcasey1]

I had this problem once in my old phase 90.  A bit simpler to figure out though.  A stray componentl ead had gotten stuck on the battery clip, shorting the terminals.  The battery was  really hot and the clip almost melted.

[jlullo]

after reading all of your posts i noticed that my IN and GROUND pads on my board were switched.  I resoldered them correctly, and then got so happy when i plugged in a cable and saw the LED power up beautifully.  Then, i plugged in the power supply, and it worked with that as well.  I went upstairs, got a guitar, and brought it back downstairs, and now it won't do anything at all!  what could have happened in the 2 minutes in between it working and not??

here are the readings on the board:

Q1
1 -  0.23
2 -  0.76
3 -  1.11

Q2
1 – 1.68
2 – 1.11
3 – 1.11

IC
P1 - 0
P2 -  0.81
P3 -  1.32
P4 -  1.48
P5 – 1.10
P6 -  1.89
P7 – 6.93
P8 – 1.48

D1
A – 1.32
K – 1.47

D2
A – 1.47
K – 1.32

D3
A – 1.32
K – 1.32

[petemoore]

  checking for continuity = diode checker = set DMM to Beep mode, verify the setting by hearing a 'beep' when the two leads are touched together.
  I use a testclip on the black lead...be that as it may, connect the black lead to ground, test that the DMM beeps by touching the red to black, then, test all ground points as shown on the schematic. then test for short between V+/V_ by touching the red lead to both battery clip buttons, for NPN Neg Gnd. [as in TS], the small button [V+ of battery clip], should beep as connected to ground, the large [female] button should Not Beep, if it does beep find the short between V+/V_ before applying power.
   Then, i plugged in the power supply, and it worked with that as well.  I went upstairs, got a guitar, and brought it back downstairs, and now it won't do anything at all!  what could have happened in the 2 minutes in between it working and not??
  Anything that would cause it to do nothing.
  I would test for DCVoltage of the power supply.

[mdh]

IC
P1 - 0
P2 -  0.81
P3 -  1.32
P4 -  1.48
P5 ? 1.10
P6 -  1.89
P7 ? 6.93
P8 ? 1.48

Well, there's clearly something weird going on around the IC, because pin 4 should be at ground (0V) and pin 8 should be at the full supply voltage (incidentally, when giving voltages, you should specify the voltage reading between ground and the positive supply). I suppose it's possible that you're numbering the pins incorrectly. But even if that's the case, at least one of the pins should show the full supply voltage. The biggest number I see is 6.93, which I believe is a pretty low voltage for a 9V battery. Not surprising, giving that you cooked it. It's possible that it just can't deliver enough current to turn on the LED now. If you get similar readings and LED behavior with the AC supply, then either you've cooked the LED, or there's still a wiring problem. It would be helpful to know the value you used for the current limiting resistor for the LED, and what the forward voltage and current ratings are for your LED.

One thing that might be helpful would be to see the component side of the board, so we can verify that the IC is plugged in correctly.

EDIT: I just saw your other thread... now you two different sets of voltages in two different threads. I think it would be easier for everyone if you stuck to a single thread.

Thanks,
Matt

[jlullo]

MDH,
hey!   i got a fresh battery today, and re-measured the IC.  These are the results i got.  I double checked to make sure that the orientation of the IC was correct, and it was.  It seems that they are still off.

Here they are with the new battery:

IC
P1 – 1.14
P2 -  1.12
P3 -  0.72
P4 -  0.00
P5 – 1.13
P6 -  7.15
P7 – 1.81
P8 – 1.02

and here they are with the AC:
IC
P1 –  0.48
P2 -  0.26
P3 -  0.17
P4 -  0.00
P5 – 0.25
P6 – 0.09
P7 –  -0.21
P8 -  0.22

obviously something has to be wired incorrectly, but i can't figure out what.  I've checked my wiring over and over again, and even resoldered joints that looked like they could possibly not be that great, and have found nothing.

as for the LED, i was messing around probing that, and with the probes i was able to make it light up even without a cord in the input jack.  it was really weird.  i turned the switch on and off, and the led would turn on and off with it.  after a few minutes it stopped doing that altogether, so i was hoping maybe i had bad solder joints on that as well.  I resoldered them and still nothing.  i checked the orientation of the anode and cathode, and where they were going, and that was correct.  I am using a 2k2 limiting resistor.

sorry about the two different threads.  i thought people would stop posting on this one, and that i'd need an "official" debugging thread .  It seems this has become that one for me.

any help or insight would be greatly appreciated!!

[mdh]

Unfortunately I'm not knowledgable enough to comment on the voltage readings in general, but until pin 8 is showing the full supply voltage, there's probably no point in worrying about pins other than 4 and 8, assuming that you're identifying the pins correctly. Just to be sure, pins are numbered as follows, looking at the IC from the component side of the board:

8 7 6 5
o
1 2 3 4

The "o" at the left represents the orientation mark of the IC (that little notch at one end). Sorry if this is too basic, I just want to make sure. Also, from the solder side, pin 1 is identified by a square pad on the Tonepad layout. It may be helpful for you to print out a reversed version of the transfer (which will then correspond to the pcb traces on the solder side of the board), and go through using the meter to check that the points that should be connected are, and those that shouldn't aren't.

Other than those suggestions, all I can do is give you a couple of educated guesses. You might check that none of the offboard wiring is shorting out on the component side -- sometimes insulation has a way of shrinking away from the board when you solder, leaving some bare wire exposed. Sometimes when this happens wires can come into contact when you cram everything into the enclosure, even when they're not touching when the board is out. I'm thinking particularly of the tone and level pots, since each of these has a connection next to the +9V connection to the board. Whatever you do, if you're taking resistance measurements on the board, remove *all* sources of power from the circuit. Since there's some uncertainty about whether the input jack is actually switching the power, this means that you should remove the battery completely for measuring resistances.

Also, if I were debugging this myself, I would probably forget about the LED for the time being. Might even be a good idea to just remove it from the circuit completely, and see what happens to the board voltages.

I know this is frustrating, but this is your first time out, so you have a lot of skills and knowledge to pick up along the way. You'll get it, just keep on banging away at it!

[petemoore]

 "New battery can get old in a big hurry when 'battery burning up..
  what is the measured battery voltage?
  Before anything else, test that the V+/V- has no shorts, for kicks read a resistance measurement there too...
  What does the battery measure alone? ..and with the circuit connected/loading it?
P1 – 1.14
P2 -  1.12
P3 -  0.72
P4 -  0.00
P5 – 1.13
P6 -  7.15
P7 – 1.81
P8 – 1.02  Something is pulling this way down if you're starting with say 8v+ on the supply voltage.
  I would pull the IC and measure pin 8 again. It could be the IC is damaged and causing pin 8 to show low voltage...er I dunno, except could be the IC.

and here they are with the AC:
  AC= Alternating Current, OA's don't likey...
  Measured DC Voltages are what we're looking for, I hope to assume you meant adapter?
IC
P1 –  0.48
P2 -  0.26
P3 -  0.17
P4 -  0.00
P5 – 0.25
P6 – 0.09
P7 –  -0.21
P8 -  0.22
  Pull this IC also...assuming you used sockets...power and measure pin 8.

[jlullo]

hey guys.  I disconnected the board took a couple of days off to clear my head.  i sat down today to start working on it again, and i realized something that i did when i wired up the board the first time.  since i have it upside down in the enclosure, i needed to flip flop the wires going to the 500k and 100k pots.  i had just wired it up according to the diagram before, without giving thought to the orientation of everything if it was upside down.  this also makes sense that before i had the 9v wired incorrectly on the board.  today, i fixed everything, wiring it correctly.  it still won't fire up.  no led either.  i don't know what else i did wrong.  please help!

here are my new measurements:

Q1
1 -  2.77
2 -  3.29
3 -  8.82

Q2
1 –  8.15
2 – 8.82
3 – 8.82

IC
P1 – 4.37
P2 -  4.34
P3 -  4.37
P4 -  4.34
P5 – 4.17
P6 -  1.73
P7 – 6.87
P8 – 8.75

D1
A – 4.34
K – 4.32

D2
A – 4.32
K – 4.34

D3
A – 4.34
K – 4.34

[jlullo]

  Before anything else, test that the V+/V- has no shorts, for kicks read a resistance measurement there too...
 

pete, what does this mean?   how do i test for this?

[mdh]

Your IC voltages are still whacked, but in a different way, now. Now it looks like pin 4 is connected to Vref (Vb on the Tonepad layout). The easiest way to make Pete's recommended resistance measurement is to remove all sources of power, plug a cable into the input jack, and measure the resistance between the terminals of the battery clip. It would also be good to check the values of the resistors in the voltage divider. Looking at the parts overlay version of the Tonepad layout, you'll see a green trace (ground), a red trace (V+) and a pink trace (Vb). There is a pair of 10k resistors, one between the red and pink traces and one between the pink and green traces. Measure the resistances across each of these components and report back to us. Remember, no power in the circuit for resistance measurements.

Taking a couple days off was a good idea.

[jlullo]

alright guys.  Tonight i realized that i had my switch rotated 90 degrees in the wrong direction (i didn't know it had to go a certain way!  stupid oversight on my part).  I turned it the right way and resoldered everything the way it is supposed to be.  I am unable to check and see if it works tonight, but the status LED is still not working (though i know this doesn't mean much).  Here are my new measurements:

Q1
1 -  2.73
2 -  3.24
3 -  8.69

Q2
1 –  8.01
2 –  8.68
3 – 8.68

IC
P1 –  4.28
P2 -  4.31
P3 -  4.28
P4 -  0
P5 – 4.09
P6 -  1.69
P7 – 6.79
P8 – 8.66

D1
A – 4.29
K – 4.27

D2
A – 4.27
K – 4.29
   
D3
A – 4.29
K – 4.29

do these look better?

Your IC voltages are still whacked, but in a different way, now. Now it looks like pin 4 is connected to Vref (Vb on the Tonepad layout). The easiest way to make Pete's recommended resistance measurement is to remove all sources of power, plug a cable into the input jack, and measure the resistance between the terminals of the battery clip. It would also be good to check the values of the resistors in the voltage divider. Looking at the parts overlay version of the Tonepad layout, you'll see a green trace (ground), a red trace (V+) and a pink trace (Vb). There is a pair of 10k resistors, one between the red and pink traces and one between the pink and green traces. Measure the resistances across each of these components and report back to us. Remember, no power in the circuit for resistance measurements.

the resistance of the battery clip (i'm measuring at 20k... is this right?) is 16.43

between the pink and red traces- 9.67
pink and greed traces- 6.51