Tubescreamer project - Diode problem

[Jbuchberg]

Hey all,

I just completed building my first pedal.  It is a TS-9 Clone.  I had just provided power to the unit and checked for continuity for both power and shorts and everything seems to be okay.  However there is a diode that is heating up quite a bit.  Is this normal?  I am reading about .8V across the diode which to my understanding is correct.  If anyone has any experience with this or has any advice it would be greatly appreciated!!

Thanks!  Looking forward to learn and contribute here.

[canman]

What did you build it on?  Maybe one of the leads is in the wrong hole?  I've done that before, several times haha.  Maybe it is oriented the wrong way? 

[duck_arse]

it sounds like your reverse polarity protector is backwards, or the supply is reversed, or you have a series protection diode and a short circuit on your board. either way, turn off the supply. check your circuit diagram.

anything on a ts-9 getting hot is a bad sign. and welcome to the forum.

[Jbuchberg]

Thanks!

So it turned out the power supply was reversed.  Once i had fixed this and plugged it in i found out i had some grounding issues, which i am still trying to work through.  The bypass works without the backcover, but the sound the circuit is producing is not very good.  still trying to trouble shoot this.  any advice would be greatly appreciated.  thanks!!

[nate77]

I think the first and most apparent issue of it not working once the back is on, one of 2 things are happening; first, and lost likely, the back panel is coming into contact with the footswitch, or maybe pressing the PCB Against a switch or pot that's not insulated well; or you could be pinching a wire to the footswitch or jacks and shorting the curciut or stressing the wiring solder. The poor sound you're getting now may be a further symptom shorting the curciut or straining any of the solder connections or may be something else. Can you post pics?

[duck_arse]

most times I say "can we see some photos", the reply comes back "oh, it's fixxed now".

can we see some photos? component side of board, solder side (whatever condition it is) and off board wiring, nice and clear and close.

thanks, and good luck.

[Jbuchberg]

For all your information I am using the AION Stratus board.  The board info and circuit can be found here:
https://www.dropbox.com/s/29cy1vnw287u9ne/aion-stratus-ts9-documentation.pdf

Pictures have been posted here.
http://imgur.com/a/xsam2#0


I hope this helps and i can get a working pedal shortly!

Thanks everyone for their help!!!

[duck_arse]

besides the loose red wire in one yr pics, I can't see anything jumping out wrong. I'll give them a squint off-line and see what is.

[Jbuchberg]

I should have mentioned that the loose red wire, is the positive lead from the power supply, since the box is a little tight for space, in order to make sure there is as little stress on the wires, i have to solder and re-solder that lead when i remove the board being the the 9V connection is nutted on the interior of the box.

[MrStab]

are you still using the same opamps etc. from when you had the power supply reversed?

If the pedal has no polarity protection, reverse polarity is a death sentence for every IC on the board. This happens in milliseconds to a few seconds. Longer reverses will kill all of the electrolytics. Often the diodes and transistors will survive this. Sometimes they will be damaged, often not. Ordinary R's and C's usually survive.

(http://www.diystompboxes.com/smfforum/index.php?topic=55003.0;)

maybe your protection diode didn't do its job for some reason (if there is one. i'd assume there is.)

[nate77]

It look like you've soldered the cap next to m1 and m2 to those specific
Pads. The f and s pads are to be connected to each other (1-3 respectively) for the fat mod and m1 to m2 should be jumpers to s1 and s2 respectively for the flat mods mod. I can tell something is soldered to m1 and 2 but I'm not sure what. That me be causing a short in the curciut or power issues. I didn't peak at the schematic but just was looking the posts really quickly. I've built a couple dozen aion electronics boards and Kevin is a great guy and these boards are some highly moddable and faithful circuits (to the originals)
Hopefully this helps?

[duck_arse]

okey dokey. you didn't specify which of your diodes was getting hot. let's hope it was D1, which is wired as shunt protection. when you reverse the battery, the diode will conduct ALL the current the battery wants to give, and will get hot. it is supposed to survive this because you will notice very quickly the wrong battery. IF you wire the connector wrong, however, it's anyones guess as to when you will notice, and which will die first, your external supply or your protection diode. when the diode goes, the rest of the polarity sensitive parts go with.

but, if you lift the diode and test it, and it is still good, you should be ok IC wise. all that aside, what is the fault we are fixing now? I looked yr board, couldn't still see anything sticking out. I'm assuming you're links for mods are correct, my eyes went funny looking with all the back and forth. so what nate said.

[Jbuchberg]

something was soldering to m1 and m2 briefly, but then i decided to go with the fat mod. so what you see is the residual solder on the pads, but they are isolated.

D1 was in fact the diode that was overheating, once changing the polarity of the power input this problem disappeared. 

The IC seems to be okay, there are no visual signs that it has been compromised, nor has it ever heated up to the point where it became a thought.  i will swap out the chip to confirm later though.

[Jbuchberg]

GOOD NEWS!

I replaced the Op-amp and the pedal sprung to life!  however,  there are some serious tone problems that need to be adressed now.  the midrange is super muddy and it seems like the the pots and switches are not doing anything except for the volume.

Any ideas as to this?  i am thinking there are shorts in the connections somewhere with these pots? 

[duck_arse]

time to apply the dmm. on ohms range, put the probes on the board pads, and rotate the pots, see if the reading changes. make sure the meter indicates the values specified in the parts list. also check continuity to and from the pots to the board.

[Jbuchberg]

I have check the pots for this already, checked the connections to the board as well, and all looks to be well.  Even when as far to replace the wiring and pot to rule out that option.  I am at a loss at this point now.

[tommycataus]

If it were me I think I'd take my cue from that dud opamp and replace the transistors and possibly electrolytic caps. Often if an electrolytic is fried, the exposed metal top looks like it is trying to burst. I hope you manage to solve the problem!

Trust me when I say all the hard work is worth it

[Jbuchberg]

I will check this out.  Everything looks like right and the voltages seem to make sense.  i have no problem with volume and gain as of now, just the tone adjustment.