ROG Tri-Vibe Disaster

[ttist25]

Hey everyone!

Well - I finished populating my tri-vibe board and hooked it up to a little prototype box I have with offboard wiring and it didn't end well. 

I got some sound with the mini switch in the on positions (left and right) but no sound in the center position (that I could hear anyway).  So the circuit was passing audio to some degree but, the LM13600 got so hot it burnt me and I fried the 22ohm resistor next to the 9v input (that thing used to be shiny blue and now it's charcoal gray!).

Anyway - I took a look at the board and found a solder bridge.  I fixed that and it still doesn't work (the chip gets hot as hell a few seconds after I connect it to power). 

This is the most complicated build I've done to date and I did not expect that it would work so I'm not too disappointed.  I made the decision to start over from scratch as I can't have confidence in any of the components after seeing that resistor and feeling the IC. 

The PCB layout I used was taken from Andre Schapps layout.  I modified it slightly because I wanted to add 90degree PCB mount pots to it.  There was a discussion of the pros and cons of that and considering everything, I'd still like to try it (my pedals sit on the floor in my living room and are treated pretty gently). 

I made an image for you guys to take a look at.  It's a layered image with Andre's original design and my modified design on top.  Can you take a look and see if there's anything I might have done that would have caused the failure I had?  I think it's probably more likely due to the solder bridge and my all around crappy soldering skills but, I wanted to post it here to be sure. 
 


See anything there that might have caused failure? 

Thanks in advance! 

[EBK]

Can you post a pic of your burned up board?

[ttist25]

Sure!  Thanks for the help.

Here's a shot of the fried resistor.  I'll send more when i get back.  Half hour or so.

[EBK]

I'd suggest buying some SIP sockets before rebuilding, if you go that route.

[ttist25]

Sockets - already on my list.  I was going for compactness and now I regret not using them. 

Here are some more pics.  Just let me know if there's a better angle or something specific you'd like me to get a pic of. 

[EBK]

A few minor observations:
1.  Even with sockets, those ICs wouldn't be the tallest things on your board.
2.  You could have given the back of those pots a bit more breathing room.
3.  When aiming for compactness, you should have a reason for it.  I recommend picking an enclosure then designing the circuit to fit.
4. It sounds like I'm scolding you, which is not terribly helpful.   

I'm thinking the solder bridge could have damaged things, but it is hard to tell if that was the only problem.  You definitely drew a lot more current than expected through that resistor   . I see lots of bridged solder joints.  I'm hoping there are board traces under all those, but I haven't compared it to the pattern.  Etch looks good though.

[ttist25]

Hey EBK!

Does not sound like scolding at all - sounds like sage advice and I'm grateful for the help. 

When I started this build I was planning on mounting those pots component side but, kind of making things up as I went - well - that probably helped me end up where I am now.  Sockets are definitely going in the next version.  That was a bad decision all the way around.

I think there is copper under all of those bridges.  I went over it with a magnifying glass, a yellow highlighter, and a printed version of the PCB layout.  I'm about as confident as I can be there are no more bridges but, I'm still "noobis maximus" so what the heck do I know. 

Given the condition of that resistor, and how hot that IC got, do you think it's a lost cause or do you think it's still worth trying to save? 

And if starting over is the way to go - does anything seem off with my layout for the PCB mounted pots? 

Thanks for the compliment on the etch!  I love the whole toner transfer/etching process.  I used an old laminating machine for this one instead of an iron and it really worked well. 

PS: my goal is to get this all into a 1590B.

[blackieNYC]

I had a triumphant tri vibe build, and then an attempt at subbing a 13600 into a Gator crushed me.
I roasted 4 of them. Or so I thought. Always read they could prove delicate if misused. But I built a simple audio VCA circuit from the bottom of a data sheet and they actually still work. On the breadboard. Might be worth a try. 

[EBK]

Another suggestion: Double check all your part values and the orientation of the polarized caps (looks like you have some tantalum caps there).  I've made some strange covfefe before when working late, so I always* double check my parts.

*I never double check my parts if everything works the first time. That way, I can avoid messing things up by "fixing" supposed errors. 

[slacker]

Where was the solder bridge? It probably killed the lm13600, which is why it's now getting hot, so it might just be a case of replacing that chip.

[duck_arse]

can I ask - where did you get your LM13600 from?

[Plexi]

I always prefer to use sockets. Prevent a lot of troubles there.
Like EBK says: a lot of covfefe happen working late at night [emoji1]

[ttist25]

Hey everyone.  Sorry for the delay in response.  Real life jobby job thing has been unrelenting.  I have dreams of retiring to a cabin in the woods and building pedals all day and rockin' out in the trees all night.

Anyway - @duck_arse I got all of my ICs for this project from SmallBear.  I ordered 4 NJM13600D, 4 TL064, and an "OpAmp IC Kit" just so I could get the TL072s.  I'm hoping I did some research and decided the NJM13600D is an acceptable replacement for the LM13600.  I mean, they both say 13600 that should be good enough, right?     Can anyone confirm that was/wasn't a bonehead move?

I noticed this morning in Andre Schapp's build he posts an image of the populated board and it's got a LM13700. 

http://www.diystompboxes.com/smfforum/index.php?topic=81099.msg671619#msg671619

So - is the reason that thing gets so hot because it's the wrong gat danged chip?  Ahh noobility. 

[bluebunny]

Can anyone confirm that was/wasn't a bonehead move?

You are not a bonehead.   

[EBK]

As far as I know, 13600 and 13700 are identical except for how the buffers are connected.  ROG specified a 13600, and that's what you used, so I believe your problem is not caused by chip choice.

[duck_arse]

the secret code word all noobs buying chips should know is "small bear". it will be good, then.

NJM is to New Japanese Radio as LM is to National Semiconductor and CD is to RCA and HEF is to Philips and MC is to Motorola and SCE is to SSS and I've probably mixed a few processes there, but you get the picture. JRC.

[ttist25]

OK I think I've got it:

(NJM+13600)=(LM+13600)
ICs + Small Bear=good
NJM13600<>Bonehead move
No Sockets=Bonehead move

@Slacker - I took a look at the board for the solder bridge.  I had to look for the scratches where I took it out but I found it. 
Check this out:



So the bridge was between the pads that connect the 3.9K resistor to the 470ohm resistor and then to pin 11 (V+) of the 13600 (if I counted correctly).  That'd do it eh?   

SO - what would you guys do? 
Remove and re-add the:

• 13600 (I've got a few)
• The 22ohm (already replaced)
• The 3K9
• The 470Ohm where the bridge was

OR

• Start over
• Remember all lessons learned

What do you think?

[bluebunny]

No Sockets=Bonehead move

No Sockets=learning opportunity 

[ttist25]

IT'S ALIIIIIIVE!!!!!!!!!!!!!!!!!!!!!!

I took all the lessons learned and kicked its butt!  It works!!!! Woo hoo!!!

Only thing left is to box it up (oh - and maybe add the rate led mod)!

If anyone is interested, I made a diylc file and uploaded it to the diylc cloud thingy.  Just search "tri-vibe" and it should come up.  The layout is Andre Schapp's 100% except that it allows for board mounted pots. 

I still haven't really played with it much but here's the obligatory four note riff for this pedal:
https://soundcloud.com/user-432009364/tri-vibe-pedal



Thanks everyone who helped me on the way to making this work!!!!

[swever]

I guess its the terrible hangover but I can not really understand what did the OP end up doing to make the thing work? Was the fake 13600 the reason it did not work?

I have just finished my build and I have the very same symptoms - the 22ohm get terribly hot in a second or two after I insert the 13600 chip. I tried all the 13600's and 13700's I've got - all dirt cheap stuff from ebay, most probably fakes. There is no sound with the switch in the middle position. There is dry signal on the output with the switch in either of the other two positions, even without the 13600 inserted. It gets somewhat distorted when I insert the chip.

I used a 330uF cap for power filtering instead of 470uF. Could this cause any problems? I also used a tl074 instead of 064. I bet it should not be a problem, though.

Also, my red led flares at the speed of lfo. I can control it's speed and maximum brightness with the pots. Is this normal?