uglyface problem, 555 heats up (FIXED!!!!!)

[tungngruv]

Built my first uglyface months ago, worked and sounded perfect. I ended up giving it to my brother who plays bass. I whipped up another one using Dan N's layout and it worked for a minute, then the sound went very week and I noticed the 555 was suoer hot. I then used all new parts except for the switch and jacks and 100K volume pot, rebuilt it exactly like the home-wrecker site's large layout and the same thing happens.This really is starting to suck, both new ones sounded great until the 555 chip heated up!!! I'm really frustrated also, having built one with no problems, then building and rebuilding, double checking, triple checking and the same problem. All grounds are correct, and the chips are lined up correctly (I'm thinking possibly the 100K volume pot has a short).Anyone have any ideas?

[jra2217]

you may have a hot wire running into the chip by accident , Did you check all the soldering, i had a problem simular and there was a very very small line of solder between 2 connection so small i passed it on 2 previous times .

Do you have a voltage meter? those things are great, i didn't have one when i first started my project and then got one because i needed to trouble shot the problems i was having .

[petemoore]

I never had that exact sequence, but I know that's no fun.
 Something is different between the old one and this ones.
 Hard to say what's making the chip heat up other than too much current, or at least I've read that's one thing that get's 'em hot.
 I'd have to say look and measure on resistors, see if you can find one thats a smaller value multiplier [10x difference, the last code line], or a short somewhere...something touching somewhere it shouldn't.
 The thing about this type problem is that by the time the chips burnt you havent been able to take voltage readings.
 Maybe read the data sheet, then apply the lowest operating voltage for that chip, applying power for 1 second and waiting for heat dissipation, then feeling at what rate it is heating up, increasing the DC application times hopefully long enough to take some readings before it reaches terminal temperatures.
 Otherwise you're left taking voltage readings out of the debugging process, triple checking node connections, reading [calculating or isolating the resistor by pulling one side of it when a reading lower than what it looks like it should be comes up], testing intuitively or randomly/systematically, using the 'beep mode continuuity checker, more calculating of electronic paths, simply trying to provide the right ones for operational status, with no 'funny' voltage readings to point the way and no audio probing to do same.

[NaBo]

I have an idea: http://diystompboxes.com/sboxforum/viewtopic.php?t=29816   :wink:

[Connoisseur of Distortion]

my personal experience with hot chips is that you have 9v where it shouldn't be. as was mentioned, check for traces where they shouldn't be and compare layout against the schematic. also, seeing that you have the chip pointing the right way wouldn't hurt...  

[tungngruv]

Fixed it. I bought the 555 from Radio Shack and they actually have two now. The new one is rated at 100 ma, half the ma as the first one I used. Put the new one in and all is well. BTW Nabo, I used the thread and search function before I even posted this question. Thanks to all who replied!!!!!!

[petemoore]

When chips are burning up is one case in which the 'regular' needs of the internet debugger [when it doesn't work] can't be filled, voltage readings being one of the key indicators of the viscinity of the problem, simply can't be taken, same goes for audio probing.

 Therefore to get any results from debugging efforts necessitates approaching from a 'different angle'.

[petemoore]

Aha !!!   ...Well you figured something out !!!

[NaBo]

Well i didnt mean he had to fill everything out such as the IC pin voltages...  But some voltage readings without the IC in the socket could have helped determine if this was a supply v issue/a short somewhere.  The different IC might have been mentioned under the parts substitutions, no?  Just trying to help...

Anyway, glad you got it working.  I'm surprised to hear the UF actually needs anything close to 100ma... Tim's circuits are usually really light on the consumption.

[tungngruv]

Yeah, it was weird!!! It worked with the 100 ma chip but then quickly died right when I was starting to have fun! Then I plugged the 555 that had a 200ma on it's spec sheet and there it is. I'm very glad it's working now (except I trashed a couple hours work on the first one when it seems it was only a chip sub :oops: ). Once again, thanks to everyone who tried to help. You guys rock!!!!! :lol:

[gez]

Yeah, it was weird!!! It worked with the 100 ma chip but then quickly died right when I was starting to have fun! Then I plugged the 555 that had a 200ma on it's spec sheet and there it is. I'm very glad it's working now (except I trashed a couple hours work on the first one when it seems it was only a chip sub :oops: ). Once again, thanks to everyone who tried to help. You guys rock!!!!! :lol:

Is it fixed?  Sounds like it might be drawing a huge amount of current and the higher power rating of the new chip is the only thing stopping it from frying.  Might be wrong, but without a link to a schematic, and in the absence of readings, that's my intial thought.

Would be an idea to check the current consumption with a meter, just to be sure.

[Tim Escobedo]

I can't tell you anything except something(s) not right! Even if you could bet a Uglyface working with a regular 555 (I specified a CMOS 555), it should not heat up or draw 100ma.

[tungngruv]

To make a long story short, after my 3rd uglyface in two days, I got one working. I perfed up 3 counting the first that worked, the other 2 kept frying the cmos 555 after about a minute of playing. I then used the lm555 timer and it worked without frying the chip but the mos555 sounded a lot better. I then used a pcb that Dan N traded to me and used one of the cmos 555's that I didn't burn up. This also overheated but when I put a new chip in, it works!!!! Sometimes even the easiiest circuits don't work for some strange reason!! :lol:  It surprised me because I actually use a highliter to mark each connection on the schem/layout as I build it. I'm thinking it's just a bad part somewhere along the line that I must have kept re-using!!!! A lot better now though!!!!! Thanks guys!!

[gez]

I then used a pcb that Dan N traded to me and used one of the cmos 555's that I didn't burn up. This also overheated but when I put a new chip in, it works!!!!

So, if I've understood you correctly, you're saying with the PCB a chip still overheated until you subbed in one with a higher power rating?

If this is the case then you may still have a problem.  Just because it 'works' doesn't mean that you don't have a problem.  

It could be that the one you 'didn't burn up' was in fact damaged, which would explain why it overheated and the sub worked, but the best thing to do would be to check the current consumption with a DMM just to be sure.  If you don't know how to do this, just say and you'll get plenty of people here willing to explain the procedure (very simple).  I'd recommend you do this as you're not going to get much life from a battery if you're drawing over 100mA!

[rankot]

I had a very similar problem, and I couldn't figure out what is going on, but then I remembered that I have changed volume pot to 10k instead of original 100k, to make output volume lower (max volume is incredibly high!). So I forgot that I have changed that and after few days noticed that 555 is getting REALLY HOT! Finally, I put 75k resistor in series with volume pot (which remaind 10k) and overheating was fixed, as well as head-chopping volume of the original setup. I use TI TCL555 IC and now everything is working fine.

I built LFO version, and also used original setup of resistors for sensitivity pot.

Hope this will help to future builders who experience overheating problems!