C1 of Gary's Pulse1 Explodes

[Ajay0707]

Hi Gurus,

I have built this unit one week back and everything was working fine since I switched it on today. Before I switched on today I have soldered the speaker wire which was broken. I have removed both the speaker wires and soldered them back again to make sure there are no bad soldering joints.

After soldering the speaker wires I have connected the battery to the unit then within no time the Capacitor 1 explodes. I have checked for the shorts but I couldnt find any. I have blown almost 6 1uF Capacitors already. The capacitors that I have used are rated 35volts though garys design asks for only 25 volts.

Kindly help me if you could understand my problem.

Thanks
Ajay

[DOOLEY]

just had a look on the schematic , c1 only goes accross the battery as a "buffer" can't understand why it kepps blowing , poss 1st blow was weak part followed by polarity wrong when you replaced many times after , double check polarity ,

+ leg of capacitor goes onto same track as the line on the diode.

[Vortxrex]

What happens when you hook the capacitor across a 35 VDC power supply? There are quite a few bad electrolytic capacitors (from an Asian manufacturer) Floating around, although it usually takes quite awhile for them to go bad (they bulge up at the top)..... I learned this from working on LCD televisions/monitors.

Dave Frank

[Ajay0707]

Hi DOOLEY,

Thanks for your kind reply. I also checked the polarity many times as it was blowing the capacitor without wasting a fraction of a second when battery is connected. Forgot to mention. I have tried to put an LED in place to indicate the on & off status of the unit. At that time I have connected the positive of the battery to the LED(+) directly and negative of the battery to the negative pad on the circuit board. The positive lead was connected to the led by a 330ohms resistor. I think it might be the reason. But when I checked the second time and so this LED was not connected.

Thanks in advance.
Ajay

[Ajay0707]

The Problem is solved

Hi Thanks for all your time..

I finally figured out the problem, when I tried to connect the LED indicator for on and off of the unit it all happened. The IC's 7660 and 1117A were burnt that was causing this issue. I have replaced them and the unit is back again in its good workin condition.

-Ajay