Help with my board - R33 burned up

[ovdojoey]

Just did a quick test run and bam. Didn't work . Checked over every single part and double checked again and everything is in the right place and is correctly polarized if needed.

So here are the problems I incurred while building my A12.

My first problem occurred when I was soldering J3 & J4 - I soldered with the short pins up on J3 - so I heated up the metal and tried to pull it back out - but it caused one of the prongs to pull out of the three prong piece - I pushed the prong back into the black plastic and I ended up getting it in right side up - and pushed the cap on J3 & J4 but it wasn't a smooth fit.

I also accidentally soldered the 2 PIN jumper into J6 instead of J5... - I corrected this as well when I spotted it.

I plugged everything in and it sparked up and I immediately shut it off - my guess as to the reason it sparked is due to me grounding the power wire to the silver separator of the power supply and one of the pins wasn't trimmed enough and must have touched that metal sheet.

After the spark occurred I trimmed all the ends to make sure nothing touched and powered it back up and plugged in a microphone - this time the R33 sparked up and then caught on fire. It was the right piece and was installed properly so I have no clue why it did this.

Anyways I've looked over my work and re-flowed the solder with no avail. Am I missing something or did I damage the unit when the back of the pins touched the grounded metal sheet.

- I still don't have a R33 anymore - I cut it off when it burned up.

Should I replace that piece and try again?

I'm just a little frustrated so any help would be greatly appreciated

Thanks all,

Joey.

[tpryan]

Make sure C16 is installed the right way round.

Make absolutely sure that you didn't swap Q1 and Q2. Check the markings with a magnifying glass if you need to. If you powered it up with those transistors installed wrong, it's likely that one or both of them will need to be replaced.

[ovdojoey]

Thank you for the prompt reply.

I double checked again and C16 is installed properly and Q1 and Q2 have the right pieces in place and are installed properly as well..

Do you think it hitting the ground wire metal sheet and sparking could ruin either one of those pieces or what is normally the reason for the R33 to burn up?

Thanks again,
Joey.

[tpryan]

Do you think it hitting the ground wire metal sheet and sparking could ruin either one of those pieces

Possibly, but of course it depends on what got shorted. Frankly, if your assembly is such that the leads are shorting against the divider you may have bigger problems. No leads should be anywhere near long enough to contact the divider.

what is normally the reason for the R33 to burn up?

Normally, R33 doesn't burn up. If it does, the most likely causes are reversed or shorted C16 and Q1 swapped with Q2. Measure C16 for a short and test Q1 and Q2 with the diode test function of your DMM. If you don't know how, google can help.