What's *your* latest mess-up?

[Th3_uN1Qu3]

There was no thread on this subject so why the heck not make one. Inspired by smason's story here, where he was ready to take the soldering iron to a power supply board when actually the switch was off, and having been thru such situations many time myself, such a thread will certainly be fun.

I'll start with my latest. I made a PCB for a class D amplifier. It didn't work, got really hot, and looked real bad on the scope. I thought my layout was bad so i made another PCB, this time double sided with ground plane. Same thing. Spent 2 days troubleshooting the new board. It no workie. Left it alone for another couple days then went back at it today. Discovered a number of inconsistencies compared to my ugly stripboard which did work, noticed i forgot to install some caps, but eventually it traced down to....

I had installed two diodes the other way round. That's right, got them wrong on the first board, got them wrong on the second board, and took me a week to realize it.

[Pyr0Beast]

Re: What's *your* latest mess-up?

Nice one )

[smason]

Re: What's *your* latest mess-up?

LOL, glad I could inspire a screw-up thread.
Here's another from a while ago:

Just finished 2 17" LG monitors I rescued from being recycled at the office.

# 1 LG 1752
Has a sticky note on it that says "Dead"
I plug it in, works fine...
Disassemble, find Samxon GF caps, all look really good.
I do a full re-cap minus the big one, and re-solder some questionable joints.
All the Samxons test fine ESR-wise, a few are a bit low in uf, but within spec.

Put it mostly back together to test, and....
It's dead Jim! Nice, I usually try NOT to make things worse when I repair... Hmm. What did I do? solder bridge? backwards cap?
I examine thoroughly, can't see anything obvious.
re-test, nothing. No 5v no 12v, 160somthing on the big cap.
re-re-examine, no long leads shorting to ground, no solder puke from my vacuum tool. I spray with flux remover, brush clean and examine under magnification.
I questionable solder joint I missed. re-solder, test. Still dead.
About to put it down and get a beer, when I decide to look closely at the pile of Samxon caps on my bench. Wait a sec! that little one is .47uf@50v NOT 47uf@50v. <slaps forehead> I bet it's the startup cap too.
I don't have any .47@50s, so I measure the Samxon, and put it back in.
Test. WHEW! Working great.

[mockingbird]

Re: What's *your* latest mess-up?

One of those .47 GF caps prevented an LG L1710s I use from functioning properly, I suggest you replace it.

[yyonline]

Re: What's *your* latest mess-up?

I was pulling some data off an IDE laptop drive. I plugged the ribbon cable in, but one pin off. Laptop drives don't have the plastic around the pins, so it's easy to do. I ended up blowing the fuse on the drive's circuit board, and melting my laptop IDE to desktop IDE adapter, IDE cable, and some of the plastic on the drive.

Fortunatley, that fuse saved my butt. I was able to replace the fuse, buy a new laptop->desktop adapter, new IDE cable and the drive is just fine. (Well, more accurately, the drive is still bad...but it was returned to its pre-mess-up condition. It was a data recovery operation to begin with.)

Moral of the story: always check your connections before hitting the power button.

[c_hegge]

Re: What's *your* latest mess-up?

My last one was when I was re-capping an Asus motherboard. I replaced all the Chemi-con KZG caps with panny FJ and FL, fired it up and Bang, Bang, Bang, Bang, Bang. The new caps all vented. As it turned out, I forgot that Asus have their screens backwards and polarised them all wrong.

[mockingbird]

Re: What's *your* latest mess-up?

That's a shame you blew those FJ/FL... They are impossible to find. (I don't trust those ones on eBay that look legitimate).

[c_hegge]

Re: What's *your* latest mess-up?

Yah, I know. At least they were freebies which I pulled from another motherboard and anyone who knows me knows that I love using caps as firecrackers (although I usually only do it to brands like fuhjyyu and sacon)

[goodpsusearch]

Re: What's *your* latest mess-up?

I replaced the main caps of a power supply and accidentally put one wrong. It worked but after 30 seconds I could hear a very strange noise like something frying.

I disconnected it from mains and only then noticed that one of the big caps has got very very hot!

I let it cool down for 30 minutes and then put the cap out, tested it with the esr meter and found it ok (well done Teapo for that!) and then put it back with the correct polarity.

It worked..

[Th3_uN1Qu3]

Re: What's *your* latest mess-up?

That was the electrolyte boiling. Big cans announce like that before bursting open. Smaller ones just blow.

[seanc]

Re: What's *your* latest mess-up?

Trying to remove the rubber end-cap from some CCFLs to re-solder the wire but breaking the end of the CCFL in the process.

[bigbeark]

Re: What's *your* latest mess-up?

I had success with the "wire trick" on Asus P2B-DS board. You can fake out the board so that it will accept Coppermines instead of Katmai core slot-1 CPUs. That one worked great.

So I thought, why not try the same thing on a P2B-S board. So I inserted the magic wire, put a coppermine chip on a Slotket, inserted it into the board and fired it up.

Unfortunately the magic wire caused the Slot-1 "finger" to short itself resulting in Magic Smoke.

Like a dummy, I tried to verify that the board was still good by removing the Slotket and the magic wire, and trying a Katmai. I fried the Slotket, the Coppermine CPU, the motherboard and the Katmai CPU in the space of 5 minutes. So much for that technique!

[Scenic]

Re: What's *your* latest mess-up?

kinda reminds me of my fujitsu siemens dual slot1 board.
2nd slot needs a voltage regulator module (sort of like the ones on socket 7 boards).

went ahead and put one in that i had been using before...popped a PII 400 in and turned it on.. beeped.. and nothing happened..
oh well.. might be incompatible... so i put another cpu (PIII 500 Katmai) in.. worked fine for a couple minutes.. then blackscreen out of nowhere..
put the third one in (PIII 550 Coppermine).. worked fine.. but i noticed a horrible "burning electronics" smell after a minute...

turned out the jumpers on that VRM module were messed up.. it was configured for a pentium pro (3.3V core) instead of a Pentium 2 (2.0V) or Pentium 3 (2.0V katmai or 1.65V coppermine)... ended up unintentionally toasting these cpus with 1.3V or 1.65V more than they were supposed to get..

that cost me 3 slot1 CPUs .___.

[Pyr0Beast]

Re: What's *your* latest mess-up?

Uff. Slot1 fun.

Removed P3 800MHz CPU from its slot.Thought board was off ... well, It wasn't

Both still worked.

Removed 32MB SDRAM and then inserted it back with power still on (was pissed at PC, freezing from a bad stick) *bang*

Some golden fingers burned off. Ram and board still worked.

[gerg]

Re: What's *your* latest mess-up?

"Repaired" an acer al1717 monitor put one of the caps on backwords up here in the lab. Everyone said it sounded like a .22 going off oh well I have a picture somewhere of what is left of the cap i will try to remember to post it later

[alexanna]

Re: What's *your* latest mess-up?

Here's a good one.I did not have the proper power supply for this monitor so I improvised.
You can see the hookup up, I couldn't find my black jumper, so don't be confused I used a red and yellow to connect the ground of the power supply and the DMM to a ground screw hole.
This monitor showed no signs of life so I decided to power it up and check some voltages.
I had 14.5 volts on both sides of the main fuse coming in to the board. And no matter where I touched on the voltage regulator legs I measured 14.5 volts.
I immediately thought a bad ground on the voltage regulators so I started checking from the ground pad of the capacitors to the voltage regulators ground leg. I really could not find any problem.
I was thinking if these voltage regulators are bad is this worth the time and money to fix.
Well after a good nights sleep and dreaming about it, I found that the screw hole I had hooked up the P/s and the voltmeter was insulated and not really a ground.
When I found the correct ground, the voltages started to make some sense. So maybe there is hope on reviving this monitor after all

[steve2]

Re: What's *your* latest mess-up?

Did the cap install backwards once on my old C band satelite reciever. Just thought I would open it up and see what I could do to maybe improve the signal. Replaced some caps and plugged it in and Pow. Then replaced a 12 regulator, diode , resistor and kicked myself in the butt for not double checking before plugging in. I triple check now to make sure.

[MXM]

Re: What's *your* latest mess-up?

i just recently fried/cooked a mobo trying to get it alive... i knew it was a dead end but wanted to give it a try...... and i know i'll try again thou

peace.

[pr0cess0r]

Re: What's *your* latest mess-up?

i melted a nintendo DS when changing the power switch with hot air !! lol

[alexanna]

Re: What's *your* latest mess-up?

This probably doesn't need to be in this thread just yet, but when I find the answer it defiantly will be.
Is it just me or has anyone else has a monitor kick there butt?
It's a really nice Gateway 22" HD monitor so it's defiantly worth fixing, I'm just to the point I am tired of it.
I know eventually I will solve it, this is just me venting.
It's a classic 2 second to black problem; another identical panel will work fine in the problem monitor.
I can find a suspect bad CCFL by substituting a new bulb of the same diameter and length, I replace that bulb and before complete assembly of the LCD I am able to power the monitor on and it stays on.
I finish the assembly of the LCD, and check again check to see if the CCFLs stay on and let it run for a good hour and it works fine. When I install the power supply and its case to the LCD and fasten everything into place within a minute I notice flickering and the 2 sec to black reoccurs.
When the LCD has been apart I have inspected wiring and solder connections for any looseness, And for the possibility of any wire touching a ground.
Done venting.