Electronics Mortuary

[davenn]

Gosh, months have flown bye since the last circuit destruction post in this thread

here's my latest contribution
Its a section of a power supply for a GPS based heavy equipment machine control system
the unit goes on a machine like a grader, dozer, excavator etc

Ya gotta love these new multilayer SMD caps but when they go bang they do a good job!!

cheers
Dave

 

[Raven Luni]

LED destroyed by a 4700uF capacitor (charged to 5V)

 

[davenn]

the latest destroyed piece of equip to grace my service bench

This unit came off a D12 Dozer that had a little mishap resulting in
a totally F.U.B.A.R. GPS receiver unit

Thats one way to destroy a $18,000 receiver unit

Dave

 

[Raven Luni]

And youre supposed to service that how?

 

[davenn]

naaa its a write off

it would cost more in parts cost and time to rebuild than it would for a replacement

the last one simarily damaged I quoted at $22,000 to repair
But I still do a quote anyway so the client has something to give to the insurance company for a claim

Dave

 

[GreenGiant]

When calibrating the battery tester I got to the thermocouple board, one of the channels hadn't been working and this is what I found.

Now this board operates on 5 volts, that's all that is supplied to it, something had to go catastrophically wrong in order to fry this part and melt the traces. It must have been a spectacular show, I'm sad that I missed it.

You can almost see the burn mark on the green connector in the 3rd picture.

 

[davenn]

ya let the smoke out !!

thanks for the post

Dave

 

[(*steve*)]

You can almost see the burn mark on the green connector in the 3rd picture.

I don't think you'll be able to salvage that tantalum capacitor.

 

[Raven Luni]

Thats not a capacitor anymore. It has become...something.....different..

 

[Raven Luni]

My bench supply - the voltage and current knobs broke on its very first use. They were attached to the pots by tiny (pin sized) plastic shafts which just crumbled under the pressure of moving them. Of course I had to open it to find that out, but it has those stupid tamper proof screws - so I bought a set of special screwdriver heads - would have been fine except the screws were at the bottom of long narrow holes so by this time I was like FúCK IT and ripped the bastard open.

The circuitry should all still be good (those heat sinks arent loose - they're fixed at that funny angle - another testament to the quality craftsmanship...).

Think I should still use it? (it have to make a new box first of course)

 

[(*steve*)]

Here's proof that capacitors can fail even before they're used.

Doesn't make me overly happy about the other ones that were next to it.

 

[davenn]

wow thats bad! any idea what their year of manufacture was ?
ie. how long have they been sitting on the shelf?


D

 

[davenn]

Thats not a capacitor anymore. It has become...something.....different..

gosh I meant to respond to this one ages ago with a bit of Monty Python...

" its passed on... Its ceased to be....if you hadnt zapped it, it would be pushing up the daisies by now .... it (^@#$in' snuffed it"

well ... Ive had a look out back... and we're right out of tantalums, got an electrolytic, will that do?

(just a little poetic licence )

sorry couldnt help myself


Dave

 

[nepow]

Burn ups!!

Great selection of pic's Guys... I can smell them from here!! Regards all

 

[(*steve*)]

No idea about manufacturing date. But I may be able to tell you when I bought them... OK, they're pretty old. Feb of 2010.

But still, it's a 105C component, and I can assure you that the conditions where it's stored do not react that sort of temperature.

 

[davenn]

Latest bit of electronics destruction from my workshop

This is a GPS receiver. These get mounted on dozers, graders, excavators and other similar heavy machinery where they are, as you could imagine, subjected to huge amounts of vibration.
This unit has stainless steel wire spirals that isolate the inner circuit board housing from the outer case and much of the vibration. But what sometimes happens is that one of the wire rope spirals starts to fray and eventually breaks and this often leasd to a cascade failure of all of them as in this case. Without any support, the inner housing just bounces and bangs around inside the outer housing causing even more damage

The unit is ~ 1ft in diameter and ~ 8 - 10" high. the right "white" section is the radome with the antenna unit, which has suffered damage and failure due to the board housing bouncing around

cheers
Dave

 

[Mongrel Shark]

DMM backwards battery

This is a medium quality DMM ($50 new) I have had for quite a while. Its seen some abuse. The thermo fuse died some time ago. When I forgot to move the leads to check the voltage in a 12v car battery.. Seems the amp range doesn't turn of with dial movement.. So no longer 200ma range.

I also got a negative capacitance reading off a Layden jar, I made with salt water in plastic bottle with aluminum foil. So thought I'd look at the inductance... Turns out the jar had leaked, and that salt water and Aluminum makes quite a good air battery... No more inductance range.. Took me a while to figure out why the inductance range had become a random number generator too!

Then, a few weeks ago, I managed to put a freshly charged 9v in backwards. Turns out the SMD caps dont like it. You can see remnants of the original orange one fused into the back cover. To top it off. It was my first SMD cap replacement, and nobody told me the stripe is on the pos side. Good thing the caps come in a 10 pack. The new black one thats surrounded by black sooty stuff was number 3.... First time I thought I got it wrong, Second time I was very careful to get the stripe on the neg rail. They make quite a noise when they go too. Could be a good one for Guy Fawkes night. Cheaper and more legal than tom thumbs.

Apart from the 200ma range, and the inductance range. It still works. Is my 4th best meter

I now get really cheap ones, in lots of 6 for $3.90 each. For anything I'm not sure about.

 

[Mongrel Shark]

50amp's through 20 amp solar controller.

This one is my old solar charge controller.

It was a cloudy week, and I was deep in online gaming. Way out in the bush. 200ah battery was getting a bit low, and I wanted to game late into the night. So I drove the car up to the front door in the morning, left it idling on L.P.gas (Surprisingly cheap way to charge the battery, compared to generator or other motors I had)My ute can spare about 40a for a charge... I plugged it into the wall input for the extra solar panel (which got stolen some time before) Right next to the 10-12A of panel already running. With my "special" lead. Consisting of 240v 3 prong plug at one end, for my wall input, and jumper lead clamps at the other end (yep its real safe ). Strangely it never blew the 20a fuse, or the IGBT pictured. That happened a bit later, just before noon, when the battery was getting fuller, and the controller was diverting a good portion of the power to the heatsink. when the sun came out from behind a cloud.... Just couldn't handle the extra 10a to the heatsink. Took me a week to realize I no longer had overcharge protection, and my (really big 200ah) gel cell was getting up to around 15.8v.... Had been charging it that way at night for some time. Was definitely the 10a from the sun that did it.

Considering it was screwed to a very dry, Australian Cypress wall (ignites easy, burns hot and fast). I was kind of thankful the house didn't catch fire. Looks like it had a fair flame out the side when it went. Shame I was down the back with the chainsaw at the time.


I replaced it with a 30a charge controller, so it wont happen again

I'll get round to ordering a new IGBT one day....

 

[dietermoreno]

An unfortunate addition to the electronics mortuary since Steve told me that repairing it is beyond my level of knowledge.

That image isn't my radio. It is just Google image search.


I will take some pictures of it when I visit my mom over summer break in 2 weeks (the radio is at her house).



by the way, the reason I didn't turn it off immediately when I heard mains hum is because hearing mains hum is very common on guitar amps and I thought it can't be that different from a tube guitar amp.

The reason I cranked the volume to 11 on the old radio was because I found that if I cranked the volume to 11 on my guitar amp it had the best results in demodulating radio waves louder than mains hum.

Maybe I'm just an idiot and demodulating radio waves on a guitar amp is very different from a super heterodyne receiver.

 

[alfa88]

I think it's time for a new multimeter. This meter displays these numbers when it first starts up.