Shocking Autopsy - Page 1
Forum section: electronics / general

author: mafio
author_rank: Contributor
timestamp: April 24, 2016, 02:56:01 am
content: My shocking autopsy stopped shocking so I noticed the large capacitor was out of spec., so I replaced it. The unit still doesn't shock. Does anyone know the large inductor original size? My MS5308 LCR is reading 15 mH. There are no markings. Sound works everything else looks ok and the smd resistors measure closely. Oh I am powering it from my power supply at 4.5 volts. When it is in shock mode I get about 1 amp pull.

author: XOIIO
author_rank: Super Contributor
timestamp: April 24, 2016, 06:05:00 am
content: It would probably help to mention what the device actually is.

author: Ian.M
author_rank: Super Contributor
timestamp: April 24, 2016, 06:41:12 am
content: probablyhttp://www.shockingfun.com/Shocking_Autopsy_p/shockingautopsy.htmAn alkaline AAA cell will only last about ten minutes under a 1A load, so unless that draw is only active when the tweezers contact the metal hole rim, something must have failed short circuit. Post good closeups of both sides of the PCB if you want suggestions what to check.

author: Brumby
author_rank: Unknown
timestamp: April 24, 2016, 06:41:40 am
content: Going by the context - here's my guess:Edit: Snap!

author: mafio
author_rank: Contributor
timestamp: April 24, 2016, 02:55:05 pm
content: Quote from: Ian.M on April 24, 2016, 06:41:12 amYes I meant the board game. 1 Amp is when active. It is a single sided PCB. 100 microF, unlabeled inductor, 2e104j Cap. The caps are in spect. Not sure on the unlabeled inductor.Brown wire goes to the board. Yellow wire are to the speaker. The long red wire is from the batteries paired with the black. The red and white pair go to the tweezers.

author: Ian.M
author_rank: Super Contributor
timestamp: April 24, 2016, 03:53:30 pm
content: Unfortunately, as it uses a COB controller, the odds aren't in your favour. Try tracing the circuit of the boost section and see if its standalone or driven by a PWM from the COB. It would be worth checking Q2 and D1. Ferrite bobbin core inductors are fairly robust and rarely fail.

author: mafio
author_rank: Contributor
timestamp: April 24, 2016, 04:23:43 pm
content: This was taken off the Q3.

author: mafio
author_rank: Contributor
timestamp: April 24, 2016, 08:55:27 pm
content: As I step down to Q2 and P2 using a x10 probe. The following pictures

author: cvanc
author_rank: Frequent Contributor
timestamp: April 24, 2016, 10:57:09 pm
content: Holy crap. In a world full of lawyers how can this game even exist?!?

author: mafio
author_rank: Contributor
timestamp: April 24, 2016, 11:46:41 pm
content: Quote from: cvanc on April 24, 2016, 10:57:09 pmThat's so American of you to say. It really isn't that bad. Just a spot of paralysis.

author: Cerebus
author_rank: Super Contributor
timestamp: April 25, 2016, 01:16:07 am
content: Quote from: cvanc on April 24, 2016, 10:57:09 pmIn a world full of lawyers how can this gamenotexist? It's the ideal Christmas present for a lawyer - it will cause them pain.I'll grant you, not quite as good as a Mk 1 Mills bomb with the pin carefully removed through the wrappings, but a good start nevertheless.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: April 25, 2016, 01:38:30 am
content: Quote from: mafio on April 24, 2016, 08:55:27 pmEr.... please allow me to give you some advice on your oscilloscope usage.1. You can make very clear screenshots by using the scope's ability to save the screen as a PNG (or jpg or bmp) file to your external thumbdrive in the USB slot. There is no need to photograph the screen on this scope. Just put the thumb drive in the front USB hole, wait for the scope to find it, then press the "print" button below the Help button.2. There is no need in this case for the confusing Fine Adjustment (Vernier) mode of the channel's vertical scale. Just stay with the Coarse mode on the channel's vertical scaling (V/division). Enter and exit the Vernier mode by pressing on the big Vertical Scale knob like a button.3. Make sure that your signal isn't going off the screen vertically (clipping) as it is in two of your shots. Use the correct baseline vertical position and correct vertical scaling so that your entire vertical waveform is actually on the screen. It also helps if you put the baseline exactly on one of the graticule lines (helps with visual crosschecking of voltage values.)4. Make sure that you are using the 10x setting on the probe _and_ on the Channel settings menu. These settings must match. From your statements we really don't know if they are matching or not. 99 percent of the time you will want to use the 10x settings on probe and channel; it is rare to need to use 1x in general scope use.5. Just saying you are measuring "Q2" isn't enough information. Are we looking at Q2 base, collector or emitter? And what do you mean by "P2" ?6. The Horizontal settings (timebase, memory depth) should be set so that you have a trace all the way across the screen instead of the horizontally "chopped" view you show in one of your shots.All of that being said, the last scopeshot does show some useful information. It at least shows that your board appears to be producing the oscillations at low voltage which should be being boosted to "shockable" voltage by the output section of the board -- so it is likely that the COB (chip-on-board) under the black blob is working properly. I would suspect things like broken wires, and/or bad solder joints in the output section.

author: Zero999
author_rank: Super Contributor
timestamp: April 25, 2016, 01:03:59 pm
content: Quote from: Ian.M on April 24, 2016, 03:53:30 pmYes, it's possible the COB IC is just for the sound and the HV section is discrete. There are lots of standard sound generator ICs available, which are often supplied as a die for the manufacturer to directly mount on the board. Not so for HV generators.The COB could be an MCU but the design costs would be greater, than an off the shelf sound IC.Start by reverse engineering the discrete transistor part first. Even if it is driven from the COB, it's most likely that it's a transistor which has failed. The fact the sound works, indicates the COB probably works.

author: mafio
author_rank: Contributor
timestamp: May 31, 2016, 01:26:06 pm
content: Replaced all the transG1's but lost the C4 cap. It works occasionally but I think the occasional working is largely due to a bad tweezers wire to the hand.