My current repair job has > 12 PICs - Page 1
Forum section: electronics / repair

author: kolbep
author_rank: Frequent Contributor
timestamp: September 24, 2013, 06:10:59 am
content: Yep, you heard me.I am busy working on repairing a Moving Head stage wash fitting (oby600 wash).Finally got the schematic, and this thing has a pic micro for almost every motor. WIth two data busses linking everything.it also had a pic for the 7seg displays and buttons, and another one that looks like the brains of it.At least I have gotten a break, in that this thing uses a linear powersupply, not switchmode.But I have to dissasemble most of tge fitting just to check the psu caps.The fault, if anybody is interested, is that you can send a dmx signal for it to go to position, and it will keep on jerking until it ges there. Sometimes it does not even try to move.Other motors are jittering the whole time, and the colour wheel keeps on rotating.Even the builtin demo mode is not working right, so it is not dmx problemGuess I am going to check the caps, then the interconnects, then the oscillator that is global fforall the micros.Unldss, on the odd chance somebody has experienced the same problems on a geni oby fitting?But, over 12 pics. Wow

author: houdini
author_rank: Regular Contributor
timestamp: September 24, 2013, 07:05:33 am
content: From the title i was expecting pictures.

author: BravoV
author_rank: Super Contributor
timestamp: September 24, 2013, 07:07:39 am
content: Quote from: houdini on September 24, 2013, 07:05:33 amSame here, and realized PIC as mcu, not picture.

author: Fsck
author_rank: Super Contributor
timestamp: September 24, 2013, 07:12:03 am
content: Quote from: BravoV on September 24, 2013, 07:07:39 amwe've all been scammed. though, a pic of 12 PICs would be amusing to see how they're used.

author: kolbep
author_rank: Frequent Contributor
timestamp: September 24, 2013, 07:42:15 am
content: Will post pics of the pics later on.Each section is almost similar, a pic monitoring a hall sensor, some also monitor optical encoders, then has some other logic glue, and then runs a stepper driver.

author: David_AVD
author_rank: Super Contributor
timestamp: September 24, 2013, 07:58:49 am
content: A lot of faults in moving head are caused by intermittent wiring harnesses (stretched or crushed). A broken harness can cause missed steps (jerkiness), loss of feedback (continuous "searching", etc.Of course you must check the power supply rails as excessive ripple or low voltage can wreak havoc in the strangest ways.

author: nitro2k01
author_rank: Frequent Contributor
timestamp: September 24, 2013, 09:14:53 am
content: Speaking of multiple PICs, remember Dave's Absopulse VFC500 Variable Frequency Converter teardown?(From around 34:35)

author: SeanB
author_rank: Super Contributor
timestamp: September 24, 2013, 09:21:57 am
content: I must upload a pic of a board from a lotto machine. Has a 68000, a 68HC11, a Z80 clone and another 6800 series IC AFAIK as processors, a lot for a board that just could use one. One does the keyboard, one does the display, one drives the printer via another processor on the printer board and the others do whatever.

author: kolbep
author_rank: Frequent Contributor
timestamp: September 24, 2013, 11:00:41 am
content: Thanks for the hint on the Harness. I will check it out.Here are some pics of the pics. There are some more that are hidden by the metalwork at the bottom of the yolk for the head.

author: amyk
author_rank: Super Contributor
timestamp: September 24, 2013, 12:19:29 pm
content: I remember mikeselectricstuff mentioning one of his installations used alotof PICs...

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 24, 2013, 01:31:18 pm
content: Quote from: amyk on September 24, 2013, 12:19:29 pmFor various reasons, this has one PIC10F322 per LED, about 2600 of them in total!http://www.uva.co.uk/work/continuum

author: free_electron
author_rank: Super Contributor
timestamp: September 24, 2013, 04:03:16 pm
content: Quote from: mikeselectricstuff on September 24, 2013, 01:31:18 pmso you made connection machine ...http://www.mission-base.com/tamiko/cm/that hing had thousands of 1 bit cpu's. 2 bits in 1 bit out. every output had an led attached. the cpu's commniceted in a hypercube configuration

author: amyk
author_rank: Super Contributor
timestamp: September 25, 2013, 10:38:30 am
content: Now try to find even one product that has > 12 AVRs...

author: hemmikall
author_rank: Newbie
timestamp: October 07, 2013, 02:48:11 am
content: my guess would be failing motor drivers, for the color wheel My guess would be that an optical encoder has failed, if it uses a hall effect sensor make sure that the magnet is still on the color wheel.the jittering may be caused by the fixture not exiting calibration mode (startup) due to failed motordrivers or sensors and that might explain why it won't go into the demo mode, in many fixtures you can access the menu while it's still in startup/recal mode but it doesn't do anything until the fixture has found home position for every functionone good way to test if motor drivers are good or not is to push the head around (manually move pan and tilt) if it has almost no resistance (really easy to turn) it may be either the motordriver or the power to it