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Author Topic: Brain schematic Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 02-19-2002 12:21 PM                     On the last page of the Strong AP operation manual, there is a very basic schematic of the brain. Does anyone have a detailed schematic of the phase control version? thx.  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 02-19-2002 12:35 PM                     Ken, I never saw one either. May I presume you have one that is dying? If so, the rest of them are not too far behind. I have converted all of mine to micros. The seem to be much more reliable over a longer period of time.  |  IP: Logged Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 02-19-2002 04:58 PM                     Paul, I do not have Strong platters. If I did, I would convert them to micro switches as well. I am simply curious as to how they work. I like to know how things work. I'm also curious how they work because of my electronics classes.  |  IP: Logged Ken Layton Phenomenal Film Handler Posts: 1452 From: Olympia, Wash. USA Registered: Sep 1999 posted 02-19-2002 05:06 PM                     The schematic and repair info on the phase control are already on the manuals page under "Field Bulletins"-> "Strong phase control adjustment and repair". I drew the schematics myself and there are two versions of the phase control.  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 02-19-2002 07:41 PM                     Ken, if you would like, I can send you a bunch of half-dead ones I took out of service. You can have them, free! Just pay the postage.  |  IP: Logged Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 02-19-2002 07:53 PM                     Paul, sweet! Let me know how much.  |  IP: Logged Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 02-19-2002 10:55 PM                     Ken, thanks for that. I had no idea that was there. Question about the schematic: Unless I'm reading something wrong, is the 1N4004 diode reverse biased? I don't get it. I assume that the symbols that look like diodes with circles around them are transistors? They look a little different than the transistor symbol I'm familiar with, but I can't think of what else they would be.  |  IP: Logged Josh Jones Redhat Posts: 1207 From: Plano, TX Registered: Apr 2000 posted 02-19-2002 11:33 PM                        if it is a diode in a circle with two legs coming out the other end it is an SCR or Silicon Controlled Rectifier. These are used to switch large currents with little input power. they are also used in cheaper lighting dimmers(more expensive ones use Diacs, which is just two SCR's back to back). Hope that helps, Josh  |  IP: Logged Josh Jones Redhat Posts: 1207 From: Plano, TX Registered: Apr 2000 posted 02-19-2002 11:41 PM                        Yup, just looked at the schematic and those two devices on the bottom near the (-) terminal are SCR's. The diode with two wavey arrows near it in a circle is an LED. the other diode in the circuit with the swastica for a gate is a Zener diode. they are used to provide a constant voltage source because their voltage drop and current draw will change with the voltage put across it. Josh  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 02-20-2002 01:19 AM                  Actually a DIAC is two diodes back to back and is used to prevent false triggering of a SCR or TRIAC. A TRIAC is basically 2 SCRs back-to-back so as to pass both halves of the ac waveform. A SCR is a controlled rectifier and as such only passes half of the ac waveform. Depending on the manufacturer and load requirements, a dimmer may use either a TRIAC or 2 back-to-back SCRs with the same results. It has nothing to do with cost. Also, a Zener diode, the one that has the wavey cathode line and is biased backwards (cathode to +), is a constant voltage device. It is installed on a regulated supply line with a specific value series resistor to form a voltage divider network. It is rated in watts like the resistor. Thus it provides a constant voltage with changing current requirements and therefore must dissipate the excess voltage like a resistor as heat. >>> Phil  |  IP: Logged Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 02-20-2002 11:42 AM                     I know that the zener diode is supposed to be reversed biased, but it looks to me like it is forward biased, and the LED and 1N4004 are reverse biased. Am I reading something wrong?  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 02-20-2002 05:31 PM                  Looking at the schematic it appears that the +'s and -'s are mislabled backwards and there is a connection missing between the anode of the zener and the (mislabled) V+ of the 334. >>> Phil  |  IP: Logged Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 02-20-2002 10:16 PM                     "Looking at the schematic it appears that the +'s and -'s are mislabled backwards...." That would definitely go a long way in explaining my confusion. Thanks!  |  IP: Logged

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