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???
05/26/06 04:52
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 		 #117126 - Getting Older
Responding to: ???'s previous message
Ok,
In the passed, when I referred to GND I meant COM. This Board only has COM coming from the power supply. However, Somewhere in the external wiring harness COM is connected to E-GND on the power supply which is connected to the Green wire in the plug in the wall.

I want to state that chip U24 is not completely dieing/Blowing out. There is only one pin on 74LCX245 that is dies at a time. And after that pin dies all the other pins still work fine. The pin that dies varyies.

In my opinion if the AC Coupling was jumping on the GND wiring. I would be having problems with out chips on the board. Which, I don't. However, If i start having problems with other chips on the board. I will try isolated the COM from the COM on the wiring harness.

Right now, I just want to find a way to prevent the individual inputs from dieing as best as possible. I was figuring that an opto-isolator input would be resist to the AC couple noise and there for not die as much.

I have a more accuracy circuit of my drawing now posted http://www.jernie.com/short.pdf

List of 66 messages in thread
TopicAuthorDate
High Tolerant Input Pins tvs, otpto,            01/01/70 00:00      
   Use a 'srial chip            01/01/70 00:00      
      But..            01/01/70 00:00      
         what's the problem?            01/01/70 00:00      
      Re: Serial Chip            01/01/70 00:00      
         better or not            01/01/70 00:00      
   Suggestion            01/01/70 00:00      
   Input            01/01/70 00:00      
      Why damaged?            01/01/70 00:00      
         Re: Why Damaged.            01/01/70 00:00      
            Another suggestion...            01/01/70 00:00      
               Yes, but...            01/01/70 00:00      
                  Schottky clamps ?            01/01/70 00:00      
                     Diode clamps            01/01/70 00:00      
                        Tranzorb            01/01/70 00:00      
      Try this...            01/01/70 00:00      
   ST overvoltage protection            01/01/70 00:00      
      A bad situation            01/01/70 00:00      
         Russell            01/01/70 00:00      
            My suggestion?            01/01/70 00:00      
   Look for PLC discrete input circuits            01/01/70 00:00      
      partially right            01/01/70 00:00      
         Even a PLC wouldn't like this circuit            01/01/70 00:00      
            OK, It's a switch - question to Scott            01/01/70 00:00      
               Speed of the input            01/01/70 00:00      
                  at lower detection rates ...            01/01/70 00:00      
                     What I recommended...            01/01/70 00:00      
   Steroids Desing            01/01/70 00:00      
      Analyse the circuit            01/01/70 00:00      
         to fully isolate            01/01/70 00:00      
            how about answering            01/01/70 00:00      
               That's obvious isn't it?            01/01/70 00:00      
                  it's not that obvious            01/01/70 00:00      
                     It's just ignorance            01/01/70 00:00      
                        opto couplers            01/01/70 00:00      
                           true enough!            01/01/70 00:00      
                           Not so strange            01/01/70 00:00      
                              Not strange, perhaps, but WRONG!            01/01/70 00:00      
                     It's just ignorance            01/01/70 00:00      
                     maybe you answered this one yourself            01/01/70 00:00      
                        still waiting            01/01/70 00:00      
                           No, though that might help            01/01/70 00:00      
   is this a newfangled idea            01/01/70 00:00      
      Downunder circuitry            01/01/70 00:00      
   Why I use the opto            01/01/70 00:00      
      Perception vs reality            01/01/70 00:00      
      +5V supply, is it isolated?            01/01/70 00:00      
         already asked and asked again            01/01/70 00:00      
            Yes, last try before I leave the thread!            01/01/70 00:00      
               The +5V is Isolated.            01/01/70 00:00      
                  incomplete answer            01/01/70 00:00      
                     Yes, what about the grounds?            01/01/70 00:00      
                        Scott, where are you?            01/01/70 00:00      
                           he left when we asked questions            01/01/70 00:00      
                              Still lost and confused            01/01/70 00:00      
                                 you do not need a scope to answer the qu            01/01/70 00:00      
                                 We cannot help you, if you do not...            01/01/70 00:00      
                                    COM and E-GND            01/01/70 00:00      
                                       still not answered            01/01/70 00:00      
                                          just a minute ...            01/01/70 00:00      
                                             SO let me rephrase: how many ohms betwee            01/01/70 00:00      
                                                Getting Older            01/01/70 00:00      
                                                   if you want help, start with some answer            01/01/70 00:00      
                                                   Problem is much more complex            01/01/70 00:00      
                                                   what do you mean by "dying"            01/01/70 00:00      
                                                      Scott, could you...            01/01/70 00:00      

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