I need some help with fsbus

[npbosch 0]

Hello to allI made my fscom/key/ledI measure 5 volt at the 7805 and 14,2 volt at the output of the 78L12, so that should be ok.I got the famous read after write error (all in flash on com and key), cable is 10 cm.Results of troubleshooter:Pin4 troubleshooter 0 volt: I read 13,7 voltPin4 troubleshooter 13,5 volt: I read 13,7 voltPin14 should be 5 volt: I read 5 voltPin12 troubleshooter 0 volt: I read 0 voltPin12 troubleshooter 5 volt: I read 0 voltPin13 troubleshooter 0 volt: I read 0-5-0-5-0-5 etc voltPin13 troubleshooter 5 volt: I read 0-5-0-5-0-5 etc voltWhen I tried FSLed I got exact the same result with the PIC on the PCB.So I think the problem is in the bus or FSCOM.In troubleshooter mode I do have a voltage of 0 on pin 1 of the bus(goes to pin 12 of the pic). Pin 2 (the pin just under pin1 gives the same result as I see on pin 13 of the pic,(as it should be, because they are connected).When I see the fscom scheme, I see that tr 2 is for bus pin 2, and tr 3 is for buspin 1. I removed the 232. If I see the scheme I should measure the same voltage on pin 1 and 2 of the bus. That's not the case. FSCOM removed from the PC, I get 5 volt on pin 2 but 0 volt on pin 1.Any suggestions?Already thanks for any helpNorbert Bosch

[Guest Robid]

First step is to check your serial cable plug to the computer.I made the mistake of wiring the plug wrong and got similar results (I wired it as null modem).David

[Guest stevelep]

And be sure in option menu that the good serial port is selected ...one day the setting was lost and the option were reseted but I havn't seen it ... I was thinking my FSBUS was out and tried many days to flash ...In my experience flash problems was always due to error of me ...false soldering, false cable wiring, false setting, false power setting etc ...Good luckBOB

[Guest GusB]

Something is strange...... on the comm PCB Tr1 is for bus pin 9, Tr2 is for bus pin 3 and Tr3 is for bus pin 1.If you measure 0V at Tr3 collector (bus pin 1), there is either a short at that node or the pull-up resistor isn't connected.Gus

[Roel_Wessels 0]

Norbert,Here are the correct port settings:Of course in your case it can be connected to another COM port, so the name of the screen could be different than mine.http://bev02.adsl.utwente.nl/Vliegvrienden...ortsettings.jpgMaybe it's of any use, cerntainly hope so.Roel.

[npbosch 0]

Thanks for the helpI checked the subd cable to fscom. It's OK.AT the C pin of TR3 I measure 0volt (no connection to the PC, just 12V on FSCOM). I measure 5V at the C pin of TR 2. (At C pin of TR1 I measure the same as at the output of the 78L12, all in flasmode).I think I need 5 volt in this config at the C pin of Tr3 (the pin directly connected to pin 1 of the bus). That pin goes to pin 12 of the PIC at which I do not read anything in troubleshooter.Could the BC548B be blown up? My soldering technique is quite adaquate I think. I even used a heatsink during soldering because I know that tr's are damagable by heat.(besides this, I now measure only 10,5V at the outout pin of the78L12, so I have to buy a new 555, made a short I think).@RoelI have these port settings. Strange is that the router sw says com connected while I have nothing connected to the com ports.To be continued.RegardsNorbert

[Roel_Wessels 0]

Norbert,To answer your remark about the router sw says connected: The router software only checks if there is a COM-port installed in the operating system. The router software cannot determine if there is a physical connection between PC and FSBUS hardware. So don't worry about that indication.Maybe check your BIOS too. I remember from some time ago making a IR port for my PC that the BIOS uses some of the COMport. In my BIOS it is called (UART use Infrared) I'm not sure if this affects the COM ports but maybe you should find out about this.Regards,Roel.

[Guest GusB]

Hummmmmmmm.... Do you have +5V on the other side of the pull-up resistor R7? Transistors are pretty robust nowadays, junction (any P-N junction) temperatures can go to 150

[npbosch 0]

Hi GusI do not understand evrything you tell me. I am no electronics expert at all, I know only the basics. Whats ohming out?I have 5 volt on the 5 volt side of R7 (pretty obvious). At the other side of the R7 - 4K7 resistor I have 0 volt. (I have 5 volt at the other side of the R4 - just besides the R7 - )Between the lines I read that I should have 5 volt at the Cpin of Tr3?regards NorbertOff topic: what is the function of this Tr? AFAIK the current on the base pin does "something" with the C pin input. That is emmitted to the E pin, but the E pin of Tr1,2,3 goes to ground?

[Guest GusB]

Hi NorbertSorry........By "ohming-out" I mean checking the "resistance" to ground with an Ohmmeter from the collector of Tr3. If you find 0 (zero) Ohms, you have a short someplace. In basic terms, the function of Tr3 is to act as a switch. When there is no signal on the base, the transistor is "off" and no current should be going through R7. If current IS flowing through R7 for some reason then there will be a voltage drop across the resistor. When the base gets above ~.6V the transistor will turn on and "pull" the collector to ground (when it's "on",think of it as a short between collector and emitter). The current that can flow is "limited" by R7 (use Ohms Law,I=V/R).Yes, the current into the base will do something. It has to do with the "current gain" of the transitor (also known as "Hfe" or "Beta"). While I haven't look up this particular transistor, "general purpose" switching transistors have a "Hfe" in the 100 to 300 range. What this means is that when the transistor is "turned-on", the current flowing from the collector to the emmiter is equal to the base current multiplied by the "Hfe" (with current flow being from plus to minus). Of course, this "amount" is limited by resistor R7.The botton line is, something is causing current to flow through R7.Hope this helps!Gus

[npbosch 0]

GusThanks for the explanation.I read your story after I found the problem.I did measure everything in the neigbourhood of Tr3 and R7.I measured R7 and it was 2K7 (it was a 4K7 resistor off course). The R beside measured 4K7. I removed Tr3, then I measured 4K7 on R7.I also measured a short between pin 1 and 6 of the BUS. I corrected the short and put Tr3 back in and it worked. The 0 - 5 - 0 - 5 - 5 volt I measured on pin 12 and 13 of the PIC was because I did not use the right com port in FSBUS. After I corrected that I measured a stable 5 v on both pins on the pic, exactly as in troubleshooter. I am not sure wheter the short was the only problem or there was a cold solder on tr3 also.I flashed FSKEY without any problem. Then I flashed FSLED without any problem too. FSKEY worked fine in test mode, FSLED not. (jumpers in N position). Can you tell me what I should measure on the pins of FSLED?(I think I will make a new fsled, less work then trouble shooting).regards and again tks for the explanationnorbert