OK - many thanks, Don. I'll get busy looking at those things. 73, Floyd
On 8/22/2015 6:33 PM, Don Wilhelm-4 [via Elecraft] wrote: > Floyd, > > You say the voltage at U4 pin 5 is -15.4 volts, and that *may* be a > perfectly valid voltage - that is a MARK. > It should not be constantly that way, so check U4 pin 12 - if it is > zero, then the MAX1406 is behaving properly in response. That line > originates from the MCU (Control Board U6) pin 25, and should be +5v > under normal conditions, but pulses to zero when the K2 sends data. > > If you find KPA100 U4 pin 12 at 5 volts while pin 5 is going negative, > then replace U4. > OTOH, if U4 pin 12 is at zero volts, suspect the K2 MCU or some problem > on the signal line between those points. > As a quick check on whether the base K2 or KPA100 is pulling that signal > to zero, remove the KPA100 ribbon cable, then power the base K2 and see > whether CB U6 pin 25 goes to +5v with the ribbon cable removed. If it > stays at 0 volts, remove the MCU and make a resistance measurement on U6 > pin 25 to make sure it is not shorted - if you read a high resistance, > replace the MCU IC. > > The most likely symptom if the KSB2 board has been damaged from plugging > in a serial cable is that you could have damaged either the KSB2 MCU > (AUXBUS line), or Q1 (high voltage on the VRFDET line or the ALC line > can do damage). > > Note that if you were previously connecting the USB to serial adapter > directly to the KPA100 AUX I/O connector, it may be possible that no > damage would occur *if* the voltage out of the adapter did not exceed 5 > volts and never went negative. In the PC world of short RS-232 > signalling, some try to "get away' with those levels, where a real > serial card will typically have voltages in excess of +/-12 volts. > So if you did not previously use the special cable, you will need to > build one - the instructions are in the KPA100 manual page 60. > > 73, > Don W3FPR > > On 8/22/2015 4:28 PM, Floyd Sense wrote: > > > > > Anyway, maybe you can help me determine what areas to focus on in the > > repair. Here's what I know: > > > > 1. The RF chokes RFC6-9 are all intact. > > 2. The ALC is functioning properly - the power control properly > > controls the output > > 3. U1 in the KPS-100 appears to be functioning as the relays are being > > activated at the right time as I switch through the bands. > > 4. Data sent from Hyperterminal through the USB/serial converter to > > the K2 shows up on Pin 6 of the KPA-100 U4 (the Max1706) and can be > > seen at pin 26 of the K2 MCU (U6). But, the K2 doesn't act on the > > commands that are sent. > > 5. The voltage on pin 5 of U4 (MAX1406) is -15.4 VDC, seems that > > indicates U4 is toast? > > > > I haven't observed any other problems. I found the document written > > by Gary Surrency and Tom Hammond regarding this situation. Which > > leads me to some questions: > > > > 1. Reference is made to possible damage to the KSB2. Do you know > > what the symptom would be in that case? > > 2. Apparently, any damage to the MCU IC might be isolated to just the > > input from the interface - pin 26. I say that because everything else > > appears to function normally. Are you aware of anything else I might > > check for regarding the MCU function? > > > > 73, Floyd > > > > > > On 8/22/2015 3:16 PM, Don Wilhelm wrote: > >> Anyone who has purchased a used K2 needs to take notice, lest it > >> happen to you too. > >> > >> That connector is marked AUX I/O for exactly that reason, it is not a > >> computer RS-232 connector even though it contains TXD, RXD and signal > >> ground. As a result, one must always use the special cable that is > >> built as part of the KPA100 to connect to a computer serial port. > >> > >> You are not likely to have damaged anything in the KPA100 when > >> connecting a standard serial cable to the K2, although KPA100 U6 may > >> have a damaged output at pin 6, and the inductors located just behind > >> the DE-9 connector should be checked for continuity. > >> The TXD and RXD signals in the serial cable will connect to U4 just > >> the same as if the special cable were used. > >> > >> You could have also damaged the computer serial port because pin 1 > >> was grounded by the K2. > >> > >> You will find most of the damage will be in the base K2. > >> Internal signals AUXBUS and VRFDET could have caused the MCU IC to be > >> damaged as well as the KSB2. > >> The fact that the 8R voltage rail appears on that connector, that may > >> have caused further damage. > >> > >> 73, > >> Don W3FPR > >> > > > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > </user/SendEmail.jtp?type=node&node=7606582&i=0> > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > </user/SendEmail.jtp?type=node&node=7606582&i=1> > > > ------------------------------------------------------------------------ > If you reply to this email, your message will be added to the > discussion below: > http://elecraft.365791.n2.nabble.com/K2-KPA100-RS232-interface-repair-tp7606571p7606582.html > > > To unsubscribe from K2 - KPA100 RS232 interface repair, click here > <http://elecraft.365791.n2.nabble.com/template/NamlServlet.jtp?macro=unsubscribe_by_code&node=7606571&code=ZmxveWRAazhhYy5uZXR8NzYwNjU3MXwxMDMyNDYzNzk0>. > NAML > <http://elecraft.365791.n2.nabble.com/template/NamlServlet.jtp?macro=macro_viewer&id=instant_html%21nabble%3Aemail.naml&base=nabble.naml.namespaces.BasicNamespace-nabble.view.web.template.NabbleNamespace-nabble.view.web.template.NodeNamespace&breadcrumbs=notify_subscribers%21nabble%3Aemail.naml-instant_emails%21nabble%3Aemail.naml-send_instant_email%21nabble%3Aemail.naml> > > -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-KPA100-RS232-interface-repair-tp7606571p7606583.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
