K2 VFO Freq Display Stuck (again)
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Back in April I had a problem with the frequency not moving (just final digit flickering) and that turned out to be a broken wire to the encoder. Again the problem has cropped up with identical outward symptoms. I checked the encoder wires again, all are fine.
Here are some measurements that were asked for last time. The voltage measurements shown are only ones that differ significantly from those listed on pg. 16 of the K2 manual, Appendix E. The manual reference voltage is in parentheses. U3: pin3 4.8 (0.8), pin 7 3.5 (2.0), pin 13 4.7 (0.2), pin 14 .1 (3.1), pin 15 4.1 (0.8), pin 18 .08 (3.6). The manual notes that all the voltages on these pins may vary. Resistance measured at each encoder pin with the FP board removed: Pin 1 24K, Pin 2 106K, Pin3 106K, Pin 4 29K Can someone help me troubleshoot this? How do I tell if the encoder itself is bad? vy 73, Casey, TI2/NA7U |
Re: K2 VFO Freq Display Stuck (again)
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Casey,
To be safe, make one check before proceeding with anything else - check the 8T signal line to be certain it is at a low voltage (CB Q1 Collector or RF board D7 anode). If it is near zero volts all is OK there, but if it is near 8 volts, then that must be corrected before investigating anything else. OK, I am going to assume that 8T is near zero volts --- (if not true, ignore what follows and get back to us). It would appear that the /ENC RD signal line is being pulled low at all times - it would be nice to observe it with a 'scope to see how frequently that signal is low. You can check the encoder by reading the voltage on the ENC A and ENC B signal lines to the microprocessor. As you slowly turn the encoder shaft, they should vary from a high level to a low level. If that happens, the encoder is likely OK. I would suggest you record all your menu settings (the K2 A to B Instructions have a nice chart for that) and then do a Master Reset - re-enter all the menu entries afterwards and see if the problem goes away. If the Master Reset did not correct it, Front Panel U3 may be faulty. 73, Don W3FPR On 12/29/2011 4:27 PM, TI2/NA7U wrote: > Back in April I had a problem with the frequency not moving (just final digit > flickering) and that turned out to be a broken wire to the encoder. Again > the problem has cropped up with identical outward symptoms. I checked the > encoder wires again, all are fine. > > Here are some measurements that were asked for last time. The voltage > measurements shown are only ones that differ significantly from those listed > on pg. 16 of the K2 manual, Appendix E. The manual reference voltage is in > parentheses. > > U3: pin3 4.8 (0.8), pin 7 3.5 (2.0), pin 13 4.7 (0.2), pin 14 .1 (3.1), pin > 15 4.1 (0.8), pin 18 .08 (3.6). The manual notes that all the voltages on > these pins may vary. > > Resistance measured at each encoder pin with the FP board removed: > Pin 1 24K, Pin 2 106K, Pin3 106K, Pin 4 29K > > Can someone help me troubleshoot this? How do I tell if the encoder itself > is bad? > > vy 73, > > Casey, TI2/NA7U > > ----- > Costa Rica Blog > -- > View this message in context: http://elecraft.365791.n2.nabble.com/K2-VFO-Freq-Display-Stuck-again-tp7136782p7136782.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:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Don,
8T line is fine, zero volts. Enc A voltage varies with turn of the encoder (approx. 5-.3V), but Enc B does not (.09-.11V). How can I get to the menu settings without a working encoder? 73, Casey On 12/29/2011 4:15 PM, Don Wilhelm wrote: > K2 A to B Instructions ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K2 VFO Freq Display Stuck (again)
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Casey,
Since the ENC B does not go to a high level, you may have a bad firmware IC - Control Board U6 Try removing the CB U6 (use good anti-static procedures) and measure the ENC B line again. If it goes both high and low, the encoder is good, but the firmware is bad. Hold off on the Master Reset until after you resolve the firmware or encoder mystery. You may be able to access the menu items using the BAND+ and BAND- buttons even if the encoder does not change anything. 73, Don W3FPR On 12/30/2011 12:59 PM, Casey wrote: > Don, > > 8T line is fine, zero volts. > Enc A voltage varies with turn of the encoder (approx. 5-.3V), but Enc > B does not (.09-.11V). > > How can I get to the menu settings without a working encoder? > > 73, > > Casey > > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Don,
With U6 removed both Enc A and B measure steady 4.76V (U6 pins 8 and 16, respectively). Re-installed U6, no change. Indeed Band +/- gets me through the menu, nice trick! I will record settings and await further instructions. 73, Casey |
Re: K2 VFO Freq Display Stuck (again)
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Casey,
I use the BAND+/- buttons to get through the menu more than I use the VFO. You can try the Master Reset, but based on what you found, I suspect that will not fix it, you apparently have a shorted input on CB U6 pin 16. As soon as you confirm that, get new firmware on order. If you do NOT already have version 2.04p (or r) installed, order FWK2MCIO which has the MCU and MCIO ICs. If you already have version 2.04p (or r) then you can order PN E610002 which is the MCU only. 73, Don W3FPR On 12/30/2011 1:39 PM, TI2/NA7U wrote: > Don, > > With U6 removed both Enc A and B measure steady 4.76V (U6 pins 8 and 16, > respectively). Re-installed U6, no change. Indeed Band +/- gets me through > the menu, nice trick! I will record settings and await further instructions. > > 73, > > Casey > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Don,
U6 removed, power off I have 74 ohms on pin socket 16. I have 2.03d FW. The problem is getting the new chips down here (long story, but postal mail is out), but I will figure that out. Thanks for your help. 73, Casey On 12/30/2011 1:03 PM, Don Wilhelm-4 [via Elecraft] wrote: Casey, |
Re: K2 VFO Freq Display Stuck (again)
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In reply to this post by Don Wilhelm-4
On 11-12-30 02:02 PM, Don Wilhelm wrote:
> I use the BAND+/- buttons to get through the menu more than I use the VFO. Interesting to see what one can still learn about the K2 after having had one for years. I've always used the buttons to navigate the menus and only used the VFO knob when adjusting the BFO/Filter frequencies. -- Cheers! Kevin. http://www.ve3syb.ca/ |"Nerds make the shiny things that distract Owner of Elecraft K2 #2172 | the mouth-breathers, and that's why we're | powerful!" #include <disclaimer/favourite> | --Chris Hardwick ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by TI2/NA7U
Yes, it's been five months or more since I posted about this problem. If you read through the thread Don W. surmised from a great distance that there was a short in the main FW chip and recommended a FW upgrade. Well, two months to get my hands on it, then 3 months to get my hands out from under my butt, ...
 and I finally installed the FW upgrade today (2.04R and IOC 1.09.
Yet, the problem with the encoder persists.  Haven't gone through all the voltage measurements again, but I'm wondering if I'm on the wrong tack?
73, Casey, TI2/NA7U |
Re: K2 VFO Freq Display Stuck (again)
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Casey,
I believe we went through slowly turning the encoder shaft while looking at the voltage changes on the ENC A and ENC B signal lines when we were checking before - if not, let me know and I can give you the instructions and expected results. There is another line on the front panel that could be the problem cause - that is /ENC RD which must go to zero to read the encoder - but it does that only in short negative going pulses. You will need either a 'scope or a logic probe to check for those pulses, they are too short to detect with a DMM. Should the pulses not appear, my best guess for the cause is a bad output at Front Panel U3 73, Don W3FPR On 6/16/2012 6:50 PM, TI2/NA7U wrote: > Yes, it's been five months or more since I posted about this problem. If you > read through the thread Don W. surmised from a great distance that there was > a short in the main FW chip and recommended a FW upgrade. Well, two months > to get my hands on it, then 3 months to get my hands out from under my butt, > ... and I finally installed the FW upgrade today (2.04R and IOC 1.09. > > Yet, the problem with the encoder persists. Haven't gone through all the > voltage measurements again, but I'm wondering if I'm on the wrong tack? > > 73, > > Casey, TI2/NA7U > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by TI2/NA7U
Don,
EncA varies between 0 and 4.8V at each "tick" of the encoder EncRD varies between 0 and about .06V EncB also varies between 0 and .06V - this seems to be a problem. 73, Casey |
Re: K2 VFO Freq Display Stuck (again)
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Casey,
Yes, it appears that both /EncRD and EncB are indicating a problem. I thought we had determined that EncB was OK the last time through, so double check that and rotate the knob through at least 1/2 turn. If both those lines are stuck at or near zero, the next step is to determine if it is the encoder or what is on the other end of those lines. Unsolder the wires from holes 3 and 4 going to the encoder - then make the same measurements directly at the encoder pins. Plus (with those wires still disconnected), make a voltage measurement at Front Panel U3 pin 14. We can use that data to determine whether the encoder is the problem or U3. 73, Don W3FPR On 6/17/2012 6:12 PM, TI2/NA7U wrote: > Don, > > EncA varies between 0 and 4.8V at each "tick" of the encoder > EncRD varies between 0 and about .06V > EncB also varies between 0 and .06V - this seems to be a problem. > > 73, > > Casey > > ----- > Cloud Warmer Ham Radio Blog > -- > View this message in context: http://elecraft.365791.n2.nabble.com/K2-VFO-Freq-Display-Stuck-again-tp7136782p7557744.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:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Yes, I remember that Enc B was fine last time, also, but it's definitely not now.
One correction to my previous post, when the encoder is connected the voltage on Enc B and Enc RD vary between .4-.46V, not from zero. With the encoder pins 3 and 4 disconnected and measuring directly at the encoder pins I see the voltage hold about 4.4V on both 3 and 4. As I turn the encoder the voltages on either pin drop to zero, but only intermittently. The voltage at U3 pin 14 is about .3V (even when the encoder pins are connected it measures about .1V, whereas the voltage chart says it should be 3.1V and varying). Hope I did the measurements correctly. 73, Casey |
Re: K2 VFO Freq Display Stuck (again)
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Casey,
Yes, you did the measurements correctly, but there is some confusion in my mind about the EncRD signal. Certainly with no load connected the voltage on U3 pin 14 should be 3.3 volts or higher. So U3 must be replaced for certain. Just as clarification, 0.4 volts is equal to zero in the digital realm and 0.46 is equal to 5 volts nominal - the data is "binary", so it is either ON or OFF - in other words, less than 1 or 2 volts and greater than 3.5 volts for TTL levels. One more check on the encoder - see if leads 3 and 4 switch voltages together - if they do, there is something shorted in the encoder and it must be replaced. If they are independent, replace only U3 and test again. Sorry for the lack of a definite answer, and I understand that VK-land is not a 2 to 3 day parts request to delivery time, but based on the info I have, that is the best answer I could muster. 73, Don W3FPR On 6/17/2012 7:17 PM, TI2/NA7U wrote: > Yes, I remember that Enc B was fine last time, also, but it's definitely not > now. > > One correction to my previous post, when the encoder is connected the > voltage on Enc B and Enc RD vary between .4-.46V, not from zero. > > With the encoder pins 3 and 4 disconnected and measuring directly at the > encoder pins I see the voltage hold about 4.4V on both 3 and 4. As I turn > the encoder the voltages on either pin drop to zero, but only > intermittently. > > The voltage at U3 pin 14 is about .3V (even when the encoder pins are > connected it measures about .1V, whereas the voltage chart says it should be > 3.1V and varying). > > Hope I did the measurements correctly. > > 73, > > Casey > > ----- > Cloud Warmer Ham Radio Blog > -- > View this message in context: http://elecraft.365791.n2.nabble.com/K2-VFO-Freq-Display-Stuck-again-tp7136782p7557747.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:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K2 VFO Freq Display Stuck (again)
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That "0.46 equal to 5 volts" below should have been "4.6 equal to 5
volts". Sorry for the misplaced decimal. It is always good to read your own posts after the fact - sometimes you realize that you have to write yourself a "dear dummy" note (while blaming it on "fat fingers".:-) 73, Don W3FPR On 6/17/2012 7:31 PM, Don Wilhelm wrote: > Just as clarification, 0.4 volts is equal to zero in the digital realm > and 0.46 is equal to 5 volts nominal - the data is "binary", so it is > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Don,
I wasn't able to reproduce the intermittent small voltage drop in encoder pins 3 and 4 today, when they are disconnected from the board. Not sure why. I reconnected them and they both show nearly identical resting voltages (4.4-4.6V) and both vary in unison by a very small voltage (~0.05V) as I turn the encoder. So, I guess the encoder is toast along with U3. Unfortunately, the encoder is about 92 bux! BTW, I'm in Costa Rica, not VK-Land, but the shipping is lengthy in either case. I have to have parts shipped via a 3rd party because Elecraft's label on the outside will get them caught in Customs, which for me is a 6 hour RT drive and 2 hours standing in line! I'd rather wait the extra month it takes to get them here to avoid that (I don't mind paying duty, but that trip is really beyond the pale). 73, Casey |
Re: K2 VFO Freq Display Stuck (again)
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Casey,
I am sorry to hear about those time delay/Customs problems. I do not know of an alternative other than to play the international shipping customs *game* and hope for the best outcome. 73, Don W3FPR On 6/18/2012 8:08 PM, TI2/NA7U wrote: > Don, > > I wasn't able to reproduce the intermittent small voltage drop in encoder > pins 3 and 4 today, when they are disconnected from the board. Not sure why. > I reconnected them and they both show nearly identical resting voltages > (4.4-4.6V) and both vary in unison by a very small voltage (~0.05V) as I > turn the encoder. So, I guess the encoder is toast along with U3. > > Unfortunately, the encoder is about 92 bux! BTW, I'm in Costa Rica, not > VK-Land, but the shipping is lengthy in either case. I have to have parts > shipped via a 3rd party because Elecraft's label on the outside will get > them caught in Customs, which for me is a 6 hour RT drive and 2 hours > standing in line! I'd rather wait the extra month it takes to get them here > to avoid that (I don't mind paying duty, but that trip is really beyond the > pale). > > 73, > > Casey > > ----- > Cloud Warmer Ham Radio Blog > -- > View this message in context: http://elecraft.365791.n2.nabble.com/K2-VFO-Freq-Display-Stuck-again-tp7136782p7557794.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:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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