Don, All three test points are not zeros. TP1 reads a solid 4918.88, TP2 reads between flickering 267 & 289, TP3 reads all zeros. The resistance from the source of Q19 to ground is 280 ohms.
I did make an interesting discovery when I took voltages again. U4, pin 5 (SDO) is 0 volts, pin 7 (SCK) is 4.8 volts. U5, pin 1 (SCK) is 4.8 volts, pin 2 (SDO) is 0 volts. These pins are just opposite what they should be (what does SDO and SCK represent?). Looks like something that is directional got switched? Sounds like we are making progress, but still a possible PLL problem? Thanks! Don, KE0PVQ Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10 From: Don Wilhelm<mailto:donw...@embarqmail.com> Sent: Thursday, September 27, 2018 4:11 PM To: Don Schroder<mailto:donandde...@hotmail.com>; elecraft@mailman.qth.net<mailto:elecraft@mailman.qth.net> Subject: Re: [Elecraft] K2 Alignment and Test, Part II issues Don, While in CAL FCTR, try the probe in TP3 and TP1 and TP2. If you have a zero reading in all 3 places, you most likely have a bad probe. Yes you might have a PLL problem, but that is not certain yet. One quick check is to measure the resistance from the source of Q19 to ground. If it is high or infinite, check the leads of RFC14 like you did for RFC16. The normal resistance is a bit more than 270 ohms. 73, Don W3FPR On 9/27/2018 4:41 PM, Don Schroder wrote: > > Don, > > Thank you for the excellent advice! I went to the bottom of the board > and checked the resistance between the ends of RFC16. It was infinite, > so I rewound RFC16 and ensured the leads were cleaned good. After > reinstalling, I now have 4.~ votes at U6 pin 5, and 8.~ at pin 8. Pin > 8 of the Thermistor Board has 8.~ volts, too. > > Now, when I select CAL FCTR and enable the frequency counter, the > counter shows 00000.00. I believe this tells me there is a problem > with the PLL Reference Oscillator. I will continue to look at those > components. Any other suggestions? > > Thanks! > > Don, KE0PVQ > > Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for > Windows 10 > > *From: *Don Wilhelm <mailto:donw...@embarqmail.com> > *Sent: *Thursday, September 27, 2018 1:34 PM > *To: *Don Schroder <mailto:donandde...@hotmail.com>; > elecraft@mailman.qth.net <mailto:elecraft@mailman.qth.net> > *Subject: *Re: [Elecraft] K2 Alignment and Test, Part II issues > > Don, > > You apparently have a problem with the thermistor board - or the 8 volts > > to it. > > A "voltage rail" are those PC traces that carry voltage to various parts > > of the circuit. > > In the K2, there is one for 12 volts, another for 8 volts and another > > for 5 volts. > > On the schematic they are labeled "12V", "8A" and "5V" respectively. > > The main 8 volt and 5 volt regulators are on the Control Board. You will > > find an "5B" voltage rail at the output of U8 on the RF Board and the > > "8B" voltage is sourced at the output side of RFC16. > > If you do not have 8 volts at the thermistor board pin 8, then > > investigate the stripping and tinning of the RFC16 leads. > > Once you have 8 volts at the thermistor board (RP3 position) pin 8, then > > recheck the voltage at U6 pin 5 - it should be quite close to 4 volts. > > 73, > > Don W3FPR > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
