http://elecraft.85.s1.nabble.com/K2-Alignment-and-Test-Part-II-issues-tp7645364p7645401.html
I finally got some time to check your suggestions. D18 is oriented properly, and it looks like C84 & C85 are marked 121 (kind of hard to read since they are installed). So I thought I would check voltages for the PLL Reference Oscillator circuit. Didn’t take long to find 7.5 volts going into X1 (the crystal) and 0 volts coming out! I resoldered the pins to ensure no cold joints, and still 0 volts coming out. Do crystals go bad, or is it possible I burned it up by too much heat on the casing when grounding it? I think I will need a new one before I can check the BFO.
another. Chek all the components in the circuit for proper values and
good soldering. You apparently can follow the schematic, if for no
>
> 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:
[hidden email]>
> *Sent: *Thursday, September 27, 2018 4:11 PM
> *To: *Don Schroder <mailto:
[hidden email]>;
>
[hidden email] <mailto:
[hidden email]>
> *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:
[hidden email]>
>
> > *Sent: *Thursday, September 27, 2018 1:34 PM
>
> > *To: *Don Schroder <mailto:
[hidden email]>;
>
> >
[hidden email] <mailto:
[hidden email]>
>
> > *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
>
> >
>
> >
>