+++++++++++++++++++ See also Troubleshooting +++++++++++++++++++ Date: Fri, 09 Aug 2002 08:37:55 -0400 From: Jonathan Broscious To: elecraft at mailman.qth.net Subject: [Elecraft] VFO drift gone Hi all, I got my K1 working again. One of the suggestions I recieved from you all said to have the cover off, and when the drift started, start "picking" at the components with a toothpick or some other such insulated object. When I did that, I came across a joint I had somehow missed soldering. (This is very embarrassing.) I guess the lead had just been leaning against the pad, and it finally shook loose. Thanks guys! 73, Jonathan Broscious, KB3HVR +++++++++++++++++++++ Date: Fri, 09 Aug 2002 09:17:48 -0500 To: Jonathan Broscious , elecraft at mailman.qth.net From: "Timothy A. Raymer" Subject: Re: [Elecraft] VFO drift gone Jonathan, Don't be embarrassed! This is how you learn (directly) and how the rest of us learn (through the list.) Your follow up post is appreciated. We all can use the gentle reminder. Glad you got the problem fixed. Tim Raymer 73 de KA0OUV At 08:37 08/09/2002 -0400, Jonathan Broscious wrote: > When I did that, I came across a joint I had somehow >missed soldering. (This is very embarrassing.) +++++++++++++++++++++ Date: Sat, 14 Sep 2002 04:25:21 -0700 From: Phil Wheeler Organization: Outstanding To: Becketts Cc: elecraft at mailman.qth.net Subject: Re: [Elecraft] K1 RF Board Voltage Checks Becketts wrote: >Well I almost made it to the end on my first kit and now I can not get the voltages listed on page 46. > >I get all of them but the following: >J7 pin 1 = 4.19 [5.1-6.7] >U9 pin 3 = 4.81 [6.0-7.0] >U9 pin 6 = 4.77 [6.0-7.0] >U9 pin 7 = 9.61 [12-14] > >Anyone have any ideas? Thanks. > Since they are all consistently low, I wonder what voltage you are supplying to the rig? Should be tested with a 13.8 volt supply. And make sure there is not a significant drop between the supply and the rig (at J4). U9 Pin 7 is the key reading. It is supplied from J4 (12 VDC) thru a diode (D16). Check the voltage at J4 and after D16. If they are also lower than 12 V, I would suspect your supply or cable. If the diode's output is much low than J4, I would think on a poor solder connection, defective diode -- or maybe larger than normal current drain for some reason. 73, Phil +++++++++++++++++ From: "John Webster" To: "Morrow, Michael A." , Date: Fri, 21 Feb 2003 15:42:17 -0800 Subject: [Elecraft] RE: Help, I think I've killed my K1 Elecrafters: Wow! One simply has to experience it for oneself. Help arrived within minutes of posting. It was spot on. It raised important considerations for a wider audience. And it made me learn quite a bit more about the circuit of the K1. Thank you Michael, Stuart, Robert, Jack, Stephen and Jessie! In fact, Mike's response to my over hasty comment: >> 2. +6v and +8v regulated power supplies seem OK. >Are you absolutely sure the front panel board 6 volt regulator U4 is >working? Are there 12 volts in and 6 volts out at FP U4? Symptoms 4, 5, >and 6 below could be due to no output voltage from FP U4. . . . was not only spot on, it arrived even before my original post appeared on the list! I had measured the 6 and 8 volt signals on the RF board and incorrectly assumed that all regulators were OK. U4 is in fact dead--12 volts in, nothing out. The discussion of the bypass protection question is interesting: > > Might see if there is room to bypass the input of the regulator > > with a disc cap of say 0.01 for RF protection. Just place it > > voltage bus to ground, flat on the back of the board or where > > convenient. > > The front panel PCB 6 volt regulator FP-U4, the likely failed component in > John's case, has FP-C4 and FP-C5 as RF bypass caps on the output. Its 12V > input side has a bypass cap, **BUT** it is located on the RF PCB (RF-C34). C5 is also placed near FP-U1 some distance from FP-U4. Not sure if this is adequate? > Perhaps a cap similar to RF-C34 installed on the front panel PCB would be > more effective for RF bypass of the input to FP-U4. The assumption here is > that, in the presence of a strong RF field, the front panel metal may not be > at RF ground potential with respect to the rest of the K1 case and > circuitry. I was not satisfied with the possibility of my K1's front panel > metal "RF floating" with respect to the remainder of the K1 case. There was > quite a lot of paint covering the points where it joined the rest of the > case. Therefore, I used a Dremel tool steel brush to remove the paint from > the inside of the case metalwork at *all* points, on all pieces of the K1 > case, where there is a fastener to hold that piece to some other case part. > This made several bare metal patches on each piece in addition to the > several that were originally provided inside the K1 case. > > The only K1 regulator which seems not to have an input RF bypass cap is the > input to the VFO 6V regulator RF-U6, which is the output of 8V regulator > RF-U5. I suspect adding a bypass cap there wouldn't hurt, but I doubt that > had anything to do with John's K1 problem. And Stuart's prudent warning is well taken: >Do not place rigs atop each other if they have aluminum or plastic cases >and antenna tuners, as there may be considerable magnetic field coupling of >the tuned circuits leading to overload of the standby rig. >Do not even place an ATU atop a rig, for the same reason if the ATU has >solenoid rather than toroid coils. Some field even escapes toroid coils so >having space between rig tuned circuits and Transmatch circuits is >desirable. Although, in my case, the antenna tuner (a British made K.W. E-Zee Match) is in an all metal enclosure, it was only an inch or two from the K1 which was probably the reason for the overload. I'll err on the side of caution in the future. Particularly, given Jessie's account of a near identical mishap: >The K1 was near the transmatch and antenna cables. It was powered >up, but not connected to the antenna. . . the little K1 started flashing and >clicking. . . . On inspection, the regulator was actually cracked. My guess >is that the RF got in and confused the regulator. . . I replaced it, and the >rig has been running fine ever since! Perhaps, given two near identical experiences, Wayne or Eric might wish to comment on the desirability of adding a bypass cap or two around FP-U4 6v regulator, for added protection? Again, thanks so much for the quick, helpful responses. Radio Shack (my only source of parts locally) does not have the 78L06 just a 7805 in the wrong package, so I will have to wait for a replacement part from Elecraft to find out if that was the only damage done. 73 John, N6JW +++++++++++++++++++ From: "John Webster" To: "Bob - AG5Q" Cc: , "Morrow, Michael A." Subject: Re: [Elecraft] Re: Help, I think I've killed my K1 Date: Sat, 22 Feb 2003 02:26:43 -0800 Thanks for your input Bob and Mike. Once again I marvel at the level of expertise this list provides! Here's what I found. I picked up a NTE988 regulator this afternoon from a local supplier. It was a bit of a battle to get the blown chip un-soldered and out, but fortunately the NTE988 is an exact fit and same pin out. I quickly went through the applicable DC resistance checks on the FP board just to make sure, and all was OK. With some trepidation, I put everything back together and fired up the rig. I used the internal 8 cell NiMH battery pack (about 10.2 volts at the time) just to keep voltages down a bit for initial checkout. Well, the LED's come on, the relays clicked and the LCD read the band and frequency. So far so good. An antenna soon proved the RX was working, with sweet CW on 40m. I have not tried to transmit. For I quickly began to find anomalies occurring: 1. A distinct hum on each press of the front panel press-switches; 2. An internal volt-meter that now displayed the battery pack voltage as 14.4volts!; 3. And eventually I found that pressing the "switch filters" button caused the MCU to go into hang up mode. I can switch off and on again and it comes to back to life. So it seems that Bob was EXACTLY right. The 6.2 volts of the NTE988 causes some spooky stuff to happen with the MCU. So it seems that I will just have to wait to get a proper ZR78L06C from Elecraft or elsewhere. At least I think I have shown that it WAS indeed the 6v regulator that blew, and hopefully nothing else. Again thanks for all the help. 73 John, N6JW ----- Original Message ----- From: Bob - AG5Q To: Morrow, Michael A. ; John Webster ; Sent: Friday, February 21, 2003 5:30 PM Subject: Re: [Elecraft] Re: Help, I think I've killed my K1 > The 7.5V spec means the device can survive that much voltage without damage > but it's only guaranteed to work like a microprocessor up to 6.0V. > > The 78L06 can be as much as 6.15V and there are a lot of K1s and K2s that > get by with that, so I wouldn't be surprised it yours works at 6.2V. For > non-critical applications, that's okay, but sometimes the problems that are > caused by the voltage being out-of tolerance can be very tough to determine. > "Is it the micro itself or is it some random input causing the problem?" > > I just mentioned the possibility, so if you do see irregular operation, you > can switch back to the 78L06. > > 73/ Bob - AG5Q ++++++++++++++++++