K1 Front Panel Resistance Issue
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K1 Front Panel Resistance Issue
 
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Hello to the list.
This is my first posting on my K1 kit building issues via the Elecraft reflector. Thanks to all in advance. I am awaiting the delivery of a digital multimeter for making resistance/voltage checks, but started construction nonetheless. I have a cheap analog meter, however, and thought that when I get to the resistance check parts I would use it, but not proceed until the DMM gets here. I completed the 4 band filter bard and the front panel (minus the 10 turn potentiometer) up to the point where the resistance checks are to be made (page 22), and, here is where my analog meter says that I am way off. The backlight kit was installed, by the way, as per its (somewhat confusing instructions) which then returned me to the page where the resistance checks are made. I get the following big discrepancies: Test pts (+) Resistance Measured DS1 (LCD pins 1-24) >100K around 2K each to ground J1 pin 6 >100K 10K J1 pin 7 >100K 5.8 to 7K (moves up)) J1 pin 8 >100K 5.8 to 7K (moves up) J1 pin 10 90-200K 2.3K J1 pin 12 >100K 5.1 to 7K (moves up) J1 pin 15 <50K 28K (yippie!) J1 pin 16 15-18K 9K J1 pin 19 >100K 5.8 to 7K (moves up) Something is definitely awry here. I don't see any bridges, cold joints, nor missed components/joints, incorrectly placed parts. However, with the LCD installed along with the backlit display, there is no way to recheck the pins of the 40 pin MCU from the top of the board, only to look under the socket from the sides. I have rechecked all the component placement and the solder connections 3 times. I cannot find any errors or solder issues. So then, can the analog meter be throwing me that far off? I doubt it. Your expertise is requested in offering advice. 73, Jozef WB2MIC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
RE: K1 Front Panel Resistance Issue
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Jozef,
Yes your analog meter CAN be thowing your readings off by that much. Do not use an analog meter to do resistance checks on solid state equipment. Many make resistance measurements by applying a voltage to the circuit under test, and that voltage is high enough to turn on solid state junctions and may actually destroy solid state devices. Measuring voltages and currents with an analog meter may often be OK, but definitely NOT resistance measurements. 73, Don W3FPR > -----Original Message----- > > Hello to the list. > > This is my first posting on my K1 kit building issues via the Elecraft > reflector. Thanks to all in advance. I am awaiting the delivery of a > digital multimeter for making resistance/voltage checks, but started > construction nonetheless. I have a cheap analog meter, however, and > thought that when I get to the resistance check parts I would use it, > but not proceed until the DMM gets here. > > I completed the 4 band filter bard and the front panel (minus the 10 > turn potentiometer) up to the point where the resistance checks are to > be made (page 22), and, here is where my analog meter says that I am way > off. The backlight kit was installed, by the way, as per its (somewhat > confusing instructions) which then returned me to the page where the > resistance checks are made. I get the following big discrepancies: > > Test pts (+) Resistance Measured > DS1 (LCD pins 1-24) >100K around 2K each to ground > J1 pin 6 >100K 10K > J1 pin 7 >100K 5.8 to 7K (moves up)) > J1 pin 8 >100K 5.8 to 7K (moves up) > J1 pin 10 90-200K 2.3K > J1 pin 12 >100K 5.1 to 7K (moves up) > J1 pin 15 <50K 28K (yippie!) > J1 pin 16 15-18K 9K > J1 pin 19 >100K 5.8 to 7K (moves up) > > Something is definitely awry here. I don't see any bridges, cold > joints, nor missed components/joints, incorrectly placed parts. > However, with the LCD installed along with the backlit display, there is > no way to recheck the pins of the 40 pin MCU from the top of the board, > only to look under the socket from the sides. I have rechecked all the > component placement and the solder connections 3 times. I cannot find > any errors or solder issues. So then, can the analog meter be throwing > me that far off? I doubt it. Your expertise is requested in offering > advice. > > 73, Jozef WB2MIC > No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.441 / Virus Database: 268.18.3/694 - Release Date: 2/20/2007 1:44 PM _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: K1 Front Panel Resistance Issue
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Hello Don and others:
Thank you kindly. This lists collective wisdom appreciated. I will cease and desist using the analog meter until my DMM arrives. May I suggest that Elecraft consider upgrading their recommendation about not using an analog meter to a warning which includes the possibility of component damage from using an analog meter. I was aware of the possibility of inaccurate readings, but not of possible damage to components. I stand educated. 73, Jozef WB2MIC Don Wilhelm wrote: > Jozef, > > Yes your analog meter CAN be thowing your readings off by that much. > Do not use an analog meter to do resistance checks on solid state equipment. > Many make resistance measurements by applying a voltage to the circuit under > test, and that voltage is high enough to turn on solid state junctions and > may actually destroy solid state devices. > > Measuring voltages and currents with an analog meter may often be OK, but > definitely NOT resistance measurements. > > 73, > Don W3FPR > > >> -----Original Message----- >> >> Hello to the list. >> >> This is my first posting on my K1 kit building issues via the Elecraft >> reflector. Thanks to all in advance. I am awaiting the delivery of a >> digital multimeter for making resistance/voltage checks, but started >> construction nonetheless. I have a cheap analog meter, however, and >> thought that when I get to the resistance check parts I would use it, >> but not proceed until the DMM gets here. >> >> I completed the 4 band filter bard and the front panel (minus the 10 >> turn potentiometer) up to the point where the resistance checks are to >> be made (page 22), and, here is where my analog meter says that I am way >> off. The backlight kit was installed, by the way, as per its (somewhat >> confusing instructions) which then returned me to the page where the >> resistance checks are made. I get the following big discrepancies: >> >> Test pts (+) Resistance Measured >> DS1 (LCD pins 1-24) >100K around 2K each to ground >> J1 pin 6 >100K 10K >> J1 pin 7 >100K 5.8 to 7K (moves up)) >> J1 pin 8 >100K 5.8 to 7K (moves up) >> J1 pin 10 90-200K 2.3K >> J1 pin 12 >100K 5.1 to 7K (moves up) >> J1 pin 15 <50K 28K (yippie!) >> J1 pin 16 15-18K 9K >> J1 pin 19 >100K 5.8 to 7K (moves up) >> >> Something is definitely awry here. I don't see any bridges, cold >> joints, nor missed components/joints, incorrectly placed parts. >> However, with the LCD installed along with the backlit display, there is >> no way to recheck the pins of the 40 pin MCU from the top of the board, >> only to look under the socket from the sides. I have rechecked all the >> component placement and the solder connections 3 times. I cannot find >> any errors or solder issues. So then, can the analog meter be throwing >> me that far off? I doubt it. Your expertise is requested in offering >> advice. >> >> 73, Jozef WB2MIC >> >> > -- > No virus found in this outgoing message. > Checked by AVG Free Edition. > Version: 7.5.441 / Virus Database: 268.18.3/694 - Release Date: 2/20/2007 > 1:44 PM > > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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