#3421 MCU problems?
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Dear Elecrafters,
I had left my rig on over night, and this mornings ice 'storm' brought a few strokes of unexpected lightning to the area. Now my K2 (with KSB2, KNB2, KAT2) is constantly transmitting dits with both mic and key removed. I'm afraid it might be the MCU. Is this problem 'resetable', (I can't seem to make any buttons work while it is transmitting - and it IS transmitting - verified by nearby receiver feeding K2 into dummy load), OR will I need to replace the MCU? Thanks, Daniel AA0NI in icy Oklahoma City _______________________________________________ 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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Hi John (and the group),
Nope - I've already checked both dit/dah lines and neither is shorted to ground. Interestingly - I can insert dahs inbetween the dits, but that doesn't stop the dits from continuing. I'm really thinking that a small portion of the MCU may be having trouble since I looked over the schematic design and I can't see anything that might buffer the MCU from the dit/mic PTT connection. Someone please correct me if I am wrong here. It appears that there's a direct connection between the PTT/DIT connection on the MCU and the key/mic connections - and if that is the case - the only solution would be swapping out the MCU. Thanks for your quick reply, and hopefully someone can confirm my suspicions. 73, Daniel AA0NI "John R. Lonigro" <[hidden email]> wrote: Dan: Just got our power back after about 12 hours, due to the same storm (but no lightning fortunately). I'm not the expert on this, but I would say to make sure it isn't something simple first, like the dit line being shorted out. I think the key jack is the same design as the headphone jack, which has seemed prone to failure. You can check that with the power off and a DMM. If the line isn't shorted out, wait for one of the big guns to reply with further suggestions. Good luck. We are expecting another freezing rain episode later this evening, but it's above freezing right now and the trees are shedding a lot of their ice. They shedded a lot of their branches last night. 73's, John AA0VE Daniel Reynolds wrote: > Dear Elecrafters, > > I had left my rig on over night, and this mornings ice 'storm' brought a few strokes of unexpected lightning to the area. Now my K2 (with KSB2, KNB2, KAT2) is constantly transmitting dits with both mic and key removed. I'm afraid it might be the MCU. Is this problem 'resetable', (I can't seem to make any buttons work while it is transmitting - and it IS transmitting - verified by nearby receiver feeding K2 into dummy load), OR will I need to replace the MCU? > > Thanks, > Daniel > AA0NI in icy Oklahoma City > > > _______________________________________________ > 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 > > _______________________________________________ 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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Daniel,
There is a direct connection between the PTT/DIT line at the MCU (pin 30) and the junction of R1,C1 and the PTT pin on the front panel Mic Config Header. But you have not done enough to confirm a bad MCU yet. Before doing anything else, put a dummy load on the antenna jack, power on and measure the voltage at Control Board U6 pin 30 - it will normally be near 5 volts with the dit paddle and PTT lines open. If it is near zero (or somewhere between zero and 3 volts) you might have a problem with the MCU - or a problem elsewhere. If you find the voltage at zero, pull U6 and again measure the voltage - if it is still not near 5 volts, check RP4 for good soldering (especially pins 5 and 6) and check for shorts on the line. If the U6 pin 30 voltage (without the MCU installed)is indeed 5 volts, then your board wiring is correct and you can then blame the MCU input pin for your problems. 73, Don W3FPR > -----Original Message----- > > Nope - I've already checked both dit/dah lines and neither is > shorted to ground. Interestingly - I can insert dahs inbetween > the dits, but that doesn't stop the dits from continuing. > > I'm really thinking that a small portion of the MCU may be > having trouble since I looked over the schematic design and I > can't see anything that might buffer the MCU from the dit/mic > PTT connection. Someone please correct me if I am wrong here. It > appears that there's a direct connection between the PTT/DIT > connection on the MCU and the key/mic connections - and if that > is the case - the only solution would be swapping out the MCU. > > Thanks for your quick reply, and hopefully someone can confirm > my suspicions. > > 73, > Daniel AA0NI > No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.16.12/628 - Release Date: 1/15/2007 11:04 AM _______________________________________________ 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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