KPA500 fan won't shut off
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Re: KPA500 fan won't shut off
 
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In looking at the schematic, I see the fan is controlled by a MJE182
{Q5}. If this transistor shorts the fan runs at full speed. I didn't see a relay in the circuit, but I could have missed it. 73 Bob, K4TAX On 11/26/2019 3:29 AM, Eric Norris wrote: > As Jack Brindle noted (and he would know), it appears to be a stuck relay. > If you don't want to send the amp back to the mothership, I'm sure Elecraft > Support could identify the relay, and if you can do rework, you could > remove the bad one and replace it yourself. > > 73 Eric WD6DBM > > On Tue, Nov 26, 2019, 12:57 AM Grant VK5GR <[hidden email]> wrote: > >> Eric, >> >> >> >> I reloaded the firmware tonight – no change (in fact I upgraded it from >> 1.47 to 1.54). >> >> >> >> If I plug the mains cable in the fans power up immediately. If I then turn >> the amplifier on, the amp works normally. When I power it off from software >> or the front panel the fans spin up and stay running. >> >> >> >> Is there something I can look at here in VK I wonder? I really don’t want >> to have to ship it back to Elecraft for this. >> >> >> >> Regards, >> >> Grant VK5GR >> >> >> >> >> >> >> >> >> >> *From:* Eric Norris [mailto:[hidden email]] >> *Sent:* Tuesday, 26 November 2019 2:20 PM >> *To:* VK5GR >> *Cc:* elecraft@mailman qth. net >> *Subject:* Re: [Elecraft] KPA500 fan won't shut off >> >> >> >> Reload the firmware. >> >> 73 Eric WD6DBM >> >> >> >> On Mon, Nov 25, 2019, 6:51 PM VK5GR <[hidden email]> wrote: >> >> FAN CTL = NOR >> >> FANs are idle while the amp is turned on - amp ambient temp was 27C at the >> time (it was powered up and had been idle for about 20 minutes). >> >> I then turned the amplifier off via the front panel push button. I would >> have expected the FANs to start up for about 10 seconds as they discharge >> the 60V rail supply but instead the FANs continue to run. the only way to >> turn them off is to unplug the amp from the mains supply. >> >> It is definitely a fault condition and not a menu selection. >> >> Thoughts? >> >> >> >> -- >> Sent from: http://elecraft.365791.n2.nabble.com/ >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] >> >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: KPA500 fan won't shut off
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When the KPA shuts down, the power relay is switched off, then the driver transistors for the fan are turned on. The microcontroller shortly executes a restart, which puts the MCU into boot mode, but does not reset the I/O ports. Thus the fans are turned on, allowing the big power capacitors to drain through the fan. Normally this works fine, leaving the MCU in low power state waiting for the next power up and the rest of the amp powered off. If the power relay is stuck on, then the MCU will be in the low-power boot mode, but the power supply is left turned on and thus the fan runs.
The solution is to correct the relay issue. Again, talk to customer support about what you and they can do to facilitate a repair. 73! Jack, W6FB > On Nov 26, 2019, at 7:28 AM, Bob McGraw K4TAX <[hidden email]> wrote: > > In looking at the schematic, I see the fan is controlled by a MJE182 {Q5}. If this transistor shorts the fan runs at full speed. I didn't see a relay in the circuit, but I could have missed it. > > 73 > > Bob, K4TAX > > > On 11/26/2019 3:29 AM, Eric Norris wrote: >> As Jack Brindle noted (and he would know), it appears to be a stuck relay. >> If you don't want to send the amp back to the mothership, I'm sure Elecraft >> Support could identify the relay, and if you can do rework, you could >> remove the bad one and replace it yourself. >> >> 73 Eric WD6DBM >> >> On Tue, Nov 26, 2019, 12:57 AM Grant VK5GR <[hidden email]> wrote: >> >>> Eric, >>> >>> >>> >>> I reloaded the firmware tonight – no change (in fact I upgraded it from >>> 1.47 to 1.54). >>> >>> >>> >>> If I plug the mains cable in the fans power up immediately. If I then turn >>> the amplifier on, the amp works normally. When I power it off from software >>> or the front panel the fans spin up and stay running. >>> >>> >>> >>> Is there something I can look at here in VK I wonder? I really don’t want >>> to have to ship it back to Elecraft for this. >>> >>> >>> >>> Regards, >>> >>> Grant VK5GR >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> *From:* Eric Norris [mailto:[hidden email]] >>> *Sent:* Tuesday, 26 November 2019 2:20 PM >>> *To:* VK5GR >>> *Cc:* elecraft@mailman qth. net >>> *Subject:* Re: [Elecraft] KPA500 fan won't shut off >>> >>> >>> >>> Reload the firmware. >>> >>> 73 Eric WD6DBM >>> >>> >>> >>> On Mon, Nov 25, 2019, 6:51 PM VK5GR <[hidden email]> wrote: >>> >>> FAN CTL = NOR >>> >>> FANs are idle while the amp is turned on - amp ambient temp was 27C at the >>> time (it was powered up and had been idle for about 20 minutes). >>> >>> I then turned the amplifier off via the front panel push button. I would >>> have expected the FANs to start up for about 10 seconds as they discharge >>> the 60V rail supply but instead the FANs continue to run. the only way to >>> turn them off is to unplug the amp from the mains supply. >>> >>> It is definitely a fault condition and not a menu selection. >>> >>> Thoughts? >>> >>> >>> >>> -- >>> Sent from: http://elecraft.365791.n2.nabble.com/ >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:[hidden email] >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> Message delivered to [hidden email] >>> >>> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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