[Drakelist] Exploding Cap' ???
Hello all, I am embarrassed but most grateful for all the kindness and helpful advice given to me. Too many to thank individually but many many thanks to all. The safety advice is taken very seriously and I will be ultra cautious bearing in mind my inexperience. Already I am puzzled. Astonished in fact. A most careful examination of every component in the AC4 and then the TR4, magnifying glass and high power flashlight and what a lot under the TR4, shows no sign of distress to any component!! Clearly the bang came from somewhere, I was not dreaming, so I guess it is time to carefully take some voltage measurements from the AC4 as a first step. DamienG3XER ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] exploding caps
Damien, This should tell you everything you need to know about the AC-4. http://www.wb4hfn.com/DRAKE/DrakeArticles/AC4_Troubleshooting/ Drake_AC3-AC4_Troubleshooting.htm 73 Rick W9WS On Aug 25, 2012, at 11:00 AM, drakelist-requ...@zerobeat.net wrote: Send Drakelist mailing list submissions to drakelist@zerobeat.net To subscribe or unsubscribe via the World Wide Web, visit http://mailman.zerobeat.net/mailman/listinfo/drakelist or, via email, send a message with subject or body 'help' to drakelist-requ...@zerobeat.net You can reach the person managing the list at drakelist-ow...@zerobeat.net When replying, please edit your Subject line so it is more specific than Re: Contents of Drakelist digest... Today's Topics: 1. Re: Exploding cap's ??? (Arthur Delibert) 2. Exploding Cap' ??? (Damien Mannix) -- Message: 1 Date: Fri, 24 Aug 2012 19:36:11 -0400 From: Arthur Delibert radio7...@msn.com To: damienman...@hotmail.com, drakelist@zerobeat.net Subject: Re: [Drakelist] Exploding cap's ??? Message-ID: snt124-w378f2d3e94b8a9ac456f32e4...@phx.gbl Content-Type: text/plain; charset=iso-8859-1 Be sure the electrolytics are fully discharged before you touch anything inside. They can retain a high enough charge to give you a serious jolt. In a lot of power supplies, the electrolytics have a bleeder resistor across them, to drain down that charge within a minute or so after the unit is turned off. But you're working in old equipment where things may have been modified and/or broken. A few years ago I bought an old transmitter with separate power supply at a hamfest. The seller assured me it was all in working condition. I think I would have been killed if I'd relied on that bit of puffery. But W1ES is right -- they're pretty straightforward, and you shouldn't have any trouble figuring out what's what or working on it. Just be sure to respect the voltages that it's capable of. --Art Delibert, KB3FJO From: damienman...@hotmail.com To: drakelist@zerobeat.net Date: Fri, 24 Aug 2012 16:03:54 + Subject: Re: [Drakelist] Exploding cap's ??? Wow, thank you so much to all for the most useful information. Yes the AC4 is wired for 240 v. Hoped to string up some sort of temporary antenna this weekend and get on the air but I now know I will be busy doing something else! Just hope I have the technical abilty to sort it out. Years ago I built a Heathkit scope but that is about my only experience with components, soldering etc. I do not suppose any Drake enthusiast will have any doubt as to why a TR4 but in case anybody has, in the late 60's and early 70's when I was active I had three receivers in a row, the last being a R4A. I thought it was magnificent and way ahead of any receiver I had tried at the time. Wish I still had it today. It is only natural that I want to return to Drake. Thanks again everyone. Damien G3XER ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist -- next part -- An HTML attachment was scrubbed... URL: http://mailman.zerobeat.net/pipermail/drakelist/attachments/ 20120824/6d5ad339/attachment-0001.html -- Message: 2 Date: Sat, 25 Aug 2012 15:36:08 + From: Damien Mannix damienman...@hotmail.com To: drakelist@zerobeat.net Subject: [Drakelist] Exploding Cap' ??? Message-ID: bay153-w50feff8d75ffe3bfc7769bd8...@phx.gbl Content-Type: text/plain; charset=iso-8859-1 Hello all, I am embarrassed but most grateful for all the kindness and helpful advice given to me. Too many to thank individually but many many thanks to all. The safety advice is taken very seriously and I will be ultra cautious bearing in mind my inexperience. Already I am puzzled. Astonished in fact. A most careful examination of every component in the AC4 and then the TR4, magnifying glass and high power flashlight and what a lot under the TR4, shows no sign of distress to any component!! Clearly the bang came from somewhere, I was not dreaming, so I guess it is time to carefully take some voltage measurements from the AC4 as a first step. DamienG3XER -- next part -- An HTML attachment was scrubbed... URL: http://mailman.zerobeat.net/pipermail/drakelist/attachments/ 20120825/3c44ffd1/attachment-0001.html -- ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist End of Drakelist Digest, Vol 50, Issue 21
Re: [Drakelist] Exploding Cap' ???
- Original Message - From: Damien Mannix damienman...@hotmail.com To: drakelist@zerobeat.net Sent: Saturday, August 25, 2012 8:36 AM Subject: [Drakelist] Exploding Cap' ??? Hello all, I am embarrassed but most grateful for all the kindness and helpful advice given to me. Too many to thank individually but many many thanks to all. The safety advice is taken very seriously and I will be ultra cautious bearing in mind my inexperience. Already I am puzzled. Astonished in fact. A most careful examination of every component in the AC4 and then the TR4, magnifying glass and high power flashlight and what a lot under the TR4, shows no sign of distress to any component!! Clearly the bang came from somewhere, I was not dreaming, so I guess it is time to carefully take some voltage measurements from the AC4 as a first step. DamienG3XER Electrolytic caps usually smell pretty strongly when they explode. Actually, these caps usually have a vent to prevent an actual explosion if they develop an internal short but they still smell when they go. Film caps do not often explode and seldom short. A resistor also smells when it heats enough to explode but the odor depends on the type. Carbon composition resistors usually have the typical carbolic acid odor of burning phenolic but film caps may not have an odor. Its possible this was an arc-over. That may be hard to find. I would certainly inspect the switch decks, especially in the RF section, very carefully. Also inspect the variable capacitors in the RF section for any sign of arcing on the plates. An arc will usually leave some sort of trace, sometimes a dark track and sometimes a small area where its melted the metal at the surface. Its possible for dirt to cause an arc and be burned away. Its also possible for moisture to cause an arc. You can check the power supply with it disconnected from the transmitter by shorting the AC switch pins on the connector. Unloaded voltages will be higher than indicated on the schematic. I variable transformer is useful here. -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Exploding Cap' ???
Sounds like an arc over and there is usually some trace of carbon but it can be hard to identify at times. Another possibility is a cracked ceramic bleeder resistor. I am not familiar with the AC-4 but my L7 power supply uses large ceramic resistors and I had one develop a crack that was not casually obvious. Dennis AE6C On 8/25/12, Damien Mannix damienman...@hotmail.com wrote: Hello all, I am embarrassed but most grateful for all the kindness and helpful advice given to me. Too many to thank individually but many many thanks to all. The safety advice is taken very seriously and I will be ultra cautious bearing in mind my inexperience. Already I am puzzled. Astonished in fact. A most careful examination of every component in the AC4 and then the TR4, magnifying glass and high power flashlight and what a lot under the TR4, shows no sign of distress to any component!! Clearly the bang came from somewhere, I was not dreaming, so I guess it is time to carefully take some voltage measurements from the AC4 as a first step. DamienG3XER ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] exploding caps
On 8/25/2012 1215, richard radke wrote: Damien, This should tell you everything you need to know about the AC-4. http://www.wb4hfn.com/DRAKE/DrakeArticles/AC4_Troubleshooting/Drake_AC3-AC4_Troubleshooting.htm I get a Forbidden error there. -- *Charles Ring W3NU* ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] exploding caps
Charles, I just try'd it and it went right to it...try this from the main page... it's the 1st item on the list of articles http:// www.wb4hfn.com/DRAKE/DrakeTechTips.htm Rick W9WS On Aug 25, 2012, at 12:11 PM, Charles Ring wrote: On 8/25/2012 1215, richard radke wrote: Damien, This should tell you everything you need to know about the AC-4. http://www.wb4hfn.com/DRAKE/DrakeArticles/AC4_Troubleshooting/ Drake_AC3-AC4_Troubleshooting.htm I get a Forbidden error there. -- Charles Ring W3NU ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] exploding caps
Got it, thanks. On 8/25/2012 1319, richard radke wrote: Charles, I just try'd it and it went right to it...try this from the main page... it's the 1st item on the list of articles http://www.wb4hfn.com/DRAKE/DrakeTechTips.htm Rick W9WS On Aug 25, 2012, at 12:11 PM, Charles Ring wrote: On 8/25/2012 1215, richard radke wrote: Damien, This should tell you everything you need to know about the AC-4. http://www.wb4hfn.com/DRAKE/DrakeArticles/AC4_Troubleshooting/Drake_AC3-AC4_Troubleshooting.htm I get a Forbidden error there. -- *Charles Ring W3NU* ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist -- *Charles Ring W3NU* ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
