Re: [Drakelist] Exploding cap? Further progress?!
Thanks Steve and Chris for your helpful advice regarding a possible bad crystal. I think you are right but somehow, despite being most careful, I seem to have made matters worse! Are 45 year old crystals particularly delicate? Should I renew them all? Tried the 15m crystal in the 10m and 40m sockets. Nothing doing. Tried the 10m and 40m crystals in the 15m socket. Nothing doing either!! Two problems by the look of it as far as 15m is concerned. The real shock came when I put the 10m and 40m crystals back in their correct places. 40m is fine but 10m is now dead. Of course I have taken it out and re-inserted it but to no avail. Maybe I wrecked it! Chris had trouble with a dirty crystal socket. Obviously I can clean the crystal pins, though they appear clean enough, but how on earth do I clean a crystal socket? Isn't Ham Radio fun! 73 Damien G3XER ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Exploding cap? Further progress?!
- Original Message - From: Damien Mannix damienman...@hotmail.com To: drakelist@zerobeat.net Sent: Saturday, September 01, 2012 9:54 AM Subject: Re: [Drakelist] Exploding cap? Further progress?! Thanks Steve and Chris for your helpful advice regarding a possible bad crystal. I think you are right but somehow, despite being most careful, I seem to have made matters worse! Are 45 year old crystals particularly delicate? Should I renew them all? Tried the 15m crystal in the 10m and 40m sockets. Nothing doing. Tried the 10m and 40m crystals in the 15m socket. Nothing doing either!! Two problems by the look of it as far as 15m is concerned. The real shock came when I put the 10m and 40m crystals back in their correct places. 40m is fine but 10m is now dead. Of course I have taken it out and re-inserted it but to no avail. Maybe I wrecked it! Chris had trouble with a dirty crystal socket. Obviously I can clean the crystal pins, though they appear clean enough, but how on earth do I clean a crystal socket? Isn't Ham Radio fun! 73 Damien G3XER I doubt if you broke the crystal. Crystals do fail with age, more often they drift. Before giving up on a crystal try cleaning the pins. The least abrasive cleaner is the eraser end of a pencil or a similar type eraser. This also works on tube pins. If that doesn't work try a fine brass brush or fine steel wool. The pins of the crystal socket are harder to clean but I suggest using Deoxit with the aid of a wooden toothpick or a small stiff brush like a tooth brush or an acid brush with the bristles cut short to make them stiff. Crystals can be tested using a grid-dip meter, if you have one. Connect the crystal across the coil terminals in place of the coils and adjust the capacitor to get oscillation. International Crystal seems to be a good source for Drake crystals. They know the characteristics. If you determine the crystals are bad I suggest calling them. -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Exploding cap? Progress
Hi all, It is time I gave all you kind folks a progress report. Found the WB4IQK AC3/4 troubleshooting guide invaluable. Tested all voltages with the covers off, very carefully! All okay. As promised by the seller I found that the two caps and four diodes in the 650v circuit have been renewed. Even though all seems to be well I will follow the advice given and approach Hayseed to see if they will supply the new parts for the 250v part of the unit. Surprise, when replacing the bottom cover I saw on the inside a charred patch about an inch in diameter with a very tiny hole almost in the middle! Never saw that before, silly me. Too busy examining components. The area is directly below the fuse holder. Probably would have been okay at 115v but it looks as though it arced at our voltage. I wonder if it has happened before? Anyway a bit of insulation and several hours running seems to suggest it is now okay. Please though, do not let anyone think they wasted their time giving me all that advice. I have loads to learn and it will all be most useful to me in the future. Fingers crossed it was time for me to try the TR4. First problem was that the MS4 speaker was silent! Fortunately all was well on phones. Turns out someone has rewired the big psu/tcvr socket with the speaker connections now on pins 5 8 which lead to the VOX relay socket! Irritating, I believe plugs for those sockets are impossible to find and correcting this in the tight space of that twelve connection socket will be quite a soldering challenge for me. As for the TR4, using a short length of bellwire as an antenna (crude I know) and a 50 ohm load for transmit all seems to be well except for 15 metres which is as dead as can be. Both TX and RX, nothing. It cannot even hear its own calibrator! Oh well, I am quite pleased really. It could be an awful lot worse and is probably good example of a TR4 once sorted. Thanks again all. DamienG3XER ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Exploding cap? Progress
Nice going, Damien - Yes, an arc of 220VAC to GND could result in some rather loud sounds. Obviously, it must have been the side that's on the supply side of the fuse, or else the fuse would have blown. Check your fuse to be sure that it's the correct value: the current rating should be half what it would be at 120 (I don't have the schematic in front of me at the moment). Complete lack of function on one band suggests a bad crystal. I'd check all of your connections off the rotary switches, then try re-seating the crystal. You may want to try swapping in the 10m crystal just to see if you get some receiver noise. If you do, the 15m crystal's definitely bad. Good luck - Steve Wedge, W1ES/4 Time flies like an arrow; fruit flies like a banana. All my computers have my signature with various pearls of wisdom appended thereto. From: Damien Mannix Sent: Monday, August 27, 2012 11:33 AM To: drakelist@zerobeat.net Subject: [Drakelist] Exploding cap? Progress Hi all, It is time I gave all you kind folks a progress report. Found the WB4IQK AC3/4 troubleshooting guide invaluable. Tested all voltages with the covers off, very carefully! All okay. As promised by the seller I found that the two caps and four diodes in the 650v circuit have been renewed. Even though all seems to be well I will follow the advice given and approach Hayseed to see if they will supply the new parts for the 250v part of the unit. Surprise, when replacing the bottom cover I saw on the inside a charred patch about an inch in diameter with a very tiny hole almost in the middle! Never saw that before, silly me. Too busy examining components. The area is directly below the fuse holder. Probably would have been okay at 115v but it looks as though it arced at our voltage. I wonder if it has happened before? Anyway a bit of insulation and several hours running seems to suggest it is now okay. Please though, do not let anyone think they wasted their time giving me all that advice. I have loads to learn and it will all be most useful to me in the future. Fingers crossed it was time for me to try the TR4. First problem was that the MS4 speaker was silent! Fortunately all was well on phones. Turns out someone has rewired the big psu/tcvr socket with the speaker connections now on pins 5 8 which lead to the VOX relay socket! Irritating, I believe plugs for those sockets are impossible to find and correcting this in the tight space of that twelve connection socket will be quite a soldering challenge for me. As for the TR4, using a short length of bellwire as an antenna (crude I know) and a 50 ohm load for transmit all seems to be well except for 15 metres which is as dead as can be. Both TX and RX, nothing. It cannot even hear its own calibrator! Oh well, I am quite pleased really. It could be an awful lot worse and is probably good example of a TR4 once sorted. Thanks again all. Damien G3XER ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[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
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
[Drakelist] Exploding cap' ???
Hi all, Bought an immaculate looking TR4 which has been out of use a long time. Also bought an AC4 which claims to have had the original EHT caps and diodes replaced. Powered them up with 20 vac for four hours, then up in 20 v steps at four hours per step, listening and sniffing for any problems. Reached 220 vac an hour ago. AC4 slightly warm and centre of TR4 top a bit warmer. Then there was one hell of a crack! Sounded like a gunshot and frightened me to death! Swiched off immediately of course. No smell that I can detect. Is that what an exploding capacitor sounds like? Any advice on where to start looking? The TR4 or the AC4? Sad day for me. Trying to return to the hobby after over 30 years. Been too busy making a living and bringing up a family. Regards, DamienG3XER ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Exploding cap' ???
Is it possible power supply was set for 110V not 220V? I do not believe it's the TR4-although of course it could be. If it was, I should think you would have lost a diode(s) or Heaven-forbid: the transformer. It could have been a faulty diode that caused it-hence, after making sure about the input voltage selector (and if it's correct, I'd check its wiring) I'd check all the diodes. Finally, it's always possible it was just the capacitor's time having come. If you've made sure about the voltage setting, then replace the cap, do the same start-up routine, and then the SAME cap goes, then yeah, it's obviously not the caps, but something else going on. Before you walk-away for the run-time test, I'd check all the voltages just to be sure they're right. That way, if it does go again (or some other cap) you'll know at least it LOOKED right prior to catastrophe. Ed Tanton website: http://www.n4xy.com/ http://www.n4xy.com All emails IN OUT checked by Norton AntiVirus with AutoProtect -- Wag more / Bark less -- From: drakelist-boun...@zerobeat.net [mailto:drakelist-boun...@zerobeat.net] On Behalf Of Damien Mannix Sent: Thursday, August 23, 2012 12:24 PM To: drakelist@zerobeat.net Subject: [Drakelist] Exploding cap' ??? Hi all, Bought an immaculate looking TR4 which has been out of use a long time. Also bought an AC4 which claims to have had the original EHT caps and diodes replaced. Powered them up with 20 vac for four hours, then up in 20 v steps at four hours per step, listening and sniffing for any problems. Reached 220 vac an hour ago. AC4 slightly warm and centre of TR4 top a bit warmer. Then there was one hell of a crack! Sounded like a gunshot and frightened me to death! Swiched off immediately of course. No smell that I can detect. Is that what an exploding capacitor sounds like? Any advice on where to start looking? The TR4 or the AC4? Sad day for me. Trying to return to the hobby after over 30 years. Been too busy making a living and bringing up a family. Regards, Damien G3XER ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Exploding cap' ???
On 8/23/2012 1224, Damien Mannix wrote: Hi all, Bought an immaculate looking TR4 which has been out of use a long time. Also bought an AC4 which claims to have had the original EHT caps and diodes replaced. Powered them up with 20 vac for four hours, then up in 20 v steps at four hours per step, listening and sniffing for any problems. Reached 220 vac an hour ago. AC4 slightly warm and centre of TR4 top a bit warmer. Then there was one hell of a crack! Sounded like a gunshot and frightened me to death! Swiched off immediately of course. No smell that I can detect. Is that what an exploding capacitor sounds like? Any advice on where to start looking? The TR4 or the AC4? Sad day for me. Trying to return to the hobby after over 30 years. Been too busy making a living and bringing up a family. Regards, Damien G3XER I had this happen to an R-4B probably 25 years ago. A medium sized lytic went off like a bomb. Many tiny fragments to extract from under the chassis but upon replacing the cap, all was fine. Very startling. -- *Charles Ring W3NU* ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Exploding cap' ???
I forgot to mention I was present when one within my Drake L7 went. Filled the basement with little tiny things that looked a lot like tiny black butterflies fluttering to the floor. I don't remember if diodes went or not. But it did repair easily enough. Ed Tanton website: http://www.n4xy.com/ http://www.n4xy.com All emails IN OUT checked by Norton AntiVirus with AutoProtect -- Wag more / Bark less -- ///snip I had this happen to an R-4B probably 25 years ago. A medium sized lytic went off like a bomb. Many tiny fragments to extract from under the chassis but upon replacing the cap, all was fine. Very startling. -- Charles Ring W3NU ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
