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Astron Power Supply problem
I've got a problem with my Astron RS-20 power supply. With no load,
it's fine, but anything above 4amps or so makes it drop way down and my rig drops out of lock. I haven't measured it under load but the rig works ok to 10 or 11 volts so it must be dropping below that. I found a schematic and downloaded it, all the voltages are fairly close to what it says on the schematic with no load, I haven't made any measurements with a load on it. I'll pick up a headlight tomorrow to put a load on it and make more measurements. Does anybody have any ideas? Thanks, Kerry, WD5ABC |
Astron Power Supply problem
"Kerry Miller" wrote in message
news:CNEzf.140599$WH.64582@dukeread01... I've got a problem with my Astron RS-20 power supply. With no load, it's fine, but anything above 4amps or so makes it drop way down and my rig drops out of lock. I haven't measured it under load but the rig works ok to 10 or 11 volts so it must be dropping below that. I found a schematic and downloaded it, all the voltages are fairly close to what it says on the schematic with no load, I haven't made any measurements with a load on it. I'll pick up a headlight tomorrow to put a load on it and make more measurements. Does anybody have any ideas? Thanks, Kerry, WD5ABC Kerry - From you description, you have lost REGULATION . Read the KBT web site for ALL required diagnosis and repair steps for linear power supplies and Astron. MENU BAR is GRAY LIST ON LEFT http://www.kbt-dc-supplies.com/index.php Replace LM723 regulator chip ... TEST PASS TRANSISTORS (2N3055 or 2N3771) How it Works - David Metz's classic article - now 10 years old http://www.seits.org/features/pwrsup.htm Index & schematics for Astron power supplies http://www.repeater-builder.com/astr...ron-index.html gb |
Astron Power Supply problem
Astron linear supplies use a 3 terminal regulator, usually an LM317. These
things do tend to fail from time to time. Can't tell if that's your problem, but it is likely, and the things are cheap enough it's worth popping a new one in to find out. ... "Kerry Miller" wrote in message news:CNEzf.140599$WH.64582@dukeread01... I've got a problem with my Astron RS-20 power supply. With no load, it's fine, but anything above 4amps or so makes it drop way down and my rig drops out of lock. I haven't measured it under load but the rig works ok to 10 or 11 volts so it must be dropping below that. I found a schematic and downloaded it, all the voltages are fairly close to what it says on the schematic with no load, I haven't made any measurements with a load on it. I'll pick up a headlight tomorrow to put a load on it and make more measurements. Does anybody have any ideas? Thanks, Kerry, WD5ABC |
Astron Power Supply problem
"xpyttl" wrote in message
... Astron linear supplies use a 3 terminal regulator, usually an LM317. These things do tend to fail from time to time. Can't tell if that's your problem, but it is likely, and the things are cheap enough it's worth popping a new one in to find out. Really? What model of Astron linear power supply have you repaired or seen that uses this design approach? I have never seen one like this -- over past 20 years. Confusing this with some other mfg. design? Astron has been using the 14-pin (30 years old) LM 723 regulator IC with NPN pass transistors (e.g. 2N3055, 2N3771) ... for as long as I have been repairing them. Check here for correct Astron information - repairs, etc. http://www.kbt-dc-supplies.com/index.php and Astron schematics (which show the LM723, not the later LM317 design) http://www.repeater-builder.com/astr...ron-index.html gb |
Astron Power Supply problem
gb wrote:
"xpyttl" wrote in message ... Astron linear supplies use a 3 terminal regulator, usually an LM317. These things do tend to fail from time to time. Can't tell if that's your problem, but it is likely, and the things are cheap enough it's worth popping a new one in to find out. Really? What model of Astron linear power supply have you repaired or seen that uses this design approach? I have never seen one like this -- over past 20 years. Confusing this with some other mfg. design? Astron has been using the 14-pin (30 years old) LM 723 regulator IC with NPN pass transistors (e.g. 2N3055, 2N3771) ... for as long as I have been repairing them. Check here for correct Astron information - repairs, etc. http://www.kbt-dc-supplies.com/index.php and Astron schematics (which show the LM723, not the later LM317 design) http://www.repeater-builder.com/astr...ron-index.html gb I can confirm that mine has a 723, not a 317. Thanks for the web sites, looks like some great information. I hooked up that headlight tonight but it ran fine, pulling a bit over 3 amps for an hour or so. Maybe I need more load to make it lose regulation. Guess I'll start digging into that regulator board, the transistors and all the big things like the transformer seem to be fine. Thanks, Kerry - WD5ABC |
Astron Power Supply problem
"Kerry Miller" wrote in message
news:UP_zf.140961$WH.46302@dukeread01... I can confirm that mine has a 723, not a 317. Thanks for the web sites, looks like some great information. I hooked up that headlight tonight but it ran fine, pulling a bit over 3 amps for an hour or so. Maybe I need more load to make it lose regulation. Guess I'll start digging into that regulator board, the transistors and all the big things like the transformer seem to be fine. Thanks, Kerry - WD5ABC First, test each NPN transistor with a VOM or DVM ... both methods of proper measurement are outlined (added proper method for DVM testing to procedures) Second, discharge electrolytic capacitors before removing or inserting the LM 723 Most Astron regulator boards have a socket for the LM 723, IF not after removing, install socket - observing proper placement of pin 1. Check bridge rectifier and diodes in circuit. The KBT site suggests substitution of a resistor value. There are also suggestions for bypass capacitors. Stray RF in your radio shack can cause problems in some supplies. gb |
Astron Power Supply problem
On Thu, 19 Jan 2006 23:47:24 -0600, Kerry Miller
wrote: gb wrote: "xpyttl" wrote in message ... Astron linear supplies use a 3 terminal regulator, usually an LM317. These things do tend to fail from time to time. Can't tell if that's your problem, but it is likely, and the things are cheap enough it's worth popping a new one in to find out. Really? What model of Astron linear power supply have you repaired or seen that uses this design approach? I have never seen one like this -- over past 20 years. Confusing this with some other mfg. design? Astron has been using the 14-pin (30 years old) LM 723 regulator IC with NPN pass transistors (e.g. 2N3055, 2N3771) ... for as long as I have been repairing them. Check here for correct Astron information - repairs, etc. http://www.kbt-dc-supplies.com/index.php and Astron schematics (which show the LM723, not the later LM317 design) http://www.repeater-builder.com/astr...ron-index.html gb I can confirm that mine has a 723, not a 317. Thanks for the web sites, looks like some great information. I hooked up that headlight tonight but it ran fine, pulling a bit over 3 amps for an hour or so. Maybe I need more load to make it lose regulation. Guess I'll start digging into that regulator board, the transistors and all the big things like the transformer seem to be fine. Thanks, Kerry - WD5ABC I would look at the radio first. Put an ameter in the 12 volt line to the radio and see how much current it is actually drawing. 73 Gary K4FMX |
Astron Power Supply problem
Kerry Miller wrote:
I've got a problem with my Astron RS-20 power supply. With no load, it's fine, but anything above 4amps or so makes it drop way down and my rig drops out of lock. I haven't measured it under load but the rig works ok to 10 or 11 volts so it must be dropping below that. I found a schematic and downloaded it, all the voltages are fairly close to what it says on the schematic with no load, I haven't made any measurements with a load on it. I'll pick up a headlight tomorrow to put a load on it and make more measurements. Does anybody have any ideas? Thanks, Kerry, WD5ABC Sounds like to me the "Fold-back Regulator circuit" just cut-in, during operation, if a adjusted threshold value is exceeded, instead of popping a fuse, the circuit just drops to a low value until the circuit is re-set by powering-Down and re-started ! Yukio YANO |
Astron Power Supply problem
Gary Schafer wrote:
I would look at the radio first. Put an ameter in the 12 volt line to the radio and see how much current it is actually drawing. 73 Gary K4FMX Actually, I first thought it was an antenna problem, the rig acted just like I had a bad problem with RF in the shack. I spent all of one afternoon reworking the grounds and tuning the antenna. I've got the best-tuned 4BTV in Texas! I tried it on a dummy load and had the same problem. So, I pulled it off the power supply and ran the rig (Yaesu FT-990) from the battery in my truck and it works fine. I also tried the supply on a second rig, a TS-430, with exactly the same problem - when I transmit the lights on the rig dim and it drops out of lock. The 430 is my mobile rig, it works fine in the truck but not on the PS. I'll follow you guys' suggestions to start testing parts. I'm in a fairly small town, so while I bought a 1000uf capacitor today at Radio Shack, they can't even order an LM723 so I'll have to find someplace else to get one. Have any of you guys tried the new switching power supplies? I've seen the one at Radio Shack (claims 25a but I doubt it), MFJ and Astron but haven't ever used one. I normally just run 1 HF rig (max 100w) and a small VHF rig (max 25w) for packet. Is a switcher solid and reliable enough for something like that? I've considered getting something like that and rebuilding the Astron when I can get the parts. I have built regulated supplies but it's been 20 yrs since I tinkered with anything analog, so I'll take all the help I can get! The info at those links looks helpful, along with the ideas you guys have given me here. 73, Kerry WD5ABC |
Astron Power Supply problem
Kerry Miller wrote:
Have any of you guys tried the new switching power supplies? I've seen the one at Radio Shack (claims 25a but I doubt it), MFJ and Astron but haven't ever used one. I normally just run 1 HF rig (max 100w) and a small VHF rig (max 25w) for packet. Is a switcher solid and reliable enough for something like that? I've considered getting something like that and rebuilding the Astron when I can get the parts. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You might be able to find a good deal on an Icom PS-125 switching power supply. Icom had a promotion where they gave one away with each purchase of an IC-746PRO. A lot of guys bought the '746 but didn't need the power supply and I've seen many for sale as a result. I have one and it's a great supply. I'm keeping mine :-) Check rec.radio.swap and eBay. Bill, W6WRT |
Astron Power Supply problem
On Wed, 18 Jan 2006 22:43:07 -0600, Kerry Miller
wrote: I've got a problem with my Astron RS-20 power supply. With no load, it's fine, but anything above 4amps or so makes it drop way down and my rig drops out of lock. I haven't measured it under load but the rig works ok to 10 or 11 volts so it must be dropping below that. I found a schematic and downloaded it, all the voltages are fairly close to what it says on the schematic with no load, I haven't made any measurements with a load on it. I'll pick up a headlight tomorrow to put a load on it and make more measurements. Does anybody have any ideas? Thanks, Kerry, WD5ABC Hi Kerry, Since you have the voltage, and I assume that you checked it at around 13.8 volts, and are not getting the current, there are usually just a few simple things that usually crap out on these power supplies. Please note, I have 3 or 4 RS-35s, (not an RS-20) but they are built alike, enough so, that you should be able to figure out the problem. First, providing the pass transisitors are good, and with the power off, and AC unplugged, and filter caps discharged, look on the backside of the supply, and you will see 4 sets of double paralelled 5 Watt .05 white, square inch long power resistors connected between the 4 pass transistors and BUS. Using a ohmmeter, check these for around ..025 Ohms resistance. If its a taste higher, OK... However, once you get to around an Ohm or more, your power supply will exibit the conditions you have mentioned. These resistors provide emitter pass transistor protection as I recall, and many times will fry, and you will not know it unless you measure them. If I find these resistors have gone south, I further test the supply by jumping the resistors with test jumpers. You'll know right away if the problem went away by using a test rig to draw some current. PLEASE NOTE, I have fixed quite a few Astron supplies, BUT if you blow your supply up (or test radio) even more than it is, don't blame me for any info I have provided. If it works, change out the resistors. I don't recommend you just jump them out..Oh, BTW, since you have the LM723 regulator, look on the bottom side of the board, and see if there is a resistor, hanging in mid air, which has a wire connected to it that runs down to the bottom floor of the supply, and is attached to a 3 prong transistor in a T0-220 case. Sometimes, this resistor will fry, causing current problems too.. One of my early supplies has the LM317 regulator, but, you won't have to worry about this, as this requlator is not there, however, the mounting holes (open of course) are still there on the mainboard in the upper left corner.. Hopefully, this will help.. Best Luck OM.. Tony, WB8MLA |
Astron Power Supply problem
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Astron Power Supply problem
In article GNhAf.141967$WH.127022@dukeread01, Kerry Miller
wrote: Have any of you guys tried the new switching power supplies? I've seen the one at Radio Shack (claims 25a but I doubt it), MFJ and Astron but haven't ever used one. I normally just run 1 HF rig (max 100w) and a small VHF rig (max 25w) for packet. Is a switcher solid and reliable enough for something like that? I've considered getting something like that and rebuilding the Astron when I can get the parts. Kerry- I have three switching supplies: One from Radio Shack, one from MFJ and one from Icom (PS-125). They all work quite well as far as delivering rated current. The problem is that the high frequency switching noise can be picked up by an HF receiver. The Radio Shack unit is TERRIBLE in this regard. The MFJ is fairly good and the Icom is the best. Even so, the Icom switching noise is picked up if it is anywhere near the antenna. I'm currently using a makeshift indoor antenna consisting of a dipole made of a pair of mobile whips on the second floor. Because of the noise problem, I've gone back to using an old Kenwood linear supply with my Icom 756 Pro II. This radio has the band scope, so you can see the noise floor increase across the band when the switching power supply is turned on. 73, Fred, K4DII |
Astron Power Supply problem
Fred McKenzie wrote:
In article GNhAf.141967$WH.127022@dukeread01, Kerry Miller wrote: Have any of you guys tried the new switching power supplies? I've seen the one at Radio Shack (claims 25a but I doubt it), MFJ and Astron but haven't ever used one. I normally just run 1 HF rig (max 100w) and a small VHF rig (max 25w) for packet. Is a switcher solid and reliable enough for something like that? I've considered getting something like that and rebuilding the Astron when I can get the parts. Kerry- I have three switching supplies: One from Radio Shack, one from MFJ and one from Icom (PS-125). They all work quite well as far as delivering rated current. The problem is that the high frequency switching noise can be picked up by an HF receiver. The Radio Shack unit is TERRIBLE in this regard. The MFJ is fairly good and the Icom is the best. Even so, the Icom switching noise is picked up if it is anywhere near the antenna. I'm currently using a makeshift indoor antenna consisting of a dipole made of a pair of mobile whips on the second floor. Because of the noise problem, I've gone back to using an old Kenwood linear supply with my Icom 756 Pro II. This radio has the band scope, so you can see the noise floor increase across the band when the switching power supply is turned on. 73, Fred, K4DII Thanks for the info. I picked up one of the RS supplies yesterday, and you're right, it's pretty noisy on 80m, especially on my longwire which terminates inside the shack. On 40m and above and on the outside antenna (dipole or vertical) it's fine and below my noise floor. I found a mod for it with some toroids and caps across the output to filter it a little, I'll probably try that but it's workable for now as-is since I don't work much 80m. It will keep me on the air until I fix the Astron, I'll probably put the Astron back on the HF rig and use the RS switching supply on VHF and UHF. 73, Kerry WD5ABC |
Astron Power Supply problem
Gudmundur wrote:
In article CNEzf.140599$WH.64582@dukeread01, says... I've got a problem with my Astron RS-20 power supply. With no load, it's fine, but anything above 4amps or so makes it drop way down and my rig drops out of lock. I haven't measured it under load but the rig works ok to 10 or 11 volts so it must be dropping below that. I found a schematic and downloaded it, all the voltages are fairly close to what it says on the schematic with no load, I haven't made any measurements with a load on it. I'll pick up a headlight tomorrow to put a load on it and make more measurements. Does anybody have any ideas? Thanks, Kerry, WD5ABC Is it just simply RF getting back into your supply and causing havoc? Perhaps the supply is O.K.? You need at least 3 headlights to get the supply under a load that compares to your rig. Try more lights and see if it craps out. Nothing normal ever seems to happen to me... I did go out to get a 2nd headlight so I could get about 7.75 amps on it. I found a 1000uf capacitor that had a leg corroded so badly that apparently during the move it wiggled around enough to break loose. I went to the local Radio Shack (which, by the way, has apparently turned into a cell phone store) and they didn't have any 1000uf but they did have some 470uf caps so I put two of them in parallel to get close to see if it mattered. Pins 11 and 12 showed about 8 or 9 volts too low before but now they are right on according to the chart on the Astron schematic. I connected one headlight (3.75 amps) and turned on the supply. It showed 13.59 volts. Then I connected the 2nd headlight (4 amps) and it stayed dead on 13.59 volts. Looks like I'm in business! Somebody has been into this supply before and butchered it, so I may clean up a few things while I'm in it. I guess I should fix that capacitor, the next guy in there will say the same about me if he sees 2 paralleled 470ufs instead of a 1000 uf! THanks for your help guys! 73, Kerry WD5ABC PS This post may look different, I'm on my Linux box out in the shack tonight. |
Astron Power Supply problem
....[snip]....
and they didn't have any 1000uf but they did have some 470uf caps so I put two of them in parallel to get close to see if it mattered.... ^^^^^^^^ I sure hope you meant "series"!-) --- -- --Myron A. Calhoun. Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448 NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol) |
Astron Power Supply problem
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Astron Power Supply problem
Mcalhoun must have been thinking about resistors!
"budgie" wrote in message ... On 25 Jan 2006 21:43:04 -0600, wrote: ....[snip].... and they didn't have any 1000uf but they did have some 470uf caps so I put two of them in parallel to get close to see if it mattered.... ^^^^^^^^ I sure hope you meant "series"!-) Why? |
Astron Power Supply problem
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Astron Power Supply problem
Me wrote: In article , wrote: ....[snip].... and they didn't have any 1000uf but they did have some 470uf caps so I put two of them in parallel to get close to see if it mattered.... ^^^^^^^^ I sure hope you meant "series"!-) --- I hope you are an underclassman, who hasn't actually taken any college level classes in Electronics Design or Circuit Evaluation. If not, you definitly ask for your money back, because you didn't learn anything. Me 2 470uf in parallel is close to 1000uf. This was on the Extra class Ham exam. I got my ticket 40 years ago. Why do you think an Amateur Radio Operator should necessarily have college level Electronics Design Experience? This is an Amateur newsgroup, unless cross-posting. Gary N4AST |
Astron Power Supply problem
wrote in message
ups.com... 2 470uf in parallel is close to 1000uf. This was on the Extra class Ham exam. Wow - I don't remember anything that basic when I took my Extra. ... |
Astron Power Supply problem
What makes you think that a janitor, who happens to be employed at a
university, would know the difference between series and parallel capacitors? "Me" wrote in message ... [stuff] Gary, I was not commenting on the OP's statement, but the responders question about capacitors in "SERIES".... If you will notice, in the header of his responce, he is posting from ksu.edu which is a university. Therefor he is either a Student, Professor, or Staff at that institution, and should have known better, than to post such a STUPID Reply. [stuff] Me |
Astron Power Supply problem
He may not be using a valid email address,
just like the one I just used ! |
Astron Power Supply problem
In article uwuCf.516236$084.262933@attbi_s22,
"John, N9JG" wrote: What makes you think that a janitor, who happens to be employed at a university, would know the difference between series and parallel capacitors? and just how many unknowledgeable Janitors do you think read this newsgroup.......and even if they did.....why would it be important enough to them to post such a meaningless reply..... Me |
Astron Power Supply problem
Well, perhaps because they enjoy trolling?
"Me" wrote in message ... In article uwuCf.516236$084.262933@attbi_s22, "John, N9JG" wrote: What makes you think that a janitor, who happens to be employed at a university, would know the difference between series and parallel capacitors? and just how many unknowledgeable Janitors do you think read this newsgroup.......and even if they did.....why would it be important enough to them to post such a meaningless reply..... |
Astron Power Supply problem
Mcalhoun must have been thinking about resistors!
Nope. Was thinking (if that word even applies here) about combining capacitors to reach a desired working voltage instead of capacitance !-( ....[snip].... and they didn't have any 1000uf but they did have some 470uf caps so I put two of them in parallel to get close to see if it mattered.... ^^^^^^^^ I sure hope you meant "series"!-) Why? The only alibi I can give is "a senior moment". But WOW! Umpteen follow-on responses discussing janitors, etc.! (Now I understand why the information-transfer rate on this newsgroup sometimes seems pretty low!) -- --Myron A. Calhoun. Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448 NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol) |
Astron Power Supply problem
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