|
Sending power into rig unused for 30 years : Precautions ?
Now retired I'm trying to become active again.
My TS-520S has not been on for 30 years. I don't have a variactor ( variable transformer ). At the TARC advice was to put a lightbulb in series to take the surge. Should I use a high resistance ( low wattage ) bulb or vice versa ? Would this be as good as a simple L-C network ? Somebody said just plug it in. Are there any other ideas ? Thanks for your kind assistance. Dave WB3DWE Temple, TX |
Sending power into rig unused for 30 years : Precautions ?
Now retired I'm trying to become active again.
My TS-520S has not been on for 30 years. I don't have a variactor ( variable transformer ). I'd strongly encourage you to ask around, find somebody who has one, and do the power-up with the variable-voltage transformer. Take your time - ease the voltage up from zerch to nominal over a period of a few minutes. At the TARC advice was to put a lightbulb in series to take the surge. Should I use a high resistance ( low wattage ) bulb or vice versa ? If you do this, do the former... low-wattage. You want to power up the rig *slowly*, so that the dielectrics in the electrolytic capacitors have a chance to re-form gently. The lower the wattage of the bulb (the higher the resistance) the longer it'll take to charge the power supply fully and the lower the final voltage will be. You could do it in stages. Wire up a standard light-bulb socket in series with a power cord for the rig. Start out with a 5-watt bulb, power up, let the rig sit for a few minutes, power down again, switch to a 25-watt bulb, repeat the process again... then go to a 100-watt bulb, then a 200-watt bulb. This approach isn't as effective, or as controllable, as using a Variac or similar variable-voltage transformer. The bulb's resistance will be low when it's cold, and will rise when it heats up... so it won't limit the initial inrush current all that effectively. Would this be as good as a simple L-C network ? Somebody said just plug it in. It might easily go BOOM if you do. If it's been sitting around un-powered for 30 years, the dielectic oxide layer in the power supply caps may have thinned and developed pinholes... hitting it with full mains voltage and no current limiting could result in a sudden short circuit inside the caps. They're quite spectacular when they blow... messy, though. Are there any other ideas ? Negative-temperature-coefficient resistor instead of a light bulb? These are used as inrush suppressors in switching power supplies... their initial resistance is high when they're cold, and drops when they warm up. Borrowing the use of a Variac for half an hour is still a better way to do it, I think. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
Sending power into rig unused for 30 years : Precautions ?
On Aug 16, 4:03 pm, (Dave Platt) wrote:
Now retired I'm trying to become active again. My TS-520S has not been on for 30 years. I don't have a variactor ( variable transformer ). KISS. Wire a 60w light globe in series, turn it on, let it sit for a few hours. Filaments OFF for this test. Havent used a variac for this for years - reason - its the switch on current surge thats going to kill old electros, and the variac has no current limiting whereas the light bulb does. You will see a brief "Flash" as the caps charge up, then maybe a dull glow, eventually, no light at all. Given that the caps used were / are modern, and of good quality to start with, the KISS method works well. Oh, BTW - when all this is done, apply full mains power, let the tube filaments soak for a few hours lest they have gone gassy. Andrew VK3BFA. |
Sending power into rig unused for 30 years : Precautions ?
I tell you what Dave:
Save the grief and replace the caps. What your'e doing is betting that you can reform the electrolyte that may be left in the capacitors after 30+ years. I hope you win that bet. 73 OM n8zu |
Sending power into rig unused for 30 years : Precautions ?
Andrew VK3BFA wrote:
On Aug 16, 4:03 pm, (Dave Platt) wrote: Now retired I'm trying to become active again. My TS-520S has not been on for 30 years. I don't have a variactor ( variable transformer ). KISS. Wire a 60w light globe in series, turn it on, let it sit for a few hours. Filaments OFF for this test. Havent used a variac for this for years - reason - its the switch on current surge thats going to kill old electros, and the variac has no current limiting whereas the light bulb does. You will see a brief "Flash" as the caps charge up, then maybe a dull glow, eventually, no light at all. ============================================== Don't understand the above. When using a variac starting at zero and gradually increasing the voltage there can't be any appreciable inrush current. I happen to have a 8 Amperes variac and would always use it to 'fire-up' a previously retired oldtimer (boat anchor) I have a rather large junk box with high capacitance value elcos and recently exposed them all to a 'zero to max working voltage' from an adjustable HV PSU. I do that once every 3 years. Frank GM0CSZ / KN6WH |
Sending power into rig unused for 30 years : Precautions ?
On Aug 18, 1:38 am, (Edmund H. Ramm) wrote:
In Andrew VK3BFA writes: Are physics reversed down under? Up here in the old world a light bulb's filament (tungsten) resistance increases with temperature. Er - yes, thats correct.So whats the problem? Andrew VK3BFA. |
Sending power into rig unused for 30 years : Precautions ?
On Aug 17, 11:21 pm, Highland Ham
wrote: ============================================== Don't understand the above. When using a variac starting at zero and gradually increasing the voltage there can't be any appreciable inrush current. I happen to have a 8 Amperes variac and would always use it to 'fire-up' a previously retired oldtimer (boat anchor) I have a rather large junk box with high capacitance value elcos and recently exposed them all to a 'zero to max working voltage' from an adjustable HV PSU. I do that once every 3 years. Frank GM0CSZ / KN6WH Well, mine took out a few SMPS power supplies, and its a pain in the arse to set up, connect meters, gingerly spend time slowly incrementing the voltage - life is too short to stuff around...... Hey, you got time to do Rocket Science, thats fine. Each to his own. Andrew VK3BFA. |
Sending power into rig unused for 30 years : Precautions ?
On Aug 20, 8:27 am, (Edmund H. Ramm) wrote:
In Andrew VK3BFA writes: There will only be negligible inrush current limiting. For that you'll need an NTC resistor like an Epcos NTC22. All you get from a light bulb is a voltage reduction -mains voltage minus the voltage drop across the bulb- but only AFTER the inrush current you intended to prevent has already flown. A light bulb in series with an inrush current limiter might be suitable for smoke testing equipment after prolonged disuse, though. Yes. Whats the DV/DT of the positor versus a light bulb? - I got no idea..... The light bulb method works - its quick and dirty, and so far I have never blown an electrolytic capacitor using this method. Its also VERY useful in firing up SMPS devices - it does current limit quick enough if theres a gross fault to prevent damage. But, each to his own. Of more concern would be corrosion /freezing of pots/switches etc. And a 30 year old mains power cable? - mm - and what about checking the insulation resistance of the power transformer.. But it ain't the Space Shuttle - live dangerously...Just Do It.... Andrew VK3BFA. |
Sending power into rig unused for 30 years : Precautions ?
The light bulb has advantages. It will light up if there is a short. You
can build a rig tester by just putting an outlet in parallel with the light switch, turn it on then plug in and turn on the Rig, then turn off the switch. The light should dim and never get brighter. |
| All times are GMT +1. The time now is 04:13 AM. |
Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
RadioBanter.com