kriegsfunker Posted January 7, 2019 Share Posted January 7, 2019 WARNING! This topic relates to voodoo, black magic, and horrible superstition. Anyone have luck with capacitor re-forming? If yes, what is your magic formula? 1 Link to comment Share on other sites More sharing options...
val Posted January 13, 2019 Share Posted January 13, 2019 You could try this, but i have never tried it by myself, so...use it at your own risk https://www.qsl.net/g3oou/reform.html Link to comment Share on other sites More sharing options...
Funksammler Posted January 13, 2019 Share Posted January 13, 2019 If the leakage is not too bad, I leave them in place, otherwise I replace them. I don't have a hard and fast rule for "too bad", I guess it depends on the effect on functionality. If the leakage is blowing your fuse or threatening your rectifier, I would definitely replace straight away... Regards, Funksammler Link to comment Share on other sites More sharing options...
tornfuté Posted January 14, 2019 Share Posted January 14, 2019 FS did you find easy capacitors of 10 UF 1.5 kv till 3 KV? I have oil capacitors of 1 or 2 Uf 1000v but it’s difficult to find higher regards Link to comment Share on other sites More sharing options...
tornfuté Posted January 14, 2019 Share Posted January 14, 2019 Some capacitors of 1UF 2UF and 4.7UF it’s oil capacitor as when i sake i heard oil moving difficult to insert such items in original ones Link to comment Share on other sites More sharing options...
Funksammler Posted January 14, 2019 Share Posted January 14, 2019 I have some limited old stock of HV capacitors, otherwise it is possible to build using modern Elco's. Elco's up to 500V are easily obtainable, you can put them in series for higher voltages. Because modern Elco's are so much smaller, they should easily fit in the original housing. regards, Funksammler Link to comment Share on other sites More sharing options...
tornfuté Posted January 15, 2019 Share Posted January 15, 2019 Of course but it divides the value , you need more to reach the right voltage and replacement value , hence less place inside container Regards Link to comment Share on other sites More sharing options...
kriegsfunker Posted January 15, 2019 Author Share Posted January 15, 2019 My NA8 has electrolytics in bakelite boxes. First time I have seen capacitors in bakelite. 1 Link to comment Share on other sites More sharing options...
val Posted January 15, 2019 Share Posted January 15, 2019 SAF is Süddeutsche Apparate Fabrik GmbH Link to comment Share on other sites More sharing options...
kriegsfunker Posted January 15, 2019 Author Share Posted January 15, 2019 (edited) That's the manufacturer of both NA8 power supplies that I have seen. Edited January 15, 2019 by kriegsfunker Link to comment Share on other sites More sharing options...
tornfuté Posted January 18, 2019 Share Posted January 18, 2019 It will be usefull for restoring psu that are over the usual 350 -400v to describe how to fill new elcos. i guess the german proof their elcos to high value , if we consider a working voltage of max 1000 v , i believe a final isolation value of 2.000V will be enough for such output voltage .If we put 5 elcos 120 UF 500V in serie it makes 24 uf 2500v. But i remember from school time there is neccessary to put on capacitor a resistor to avoid damages.What will be the value,? 120 UF size is 20 x 30 mm like FS said enough place to fill in original can regards Link to comment Share on other sites More sharing options...
kriegsfunker Posted January 18, 2019 Author Share Posted January 18, 2019 6 hours ago, tornfuté said: It will be usefull for restoring psu that are over the usual 350 -400v to describe how to fill new elcos. i guess the german proof their elcos to high value , if we consider a working voltage of max 1000 v , i believe a final isolation value of 2.000V will be enough for such output voltage .If we put 5 elcos 120 UF 500V in serie it makes 24 uf 2500v. But i remember from school time there is neccessary to put on capacitor a resistor to avoid damages.What will be the value,? 120 UF size is 20 x 30 mm like FS said enough place to fill in original can regards The resistor size depends on the voltage drop you want to achieve. R = Voltage drop / current 1 Link to comment Share on other sites More sharing options...
Funksammler Posted January 19, 2019 Share Posted January 19, 2019 I guess to ensure an equal DC voltage distribution over the Elco's in the chain, you could put a resistor in parallel to each capacitor. The 50Hz and higher frequencies will see a low enough reactance to automatically distribute equally over the capacitors. So at the 1000V you may want to limit the DC leakage to 1% of your rated current, let's assume you set the leakage at 1 mA, in which case you need 1 MOhm in total, giving 200 kOhm for each resistor with a minimum rating of 0.2 Watt. regards, Funksammler Link to comment Share on other sites More sharing options...
tornfuté Posted January 24, 2019 Share Posted January 24, 2019 Thanks FS may be it will help kriegsfunker if he needs to replace the HV capacitors , i remember i got a U100 in good cosmetic outside , but when i open the base the HV capacitors are explosed, guess somebody put it working and they heated and finaly explose. As a rule never try directly a set or a psu before checking all seems ok , check LV first later on HV, try without valves and then measure inside valve socket if LV is present , then HV, add fuses to protect the set and caution when using U80 or U100,Na8 Sglt100 , it’s lethal voltage Link to comment Share on other sites More sharing options...
val Posted January 24, 2019 Share Posted January 24, 2019 2 hours ago, tornfuté said: add fuses to protect the set and caution when using U80 or U100,Na8 Sglt100 , it’s lethal voltage For testing PSU ordinary Incandescent light bulb in series in 230V circuit limits current when something bad happens - i prefer it to fuses. When bulb light up you see right away that there's a problem and it's natural property to limit current is invaluable. https://www.vintage-radio.com/projects/lamp-limiter.html 1 Link to comment Share on other sites More sharing options...
kriegsfunker Posted January 25, 2019 Author Share Posted January 25, 2019 All the capacitors are finally out: 1 1 Link to comment Share on other sites More sharing options...
Funksammler Posted January 25, 2019 Share Posted January 25, 2019 Indeed, to test a mains power supply, use a Variac and slowly increase the voltage. You will find out if you have a problem long before you reach full voltage. regards, Funksammler 1 1 Link to comment Share on other sites More sharing options...
Afrikakorpsrat64 Posted January 25, 2019 Share Posted January 25, 2019 On 06/01/2019 at 18:36, kriegsfunker said: WARNING! This topic relates to voodoo, black magic, and horrible superstition. Anyone have luck with capacitor re-forming? If yes, what is your magic formula? I wish my dad was still alive, he would love all this! He repaired old Radios etc, and later TVs . Worked for Lockheed Missile and space. I used to have 100's of old tubes, capacitors, transformers etc. Great stuff Guys! 1 Link to comment Share on other sites More sharing options...
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