Da audio_fan Lun Dic 11 2023, 07:29
Ho un amplificatore anni '70 con pochissime ore di accensione (vicino a zero negli ultimi 40 anni, alcune migliaia nei primi anni di vita) apparentemente è funzionante (al massimo necessita di essere spolverato).
A mio avviso però la prestazione dei condensatori non può essere valutata con un semplice "funziona / non funziona", il degrado delle prestazioni può essere parziale e non non sono sicuro che si possa scoprire a orecchio a meno di non disporre di un apparecchio gemello con i condensatori nuovi.
Da una discussione simile ho estratto un illuminante intervento di un utente che si definisce un "esperto di componenti, ora in pensione" ("retired component engr"):
"Not all electrolytics are the same. There are general purpose caps designed for 60 Hz and 120 Hz filter applications and a separate series low-ESR caps for switching power supplies. Put GP caps in a switcher and they will most likely fail. If the cap series isn't labeled low-ESR and the ESR isn't specified @ 100 KHz, then they shouldn't be used in low ESR applications. Many quality name-brand electrolytics are specified at 2000 hrs at their rated voltage, temp, and ripple-currents. So pushing their "envelopes" application-wise will shorten their lives, especially in high-temp, high ripple-current environments. If you ARE "pushing their envelopes", higher reliability caps are available. I have had very good luck with all quality name-brand caps: CDE, Nichicon, RubyCon, Mallory, Sprague, Panasonic, etc. Even Samwha, Samxon, and Elna, demonstrated good reliability. For demanding pwr sply applications, I will not use a no-name economy electrolytic. As a retired component engr, I also evaluated the sqr inches of foil in any potential alternate supplier's caps. I performed a detailed "autopsy" (aka teardown) of all caps evaluated and compared that "autopsy" against a gold-standard. The cheaper, smaller, no-name caps are just too small to replace their original brand-name caps in high ripple-current environments. They will fail..... Also, if ambient temps are higher, use 105°C caps instead of the 85°C, as their reliability will be higher. Many electrolytic failures can be traced to application-specific environments - it's not the caps fault."
Note: ESR = resistenza interna; GP = lo interpreto come General Purpose Non ho messo il google translate perché "caps" diventa "cappellini" e non mi è sembrato il caso.
https://www.antiqueradios.com/forums/viewtopic.php?t=152947