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Old 7th February 2018
  #15
Here for the gear
 
Opened my beloved JD-990 today and checked 100uF 6V capacitor found on SR-JV80-04 Vintage Synth card using LCR meter. I'm glad I did! Capacitor's ESR was 4.2 Ohm which is way to much for a 100uF cap, so I replaced it with a 100uF 25V SMD cap I happened to have on hand. The replacement cap is Nichicon UCW1E101MCL1GS (Digikey part # 493-9418-1-ND) with 7000 Hrs lifetime @ 105°C. Measured ESR is now 0.8 Ohm, which is about right.

High ESR means that electrolytic capacitor dried up and lost its properties. Since JD-990 digital electronics is powered by +5V, that 100uF cap rated for 6V has very little margin and when degraded, has high chance of exploding. So it's a ticking bomb :(

If you are using SR-JV80 cards, you must replace that electrolytic capacitor as soon as possible. Roland's recommendation to stop using these cards on their Japanese site is no joke. I wonder why they did not post it on English site.

/Peter
Attached Thumbnails
Exploding JV2080 expansion card-sr-jv80-04_100uf_6v_original.jpg   Exploding JV2080 expansion card-sr-jv80-04_100uf_25v_replacement.jpg.jpg