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Why X68000's caps are almost broken
In 1980s, aluminum electrolytic capacitors with quaternary salt were used. It was said high performance and long life. Many companies made them. But about 5 years goes, they started leaking solutions that was high pH (having strong alkalinity). It was found that quaternary salt became alkaline belong long time use. That problems was not found in condensed test in labs. As a result, almost high performance caps in 1980 leaks in about 10 years. High pH caps not only leaks but makes short circuit. Then one day, PSU fires.
To prevent break down,we must need to renew all caps. But now, it is too late. Almost PSU is broken,isn't it?
We must replace not only caps but zener-diodes, photo couplers, some transistors, resistors, and so on. Ideally, all pars to be replaced but some parts was discontinued.
I researched succeeding parts, but it is imperfect. Any advices is welcome.
p.s. Original X68000 PSU seems not to use quaternary salt. But they are too old, so they should be replaced.
Original model
ACE (SH2 Unit)
EXPERT,SUPER,XVI,030 (SH4 Unit)
PSU part number | Part description | Specifications |
F1 | 125V 4A fuse | (MZ) smaller type Midget |
ZD31 | RD6.8EB etc. | 6.8V 500ma Zener diode |
ZD32 | RD4.3EB etc. | 4.3V 500ma Zener diode |
ZD51 | RD15EB etc. | 15V 500ma Zener diode |
PC31, PC51 | PC8170, TLP521-1 etc. | Equivalent wealth in each manufacturer |
PC52 | S12MD1, TLP541G etc. | Equivalent wealth in each manufacturer |
Q31 | 2SC2333 / 2SC2335 | |
Q32, Q33, Q53 | 2SC1815Y | Genuine is also Y grade. Is sufficient Y grade. |
C9 | 105 ℃ etc. 200V470μF | It does not fit in case board and not mounting height: 41mm or less in diameter or less to 25.8mm, 180V470μF 85 ℃ in the genuine you can not secure the electrolytic capacitor rupture time and do not keep the mounting height |
C24 | 25V1000μF 105 ℃ | |
C25 | It might be using the 25V of 105 ℃ ↑ 16V1000μF | Genuine: 16V680μF |
C27 | 25V220μF 105 ℃ | Genuine: 25V120μF |
C28 | 105 ℃ (OS-CON Allowed) 16V100μF | |
C31 | 105 ℃ (OS-CON Allowed) 16V100μF | Genuine: 10V100μF |
C33 | 16V220μF 105 ℃ | Optional: 25V products the same as the C27 |
C34 | 10V100μF 105 ℃ | Genuine: There information is acceptable if OS-CON 10V100μF of 6.3V100μF SS series (6.3mm × 9.8mm) provide information RUN's. Availability of OS-CON XPS inventory be mounted diagonally References |
C35 | 50V10μF 105 ℃ | Genuine: 25V10μF |
C38 | 50V3.3μF 105 ℃ | |
C40, C41 | 16V6800μF 105 ℃ | Genuine: 10V5600μF |
C42 | 10V2200μF 105 ℃ | Genuine: 6.3V2200μF |
R33, R34 | 100Ω 1 / 6W metallization new small | |
R35 | 3Ω 1 / 4W metal coating | Genuine: 3.3Ω |
R40 | 2KΩ 1 / 6W metal coating | |
R98 | 2.2KΩ 1 / 4W metallization new small | Genuine: 1 / 6W |