NEC PC-9821Na7
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- For more information, see this article's corresponding Wikipedia page: https://en.wikipedia.org/wiki/PC-98.
NEC PC-9821NA7
| Preliminary Information | |
|---|---|
| Release Year | 1980 |
| Leak Risk | Medium |
| Batteries | None |
| Mounting Technology | Through Hole, SMD, BGA, Sockets |
| Capacitor Types | Aluminum Electrolytic, Tantalum, Ceramic, Polymer |
| Destructive Entry | No |
NEC PC-9821 series notebook.
Known Issues
Only powers on intermittently.
Causes
- Bad PSU, bad caps, leaking battery.
Solutions
- Unknown at this stage.
Battery leakage near memory socket.
The Ni-Cd battery for the RTC and settings can leak after time. Leakage can wick up the wires to the socket, and contaminate the memory socket.
The memory socket is a Hirose SX1BA-72S-0.635SH, but they are no longer available.
Disassembly Notes
Disassembly video: https://www.youtube.com/watch?v=VlzsPEkEGVc
Being old and brittle plastic, it's easy to snap the small clips when unhooking the sides and front.
Original Parts
Mezzanine board EMMM1 94V-0 / PDU66 / EHMDD955-4.
Soldered to the lower board.
| RefDes | Qty | Capacitance | Voltage | Mount | Diameter/Size | Height | Lead Spacing | Temp | Type | Brand | Series |
|---|---|---|---|---|---|---|---|---|---|---|---|
| C01?, C02 | 2 | 180 µF | 16V | TH | 6mm | 14mm | 2.54mm | 105 °C | Electrolytic | Panasonic | HFQ |
| C16, C18, C26 | 3 | 470 µF | 10V | TH | 8mm | 16mm | 4mm | 105 °C | Electrolytic | Panasonic | HFQ |
Lower board G8TXT Z C5B
PCB on the base of the computer, with the drive connectors.
All caps not listed here are SMD ceramic or tantalum.
| RefDes | Qty | Capacitance | Voltage | Mount | Diameter/Size | Height | Lead Spacing | Temp | Type | Brand | Series |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Unlabelled?
7K2 and 8K1 above it. |
1 | 220 µF | 6V | SMD | 8mm | Electrolytic | Nichicon |
Replacement Parts
Basic PCB Name
| RefDes | Qty | Compatible Part Number | Order Links |
|---|---|---|---|
| C01?, C02 | 2 | EEU-FC1E181BJ / 35ZLJ180MTTIT78X11.5 | Digikey Mouser LCSC |
| C16, C18, C26 | 3 | EKZE160ETD471MH15D / UPW1C471MPD6 / 10YXG470MEFCT78X11.5 | Digikey Mouser LCSC |
If parts are not available or different selection is preferred, you can use the values in the Original Parts section to perform a parametric search.
Kits
- Digikey BOM: https://www.digikey.com/