Digital Rainbow PC100B Power Supply
| This device is in the WorkNeeded:OriginalParts category because it was flagged as missing information on the original parts. It may have replacement parts listed but those cannot be assumed to be identical to the originals. If you have a list of the original parts, please feel free to add them by copying the relevant table from EditorsToolbox:Tables | 
|
| Preliminary Information | |
|---|---|
| Release Year | 1982 |
| Leak Risk | Unknown |
| Batteries | None |
| Mounting Technology | Through Hole |
| Capacitor Types | Aluminum Electrolytic? |
| Destructive Entry | No |
The Digital Equipment Corporation Rainbow PC100 is an odd amalgamation of a VT100, Z80-based CP/M computer, and early DOS PC. It has both a Z80 and Intel 8088 CPU on the same motherboard and the system ROM also supports running as a VT100.
Known Issues
Symptom or Problem Encountered
The circuit breaker immediately trips when power is switched on.
Causes
- power transistor failed, shorting the 12V output to ground
Solutions
- Replace the failed transistor and also a diode array that had also failed-short
Disassembly Notes
It comes apart really simply. 4 screws to take the top of the case off, two more to detach the IEC socket, then disconnecting plastic connectors to be able to get to all of the screws holding the board down. There was one security Torx screws (size?), the rest are #2 Phillips.
The parts that went bad for me are circled in this picture:
Original Parts
Basic PCB Name
Note model numbers and board revisions here
| RefDes | Qty | Capacitance | Voltage | Mount | Diameter/Size | Temp | Type | Brand | Series |
|---|---|---|---|---|---|---|---|---|---|
| 0 µF |
| RefDes | Qty | Part # | Mount | Type | Brand | Series |
|---|---|---|---|---|---|---|
| 1 | BUV48A | TO-247-3 | ||||
| 1 | FE16C | TO-220 |
Replacement Parts
Basic PCB Name
| RefDes | Qty | Compatible Part Number | Order Links |
|---|---|---|---|
| 1 | ST BUV48A | Digikey Mouser LCSC | |
| 1 | NTE6240 | https://www.digikey.com/en/products/detail/NTE6240/2368-NTE6240-ND/11648400 |
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.