Cooling Fans
IMSAI recommends a cooling fan for systems and cabinets with more than a couple of S-100 cards installed.
It is highly recommended that all systems and cabinets with linear power supplies
(those with large electrolytic capacitors in cans), because these systems typically dissipate much more power than
newer systems and cabinets with switching power supplies.
Power Supply Compatibility
The following table lists the fan modules and their compatibility with IMSAI power supplies.
| Fan Module |
Comments |
Power Supply |
| PS-28 ¹ |
PS-28U |
PS-28S |
| FM |
100 CFM |
Yes |
Yes |
Yes ³ |
| FM 230 |
90 CFM |
No |
Yes ² |
Yes ⁴ |
| FM 12 |
55 CFM |
No |
No |
55 CFM |
| FM 12-LOW |
24 CFM |
No |
No |
24 CFM |
| FM 12-PWM |
PWM, up to 81 CFM |
No |
No |
81 CFM |
| FM 12-TC |
Temperature controlled, up to 56 CFM |
No |
No |
≤ 56 CFM |
¹ Includes PS-28 and all predecessors with 115 VAC power transformers.
² Requires wiring to the PCB switched outlet pads instead of the 115 VAC primary tap.
³ For systems on 115 VAC mains power.
⁴ For systems on 230 VAC mains power.
Newer IMSAI power supplies, beginning with the PS-28S support standard 120mm PC case fans with up to 4 pins.
PC case fans are available in a variety of designs with varying airflows.
Most of the popular online stores carry PC case fans. Just make sure they are 120mm and draw 6 watts or less.
In systems with a switching power supply, high airflow is typically not needed.
The FM and FM 230 kits come with the fan, cables, heat-shrink tubing, and instructions.
The FM 12 kits come with the fan with integrated cable and 3 or 4-pin connector and instructions.
Ordering
| Description | Part Number | Availability | Unit Price (USD) | Quantity | Ordering |
Fan, 115 VAC | FM | 4/1/2025 | $49.00 | | |
| Fan, 12 VDC, 55 CFM | FM 12 | 4/1/2025 | $19.00 | | |
| Fan, 12 VDC, 24 CFM | FM 12-LOW | 4/1/2025 | $29.00 | | |
| Fan, 12 VDC, PWM, 81 CFM | FM 12-PWM | 4/1/2025 | $29.00 | | |
| Fan, 12 VDC, temperature controlled, up to 56 CFM | FM 12-TC | 4/1/2025 | $49.00 | | |
| Fan, 230 VAC | FM 230 | 4/1/2025 | $59.00 | | |
Cabinet Fan Finger Guard, 3-ring Metal (Rev. 1) | 70-90000000 | 10 day lead time | $8.00 | | |
| Cabinet Fan Finger Guard, 6-ring Plastic (Rev. 2) | 70-90000001 | In stock | $8.00 | | |
The original IMSAI FM was the ebm papst 4530N, and is no longer in production.
You may download the original datasheet here.
The manufacturer has replaced the original fan with an “improved version.”
It is listed in the Product Change Notice.
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