Table of Contents
Unitron Frequency Converter
Starting 1/24/2019, trying to fix the Unitron Frequency Converter, located at ClayLacy, which is not working properly when connected to the Challenger 604.
| Model | GFC-25M |
|---|---|
| Part No. | 195-39000-19 |
| Serial No. | 658 |
| Date Mfd | 2/26/97 |
| kVA | 25 |
| P.F. | 0.8 |
| Max Weight | 700 lbs. |
| Input | 480 Volts, 60 Hz Max Amps 27, Phase 3 |
| Output | 115/200, 400 Hz Max Amps 73, Phase 3 |
| Output Pin Out | A - Phase A B - Phase B C - Phase C D - Grounded Neutral E - 28 VDC Safety Signal Out F - 28 VDC Safety Signal In |
| Unitron Contact | Patrick McCormick 214-340-8600, X192 |
|---|
Photos
Click to enlarge
Notes
On 1/24/2019, measured output of Pin F on the Challenger 604, and it measures 24 V (different than the expected 28 V). However, connecting the Frequency Converter to the Challenger and in Remote mode, power seemed to be flowing fine. Turning on the avionics was successful. 116V and 400 Hz was reported. Everything was fine when turning on Hydraulic pump 1, and pump 2, but when pump 3 was turned on, the aircraft disconnected and immediately powered off without comment.
We repeated this, while looking at the meters on the GFC-25M. The volts meter dipped a bit, perhaps 2 or 3 volts, the amp meter swung somewhat indicating load, and it chirped, but the plane powered down on the activation of pump 3 as before.
We cleaned the input plug, sanding the main 115V power pins. Sprayed with contact cleaner, repeated test, same result, although it seemed to do worse, perhaps shutting down on the activation of Pump 2 or even Pump 1 this time. Discontinued testing to not hurt the avionics.
* Called 2/5/2019, 9:50 a.m. PT, no answer. * Called 2/6/2019, talking with Barry
Plug
Replaced the plug which connects to the aircraft. The old one had a lot of corrosion, and the sockets look like they were not as tight around the pins as they should be. The new ones are silver plated copper.
The general part number is MS25486, which is a standard. The part number on the original plug is 195-60044-1-30
Replacement 400 Hz, AC 1/0 GPU Connector Plug, 6-Pole Female, $299.00 (received 6/21/2019).
Capacitors
There have been problems with the Unitron GPU. When connected to the Challenger 604, and when engaging heavy load (all of the hydraulic pumps), the Challenger disconnects from the power.
After various troubleshooting activities, and after the manufacturer suggested it, I measured the AC Filter capacitors, and it appears that 11 of the 18 are not working. That is, they don't show the 25 uf that they should have. Internally they may be open.
6/23/2019
Talked to Barry today. He said the part number is 150-18065-1. He said to call back tomorrow X138 and they can sell me the capacitors. He thought they would be less than $15 each.
6/25/2019
Ordered 18 capacitors from Unitron today, about $10 each, requesting fastest shipping.
6/26/2019
Capacitors arrived, tested OK, installed in unit today.
6/27/2019
Following is a diagram, drawn as though viewed from the top, and the bottom of the drawing is closest to the front door. It shows dots (“d”) and lines that I drew on the white wires before removing them to do the capacitor replacement.
Measured capacitors after removal. As expected, 11 were bad, 7 were good. The 7 good ones I put into the tool cabinet in the hangar.
Capacitors reinstalled
In addition to installing replacement capacitors, I also tightened the push-on connectors for better connections.
They report that the GPU is not working correctly with the Challenger 604. 7/3/2019.
New Capacitor Closeup
