OPEN COIL ON REED RELAY WHEN TESTING THE PCB
I found that one of the relays had a completely open coil. Excavating to try to find live ends of the coil wire was not successful, leaving me no choice but to replace it. The manufacturer, Elec-Trol, no longer exists nor is anyone making current versions of this part. It is a 48V coil with a DPDT switch.
BOUGHT TWO FAST MODERN SPDT REED RELAYS
I purchased a couple of Potter & Brumfield SPDT reed relays - can handle the contact voltages and currents but have 5V coils. Using a dropping resistor in series with the two relay coils will give me the right current and voltage.
The relay has a 200 ohm coil and draws 25ma when operating, with a minimum of 3.8V across the coil needed to operate and a maximum of 6V. At 25ma, that means a resistor of 1.6K would do the job. It will dissipate 1 watt but to ensure cool operation I will uses a 2W resistor. This gives the voltage across each coil of 4.8 to 5.1V with the range of voltages seen from the 1130's 48V power supply.
WHIPPED UP SMALL PCB FOR CLEAN INSTALLATION
I whipped up a small PCB to mount the two relays and the dropping resistor. I set up pads to insert and solder wires that will hook this to the main PCB where we are replacing a relay. I chose the low cost but pokey delivery service from China, claimed at 8 to 13 business days after the PCB is fabricated. I expect this to come in three to four weeks, which is plenty of time to add it to the 1132. That dropped my total cost to under $7 for the batch of five PCBs.
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