Relay coil test
NOTE - NEVER USE A FILE TO CLEAN A RELAY CONTACT. USE COURSE PAPER OR A
RELAY BURNISHING TOOL.
All relays coils are 120 +/- 10% ohms. Measure the coils from the terminal strip or
at the end of your cable run if you have it on a tower. Measure from the relay terminal
to the GND terminal.
If you find an open coil it may not really be an open coil. It maybe that the
adjacent relay has an open or dirty interlock contact. The way the interlock works is
that the coil routes from each relay goes through the adjacent relay’s contacts. The
coil contacts are the ones with the small wires soldered to them. One wire per relay.
Wiggle the adjacent contact around and see if the faulting relay pulls in. If so burnish
the contact and it should work fine.
For instance A10 is not pulling in. By wiggling the armature of B10 you may find that
A10 starts working.
Many cases the spring tension of the relay that is not making good contact may need
to be increased. This is easy to do with a small needle nose pliers. Just bend the
spring tab a little to increase the tension. This will force the armature contact to be
tighter against the normally closed contact so it will clean itself better with use.
We test the relays to pull in at approximately 11.5 volts. If you put too much tension on the relay it
will not pull in and you will immediately know it.
You can use your ohm meter to trace the continuity path through the relays and
establish where the break in continuity occurs.
If the break is truly an open relay coil, then replace relay. This is
very rare.
There is also a voltage fly-back diode and bypass capacitor on each relay coil. Make
sure these components are not shorted or open. I have seen capacitors blown apart due to
lightning. If so you must take the board out of the tray and look for trace damage. If
it’s a small surge the traces can be repaired with small wires soldered to the open
trace areas.
How to adjust and maintain the SixPak
We set up the armature tension spring by applying 10 V DC to a relay
terminal and ground. If the relay pulls in then their is too little
tension on the spring. Adjust the spring tab with small needle nose
pliers to add more tension to the spring so it will not pull in at 10 V DC.
Now adjust the variable DC supply to 12VDC and the relay should pull in
very strongly. This is the correct way the relay should work.
Remember two relays are in a circuit, you must adjust the A and B side
relays on each band with the above method. The continuity through each
of the relay coils rely on the adjacent relay to have a clean and correctly
tensioned normally closed contact.
If lightning caused the damage, then you may replace the relay by taking the board
out of the SixPak by removing the 16 nuts and washers. The whole assembly will come out
of the tray including the RF connectors. Giving you access to unsolder the relay.
Test the control unit by placing power on the unit and testing for 12V DC output to
the correct terminal strips on the Radio A and Radio B sides.
The corresponding LED should also light.
If not use standard troubleshooting techniques to find the bad diode, fuse, or the
switch itself at fault. There are resistors in each LED line. A
schematic of the switch is in your manual.
Intermittent relay with my setup when I use it with band decoders or the
manual switch
We see that sometimes when the drive voltage from a band decoder or manual
switch doesn't have enough current drive or voltage level. Or the voltage
levels are on the edge of the relays threshold to pull in. Measure the
voltage levels out of your manual switch or band decoder. Make sure your
applying a good 12VDC - 15VDC with at least 100 MA to your SixPak
relays. It is not uncommon for band decoder to drop 1.2 VDC in the
output transistors or not be able to supply 100 MA to the relay if they have
other relays they are driving for instance a set of band pass filters in
parallel with the SixPak. You may have to increase the voltage to your
band decoders if the above adjustment procedure doesn't fix the problem or you
see that the voltage is not high enough on the SixPak.
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