RFC-1 Troubleshooting and Factory Service page 8.2
Problem: There is hum on the line when the RFC-1 answers a call but there is no hum when operated locally.
Solutions: The telephone line may be shorted or the telephone line is too long and is receiving interference. Check
the line. If it is okay, try shielded cable and an off-the-shelf inline filter to eliminate the offending signal.
Depending on the frequency of the interference ferrite beads, filter capacitors or chokes may be
necessary.
Problem: The RFC-1 operates normally from the local phone but works intermittently from remote locations.
Solutions: Check the telephone line for problems or interference and eliminate any problems on the line. Try
shielded cable and an off-the-shelf inline filter to eliminate the offending signal. Depending on the
frequency of the interference ferrite beads, filter capacitors or chokes may be necessary.
If the RFC-1 only fails to recognize tones from a specific location, it is likely that there is something
unusual about the phones at that site. Many phone systems produce only short tone bursts when a key
is pressed. These tone bursts are typically on the order of about 50ms. The RFC-1 requires 40ms of
clean tone to detect and decode. It only takes about 10ms of distortion to make this fail. Some
telephone systems (and cellular phones) have longer tones as a programming option.
Line level can also be a factor particularly with cellular phones. The tone detector in the RFC-1 is not
adjustable but passing more signal into the detector can be helpful in this situation. Possible adjustments
to the system vary by board revision. A very detailed discussion is available on our website:
http://www.sinesystems.com.
Problem: The telephone line to the RFC-1 always rings busy when the RFC-1 is connected to the line. When the
RFC-1 is not connected to the line, the telephone rings normally.
Solutions: It is very likely that memory address 0996 was overwritten by accident when the site ID phrase was
reprogrammed. Reprogram address with the value “1” and the RFC-1 should return to normal operation.
Here is the procedure step by step. Enter the keystrokes in bold type.
1. Connect with the RFC-1/B from the local phone
2. Enter the programming mode: 80
3. The RFC-1/B will prompt for the advanced programming security code: 4150
4. The RFC-1/B will prompt for a four digit address: 0996
5. The RFC-1/B will repeat the address and wait for a command
6. Enter the correct value and press the pound key (#): 1#
7. Exit the programming mode by pressing the star (*) key: *
8. Disconnect from the RFC-1/B and hang up: 99
Problem: A latching control relay contact is needed and the RFC-1 control relays only momentary activation.
Solutions: The RFC-1 cannot latch the control relays. An outboard latching relay is required. A dual-coil, latching
relay is probably easiest to connect. Select the coil and contact ratings as required for the specific
installation. Use the RFC-1 control relays to switch the control voltage to the coils of the latching relay.
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