Engineering Bulletin

Power Transformer Issue

This bulletin only applies to customers with multiple RP-8 relay panels in use.

The power supply that shipped with some RFC-1/B systems may not operate reliably in when more than one RP-8 relay panel is installed. Systems using the RAK-1 Intelligent Rack Adapter have an internal power supply so they are not affected.

  • This bulletin does not apply to systems with only one relay panel
  • This bulletin does not apply to systems using the RAK-1 Intelligent Rack Adapter

Part Identification

The RFC-1/B has always shipped with a 12VAC 1A power transformer. This document refers to one specific part. The part is identified by the following numbers:

  • Model: KA12A120100044U
  • Part #: DPA120100-S/T-TK

An image of the affected part is shown below. In addition to the part numbers, note the rounded overall shape of the part and the shape of the ID label.

image of part label

part image

The RFC-1/B has always used some variation of 12 VAC/1000 mA power transformer. Several manufacturers have been used.

We shipped parts from this supplier for several years–many with the same model number. Only a small number of supplies are affected. The parts in question shipped with RFC-1/B systems from mid 2005 through January 2006.

Using this part does not damage the system in any way nor does it present any danger to the system or personnel.

Description of Symptoms

The control relays on some channels of the RP-8 relay panel will engage and not release until either the opposite control function on the channel is engaged or until a new channel is selected. It is not predictable on what channel(s) this will occur but the condition is repeatable on a specific channel when this problem is identified.

Most of the channels will work normally. When a channel displays this symptom, it may occur on either the on/raise or the off/lower relay but not necessarily both relays.


First and foremost, verify that your system programming is correct. Specifically, make sure that the "auto control relay" feature is not enabled on the suspected channel(s).

When the auto control relay feature is enabled on a channel, the off/lower relay on that channel is engaged as long as the channel is selected. This is a feature allows the RFC-1/B to operate antenna monitors.

This kind of programming mistake closely mimics the issue described here. The RFC-1/B retains its programming when power is lost so changing the power transformer will have absolutely no effect on issues caused by incorrect settings.

Intermittent control relay operation is also frequently a symptom of lightning damage. Replacing the power supply typically has little effect in this case.


Take reasonable steps to verify the following items.

  • this symptom is not a result of surge/lightning damage
  • and you have verified the programming on the channel(s) in question in your system
  • and you have verified the part number of the power transformer in use
  • and you have also verified the physical appearance of the power transformer in use
  • and that your system was purchased during the time frame specified above

This part will be replaced free of charge during the factory warranty period. The warranty period is one year from the date the system shipped from Sine Systems.

All systems that shipped with this part are now out of warranty. Contact us to order a replacement part.