Seattle, WA. 98115

206.522.0908 phone 206.522.5292 fax

BOARD IN A TRANSWORLD A1-5020 CONTROL.

Turn off power to the control at the wall breaker.  Turn the control around so you are facing the back.  Remove the back upper panel held by 6 screws.

On the right side (facing the back) you will find two boards "piggy backed". The upper board is the Logic board and it must be removed to get at the Power Supply board. Remove the upper board by removing 1 or 2 screws at the top of the board. Remove the wire harness that is plugged into the Logic board. Now unplug the Logic board from the J102 connector on the Power Supply Board and lay aside. Now is a good time to clean the pins on the card edge connector of the Logic board with a soft rubber erasure.

The Power supply board is the board remaining. It is held by one or two top screws and sits on what appears to be screws, but are actually mounting studs and do not need to be removed. Remove the top 2 screws (generally there is only one due to previous service and the back one is seldom replaced) thus freeing the Power Supply board and the metal chassis to which it is mounted. There are 4 small wire harnesses that attach to the PS board and they must be unplugged. Note the colored wires and which plug connects to which connector. NOTE: There is a relay (RY7 as I recall) that tends to interfere with PS board removal. I generally remove it and set it on top of the control for replacement later. It can only go in one way to its socket as you can see, so note the orientation.

Now examine the screws that hold the Power Supply board to its chassis. There are probably about 6 of them; some on the edges, and some are in the middle of the board and go into "standoffs". You can see by inspection how to remove them. Note how the chassis goes back on for re-assembly.

At the end of the board there are a number of colored wires that attach to a row of terminals on TB8. The enclosed part of the Point to Point drawing gives the color code but I suggest that you can either write down the color codes; or you can carefully interchange the new board with the old wire by wire. I generally "interchange" as I find it less prone to error.

After replacing the wires and verifying that all terminal screws are tight, replace the chassis. Re-assembly in reverse order, remounting the Power Supply board, installing the relay, and connecting the wire plugs. Now insert the logic board and replace the top screw. Note that this screw is a slightly smaller screw than the ones used for the Power supply board and we don’t know why but it is. Plug in the wire harness.

Turn the wall breaker back on and test.  Put the cover back on and you should be back up and running.

WE NO LONGER SELL REBUILT POWER SUPPLY BOARDS.  (6/03/2011)

You may call for additional assistance if required during business hours. The Point to Point drawing and Schematic for the A1-5020 Control is on our website Leswilkins.com.

Roy M. Duncan,  President

Last Updated 1/30/2012

Copyright 1999