fcwilt

Hi John, Well that was fast. Just need to determine what outputs from the processor are driving the select inputs of the multiplexer and that should be easy. Recall that on my system I am seeing that the first four sensors always reporting "unoccupied" and the last four always "occupied". That suggests that something is wrong with the signals coming out of the multiplexer OR those signals into the processor are not being processed correctly. It won't take long to check the inputs to the processor to see if they are correct. It's interesting that the power requirements are listed as 14 to 18 VAC. It should also work on DC and 14 may be higher then required. Need to run some tests. Thanks very much. Frederick

Hi, I made a mistake. I listed IC1 pin 1 going to the anode of D34 - it should have said D35 (a typo on my part). Frederick

Hi, I used the continuity/diode range on my Fluke meter. Frederick

Hi, I forgot to include this link to some hi-res photos of the RS-8 - both sides at some different lighting angles. https://www.dropbox.com/sh/saf5nuxk25cfnsu/AADHuOLSzy-1AQcyXCLVFRPMa?dl=0 Frederick

Hi, When tracing I got most of what Keith got but there were some additions and differences. Additions IC7 pin 9 to pin 1 of IC2 IC1 pin 1 to anode of D34 IC1 pin 1 to top of R24 D36 anode to anode of D34 D36 anode to left of R9 Differences IC7 pin 11 to pin 5 of IC2 IC1 pin 4 to pin 2 of IC5 D36 anode to emitter of T1 (upper BC337 of three) I admit I stopped when I found the first connection unless other connections were obvious. If the results don't make sense I will go back and do more extensive tracing. I have been a little busy today. Frederick

OK I'm up and fed. Time to take some pics and do some tracing. Frederick

Be glad to take pictures and do whatever tests you need - but it's late here and I'm going to bed. Can you wait until tomorrow (Sunday)? Frederick

Hi, Having the parts list and "silk screen" will make it much easier to reverse engineer the schematic. Thanks much. Frederick

I did some testing on the RS-8. The two 1.5K resistors are dissipating about 400 mW which may account for the heat. Poking around in that circuitry with a scope indicates nothing unusual. The outputs of the dual 4-input multiplexer are correctly indicating the occupied state of the track sensing inputs. However I have not yet figured out how the output states ultimately end up being transmitted on the RS bus. Perhaps that part of the device has a problem. Anybody have the schematic for an RS-8? Thanks. Frederick

No connection for the emitter? That doesn't seem reasonable. I will have to check my RS-8 units. Frederick

Hi Keith, I finally got my LDT RS-8 to be seen by the DR5000. The problem seems to be that the RS-8 requires the track power output from the DR5000 to be connected to BOTH sets of track power inputs (IN1 and IN2) on the RS-8. Previously I only had IN1 connected. However the "occupancy" states are wrong. See attached. The first four sensors are reporting unoccupied and that last four sensors are reporting occupied REGARDLESS of the actual circumstances. Also in the area marked in RED in the attached image a component is VERY hot. Do you suppose that hooking up the RS-8 without the IN2 connections has damaged the board? Back when I first started trying to get the RS-8 units to work I tried both of the two units I have. And both times I did not connect IN2. So if not connecting IN2 can damage a board I did it to both of mine - but that seems a rather fragile design. So could you check the area I marked in red on your RS-8 units and see if a component in that area is very hot? Thanks much. Frederick