RMweb Premium melmerby Posted July 24, 2016 Author RMweb Premium Share Posted July 24, 2016 (edited) Hi John Post #13 I uploaded some status pictures and I have the LDT timing ticked, I assume that's correct? I did swap around the J and K feed to my layout and TrainController now reports all occupancy. It seems the JK sensitivity with the LDT boards affects the DR5000 somehow Next RS-8 connexions: IC9 Pin2 goes to IC6 pin1 = IN1 K, it's the DCC signal to rest of the circuitry IC7 pin 15 goes to IC2 pin 4 IC7 pin 13 goes to IC2 pin 2 IC7 pin 11 goes to IC2 pin 1 Keith more to come IC6 pin 11 goes to IC2 pin 14 IC6 pin 13 goes to IC2 pin 15 IC1 pin 1 goes to IC4 pin 5 IC1 pin 4 goes to IC5 pin 3 IC1 pin 8 goes to top of R18 IC1 pin 9 goes to top of R20 + IC2 pin 3 D36 goes to T2 emitter The last time I traced things out was before I retired from my electronics job 20+ years ago!! I've also go a spare RS-16 if anybody's interested in more circuitry! Edited July 24, 2016 by melmerby Link to post Share on other sites More sharing options...
fcwilt Posted July 24, 2016 Share Posted July 24, 2016 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 Link to post Share on other sites More sharing options...
fcwilt Posted July 24, 2016 Share Posted July 24, 2016 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 Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted July 24, 2016 Author RMweb Premium Share Posted July 24, 2016 (edited) 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 Hi Frederick Did you trace visually or use a DMM? I shone a very bright light through the board to see where the tracks went and then used a DMM to confirm. I expect an odd mistake! Cheers Keith Edited July 24, 2016 by melmerby Link to post Share on other sites More sharing options...
fcwilt Posted July 24, 2016 Share Posted July 24, 2016 Hi, I used the continuity/diode range on my Fluke meter. Frederick Link to post Share on other sites More sharing options...
john barry Posted July 24, 2016 Share Posted July 24, 2016 Hi, Frederick, from post #27 you have IC1 pin 1 to anode of D34. Could you check that because D34 seems to be in the isolated R-S section. I would use the Fluke on the lowest normal ohms range and only count connections less than a few ohms. The diode/continuity setting may turn semiconductors on. 30 years ago I worked in a production facility with a 'bed of nails' automatic board tester made by Genrad (near Boston). It was an impressive thing capable of testing the naked board and then the assembled board including tests of each component right up to processor chips. It pretty well eliminated any need for diagnostic fault finding. I often wonder what might be possible now with modern computing power. Pleasing to see that the R-S section is pretty close to the one in the on line description I posted before. Its always easier to draw the circuit if you know what to expect. As promised a quick summary of my method: 1. If lucky start with parts list and silk screen. Otherwise make a big enough picture, assign names to all components, mark on picture and make up parts list. 2. Designate all component pins (eg R1-left, R1-right, IC3-1 etc) and add to parts list. The photocopier is your friend here, keep unmarked copies for error recovery. 3. Generate a 'netlist'. This is a list of groups of things that are connected together. As each pin is added to a group it is crossed off the parts list. This is the hard part...especially from photos! Sometimes it is necessary to just look for continuity from a pin to every other pin to be sure. COntinue until all pins are crossed off the parts list. 4. Draw circuit from (a copy of) the netlist, crossing pins and groups off as you go. This often requires restarts and revisions as the picture emerges, re-arranging the layout for clarity. This is pretty foolproof but requires patience. I have never tried it before without having the actual board. I once tried putting the netlist into pcb drafting software to get a schematic but the results were disappointing. -john Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted July 24, 2016 Author RMweb Premium Share Posted July 24, 2016 (edited) John Did you mean D36 cathode? Here is an underneath view of the area around D36, D34 and T1, T2 & T3: the two arrowed points are connected I make that D36 cathode and T2 emitter R9, D34 & D36 are all connected RH side Keith Edited July 24, 2016 by melmerby Link to post Share on other sites More sharing options...
john barry Posted July 25, 2016 Share Posted July 25, 2016 Yes Keith. D36 cathode was the missing link I couldn't see. There must be some more connections around T2 and T3 to make a current source. Also so far I haven't any idea where T4 fits in. Updated schematic coming soon. Frederic have you decompiled the code yet? Just kidding! -john Link to post Share on other sites More sharing options...
john barry Posted July 25, 2016 Share Posted July 25, 2016 Here is v2. I have taken both your replies and put in what seems right. I have placed all the components but some unnconnected. C1, C2, C3 are OK just 5V bypass. I think R24 220K will be pull up or down on the link IC-1 to IC4-5 as in the points decoder. Check needed. IC5-1 probably has a pull up resistor to 5V Still missing IC2-9, IC2-10 IC1-3, IC1-10, 11, 12 IC8-3, IC8-4 Area around T4, D37, D38, C5, C6 which will be power supply. -john Link to post Share on other sites More sharing options...
fcwilt Posted July 25, 2016 Share Posted July 25, 2016 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 Link to post Share on other sites More sharing options...
john barry Posted July 25, 2016 Share Posted July 25, 2016 Interesting use of IC4 and IC9. IC9 would be on continuously if DCC was present on IN-1 as it is an AC optocoupler. This would 'enable' IC4 to pass the IN-2 DCC to the processor via the 'dodgy' LDT standard circuit. So both DCC connections are required. Only experiment will show if this is just for address setting (when it is essential) or if they have used the firmware to make it a requirement for normal operation. For the future...write Arduino / ATmega code and make my own one, just for the satisfaction. Only if I can completely understand RS Bus signalling. -john Link to post Share on other sites More sharing options...
john barry Posted July 25, 2016 Share Posted July 25, 2016 From post #13 23rd July Frederick asked 'Anybody have the schematic for an RS-8?' Well here it is: Only two connections between IC2 and IC1 missing and I'm not to sure about the area around T2, T3 and R11. It should form a 3mA current regulator. Thats it. SWMBO says I have been sitting here too long. -john Link to post Share on other sites More sharing options...
john barry Posted July 25, 2016 Share Posted July 25, 2016 OK one more go. https://sites.google.com/site/dcctrains/rs-bus-feed/hardware shows how the current source must be. -john Link to post Share on other sites More sharing options...
fcwilt Posted July 25, 2016 Share Posted July 25, 2016 (edited) 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 Edited July 25, 2016 by fcwilt Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted July 25, 2016 Author RMweb Premium Share Posted July 25, 2016 (edited) Interesting use of IC4 and IC9. IC9 would be on continuously if DCC was present on IN-1 as it is an AC optocoupler. This would 'enable' IC4 to pass the IN-2 DCC to the processor via the 'dodgy' LDT standard circuit. So both DCC connections are required. Only experiment will show if this is just for address setting (when it is essential) or if they have used the firmware to make it a requirement for normal operation. -john Won't the optocoupler be passing the the DCC waveform (basically square) clipped to the level across the back to back diodes (approx 1.2v P-P) through to the next component? LDT say this: "Important for a correct feedback report is: It is absolutely required that both inputs ( IN1 and IN2) will receive the supply of digital current" Re pin outs to the Z86E08 CD4052 pin 9 goes to Z86 pin 12 CD4052 pin 10 goes to Z86 pin 11 Keith Edited July 25, 2016 by melmerby Link to post Share on other sites More sharing options...
john barry Posted July 25, 2016 Share Posted July 25, 2016 Hi Keith, "Won't the optocoupler be passing the the DCC waveform (basically square) clipped to the level across the back to back diodes (approx 1.2v P-P) through to the next component?" The answer is no because the LTV844 optocouplers use two leds one each way so whichever way the DCC switches one led is on and the phototransistor gets constant light and stays conducting. An optical full wave rectifier if you like. S88 modules (at least the ones I have) use exactly the same arrangement. Thats why a single led opto is necessary to get the DCC signal for decoding. In the real world the DCC transitions have a rise time so there could be dropouts on transitions but it is a few uSec at most. Probably the opto output response time would mask it. Something to check with the oscilloscope some time. I don't have the plots to hand but I did compare rise times of the Lenz LZV100 and the DR5000. The Lenz is very fast and very clean. The DR5000 less so with a slight step at the zero crossing in both directions. I will look up the figures tomorrow. I suppose I will do the final schematic version tomorrow. I worry slightly about leaving all the previous versions there. J.F. wouldn't like it. -john Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted July 25, 2016 Author RMweb Premium Share Posted July 25, 2016 (edited) Hi John You have KL7 & KL8 reversed KL7 is AC input, KL8 is RS output. Cheers Keith EDIT Been poking around with my scope. Unfortinately since I last used it the trigger has decided to play up. Although the timebase trigger light comes on when you adjust trigger level it does not lock the display! Must get something more modern (and compact.) Last time I switched it on I had to repair the blanking stage. (It is a Tek 7704A which is 44 years old!) Edited July 25, 2016 by melmerby Link to post Share on other sites More sharing options...
fcwilt Posted July 25, 2016 Share Posted July 25, 2016 Hi, Well I scoped the inputs of the processor and the correct signals (based on occupancy) are appearing at the inputs. So either something has gone wrong with the processor OR there is still something wrong with the DR5000 implementation of the RS bus. I went ahead and ordered an RS-8 and an RS-16 in kit form. Perhaps these will help find the solution to getting the DR5000 working with the RS bus. I used to have an small electronics R&D firm and we had many Tektronix products. When I closed the company I got rid of all of the gear to schools and such. Years later I wanted a scope again so I got the B model (now discontinued) of this unit: http://www.testequipmentdepot.com/tektronix/oscilloscope/tds2024c.htm Very happy - does a lot more then the old stuff I used to have. Frederick Link to post Share on other sites More sharing options...
john barry Posted July 25, 2016 Share Posted July 25, 2016 My oscilloscope story: My last job was 15 yrs at a large government research establishment. They occasionally sold off old equipment and I now have a 7704A with a collection of plug ins, a 453A (portable) and my pride and joy a 531A with trolley and many plug ins including a spectrum analyser. My problem was becoming used to using state of the art digital scopes at work and it is hard to go back so now I use a PC based PicoScope and the beautiful old collection gather dust under Amsterdam Centraal. https://www.youtube.com/watch?v=b4KBJ__IvcE The 7704A is the only one I've had to repair...tantalum capacitors gone shorted. They all still work although the valve (tube) based spectrum analyser is too unstable for real use. I recommend the PicoScope. Base model for ~$200 and I was amazed to find it even decodes DCC. With a laptop it is good for floating measurements too. -john Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted July 25, 2016 Author RMweb Premium Share Posted July 25, 2016 (edited) My oscilloscope story: My last job was 15 yrs at a large government research establishment. They occasionally sold off old equipment and I now have a 7704A with a collection of plug ins, a 453A (portable) and my pride and joy a 531A with trolley and many plug ins including a spectrum analyser. My problem was becoming used to using state of the art digital scopes at work and it is hard to go back so now I use a PC based PicoScope and the beautiful old collection gather dust under Amsterdam Centraal. https://www.youtube.com/watch?v=b4KBJ__IvcE The 7704A is the only one I've had to repair...tantalum capacitors gone shorted. They all still work although the valve (tube) based spectrum analyser is too unstable for real use. I recommend the PicoScope. Base model for ~$200 and I was amazed to find it even decodes DCC. With a laptop it is good for floating measurements too. -john Which one is the base Picoscope - This? https://www.amazon.co.uk/PicoScope-2204A-D2-Channel-Oscilloscope-without/dp/B00IOQMVTK/ref=sr_1_2?ie=UTF8&qid=1469485246&sr=8-2&keywords=picoscope+2204a I notice there is also a firm called Hantek doing similar items: https://www.amazon.co.uk/Hantek-Professional-Oscilloscope-Bandwidth-Independent/dp/B01FLTOZYQ/ref=sr_1_7?s=diy&ie=UTF8&qid=1469485435&sr=1-7&keywords=hantek+oscilloscope The problem with my 7704A is, I imagine, lack of use! It was last serviced by the place I worked in about 1992. I had it shortly after (as scrap) when there was a clear-out of redundant kit with several plug-ins including a sampling unit & a complete set of manuals including service. (I also managed to get a 500Mhz frequency counter, a 500Mhz sig gen, a LF function generator a component bridge and some other odds and ends) I haven't used it much but each time I have to operate all the switches several times, take the plug-ins out and clean the edge connectors etc. before it will work. One occasion the fly-back blanking failed but it turned out to be a dud general purpose transistor. It's convenient that most of the semi-conductors plug in, including transistors. I used to service the damn things but I don't fancy spending hours putting it right any more. It's also extremely heavy, large and gets hot! Cheers Keith Edited July 25, 2016 by melmerby Link to post Share on other sites More sharing options...
john barry Posted July 26, 2016 Share Posted July 26, 2016 Yes mine is the 10MHz one as shown. I bought it as a special through Elector magazine. It included two probes which the one in your link doesn't. There is also a built in waveform generator. If I went again I might up it to a 100 MHz one although the 10 MHz is good enough to show and measure the frequency of the 16MHz crystal on an Arduino. If you wanted to spend more they have models which do mixed signal. ie analog channels and 16 logic inputs. -john Link to post Share on other sites More sharing options...
fcwilt Posted July 26, 2016 Share Posted July 26, 2016 (edited) There are an amazing number of versions of the Pico brand products - ranging in price from $130 to nearly $30,000. I had no idea this type of device could be so pricey. Interesting. The need for a computer of some sort is not ideal for me but certainly perfectly fine for many, many applications. Frederick Edited July 26, 2016 by fcwilt Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted July 26, 2016 Author RMweb Premium Share Posted July 26, 2016 Yes mine is the 10MHz one as shown. I bought it as a special through Elector magazine. It included two probes which the one in your link doesn't. There is also a built in waveform generator. If I went again I might up it to a 100 MHz one although the 10 MHz is good enough to show and measure the frequency of the 16MHz crystal on an Arduino. If you wanted to spend more they have models which do mixed signal. ie analog channels and 16 logic inputs. -john I've decided the 7704A has got to go. It'll free up some floor space under the layout and a cupboard in the shed where the spare plug-ins are. I have ordered a Pico 2205A from Amazon. Decided to go for the one above base level. It will be delivered express carriage direct from Pico's UK warehouse in Cambridgeshire and could be here possibly AM tomorrow. I thought about the Hantek ones which are cheaper but the reviews for Pico seem to be better and at least they have a proper UK support base. Cheers Keith Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted July 27, 2016 Author RMweb Premium Share Posted July 27, 2016 The Picoscope arrived almost exactly 24hrs after it was ordered. Nice job. I've been having a bit of a play. But I should have ordered some of Pico's x1 probes, I forgot that all mine are x10 Tek probes! That's usually all we used where I worked Frederick, if you want I can do some checking on the RS-8 to see what waveforms should be around at different points. Cheers Keith Link to post Share on other sites More sharing options...
fcwilt Posted July 28, 2016 Share Posted July 28, 2016 The Picoscope arrived almost exactly 24hrs after it was ordered. Nice job. I've been having a bit of a play. But I should have ordered some of Pico's x1 probes, I forgot that all mine are x10 Tek probes! That's usually all we used where I worked Frederick, if you want I can do some checking on the RS-8 to see what waveforms should be around at different points. Cheers Keith Hi Keith, Given that I have a computer (three actually) at my work bench I was thinking that a Pico as standard equipment on the bench might be nice. In the past I had a HP Logic Analyzer which was much used. So I was thinking about one of the MSO versions of the Pico. Still thinking. I was working today with the DR5000 along with a DR4018 and a DR4024 making sure that they worked as advertised. I noticed that the DR5000 doesn't display the track current very often. I've seen it come up a few times but then it goes back to zero. Any track current displayed on your unit? Thanks. Frederick Link to post Share on other sites More sharing options...
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