Decoder to identify if possible

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ixldoc		#1 Posted : 18 April 2020 07:37:00(UTC) Retweet
Joined: 18/11/2015(UTC) Posts: 221 Location: Brisbane,Australia		Hi all, I hope someone on the forum might be able to help with this unknown decoder. I was given it a while ago and I hoped to be able to use it at some time. Unfortunately all the wires were removed and I have been unable to decide what type of decoder it is and the correct wire connections. If someone does recognize it and knows the wire connections, could you indicate the correct connections on the first photo starting with the top solder tab and working down. Thanks, Howard.


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kiwiAlan		#2 Posted : 18 April 2020 12:54:26(UTC) Retweet
Joined: 23/07/2014(UTC) Posts: 8,706 Location: ENGLAND, Didcot		Originally Posted by: ixldoc If someone does recognize it and knows the wire connections, could you indicate the correct connections on the first photo starting with the top solder tab and working down. Thanks, Howard. Well, the top connection is one of the track inputs, and the 5th one down is the other. You can tell this because they each connect to two of the diodes that rectify the track signal to obtain the DC for the electronics. But other than that I don't recognize the decoder off hand.


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bph		#3 Posted : 18 April 2020 16:21:42(UTC) Retweet
Joined: 04/08/2018(UTC) Posts: 1,290		Originally Posted by: ixldoc Hi all, I hope someone on the forum might be able to help with this unknown decoder. I was given it a while ago and I hoped to be able to use it at some time. Unfortunately all the wires were removed and I have been unable to decide what type of decoder it is and the correct wire connections. If someone does recognize it and knows the wire connections, could you indicate the correct connections on the first photo starting with the top solder tab and working down. Thanks, Howard. Whats the numbers/id on the big chip ? Try google those.


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H0		#4 Posted : 20 April 2020 10:52:45(UTC) Retweet
Joined: 16/02/2004(UTC) Posts: 15,572 Location: DE-NW		Hi! The decoder PCB is blue, so maybe it is an ESU LokPilot. The holes for the 21MTC are missing, so I assume it is an older LokPilot.
		Regards Tom --- "In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS

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mvd71		#5 Posted : 20 April 2020 11:18:24(UTC) Retweet
Joined: 09/08/2008(UTC) Posts: 1,982 Location: Auckland,		Originally Posted by: H0 Hi! The decoder PCB is blue, so maybe it is an ESU LokPilot. The holes for the 21MTC are missing, so I assume it is an older LokPilot. That was my thought too, I may have one somewhere. I'll take a look tomorrow morning and see if I do. Cheers.... Mike

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Chook		#6 Posted : 21 April 2020 04:20:21(UTC) Retweet
Joined: 15/08/2012(UTC) Posts: 234 Location: Perth, Western Australia.		Hi Howard. My guess is that the 4 glass diodes on the top PCB are the connections to the track. Lets start the wiring pin count from the top as pin #1, so pin #1 and pin #5 are your track/wheel and slider connections. I am guessing that the 2 IC,s on the top PCB are your bridge motor controllers. This could be confirmed if you look up the identification numbers which I cant read from your pics on those 2 IC's. They will give you an output pin on the IC which you can follow to the wiring pins. One of those pins appears to be wiring pin #7. The rest I have no idea about. Regards.......Chook.


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ixldoc		#7 Posted : 22 April 2020 00:53:16(UTC) Retweet
Joined: 18/11/2015(UTC) Posts: 221 Location: Brisbane,Australia		Thanks Chook. I will try that idea. So far I have connected pin 1 and 5 to the Ecos and all was well. I can find 16VDC on pin 4 and 7 but nothing happens if I use pin4 to any other pin ( with resistor and LED) with F0,F1 and F2 turned on or off. I have used both DCC and MM formats. Bizarre. Now I wonder if the decoder is kaput despite macroscopically looking normaal. I will have another look but I am rapidly losing interest! Regards, Howard.


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Chook		#8 Posted : 23 April 2020 04:25:03(UTC) Retweet
Joined: 15/08/2012(UTC) Posts: 234 Location: Perth, Western Australia.		Howard are you able to see the IC numbers on the same side as the diodes and put them on this post please? Regards......Chook.


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ixldoc		#9 Posted : 24 April 2020 01:24:38(UTC) Retweet
Joined: 18/11/2015(UTC) Posts: 221 Location: Brisbane,Australia		Hi Chook, Thanks for your persistence on this decoder. I had a close look at it and in fact was able to discern the print on the large IC on the reverse of the board as well. I thought I would take a photo of the writing as my keyboard would not have been able to cope. I was told the address was 3 (probably) but no guarantee. I can't interrogate the chip with my Ecos because it needs a load on the motor wires and I don't know which they are! Don't lose sleep over this, and thanks again. Howard.


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Chook		#10 Posted : 24 April 2020 05:52:46(UTC) Retweet
Joined: 15/08/2012(UTC) Posts: 234 Location: Perth, Western Australia.		Good work Howard. 9953a.pdf (503kb) downloaded 16 time(s). 9956A.pdf (506kb) downloaded 12 time(s). Your IC data sheets are attached. They are as I suspected a dual P and N channnel FET driver capable of working with 30v at 2.7amps. The outputs are on the 5,6,7,8 pin side of the chips and as I determined wiring pin 7 on the PCB is definitely one of them. The other outputs from the chips are joined and pass through the PCB to the other side and then again back to the original side of the PCB. If you have and can use a multimeter (ohms X1) can I get you to check for continuity between pin 5&6 of the 9956A chip and probably wiring pin 9 of the PCB. If this is a dead short then your motor wiring pins will be pins 7 & 9. If you don't get continuity with pin 9 then my next best guess will be pin 8 which will give you pin 7 & 8 as your motor wiring connections. Again check this combination with your meter. Looking forward for your results. Regards...........Chook.


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ixldoc		#11 Posted : 24 April 2020 08:05:58(UTC) Retweet
Joined: 18/11/2015(UTC) Posts: 221 Location: Brisbane,Australia		Hi Chook and thanks for the info and suggestions. I took a punt and connected a small motor to pins 7 and 9 and it worked. This allowed me to interrogate the decoder and read CV 8. The readout was 42 which corresponds with the manufacturer Digirails. The address was 3 and it responded to DCC. I found pin 4 was the +16 volt supply and then pin 2 the front light. Pins 6,8 and 10 were Fi,F2 and F3 respectively. Pin 2 is the problem as it is permanently grounded by the look of it. Using my Ecos decoder tester, the rear light is permanently on, regardless of F0 and direction of the loco. I have tried to find out how to reset the decoder but so far no luck with the suggestions on the internet. (CV 8 to 8 and others. Just get "error" message.) Maybe the output is cactus. I wondered if a CV setting is doing this but I have no manual. Anyway, the problem is nearly solved and I thank you for your help. Maybe someone on the forum would know the reset CV and value? Regards, Howard.

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kiwiAlan		#12 Posted : 24 April 2020 08:51:33(UTC) Retweet
Joined: 23/07/2014(UTC) Posts: 8,706 Location: ENGLAND, Didcot		Originally Posted by: ixldoc Using my Ecos decoder tester, the rear light is permanently on, regardless of F0 and direction of the loco. Good to see that you have made a lot of progress with the decoder. Digirails is not a manufacturer I know, so can't help with any details. But F0R will be driven by one of the little three pin transistors. I would trace the track back from the pin to work out which one it is. Then look to see which pin is connected to multiple other transistors, and the third pin will be the drive from the microprocessor (the PIC16F872). Using a voltmeter you should be able to see the voltage on the third pin change as you turn F0 off and on. The change will be only about 0.6V if they have used bipolar transistors, but could be close to 5V if the have used FETs.

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ROBMODEL		#13 Posted : 24 April 2020 14:53:16(UTC) Retweet
Joined: 08/06/2012(UTC) Posts: 48		As far as I know digirails is by a dutch company digikeijs. https://www.digikeijs.com/en/ Regards Rob

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