Gunners TekZone Posted January 17 Posted January 17 (edited) Hello All. First some background... For the TL:DR crowd, there are some pretty pictures below :P So, while in my mid/late 50's and having been dealing with ME/CFS for past decade... I recently found that getting back into LEGO was a great self-help/therapeutic method to get my brain back into gear (but a rather big hit on the bank... Pro Tip: never have one-click purchasing available for online shopping while under the influence of a very foggy, groggy, unfocused but desperate for stimulus brain). After I got past the costly Classic Space nostalgia, I decided to stick with the equally costly :P MINDSTORMS, Technic, trains and things that actually did stuff. I am fairly new to the vintage LEGO computer interface devices of the late 80's-90's... I have the Control Center II, Dacta Interface-A, and now three Dacta Interface_Bs... And I instantly fell into a minor obsession with the Interface-B. My 1st one came from Europe (I is in Canaderpia) a few months ago, and was thankfully fully functional. But I had to learn how to use it with the old Control Lab on Windows 7... Check that out here, controlling in a LEGO train...https://youtu.be/hLKNcO3VmvQ Now a few months later, I wanted MOWR!! So I found a very low priced one in the US, on ebay. I received it on this past Christmas Day... YAY!!! However, while it powered on (as seller had stated, but wasn't able to test further) I discovered that nothing happened. It would not properly connect to the program, it just kept going online/offline (based on the Stop LED on the device). Needless to say there was great disappointment... There is very little information on the internal workings, that I could find, so no help there. And since the ebay return would still ding me the shipping costs, I opted to keep it for "parts" and the seller gave me a partial refund. I then noticed he had a 2nd one... So he gave me a good discount on it and I panic purchased it (the only others I could find online where going for 2X-3X the price). Then over the next few days I got curious as to what I could salvage from the one dead one I had... Opening it up showed no signs of burnt or overheated parts. I had the idea of gutting it and using H-Bridges and optoisolators to convert the top connectors to an Arduino or something, and basically make my own type of interface. I ordered the cheep parts on Aliexpress and called it done. ----------------------------------------------------------------------------- But... I couldn't let go... I prayed over it, and shortly later had a gut feeling that I needed to dig deeper. But due the ME/CFS, digging deeper into electronics was something I haven't been more than a basic hobbyist in (and that in the distant past) and thus it wasn't a thing I felt mentally/physically focused enough to do. But the feeling persisted. So after doing a metric butt ton of Googling about the Interface-B, troubleshooting serial communicating issues, and how this Interface used such serial phrases to initiate and complete a connection... I also came across someone's reference to using an oscilloscope to read and analyze serial signals. Now, I have a dirt cheep digital one, that doesn't support the serial translation (of course, that would be too convenient)... But with time and some tracing, I managed to see squiggly lines when the application sent it's opening signal: p\0###Do you byte, when I knock?$$$ But I had no way of telling if that was what the squiggly line on the oscilloscope ment. Another dead end and I had I take a break. Then another inspiration hit... Years ago, I used to mess around with Arduinos and other microcontrollers to combat the grogginess, before my health totally nosedived... And I still had a few USB-TTL Serial Adapters. Combined with a terminal program I like, called Termite, I managed to use the TXD pin on the adapter, insead of the scope, to poke and prod at board traces. And this time I ran into the readable incoming signal from the PC!!. Now I had an idea where that circuitry was, so I started looking for the interface's response: ###Just a bit of the block!$$$ ... But couldn't find it in the area I expected it to be... Thus I figured the logic was dead on the board... Took another sad sleep break. Then the formerly unthinkable kicked in... "Let's poke around the actual CPU while under power... What could possibly go wrong with such little pins and my exhausted shaky hands" :P However, instead of randomly poking around, I got smrt and found the pinouts for the on-board CPU (Infineon SAB 80C515-N): Thankfully I saw there was some test points leading out from those pins... Less likely to short something out. And behold! Both incoming and outgoing signals visible!! It's Alive!! A quick look followed the trace (on the backside of board) to the area in the serial circuit that the transmitting signal should be found. And I was able to find it on the incoming side of a 3.2K resistor, but not on the outgoing side. Odd. So I shorted out the resistor with some fine tweezers, and suddenly the link between the PC and the board connected... It's Alive and Talking!! Now this is a very tiny surface mount resistor... and I don't have. So I simply removed it and shorted it out... Hey if it works, who cares :P Well that was a (relatively) quick repair and I have two fully functional Dacta Interface-Bs to mess around with... I was elated and praising THE LORD for giving me the energy and insight to do something I haven't been able to manage in many years... Sure beats bingeing on NetFlix while I sleepily drool on the cats on my lap :D But now... What about the 3rd panic purchase on another Interface-B that I had made? I live on a disability income, so even at discounted pricing it was a now unneeded expense. Oh well, wait and see, perhaps I can return it and eat the shipping cost, or possibly resell it if I didn't find a good use for it. ----------------------------------------------------------------------------- And so, almost three weeks later, I received the 3rd one (insert mini rant: ebay's International Shipping Service is costly and slow... Booo, ebay... Booo!! ). And much to my dismay... It too failed in the same way... Powered on but NO communication! What are the odds??? Is this a common failure point? The serial transmit circuit is the most heavily used, as the Interface-B is constantly sending out data, whereas it only receives when needed. Anyhow, I figured no problem... I opened it up, shorted the resistor and... Nothing??!?!?... Very sad and confused face :( There was no quick "resistor bypass fix" for this one... Something is completely blocking or garbling the signal (based on following tests). And after many loooong hours testing and trying... I gave up, accepted the loss (return still wasn't valid option) and bagged all the parts for storage... I then quickly prayed over it and repented for what I knew had been an impulse purchase (particularly as spending $$ on food is generally preferable)... And went to bed... Wherein I had some further insight 💡 while either drifting into sleep or a dream... I can't really tell at times. I couldn't keep the thought out of my mind... So after a day of rest to steady the hand, I tested my theory of bypassing ALL of the serial circuitry, and hooked a USB to TTL Serial Converter Adapter directly to the CPUs' RDX and TDX pins, while running a repeating inistating msg from Termite on my PC. And behold, Again!! That worked!!! So... Now I wait for when I am alert and focused enough for the fine soldering, and my plan is to bypass the original circuit and transplant in the new USB-TTL Serial Adapter into the casing... Basically, my plan is to replace the DB9 Serial connection with it. I will follow-up with another post when I am finished. Anyhow... I truly hope this will help others with a "mostly dead" Interface-B to take a closer look and poke around. You just might discover an easy, or unique, repair option. These are getting rarer and more expensive as time goes on. But with greatly appreciated efforts from @Bliss over on another topic (link below)... They are now easier to get running on modern PCs, and will run with Python programmability!!! Take care and GOD Bless. Feel free to post your own Interface-B repairs here if you have any. ----------------------------------------------------------------------------- Edited January 17 by Gunners TekZone Quote
Toastie Posted January 17 Posted January 17 7 hours ago, Gunners TekZone said: And behold, Again!! That worked!!! @Gunners TekZone CONGRATULATIONS! I knew you could do it (provided the Siemens 1001 feet chippie wouldn't be in Chip heaven). Really nice to know. So that means the built-in serial to TTL chip has gone bye-bye, right? Did you need to take that "away" from the RX/TX lines of the microcontroller? Very nice!!! All the best, Thorsten Quote
evank Posted January 17 Posted January 17 12 hours ago, Gunners TekZone said: I truly hope this will help others with a "mostly dead" Interface-B to take a closer look and poke around. Quote
Bliss Posted January 17 Posted January 17 (edited) @Gunners TekZone, wow you're da man! Not much people still play with those Interface B but they are quite unique in some way as they offer the most quantity of inputs and outputs in one box... And if you can connect 3 or more on a same PC interface, it offers 24/32 Inputs and same for outputs all available in one programming environment to achieve big projects. I have an EV3 kit but never opened it yet... So I don't really know how it can expand itself and interact with other EV3 or other systems... But I see these RCX, EV3, NXT more like small standalone controller that have there own independant program and very limited IO capability... I understand that like the RCX, EV3's probably have a way to send messages between each other but it's not the same... Can one EV3 expands its IO capacity somehow? Did lego completely stopped production of mindstorm? I see today in their education line some spike and BricQ ? technic hub? EV3 is marked retired. I'm clearly behind on this :-) Are they working on a new version? That would be great if they could enter the IoT world making wireless sensors using battery button like zigbee and BLE stuff... (Touch, light, temperature, IR motion sensors). (Wires can be a pain in projects) Is there a thread about what would be the best new Lego Smart System for you ? I think I saw on TikTok, lego projects using motors and electronics I've never saw in a lego store... Third party bricks? Edited January 17 by Bliss Quote
Gunners TekZone Posted January 17 Author Posted January 17 4 hours ago, evank said: Princes Bride - Mosty dead Yes, you got it! And it was my "True love... of tinkering" that helped with its reason to "live" :D 10 hours ago, Toastie said: Did you need to take that "away" from the RX/TX lines of the microcontroller? Partially... At the time of initial diagnosis, I had removed the 3.2K resistor (the 1st component on the trace from the CPU... so that effectively cut) out the transmission circuit. And no serial cable was hooked up, so not receiving alternate transmission. At this time, I am debating ways to use the original cable to transmit the signals from the CPU to the USB-TTL Serial Adapter, which I hope will physically replace the DB9 connector... if it fits. Quote
Bliss Posted January 17 Posted January 17 (edited) What would be great is to have an easy solution to get rid of the Serial data cable and the PSU 12VAC 7VA. So removing the RS232 circuit and replace by a FTDI USB input USB-C or USB-A. And, use the 5V from the USB with a step up board to provide 9vdc at about 1A or less. I don't know what the lego outputs capacity... but 7VA is not much... I think a USB port on a computer should be able to supply the whole thing no? Edited January 17 by Bliss Quote
Gunners TekZone Posted January 17 Author Posted January 17 (edited) 3 hours ago, Bliss said: Did lego completely stopped production of mindstorm? I see today in their education line some spike and BricQ ? technic hub? EV3 is marked retired. I'm clearly behind on this :-) Are they working on a new version? Kinda?. Yes, in education. With PyBricks it stays relevant. Long retired, yet still very capable... and $$$. Aren't we all to some degree :D 3 hours ago, Bliss said: I have an EV3 kit but never opened it yet... So I don't really know how it can expand itself and interact with other EV3 or other systems... Wow! If mint, it might be worth more to sell it... For more of the current Spike stuff? (The yellow and cyan? coloured stuff... And some educational stores sell to anyone) as it is fully compatible with the last generation (now retired) 51515 Robot Inventor System (the teal coloured ones) which is also better with PyBricks :D That said... The EV3 has a capable linux based CPU, so lots of programmable options. I have couple of EV3 sets (and NXT), but rarely do much with them, as the newer stuff is just simpler to get running with PyBricks... Not affiliated, honest ;) 1 minute ago, Bliss said: FTDI USB input USB-C YES! I was actually looking for one with power delivery (haven't found one) .. for this exact reason. But then, I don't have a PC with USB-C, let alone PD capable, anyhow. So wouldn't do me any good. Edited January 17 by Gunners TekZone Quote
Toastie Posted January 17 Posted January 17 (edited) 39 minutes ago, Gunners TekZone said: At this time, I am debating ways to use the original cable to transmit the signals from the CPU to the USB-TTL Serial Adapter, which I hope will physically replace the DB9 connector... if it fits. Well, then I sure hope it does fit! I am planning to go partly wireless (Bluetooth) on all my control boxes (2 x 8485 CCII, 2 x 9750 and 1 x 9751). So far, my modified 8485 (), which behaves more or less like the outputs of 9750 has currently such a BT thingy (https://www.eurobricks.com/forum/index.php?/forums/topic/192941-lego-interface-a-97509771-–-lego-technic-control-1-tc1-referenceideas-thread/&do=findComment&comment=3734005). 9751 also does 9600 Baud. Why don't you hook up an HC05 directly to the TTL RX/TX lines (with a 1k/2.2k voltage divider on the TX=input from 9750, HC05 are 3.3V, but tolerate 5V VCC; and the RX of the Siemens chips will be happy with 3 V TTL input)? The 5V are available inside 9751. Result: No more cables, just the power cord of 9751. Well, I'll try and report back ;) All the best, Thorsten 16 minutes ago, Bliss said: I think a USB port on a computer should be ably to supply the whole thing no? Hmm. The brain, for sure, but 8 x 9V motor outputs? ... maybe two motors stalled - that would add up, doesn't it? Philo's page suggests it would. I just replaced three "12V" AC wall warts (they generate anything between 12 and 16 V of course) with one 12V, 8A old-fashioned incandescent Christmas lights PSU weighing a ton, which I got from my neighbor - he said, it may be of value to me . That one powers my 8485, 9750 and 9751 boxes. I would not so much have my laptop providing motor power via USB, but I could work, of course! Best, Thorsten Edited January 17 by Toastie Quote
Gunners TekZone Posted January 17 Author Posted January 17 14 minutes ago, Bliss said: I think a USB port on a computer should be ably to supply the whole thing no? I am totally out of touch on latest computer stuff (especially considering I used to be a PC tech)... But I think USB A (3.x) would be totally out of it's power league for that. USB-C should be OK (depending on specs... I think those are all over the place. 1 connector to rule them all... unless you use it with physically matching but electronically incorrect host or peripheral :P Quote
Bliss Posted January 17 Posted January 17 (edited) The original Lego PSU is 12VAC 7VA so we talk basically of 600mA at 12 VAC for the whole box... It not much... Can the Box use more amps if we connect a bigger PSU say 12VAC at 2A (24VA)? No matter USB-C or USB-A, from a computer port it is not like a PD Charger I think... I would use the USB from a computer to have both DATA and Power. But anyway, saying this, google tell me: Most computer USB ports supply 5V of electricity with a maximum current of 0.5A. So maybe not enough to use the interface at least like the spec... but still... Edited January 17 by Bliss Quote
Gunners TekZone Posted January 17 Author Posted January 17 14 minutes ago, Toastie said: 9750 has currently such a BT thingy Nicely done!! I might consider something like that on this one Interface-B of mine... I don't like to hack vintage stuff that is already fully functional, like my Interface-A (unless it is simply plug in, like your original Arduino interface). But stuff that already needs repair is fair game :P Quote
Toastie Posted January 17 Posted January 17 3 minutes ago, Bliss said: Can the Box use more amps if we connect a bigger PSU say 12VAC at 2A (24VA)? Well, fortunately, we have our hardware guru @Gunners TekZone at work: What type are the H-bridge drivers inside the box? As I don't bet: I think they can deliver more than 100 mA each? Best, Thorsten 1 minute ago, Gunners TekZone said: But stuff that already needs repair is fair game :P I totally agree! My take as well. Best, Thorsten Quote
Gunners TekZone Posted January 17 Author Posted January 17 (edited) 8 minutes ago, Bliss said: Can the Box use more amps if we connect a bigger PSU say 12VAC at 2A (24VA)? My understanding of current usage (amperage) is that a properly designed device will only use as much as it needs, or has been designed for. Having more available current is just a nice buffer to keep things stable under full loads, but doesn't automatically increase load capacity. 4 minutes ago, Toastie said: What type are the H-bridge drivers inside the box? Edited January 17 by Gunners TekZone Quote
Toastie Posted January 17 Posted January 17 (edited) 18 minutes ago, Bliss said: The original Lego PSU is 12VAC 7VA On another thought: The LEGO PSU for 9750 is also a joke, considering what they soldered as MOSFET drivers into the output circuits: 2x MTP3055's ... they can handle >10A each ... I guess they just wanted to be on the safe side. I mean, a 12 Wall wart just bends over when currents go crazy ... but the box can handle more, I believe. Best, Thorsten Lotsatraffic here Nice photograph! You'll find the data sheet on Philo's pages as well (https://www.philohome.com/motors/mlx10402.pdf) - they do 500 mA each; x 8 = 4A max. Best, Thorsten Edited January 17 by Toastie Quote
Bliss Posted January 17 Posted January 17 (edited) Is there a fuse or other protection inside? I'm certain that with the original PSU, 8 outputs of interface B cannot power 8 X 9v lego train. But could it do it if we use bigger PSU? Of course, the thin board power trace must be able to take it... (I'm pretty sure it cannot take 10A though)... But maybe 2Amps? Edited January 17 by Bliss Quote
Toastie Posted January 17 Posted January 17 1 minute ago, Bliss said: Is there a fuse or other protection inside? The MLX 10402's have current limiters inside the chip. Best, Thorsten Quote
Bliss Posted January 17 Posted January 17 I see so 4A total for 8 outputs, but the box must allow it. So is there a main protection at the power intput of the interface? Quote
Gunners TekZone Posted January 17 Author Posted January 17 (edited) 26 minutes ago, Toastie said: Well, fortunately, we have our hardware guru @Gunners TekZone at work: Hah... Says the teacher to the noob I am (dare I say very?) technically proficient at an intuitive level, and capable enough with tools and sharp objects... But due Dyslexic/Dyscalculia issues I am often hobbled at every step when it involves using or recalling letters, words, numbers... oh my! Thus I stay mostly at a hobbyist level. 44 minutes ago, Toastie said: all my control boxes (2 x 8485 CCII, 2 x 9750 and 1 x 9751) I can't even keep these numbers straight in my mind, so I use the names for these LEGO/Dacta interfaces... But I get by Edited January 17 by Gunners TekZone Quote
Toastie Posted January 17 Posted January 17 2 minutes ago, Gunners TekZone said: Thus I stay mostly at a hobbyist level. OK, then your hobbyist level in your world is guru level in my world! 8485 = Control Center II, 9750 = Interface A, 9751 = Interface B ... for some reason I can recall numbers and images - nothing I am proud of, it simply is what it is. Sorry. Best, Thorsten Quote
Gunners TekZone Posted January 17 Author Posted January 17 13 minutes ago, Bliss said: But could it do it if we use bigger PSU? As I understand... and in totaly layman terms as I can formulate them... More current capacity is always better than not enough, but what is useabe is still limited to the lowest common denominator in the circuit (in this case, but perhaps not limited to, the motor drivers). But NOT the same with voltage... Too much can allow the extra current to push through and fry stuff. Quote
Toastie Posted January 17 Posted January 17 (edited) 22 minutes ago, Bliss said: So is there a main protection at the power intput of the interface? There is a L78S09 as 9V regulator = 2A max. or it will limit current. So this is it, I guess: 2A. No fuses, just the active power controllers (78** and H-bridge chippies). It is the same in 9750 - the MOSFETs can do 10A each, but the linear 4.5V power driver is a BDX34B = 10A max. The Interface A is one power monster - totally dumb, "just" a TTL driver (plus ingenious sensor circuits), but so nicely designed! I believe they had to do it as a) the olden days were better and LEGO was unbreakable and b) 4.5V motors easily stalled. Best, Thorsten Edited January 17 by Toastie Quote
Gunners TekZone Posted January 17 Author Posted January 17 (edited) 12 minutes ago, Toastie said: 8485 = Control Center II, 9750 = Interface A, 9751 = Interface B Haha... Yes, I suspected as such... But admittedly still have to Google when I see just the numbers. It is not that I can't memorise things, in fact I think I recall much more than I suspect... It is mostly that all my memories get jumbled up without other clear marker clues or recall procedures. As a basic example, I can remember my phone number, but only if I say the whole thing (same with the order of letters in the alphabet). But don't spell at me or ask me my current age (without giving me time to figure it out in my head, or better, my fingers ) And yet, I am self taught in most everything technical/programical/electrical that I know to do... go fig. Anyhow, enough about my issues... This is about repairing/enhancing LEGO interface stuffs... Repairing my mind is up to THE LORD Edited January 17 by Gunners TekZone Quote
Toastie Posted January 17 Posted January 17 5 minutes ago, Gunners TekZone said: It is mostly that all my memories get jumbled up without other clear marker clues or recall procedures. It is good to know that. Because then I won't use bloody numbers but names or "descriptions" (as good as I can, I am wildly guessing here) when asking you for a favor or suggesting some things. Which is so easy to do. You know, every now and then, there are students in my classes having diverse health issues, and every time we (together) have worked out something to get them trough. Time - is relative. I love "success" (define success - it is a myriad of things that may or may not - evolve). Regardless of time. As far as I have read your messages on EB, you have provided so much insight, I would have >never< ever figured out. Hey, like to come over to Germany and have fun in my group? I'd hire you right away. And I am not joking (as I enjoy so much to do under other circumstances). All the very best, and with a bow Thorsten Quote
Gunners TekZone Posted January 17 Author Posted January 17 18 minutes ago, Toastie said: Because then I won't use bloody numbers but names or "descriptions" eh... no worries. As long as I can Google, I get by... Makes me wonder how I learned anything in my youth (oh, right... despite dyslexic tendencies, I always was/am a very competent reader. And great at trial and error :P 22 minutes ago, Toastie said: Hey, like to come over to Germany and have fun in my group? I'd hire you right away If I get back to the point of having the energy to leave the house for more than a quick weekly foodbank/grocery store trip, I might contemplate such an adventure (oh, wait, I don't care much for travel... I better get working on my teleportation skillz ) Quote
Toastie Posted January 17 Posted January 17 34 minutes ago, Gunners TekZone said: I better get working on my teleportation skillz Just let me know what I have to install on my side - no, no wait, the Star Trek folks teleported without any device present on the target site. OK, tell me when you need some free space/area, I clear that. Best, Thorsten Quote
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