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Need advice on DEC RAINBOW adapter

VERAULT

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I have a DEC RAINBOW PC100-B2. I dont have the CRT.. and juding by eBays prices I am not going to get one. I know you can build an adapter to connect a composite monitor and the keyboard to. Does anyone sell this? Or are there good plans online to make this cable (preferably with a BOM)?

I realize the downside of using this cable is you could only get monochrome video out but that is better that nothing and again the color displays are really expensive..

Such an odd choice to have the KB and monitor share a cable but its not unheard of.
 

VERAULT

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I haver seen that link PG31. Just things like the phone adapter connector (RJ11 I assume but 4P? handset size or full size? Where can I source them?) I get this question alot as I fix keyboard connectors for Kaypro computers and they are not easy to come by)
 

PG31

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Hello Verault, the connector for the keyboard will need to be the female socket version of the connector on the end of your LKxxx keyboard.
LK201 keyboard springs to mind, some info is below I don't know a place that stocks the socket (4 pin) but I don't think it will be that difficult to find.

 

VERAULT

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Ok I made a protoype of the DEC Rainbow Composite cable/keyboard cable and I need some help. Here are some photos of it.
IMG_20220314_145918.jpg
IMG_20220314_145933.jpg
IMG_20220314_145950.jpg
Going by this pinout: http://www.larosse.net/pc100/dec100-vr201-cable.html
And this one for the keyboard: http://www.netbsd.org/docs/Hardware/Machines/DEC/lk2

For video I have the composite video pin connected to pin 12 of the DB15 connector with ground going to pins 4,5, and 6 (all bridged)
Pins 7 and 8 on the db15 connector are bridged (12v)

As for the keyboard connector (RJ 11 connector) I have pin 1 (black) going to DB15 pin 14. Pin 2 (red) going to DB15 pins 7 and 8 (12v). Pin 3 (green) is going to the DB15 bridged ground connectors (4,5, and 6). Pin 4 (yellow) is going to DB15 Pin 15. I am not sure the orientation of transmit and receive and I have swapped pins 14 and 15 but it didnt change anything.


So This unit did not have a keyboard or monitor (which the keyboard connects into) So I bought a DEC LK201AA keyboard as I was under the impression this is the correct keyboard for this model.
IMG_20220314_151840.jpg




With the video connected there is overscan but you can see it outputs an image
IMG_20220314_151748.jpg

With the keyboard connected the keyboard gives a chip and all the LEDS are illuminated (and wont go out)
IMG_20220314_151828.jpg

And this is what the LEDS on the back of the computer look like when at this state:
IMG_20220314_152659.jpg


Anyone familiar with these units,, help would be appreciated.
 

HoJoPo

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Ok I made a protoype of the DEC Rainbow Composite cable/keyboard cable and I need some help. Here are some photos of it.
View attachment 1239360
View attachment 1239361
View attachment 1239362
Going by this pinout: http://www.larosse.net/pc100/dec100-vr201-cable.html
And this one for the keyboard: http://www.netbsd.org/docs/Hardware/Machines/DEC/lk2

For video I have the composite video pin connected to pin 12 of the DB15 connector with ground going to pins 4,5, and 6 (all bridged)
Pins 7 and 8 on the db15 connector are bridged (12v)

As for the keyboard connector (RJ 11 connector) I have pin 1 (black) going to DB15 pin 14. Pin 2 (red) going to DB15 pins 7 and 8 (12v). Pin 3 (green) is going to the DB15 bridged ground connectors (4,5, and 6). Pin 4 (yellow) is going to DB15 Pin 15. I am not sure the orientation of transmit and receive and I have swapped pins 14 and 15 but it didnt change anything.


So This unit did not have a keyboard or monitor (which the keyboard connects into) So I bought a DEC LK201AA keyboard as I was under the impression this is the correct keyboard for this model.
View attachment 1239368




With the video connected there is overscan but you can see it outputs an image
View attachment 1239366

With the keyboard connected the keyboard gives a chip and all the LEDS are illuminated (and wont go out)
View attachment 1239367

And this is what the LEDS on the back of the computer look like when at this state:
View attachment 1239369


Anyone familiar with these units,, help would be appreciated.
From the Rainbow 100 technical manual here: http://www.bitsavers.org/pdf/dec/rainbow/EK-PC100-TM-001_Rainbow_100_Technical_Manual_May84.pdf

Appendix B-1 covers the LEDs. LEDS 1, 2, 4 and 6 lit shows a keyboard error. I'd check the wiring and make sure you don't have anything reversed.

Error 13 Keyboard - Make sure keyboard cable is plugged
in. Do not press any keys while the
computer is going through power-up
or reset. Check for any keys that may
be stuck. Make sure video cable is se-
curely plugged in. Replace keyboard
or its cable.
 

VERAULT

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Ok I can really really use some help on this. I have gone over the wiring time and time again. I cannot get any further than I have. I have video and the KB LEDS stay on and the same error messages and lights. Tried another kb phone cable (correct pinout phone line) and no change either. Can the LK201AA work on the DEC Rainbow PC100-B2? Whats the difference between the LK201 and the LK201AA? I bought this KB on ebay and have nothing else I can test it out on.

Anyone with a Dec rainbow willing to throw together this little adapter of 7 pins on a db 15 female?
 

harry

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Its been a while since I made an adapter, but at the time I used the info from retro hacker, and things worked,... below was his instructions I followed..


" You simply need a 15 pin DSUB connector, some wire, a phone jack, and an RCA jack:

Video:
Pin 12 to center pin of RCA jack
Pin 4 to outer ring of RCA jack

Keyboard:
Pin 7 (or 8) to keyboard +12v
Pin 5 (or 6) to keyboard ground
Pin 14 - received data from keyboard
Pin 15 - transmitted data from keyboard

Attached is a drawing of the LK201 pinout. "

-Ian

LK201_connector.jpg

I have several LK201 kb's some working, some not, the ones which are stuck with all LED's on, appear not in working order?

Harry.
 

VERAULT

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Its been a while since I made an adapter, but at the time I used the info from retro hacker, and things worked,... below was his instructions I followed..


" You simply need a 15 pin DSUB connector, some wire, a phone jack, and an RCA jack:

Video:
Pin 12 to center pin of RCA jack
Pin 4 to outer ring of RCA jack

Keyboard:
Pin 7 (or 8) to keyboard +12v
Pin 5 (or 6) to keyboard ground
Pin 14 - received data from keyboard
Pin 15 - transmitted data from keyboard

Attached is a drawing of the LK201 pinout. "

-Ian

LK201_connector.jpg

I have several LK201 kb's some working, some not, the ones which are stuck with all LED's on, appear not in working order?

Harry.
Thanks Harry I will give it a once over one more time in the next day or so. But are you saying keyboards with a fault show all the LEDS stuck on? Which sort of implies I have a bad keyboard.
 

HoJoPo

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Thanks Harry I will give it a once over one more time in the next day or so. But are you saying keyboards with a fault show all the LEDS stuck on? Which sort of implies I have a bad keyboard.
A quick google for "LK201 all leds on" led to this old CC-talk post from 1997:


Evidently, the membrane keyboard degrades and sticks a key on, possibly shorting the matrix in an odd way, which confuses the micro-controller. The linked post details some troubleshooting steps to determine that is the cause.

Unfortunately, it appears the keyboard matrix is un-repairable.
 

HoJoPo

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Good news, if you are handy someone did make a PS/2 to LK201 keyboard adapter using an Arduino Nano:

Bad news, though the source code is available, the schematics were lost, so it may take reading the source to determine what needs to connect where.... (I checked archive.org and the .pdf of the schematic wasn't archived.)


Double bad news, it appears not to work well on the Rainbow, but some better news, the picture in this thread shows the UART hat connected to PS/2 and LK201 cables....


However, for 110 or 120 pounds, this company sells PS/2 or USB to LK201 adapters:


Somewhat good news, the LK401 is compatible with the LK201, so if you can find a good LK401... but it seems the LK401 was also known to be unreliable, so any used keyboard is a crapshoot unless it's tested/good.

Absolute best news: There is a newer LK201 emulator project! Confirmed to work with the Rainbow...


And it uses standard USB keyboards. :)

Edit: Did some checking, the PCB is $15 each from OSHpark, and the BOM including the Adafruit Trinket is also only $15, for about $31 dollars plus shipping for materials. Unfortunately, the DIP package version of the RS232 level converter used is on backorder, and so is the 40V NPN transistor. The transistor is probably easy to substitute, the surface mount version of the RS232 level converter is available, but of course would require the board to be redesigned....

Edit2: There are substitutes for the backordered parts available, but they'd add about $3 to the BOM cost. :) So $35 plus a micro-USB to USB-A cable (also known as an OTG (on the go) host cable) which is about $6, plus time to assemble and program the Adafruit Trinket.

Edit3: The OSHpark order is 3 PCBs for $15. Tripling the Digikey order with the substitute RS232 level converter is $51, and then another $4 for 20 of the 2n3904 transistors from eBay (cheaper than Digikey), for a nice even total of $70 for 3 units. I'm considering ordering enough to build 3 of these.... with the time needed to assemble and test, I'd probably charge $75 each for them assembled, programmed and tested. To that you'd have to add a telephone handset cable (I may have an e-waste source for those cheap) and the OTG USB adapters (I can get three for $7 on Amazon, so I could include them in the $75 price.) Would take a couple weeks to get all the parts, build and test. Especially since I don't have a VT terminal or VR-201 for the Rainbow I have access to to test... so I'd have to bodge together a 15 pin to phone jack / composite video adapter to test with.
 
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VERAULT

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A quick google for "LK201 all leds on" led to this old CC-talk post from 1997:


Evidently, the membrane keyboard degrades and sticks a key on, possibly shorting the matrix in an odd way, which confuses the micro-controller. The linked post details some troubleshooting steps to determine that is the cause.

Unfortunately, it appears the keyboard matrix is un-repairable.
So I followed the post and removed the kb controller board from the membrane and tried it with the computer. Now I get the chirp and all the lights flash and go out.. I still get the "MESSAGE 13 - KEYBOARD" But I believe the fault at this point is the keyboard itself.

I connected the membrane back to the KB control board and all the lights are on again.

I opened up a return on the keyboard. What a damn shame.


EDIT: Just curious. If they have several keyboard replacement projects.. Are there any Color video out adapters? Reason being the composite adapter I built will only display monochrome even though this is a color computer.
 
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HoJoPo

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So I followed the post and removed the kb controller board from the membrane and tried it with the computer. Now I get the chirp and all the lights flash and go out.. I still get the "MESSAGE 13 - KEYBOARD" But I believe the fault at this point is the keyboard itself.

I connected the membrane back to the KB control board and all the lights are on again.

I opened up a return on the keyboard. What a damn shame.


EDIT: Just curious. If they have several keyboard replacement projects.. Are there any Color video out adapters? Reason being the composite adapter I built will only display monochrome even though this is a color computer.
Looks like the RGB signals are documented on table 3-6 of the tech reference, 15.7khz/60hz analog RGB signal. Video resolution is odd though:

• Low resolution mode - 384 X 240 pixels X 4 planes
• High resolution mode - 800 X 240 pixels X 2 planes
• 16 simultaneous colors from a palette of 4096 (in low resolution mode)
• 4 simultaneous colors from a palette of 1024 (in high resolution mode)

The VR241 monitor used a break out cable to BNC connectors, the keyboard connected to the monitor cable. So if you can find a VR241 cable, many RGB monitors that handle 15khz and take three RGB analog BNC connectors should work (sync on green).

Here's some info on the BCC17 cable that is used: http://www.larosse.net/pc100/VR241.html

Here's a thread from here discussing modern monitor options: https://forum.vcfed.org/index.php?threads/dec-rainbow-modern-display-options.65212/
 

zamp

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Good news, if you are handy someone did make a PS/2 to LK201 keyboard adapter using an Arduino Nano:

Bad news, though the source code is available, the schematics were lost, so it may take reading the source to determine what needs to connect where.... (I checked archive.org and the .pdf of the schematic wasn't archived.)


Some one shared a copy of the schematic in their google drive. Q and A on schematic availability here, schematic itself at https://drive.google.com/file/d/1XmRClTCoIedfXDcUbcaJi-A9QXr7SCEo/view .

In case it goes missing from that google drive. I have attached a copy here.
 

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VERAULT

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Well the seller was very reasonable and refunded me. He didnt want the KB back. I will see if I can find or fix the matrix, but I highly doubt it as its construction is LAUGHABLE and I think finding a modern replacement and not using an LK201 (because they were expensive yet built like garbage).
 

VERAULT

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Well I finally got around to finding a compatible monitor for my DEC Rainbow. A Digital VR201 Amber monitor. Bought it from an online Seller out of Canada. Seems it was dipped in cancer and lived in someones septic by how filthy it was sent (doesnt anyone at least wipe down the stuf they sell?).

IT works and needs a complete deep cleaning... And yes there is the faintest hint of smoker... super good times.

Im happy it works. I just need to get around to trying to fix that membrane keyboard.

I have to go wash the burning sensation from my hands now...

IMG_20220816_163640.jpg
 

Teletech

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I'll be interested to see how your keyboard adapter goes. I have several LK201s, but I dislike them because they just take up so much real-estate. Fine for a Professional 350, but awful on a VT320 on a cramped workspace.
 
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