#396

I don’t know what to tell you. Make sure everything else is right and then replace a chip. Super painful and stressful. Search the thread for my posts… I detailed all the checks I did. I was so doubtful I could fix it that I bought a used one.

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#397

Thank you for the encouragement Gerald. I replaced, U3/U4 and U7. The PARAM pot now has two values after calibration, -1638 and 16383, nothing in between. And for IN this is -8191 at 0v and then goes directly to 16383. I think the problem is still the same. (at least I learned how to remove chips with a stanley knive :slight_smile: it worked better than I hoped for)

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#398

Did you check the Via problem? Teletype hardware: open

#399

yes, I connected R26 to ground before I changed the chips.

#401

this is such a killer build! Congrats!!

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#402

Had some free time today so I fixed up some of the problems I had with my build from a few months ago. Finally got the PARAM knob and IN jack working properly but the CV LEDs still won’t light up. All four outputs are working as they should, just not the LEDs. Similar to @Gerald_Stevens, they will light up if one is lightly connected to another but after checking all the components and such related to this part of the circuit, I’m stumped. Anyone else have this problem? Hopefully this doesn’t come to replacing any chips…

#403

Are the dacs outputting correct voltages when a command is input to the TT? If so, I’d check the 10k resistor and LED orientation. If not I’d make sure the DAC then the op amp were doing their respective jobs. The Leds just receive the dac output and if you’re testing with output voltages < ~2V (im sure someone can correct me with a more accurate value) then you probably won’t see it light up because the forward voltage to the LED won’t be enough.

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#404

Just checked again and no I’m not getting correct voltages (thought I had checked this earlier but apparently not). Gave the DACs a reflow and still no luck. Can’t find anything grounded or not making a connection though. I suppose this means I need to replace the chips as others did? :frowning:

#405

Have you measured the dac outputs from the chip and not the jack? I think the highest voltage you’ll get from them is 2.5V and the op amp does an x4 on that to get to the 10V max. It could be the amplification/op amp or the dacs. See if the dac responds then you know it’s the amp stage and if there is no response it’s the dac.

#406

make sure it is the chips are the culprit. I also thought this was the problem, but after replacing the chips the problems remained.

#407

Did anybody try to use the AD5687BRUZ (non R version) with an external 2.5 vref? I tried to check the teletype/main.c which does not seem to write anything reference related to the dac, soo theoretically it should work right?

#408

R version i think just means it comes on a reel. same part? check the datasheet.

#409

Nope, I checked the datasheet, the ‚R’ refers to the internal voltage reference.

#410

cool, thanks for checking. haven’t tried it, but i figure the SPI protocol is compatible.

are the R version sold out everywhere?

#411

Yeah mouser, digikey, distrelec, farnell & arrow are all sold out and unfortunately the non-R version is currently only available at arrow. So this seems to be the only possibility to build a teletype right now

#412

I have a new DIY terminal build using a pusherman semi prepopulated board, I used the at32uc3b0256 and a white display that was recommended and in stock, the Newhaven NHD-2.7-1286-4WDW3

Do I need R48 jumper for this display? My display is not working but I would like to know if R48 should be on, then that will be one thing out of the picture so to speak.

#413

Edit: got it to program just fine! Now at the welcome screen, LEDS 5-8 cycle on and off in a neat little pattern. I haven’t hooked a keyboard up to the module yet. Is THIS behavior normal?

Hey everyone! I just finished the SMD components of a build and plugged the board into a power supply to test it before I add the screen. On power up pre-programming, I see that LED1 and LED2 light up solid, but none of the other LEDs turn on. Is this normal behavior before the firmware is flashed? I haven’t added the screen yet; do you recommend I add it before flashing the firmware? What kind of LED behavior should I expect once I flash the firmware?

Thanks for your help!

#414

If I remember correctly I had a kind of random LED lighting before the firmware was flashed. I think the firmware flashing guide even mentions that some leds might be lit, might not, just flash it.

#416

Thanks so much! I was able to flash successfully but now I need to grab a keyboard and test all the ins and outs. Before I put the jacks and pot on, do you have a suggestion of how I should go about testing everything? Walk through the Teletype studies?

#417

Yeah, that’s what I did. Use the studies to familiarize yourself with the commands then pulse some gates and use a meter to make sure your CV range is the full amount. Get a simple something on each script and then trig inputs to make sure everything is working.