TR3 on newly shipped Teletype units (black PCB) does not output full voltage, which causes various problems when triggering other modules.
how to check
all units shipped in 2018 have this issue. if you have a used module, and stumbled across this thread far in the future, check if TR3 outputs ~10V, and if so, you’re fine, it was fixed. the LEDs across all TRs should be the same brightness. problem TR3 will be dimmer.
what to do
i’ll fix it for you, by hand, and ship it back. i’ll refund your shipping costs against your original order.
e-mail firstname.lastname@example.org with TTFIX in the subject, include your return shipping address in the body, and i’ll send further instructions.
unfortunately our circuit assembler confirmed some swapped parts. i messed up the soldermask (white name of part on the circuit board) but the placement data was correct, and the machine operator went with the wrong data without double-checking with me. and then our in-house testing methodology wasn’t triggered by the issue. lessons learned.
it’s super minor, but tiny. 0402 surface mount. an R and C are swapped: R22 and C22. R22 is 10k, C22 is 100n. if you know how to move around 0402 parts, go for it. here’s a photo.
i apologize for the trouble. i know it’s super annoying. i’ll make it right.