Tube🍂Time

me: so i name all my cats after numbers! them: oh? me: cat3, cat5 them: you skipped four-- me (ignoring them): cat5e them: but 'e' is not a number me (continuing to ignore them): cat6, cat6a, cat7, cat8

this thing is puzzling. it takes the place of the ball-in-tube inclinometer. it seems to be added after the fact. the thing is glued in place, has a resistor divider (100 ohm low side, 5.3K high side), and has been wired up to 2 spare pins on the connector with a different color of sleeving.

while that glues, take a look at the illumination bar. surprisingly enough -- it's red!

there are some cracked plastics on the front, like the mounting bracket for the illumination bar. i'll have to fix that.

connectors. i need to reverse engineer the wiring and pinouts.

turns out those wires ran to small light bulbs inside the white pointer indicators. they light up red!

a bit of bad news: there are a bunch of connections on the slip rings here that seem to be shorted together.

this is probably an ancient repair. whoever did it glued the screw to the bracket. ugh. does anyone have recommendations for glue that will hold up better?

the surround came out! i had to be super careful of all those indicator flags, which are held back by blue tape.

think i figured out why this was bodged in: it's replacing a ball-and-tube inclinometer because this may have been installed in a stationary setup, like a simulator, and they needed to emulate the motion of the ball.

it has some neat illustrations, including this one of a toilet. (the book makes a point about avoiding any form of the water analogy)

mini-repair monday: my EGA monitor has been slowly fading away over the past few years. at VCF West this year it was too dim to use and i had to borrow one. but let's go fix it now!

then i have to remove these four tiny bolts. they are SUPER fiddly.

to disassemble the ball, i have to remove this surround. it's got green and white wires that go to some illumination bulbs, and those have to get desoldered.

Chip companies: you pick QFP or LCC NXP: this one is both!

be sure to have that disk in hand!

at some point RF engineers just have to admit that they're plumbers.

interesting turntable is very vertical

and here's the other side.

holy crap i just realized i did this entire project in a week. https://mastodon.social/@tubetime/116871125300056511

digikey: $17 mouser: $14 aliexpress (clone): $1 amazing, almost a factor of 20.

looks like this tube has gone a bit gassy

and now it is time to reinstall the parts.

ooh nice curve tracer.

where was i? oh yeah, repairing this card. so these traces were carved through and cut, and i've reconnected them with fine wires. it's easy to remove the solder mask using a fiberglass pen, although they're terrible about leaving tiny fibers everywhere. i'm careful about wearing gloves and cleaning up...

whoever was trying to remove the 93C66 left some very deep gouges from the soldering iron on the back of the board, severing a bunch of traces in the process! rough...

i have some UV cure soldermask in a variety of colors. you just paint it on and expose it to UV light. sometimes i'll put a piece of plastic on top to flatten it out.

*sigh*

also the drive is running very smoothly now. a few days ago it was making horrible screeching sounds but i think that was the spindle bearing. i've been running it upside down to allow the oil to warm up and drain back into the bearing.

there was corrosion lurking underneath components. what a mess.

someone's been here before, and they were having problems desoldering components. this is probably because of all those grey, crusty solder joints -- a clear sign of leaky electrolytic caps.

that wasn't so bad. two days for a complete clone.

'file' is superintelligent these days. it knows about LIF disks! looks like the binary data is good!

bad sectors were on tracks 37, 75, 113, and 152. the 9133a uses hardware partitioning to get four logical volumes, so these "bad sectors" are really just extra sectors at the end of each disk. for posterity, the command i used was ./mfm_read --format Xebec_104527_C0_256B --sectors 32,0 --heads 4 --cylinders 153 --header_crc 0x0,0xa00805,32,2 --data_crc 0x0,0xa00805,32,2 --sector_length 256 --retries 50,4 --drive 1 --xebec_skew --begin_time 151000 --tran hp9133a_st506 --ext hp9133a_st506.bin

there are a lot of missing surface mount resistors and capacitors in the audio amplifier area, so that's not great. does anyone have one of these cards? can you take some closeup photos?

@straithe@infosec.exchange ooh i've got a good one, but it's a secret.

@straithe@infosec.exchange no that's the joke, the name is a secret, privately held in a secure location. you'd have to hack in to get it.

@vga256@mastodon.tomodori.net reminds me of the tools used to author Windows HLP files.

so it looks like there are 4 different values of electrolytic capacitors on this board. if anyone has a Gravis Ultrasound PnP, do you mind reading off those values for me? capacitance and voltage rating would be great!

@bsdphk@fosstodon.org if you want to experiment, i put the whole disk image here: https://drive.google.com/file/d/1aTSBuvYilyCwlMffqJVZQTnmUwSarSrB/view?usp=sharing

@bsdphk@fosstodon.org ahh that solved it. new issue though, it looks like this hard drive image has 4 volumes but each has lifver set to 0, and the volume header is missing the track, head, and sector count fields, triggering a bug:

@bsdphk@fosstodon.org Traceback (most recent call last): File "/home/eric/src_other/AutoArchaeologist/run_example.py", line 11, in from autoarchaeologist.container import argv File "/home/eric/src_other/AutoArchaeologist/autoarchaeologist/container/argv.py", line 17, in import ddhf_bitstore_metadata ModuleNotFoundError: No module named 'ddhf_bitstore_metadata'

@bsdphk@fosstodon.org David Gesswein pointed out to me by email that this image file has a software interleave of 9 and each track has a spare sector 31 which contains just a fill pattern and can be ignored. so that might explain some of the parsing difficulties.

ever had questions about how professional PCBs are designed? i'm answering questions LIVE! https://www.twitch.tv/tubetimeus