Posts by arroz@mastodon.social
(DIR) Post #B1hMjxjvnWnorHRJwG by arroz@mastodon.social
2025-12-27T16:38:48Z
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Starting to look at the ImageWriter to get it ready for #MARCHintosh. Managed to pop out the board through the bottom panel after disconnecting the printer head cable and a lot of other connectors. Aside from the dust it looks OK! I had never seen a 15000uF cap…
(DIR) Post #B1hMjz8macH9Ce4gJU by arroz@mastodon.social
2025-12-27T16:55:19Z
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Well, this screw is not cooperating. Kinda hard to dust this and do more work inside without disconnecting this ground cable. 😖
(DIR) Post #B1hMk0NLzvWd27tpfE by arroz@mastodon.social
2025-12-27T16:58:56Z
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It’s out! Thanks to @luisfcorreia since I didn’t realize this was a terminal.🤦♂️
(DIR) Post #B1hMk1Re1SYGLiulzU by arroz@mastodon.social
2025-12-27T17:14:28Z
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This uses an Intel 8085 as its main CPU plus some Toshiba fancy RAMs.There are two spots on the board with some weird stuff. Rust? Just dirty? Not sure what they are, there are no caps or batteries nearby that may have leaked.
(DIR) Post #B1hMk2AfK4Z2bLyjAG by arroz@mastodon.social
2025-12-27T17:22:19Z
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Just dirt. IPA took it out. I wonder is I should recap first or just turn this thing on… maybe I recap the smaller caps with the stuff I have around and leave the huge ones in place? Huummm…
(DIR) Post #B1hMk2z0IupX7TWvcu by arroz@mastodon.social
2025-12-27T17:25:14Z
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Heh look at this old diodes!
(DIR) Post #B1hMk3mdKOWrbOkYz2 by arroz@mastodon.social
2025-12-27T18:47:56Z
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Ok so I measured the resistance between the two AC poles and it reads 19 ohm. That is waaaay too low. Not gonna plug it in yet.There are a few things I assume are filtering caps inside a sleeve next to the transformer which may be bad, but I can't get to it from the PCB panel.I think I found a way to pop out the top plastic case, but I can't get to the screws without removing a lot of the printing mechanism, and I'm not sure I want to do that… at least not today.
(DIR) Post #B1hMk4ZYOVf237ddEe by arroz@mastodon.social
2025-12-27T18:51:01Z
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I measured the huge caps (in circuit) and they seem fine, so there's that.I'll continue another day, after a bit more research on how to open this thing properly. But we'll get there, hopefully!
(DIR) Post #B1hMk5Sr4tteodVnQu by arroz@mastodon.social
2025-12-27T18:52:27Z
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Meanwhile if anyone has an ImageWriter (even a II or LQ), can you discharge the capacitors (by pressing the power button to turn it on *after* unplugging the mains cable) and then measure the resistance between the two AC power cable poles, and let me know how much it measures? Thank you! Doesn't need saying, but MAKE SURE NOTHING IS CONNECTED TO THE MAINS. I want you to measure the poles of the AC cable connected to the printer, not the mains! Don't do it unless you know what you're doing.
(DIR) Post #B1hMk6ewdRA4WQAxuq by arroz@mastodon.social
2025-12-27T21:17:03Z
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Ok folks are saying the low resistance is normal because it’s a transformer so the electromagnetic fields will do their magic and not draw 11 amps. So you know what, let’s dooooooo it! Preparing for powering this thing on for the first time in who knows how many decades.May I note that none of these caps have pressure relief vents so there’s potential for fun here.
(DIR) Post #B1hMk7WTQPynCRDiLo by arroz@mastodon.social
2025-12-27T21:25:11Z
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OMG it works! 😁 At least the basics. Let’s wire this thing to that thing and see what happens.Also as @danieltufvesson suggested, the transformer has two inputs, one for 220V and one for 240V, and because Portugal used to be 220V, that’s what this printer is wired for. We are now at 230V so I should rewrite this which will be a problem since I need to figure out how to get to the transformer.
(DIR) Post #B1hMk8HGcRPTXZ75Hs by arroz@mastodon.social
2025-12-27T21:28:07Z
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As curiosity, here's the voltage and frequency here in the past 24h (on a different phase, though, because I still didn't get rid of the dumb three-phase system at home):
(DIR) Post #B1hMk8x66us1dIgUUK by arroz@mastodon.social
2025-12-27T21:40:30Z
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It has been a while since I plugged in one of these cables. And PowerBook still works!
(DIR) Post #B1hMk9gTODANu1ujDM by arroz@mastodon.social
2025-12-27T21:49:30Z
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WOW! It prints! And I don’t mean “the printing head works”. I mean it ACTUALLY prints! The ink is not dry after decades, literally, decades of being stored in a closet! I’m speechless and giggling! Folks, how do I share this thing on #globaltalk?
(DIR) Post #B1hMkBrtGjUIg1GsHw by arroz@mastodon.social
2025-12-27T23:48:30Z
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@billgoats Yeah, that’s what I’m hoping for. Aren’t folks doing that already? Or is every image and style writer on GlobalTalk a real network printer, with an AppleTalk card?
(DIR) Post #B1hMkIBbmKpEGuXhr6 by arroz@mastodon.social
2025-12-27T22:08:26Z
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(DIR) Post #B35dsHqlRBxCT19mN6 by arroz@mastodon.social
2026-02-07T10:34:26Z
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Ok question for #electronics and #retrocomputing folks, if I disable all sorts of hardware and software handshakes, and I wire the TXD directly to the RXD pins of a RS-232 serial port, I should see the echo of the data I'm sending, correct? And I should see the signal bouncing between >3V and <-3V on that wire?I'm starting to think the USB-serial adapter I bought is broken.
(DIR) Post #B35dsMyOOG1iM7lRSK by arroz@mastodon.social
2026-02-07T10:58:12Z
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So here's what happening: the yellow line is the TXD, blue is RXD. On the first two photos, both are NOT wired together. TXD goes low, RXD goes high (weird, but maybe bias?). The signal is clearly seen going up and down the threshold, and TXD works fine. Third photo is both lines wired together (and blue probe disconnected). The signal never goes below 0V! And naturally I get no data back. Is the RXD line broken? #electronics #retrocomputing
(DIR) Post #B35dsRpMLGlvPYZnZQ by arroz@mastodon.social
2026-02-07T11:14:55Z
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Mystery solved, this thing is working, but wired wrong. 😂 Thank you @barries! https://mastodon.sdf.org/@barries/116029020950642130 So now I have to wire two non-standard RS-232 ports, the FDD 3000 from 40 years ago and the new adapter, and at some point an old PowerBook with also a non-standard thing. My brain is feeling the pain already. #electronics #retrocomputing
(DIR) Post #B35dsWwzIKqRIfBSee by arroz@mastodon.social
2026-02-07T11:40:54Z
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Here's the pinout of this stupid adapter:USB-serial adapter:Pin 2: DTRPin 3: TXDPin 4: RXDPin 5: Ground, I think. I hope.Pin 7: CTSPin 8: RTSPin 9: DSRWhat a lovely thing.