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MindWalker

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  1. MindWalker

    512k: a battery-thingy and a serial cable adapter

    Here's the wiring for the serial adapter. Note that the symbol for the 8-pin female mini din connector is not correct (didn't have it in KiCad, don't know how to edit). Pins 3+4 are the ones closer together, and pin 7 on the top row is on the same level as pins 6 and 8. Sources: https://whitefiles.org/tec/pgs/h10b.htm
  2. Here are two things I was playing with on my Mac 512Ke today First is a 3D-printed "battery replacement" for the early Macs. It uses three LR44 batteries in series (counting up to the 4,5v as the original) and mounts in place of the original battery. Much cheaper than buying one of those Exell A21PX (yes, still available). The STL-file is now available in Thingiverse: https://www.thingiverse.com/thing:4558846. You need to add a piece of wire and some sort of a battery contact on the negative end. Downside of this solution is that the capacity is only about half of the original battery (330 vs. 600mAh). But as a temporary measure it should work fine, and perhaps the LR44s are not as prone to leak and cause havoc as those big batteries. (I did think about having the batteries not touching either terminals of the Mac to further make sure leakage wouldn't get there, but as I don't have any good battery contacts to use, I went with this way: the top of the battery makes for the other contact and the other is wired over). Here is the adapter next to an original (removed) battery: And here is how it looks: Second is a serial cable adapter. This is mostly just a heads-up, I tried to google if this really worked, but I couldn't find a definite answer. Yes it does! The early Macs have 9-pin D-connector, unlike the later Macs that use a mini-din 8-pin connector. Most of the easily availabe serial cables (and PhoneNet adapters!) use the later connector. The early ones do exist, but are hard to come by. With this adapter, I was able to use LocalTalk over a mini-din 8-pin serial cable and access files my Performa, nice! The PhoneNet adapters should work too (only stuff that needs both the HSKi and HSKo handshake lines might not, as the D9 only has HSKi available). I had a peek inside one of my PhoneNet adapters and that was not wired to those pins at all so I'd guess they will work too. You need the AppleShare File Server 2.01 with the "AS201 WS 512Ke.image" to install the additional pieces (AppleTalk addin, plus a System update, after install I am now at Finder 6.1 and System 3.4, this is on a Mac 512Ke). It's just a 6-wire cable with a male D9 on one end and a 8-pin mini din female on the other. Those mini-din connectors are a pain to solder, but yeah, doable if you go slowly. I'll clean up my notes and post the wiring here tomorrow. It just adapts the signals from the different connector to the other, no need to add anything or swap pins.
  3. Ok, an update on this. I didn't really felt like I was making any progress, so I turned to eBay. To my surprise there was a untested 630-0102 analog board (also 120V) for sale in german eBay. I thought why not, it was only 30 eur + shipping, I also got some needed spares from the same seller (a long serial cable, and a bag of spare Mac screws). I got the parcel today. The board was very similar to mine. There was a Rifa mains filter cap, I replaced that on the spot (just to make sure...), reflowed all connectors and removed a somewhat oxidized battery holder. I looked around the board, everything seemed to be in order. I installed the board into my 512k, and flipped the switch. OMG, a loud boing!! And soon there was a ?-mark floppy icon on the screen - the machine was working! I did some quick testing, kept the machine running for some half an hour, and so far everything seems to be pretty much Ok. The 5/12v rails measure fine, the floppy drive works (I cleaned and lubricated it already earlier) and the CRT is sharp and has good brightness. The geometry will need some slight adjusting, I already tweaked the height up a bit. I'll also need to move the battery holder over from the original analog board (it was cleaner) to this one and I'll surely re-cap the analog board while there.
  4. MindWalker

    Macintosh Portable, what is R21 resistor value?

    R21 should be a 100K EDIT: here's the link, took some time to find it --> https://github.com/nickpunt/nubus-se30/tree/master/Schematics/apple The screenshot is from sheet 14-19, bottom center.
  5. Still no dice I have noticed one bigger issue. In the Dead Mac Scrolls (Troubleshooting, flup-flup- issues, page 24) there is a description that one should be able to measure a lowish 31/30 ohm resistance over the CR20 rectifier diode. And 52/53 ohm across CR21. If I try to measure that on my board, I briefly get about the correct value but then it starts rising, and ends up somewhere over 2-2,5 kOhm. I can't quite figure out why, as I have replaced both CR20 and CR21, and the electrolytics around them. Also adjusting R56 (+5V adj) fully counterclockwise (page 27) does not help the issue.
  6. Hi @Will Cheyney, thanks for writing! Good to know that you got yours working afer the issue, that does give me hope! Those resistors R47, R49 were indeed bad in my board, too. My board already has had more damage (Q9, Q11) but hopefully I can still figure this out. I am not sure if I have yet checked those CR23 and -25 (looking at my photos I think those diodes are partly under the glue holding the adjucent big cap on my board) - but I do have a plenty of those 1N4007s at stock if needed. I am waiting for some more components to arrive (tomorrow or the day after), then I can get back to working on the 512k.
  7. MindWalker

    Opening Powerbook adapter

    I re-capped my PB100's charger just a while ago. I used a vice with small blocks of wood and indeed it worked nicely!
  8. @max1zzz: yes, I had the logic board attached. @cheesestraws: ok, saw that just now. (Thanks to both of you). In the listings the only given non-OEM part number is Philips ECG5589, and that is a huge bolt-like (ST-75 package) 550A part (according to Philips datasheet). I think that must be where the description in the manual comes (and must be a mistake). The original parts is a tiny package and it's current rating must be much, much smaller. Hmm, must have a look at the component itself when I have the board out next time. I am not sure that's my real problem, but other than that I am not sure what else to try
  9. Ok, I have now replaced the burnt resistors, and also Q9 (2N3906) and Q11 (2SC2810) which I found shorted. Now powering the machine up with a step-down transformer, I get a hiccuping sound (I guess this is the "flup flup flup" as described in The Dead Mac Scrolls). I quickly powered down. Following now the troubleshooting guide of the Dead Mac Scrolls; I am having trouble sourcing a replacement (or testing) the Q10 silicon controlled rectifier (CR400Y). With the CR400Y part number I can found pretty much nothing, and the parts list in Macintosh_Repair_&_Upgrade_Secrets_1990.pdf doesn't help either, the part numbers bring no search results. The description of "SCR,1200 V,550 A" sounds strange (really, 550A?). What could I use as a replacement there?
  10. MindWalker

    Macintosh Portable audio issue

    Nice! I think that the Portable is not supposed to be run without the main battery, it might cause strange issues. If you look at my link (a write-up on Reddit) you can see that the PSU is glued and you need to crack it open. I used a vice and it worked reasonably easy and there was very little damage to the casing (which I glued back together).
  11. MindWalker

    Macintosh Portable audio issue

    I just recently recapped my Portable. While testing it, I had some random audio issues, rarely loud, usually just faint noise/buzzing. A bit later I noticed that my charger was actually very sick (later on had no output at all) and needed recapping. Since that I don't think I've had those audio issues anymore (I have not used the machine that much, though). So I guess it could be a PSU related issue, do you have another PSU to test with?
  12. Hi! New here Was going to post this here first, but as my activation email didn't get thrue until today, I posted this already in Reddit /r/vintageMac. I came across a local ad for a Mac 512K keyboard and mouse. Reading the ad, I noticed that it actually noted "a non-working Mac 512K can also be included". This was interesting as I rarely see Macs of this vintage locally, and this was only a short distance away from me. From the photos I could see that the machine was a 120V which was interesting (living in a 220V country). Ok, I went to bought the set for less than 100$. What I have observed so far: Serial number dates the unit to a late 1985 A battery was still inside, but it had leaked only a very little and after cleaning and scraping the battery contacts they look Ok. There was no damage to the PCB where the holder sits. The floppy drive is a Sony MP-F51W, meaning that it has been upgraded (800k) ROMs are 23512-1010 and 23512-1007 (ie. "old ROMs" if I am not mistaken?) The analog board is marked 630-0102-J (ie. US, 110V non-switchable?) The digital board looks pristine and all the solder joints look original as well. Keyboard (M0110, 1985 per serial) and mouse (M0100, 1985) look intact and are reasonably clean. Keyboard cable is missing (seller said he might still have it, I might get it later). Externally the computer is in average condition, only major issue being a burnt spot in the plastic at the top left (covering part of the vent and also a bit of the front panel's top). The two short T15 screws were missing, perhaps a repair-attempt was made but they never get the case open due to the two recessed screws in the handle-space I have not tried to power up the unit yet. There was no backstory of how it failed, but being a 120V set in a 220V country, it's most likely that it was plugged in without step-down transfomer and was struck with overvoltage mains. Looking at the analog board, I see very little obvious damage. The fuse and resistor R51 next to the mains input have obviously burnt. On the bottom of the board resistors R46, R47 and R49 have slight discoloration and all three had their values gone very high. I have also done some measurements according to the books "Macintosh_Repair_&_Upgrade_Secrets_1990" and "The_Dead_Mac_Scrolls_1992" (there are plenty of in-circuit resistance measurements to go by). At the moment I am thinking about replacing the obviously burnt (/gone-high value) resistors, keep measuring around to find anything else obvious, and then power up (with a proper step-down converter). Adding to a larger component order (need to do this during the weekend), I'll also buy some spares of the nearby components (next to the burnt resistors in the schematics) like Q11, Q9 and perhaps the opto-coupler U3 too? Also some electrolytics, but I am not bothing a full re-cap yet. At first I'd like to see if replacing the obvious faults would give me any signs of life. Now my main question is; has anyone experienced a similar 120/220V over-voltage repair? How much was damaged etc. Any other pointers on what to keep an eye on?
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