68kMLA Classic Interface

This is a version of the 68kMLA forums for viewing on your favorite old mac. Visitors on modern platforms may prefer the main site.

Click here to select a new forum.

Dynamac Smokin!

Posted by: aplmak on 2017-09-25 10:48:40 Well I powered up one of my Dynamac's this past weekend... Works fine... and then it started smokin again.. But it remained powered on... the fan just kept blowing a nice breeze of smoke... So it's time to recap that power supply.... The offender was a .22 X2 safety cap.... after removing it there was goo and yuk where it was on the board... but I cleaned it all up.. It didn't pop thank god.. just oozed out... This has to be one of the most irritating power supplies to recap... I cannot wait till it's done.. I have all new caps in except for the .22 X2 caps and another one.. Those should be in this week...  Can't mess this power supply up... not easy to find a replacement for these!!! It's funny because a sticker on the side says "This is the Heart of your System"....

Posted by: 68krazy on 2017-09-25 21:09:28 Interesting.  What makes this model so particularly irritating to recap?  And do you have a picture of the sticker?

Posted by: Unknown_K on 2017-09-25 21:26:03 Power supplies are cramped, I don't like working on them either.

Posted by: aplmak on 2017-09-26 06:59:30 It is just very cramped... Not easy to work on... It's amazing a replacement for this is probably 1/4 of it's size now. They bent a lot of the cap pins in the thru hole solder connections.. and there was a trace on both sides connecting to the caps.. so not easy to lift caps out without damaging a trace.. Had to perform a few trace repairs. I tried like hell to not damage anything. I will upload a pic of the sticker when I get home today.. 🙂

Posted by: 360alaska on 2017-09-26 10:47:59 I bet the new caps are smaller at least. 🙂

Posted by: aplmak on 2017-09-27 06:55:00 Some are smaller.. but some not so because I upped the voltage... so there almost the same size with a higher voltage... lol... Here's the sticker!!

Posted by: james_w on 2017-09-29 01:53:40 Yep had to do the same to mine. Not fun to work on that PSU!

Posted by: aplmak on 2017-09-29 08:58:37 I couldn't get it to power on after the recap.... after searching found a MOSFET with a broken middle leg... That fixed the issue!!!! One little broken leg and nothing!!! I have the SE/30 version too.. I still have to do that machine...

Posted by: 68krazy on 2017-09-29 12:51:42 Interesting that the company that made the PSU is based in Vista, California. That’s less than half an hour from where I am originally from and have lived most of my life (Escondido, CA).

Posted by: Rajel on 2017-10-02 10:12:48 Oh jeez, just looking at that and thinking about recapping it makes me cringe, and I've got a decent setup for it. Bent pins on the other side of the through-hole, and traces on both sides are such a pain. I almost hosed my NES PPU mod due to crap like that, there's 4 pins that connect to a thermally-massive ground plane, and they're soldered on both top and bottom.

Posted by: aplmak on 2017-10-02 19:39:02 Yeah it sucks when the pins are bent on the other side... I do my best to glob it with plenty of solder to try to remove without damage to the through hole.. It's not bad on these old power supplies as running a jumper line is pretty easy.. I just like to keep it as original as possible.. I was so aggravated with this power supply I was going to throw in the towel.. It was that broken middle MOSFET connection.. I can't believe I actually found it.. Anyhow she's running great now!!!

Posted by: awulf on 2019-09-05 22:30:21 I have a Dynamc with a blown up power supply (a friend found it in the rubbish), Am interested in restoring it. I don't think the power supply itself is salvageable (unless I have the schematics). The hard drive definitely still works as I've tried it on a another Mac. Question is does anyone know the voltages coming out of the power supply, so that I can find/build something else?

Posted by: awulf on 2019-09-08 05:03:40 I deduced the voltages by following where they go: 1 Orange: +25v - To display pin 3 & 11 2 Yellow: +12v 3 Red: +5v 4 Orange/White: +5v 5 Black: GND 6 Grey: +15v - To display pin 1 & 9 7 Blue: GND 8 Blue/White: -12v By following the molex, the Mac Plus logic board and the Sharp LJ640U26 display. Now I Just need to make/find something

Posted by: awulf on 2019-09-24 07:19:54 Some success. Now to build it a power supply.

Posted by: trag on 2019-09-24 09:35:07 Nice work.   It's always nice to read about this kind of project and rescue.

Posted by: Ferrix97 on 2019-11-24 05:12:59 Had to rebuild a PSU too, the one that Cisco used in it's routers (1800 iirc) fits inside the casing perfectly along with two DC-DC step-up converters for the display. It's slightly less powerful than the original one, but seems to work fine.

Posted by: awulf on 2019-11-24 14:09:03 Few weeks ago I got it running, (tried posting on this forum then, but was down). The power supply I used is an XP Power ECP60UT01 bought from RS Components, and a couple of adjustable step ups from Banggood (5v -> 15v & 12v->25v). And I etched a little board to make things neat.

Posted by: aplmak on 2020-05-14 08:26:17 WOW! Just reading this now!! Nice job!!! Another SAVED Dynamac!!!! Check out this video from The Computer Chronicles... featuring a Dynamac...  https://player.vimeo.com/video/118760544?app_id=122963

Posted by: Trash80toHP_Mini on 2020-05-14 09:13:26 Can't believe I missed this thread, geat stuff. Has anyone out there on the web documented the Gas Plasma(?) display adapter? Especially interested in identifying the OEM and model of the panel. I wonder if it's the same one as in my Toshiba?

1 >