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Dynamac Smokin!


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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"....

 

post-2150-0-16775900-1506361618_thumb.jpg

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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.. :)

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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...

Edited by aplmak
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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.

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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!!! 

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  • 1 year later...

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? 

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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

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  • 3 weeks later...
  • 1 month later...

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.

DynamacPowerSupply.jpg

DynamacRunning.jpg

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  • 5 months later...
  • 68kMLA Supporter

I think they may have been a gas plasma display, but all the Dynamacs I've seen, including my own have an electroluminescent screen. I think it's also why the model number has an "EL" in it.

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  • 3 weeks later...

I ran into another problem with the DynaMac, the Mac Plus logic board developed a fault, think a while ago probably before repairing the PSU, where it would freeze after being on for more than 5minutes. After much diagnosing (using the board hanging out the back of a Mac Plus and using freeze spray), the problem turned out to be the two LS245 chips in the corner where the keyboard plugs in, bought a couple of new chips from RS components, soldered them in and all has been fine since.

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  • 2 weeks later...

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