68kMLA Classic Interface
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| Click here to select a new forum. | | modded mac 512k | Posted by: weldum on 2021-07-14 17:42:16
hi, I have a modded mac 512k, it was upgraded to support scsi, 1mb of ram and the macintosh plus rom (acting effectively as a mac plus without the ram maxxed out)
however it had some problems, the rifa cap blew up but i've got replaced it and it works wonderful
the mouse doesn't work right, but I have been told that an amiga mouse should work fine as long as I change the pinout in the connector
the keyboard works but has problems, some keys don't work, i'm trying to see what's wrong with it
also I have the floppyemu and is awesome to look at, loading things fast, specially in hd20 mode, but i want to know what are the latest or better versions of ms word, ms excel and claris works for that machine, also the best, snappiest system software version for the machine
thanks. | Posted by: joshc on 2021-07-15 02:30:14
also the best, snappiest system software version for the machine System 6 or lower for this. With just 1MB RAM, you want older software rather than anything newer running on this.
but i want to know what are the latest or better versions of ms word, ms excel and claris works for that machine I'd recommend earlier versions rather than later ones, they are less bloated and tend to run better on old systems with low RAM.
My favourite word processor for old Macs is actually WriteNow, not Word: https://macintoshgarden.org/apps/writenow | Posted by: weldum on 2021-07-15 18:41:45
thanks i'll check it out later, now i'm facing new problems.
I've recapped the analog board as it seems to be in very bad condition. before that the machine would just work fine (and then the rifa cap blew up)
but now the machine boots fine but makes a loud noise, like coil whine or a problem in the flyback transformer, also, the image looks zoomed in and shifted to the right
i'm trying to see what could be the problem, all the solder work i've made for the recap is fine and as clean as possible, i've checked it a lot of times now
i've noticed that the anode cap looks like if it's slightly broken on one of the tips that goes into the crt
i need help and/or a manual on how to troubleshoot it, the board is an international 220v one | Posted by: joshc on 2021-07-16 02:17:53
Analog boards in these machines suffer from dry/cracked/weak solder joints. As the machine only has passive cooling, the analog board and its components get very hot during normal operation, this affects the lifetime of the parts and the joints on the board. If you haven't done it already, all the solder joints on the board should be reflowed with new solder.
Can you please post photos of your analog board and the flyback transformer in particular? A dark colour of the sealant around the top of the flyback usually means its had a hard life, the colour when new is yellow.
A recording of the noise might be useful too.
I had a Plus with a broken tip on the anode cap, I ended up sourcing a replacement flyback. Spare analog boards are the best way to find a replacement flyback. | Posted by: weldum on 2021-07-16 18:09:15
mac with problems
that's the video with the problem, i can't see anything like a spark
the flyback is orange at the top and also i've checked an soldered all solder joints
i wonder what is causing this issue, as the machine worked just fine before | Posted by: joshc on 2021-07-16 23:22:06
When you say you checked the solder joints, you mean you looked at them physically and they look good? Reflow them all anyway.
As the board worked fine before it was recapped, it is possible it doesn't like one of the caps you used. What are the specs/ratings of the ones you used?
C1 doesn't appear to have been replaced - is that right? It's a non polarised high frequency capacitor, it can be replaced with a metallised polyster capacitor. C1 is an important component on these.
Identifying bad connections or shorts would be where I'd start. | Posted by: bdurbrow on 2021-07-17 01:50:45
In order of probability: bad connection, short, bad or incompatible capacitor, bad trimpot, bad transistor, bad resistor, or bad inductor.
Specifically I'd be looking at everything in the horizontal sweep circuit first. | Posted by: weldum on 2021-07-17 08:43:28
all caps are the same value as the old ones where possible, or with a bit higher voltage, farads are the same on all of these
I've reflowed all the solder joints
c1 cap is the only one that couldn't replace but I've found a suitable replacement now
some traces were lifted up and they're been fixed | | 1 |
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