Macintosh LC II: Power Supply Connector and Video Troubles

[jazzius]

I am posting this because I want a definitive answer to 2 questions if anyone might be able to help me;

1: I recently was able to get my LC II’s board to chime and boot, but the trouble is the video adapter I am using does not give me any picture on any monitor I have tried, and while my monitors will register that it’s trying to output a signal and wake up the monitor, all I get is a Black screen. What I wonder is, because the LC II automatically defaults to outputting in 512 x 384, do I need a different video adapter? Even with a good PRAM battery and checking and cleaning the VRAM module pins, I can’t get seem to get anything

2: This is the really important Question. I was going to go about recapping my LC II’s PSU, however, cap leakage from the board has damaged the pins inside the connector that bridges the PSU to the board. Now I did do a bit of my own research into this and this connector in question is a Molex KK 396, and while people were posting links to the part that you need to crimp, my question is, what tool do you actually need to crimp this? Also, are there crimpers that I can get for this that aren’t $400? I really don’t want to shell out more money for a whole new PSU on eBay, and I couldn’t find the LC’s power connector by itself anywhere, so this is my only solution to really fixing this problem right now unless I manage to come up with something else.

Unfortunately, in the phase I am in, I need to get the original PSU working to keep testing this system, as the only other power supply I had that gave me -5V was old and randomly decided to die on me while I was testing this system :/

Also, a side note, for anyone telling me that this project isn’t worth it because (it’s just an LC!), I would say that, except when I bought this unit, the previous owner amazingly left a Daystar PowerCache Card in it, so there is no reason not to get it working in my eyes.

 

[cheesestraws]

Now I did do a bit of my own research into this and this connector in question is a Molex KK 396

It is!

while people were posting links to the part that you need to crimp

I'm going to answer this and your next question, but please read to the end of this post, because there's actually another option that might be easier for you here.

It's always worth remembering that there are lots of cheap "compatible" connectors for KK396 available on eBay or from your favourite budget components distributor. So long as you get from a reasonably reputable seller, these are fine for hobby projects, and are what I use for most KK396ish stuff. There is no need to pay the high molex price unless you really need the high repeatability or you're planning to run the connector near its current rating.

what tool do you actually need to crimp this? Also, are there crimpers that I can get for this that aren’t $400?

Please don't spend $400 on a crimping tool! You really don't need to. Once again, there are various compatible crimping tools available - I don't mean fake ones that are pretending to be Molex ones, I mean general cheapish multipurpose crimping tools. I got this set five years ago largely for the tool and it's still going: https://www.amazon.co.uk/dp/B07QNPZDTW - is it as ergonomic and as nice to use as a proper Molex one? No. Would I trust the crimps it made with highish voltages or currents? No. Is it 10% of the price of the official one and fine for low-power stuff? Yurp.

But!

Unless you're planning to be crimping multiple cables, consider buying cable assemblies. They're much more expensive than crimping your own, but considerably cheaper than buying a crimping tool then crimping your own. I'm in the UK and would go to RS for something along the lines of this https://uk.rs-online.com/web/p/wire-to-board-cables/2558964 (may be wrong connector, I can't remember off the top of my head how many ways the LC PSU connector has). They're a molex product so I'm sure you can get them in the US as well. If you want to learn to make cables or you anticipate making a lot of them, then it's worth getting the tool and learning to use it, but you don't actually *have* to if all you want is a cable with a KK396 on one end.

as the only other power supply I had that gave me -5V was old and randomly decided to die on me while I was testing this system

In case you aren't aware, -5V isn't actually necessary to get most of the computer working. IIRC the only thing it's needed for is LocalTalk, so the machine should boot fine and mostly work without it.

Also, a side note, for anyone telling me that this project isn’t worth it because (it’s just an LC!),

If you are enjoying doing the project or finding it interesting, it's worth doing, and don't let anyone tell you otherwise.

 

[volvo242gt]

Is the other power supply also an LC-series power supply? Reason I ask is that, for now, you could use butt connectors to splice on the harness plug from the dead power supply. That would fix the issue with the connector, at least for testing purposes.

With respect to the adapter, turn on 3 and 4, and leave the rest turned off. Your monitor should give you a 640x480 image, like what my old Dell gave me with my old LC III, as seen below.

 

[jazzius]

Is the other power supply also an LC-series power supply? Reason I ask is that, for now, you could use butt connectors to splice on the harness plug from the dead power supply. That would fix the issue with the connector, at least for testing purposes.

With respect to the adapter, turn on 3 and 4, and leave the rest turned off. Your monitor should give you a 640x480 image, like what my old Dell gave me with my old LC III, as seen below.

No, I wasn't using an LC series supply. It was an old AT class PC supply
I will definitely try the different settings on the video adapter though. I already tried basically every setting on the adapter initially, but I will try again with that configuration and a different monitor.

 

[jazzius]

Please don't spend $400 on a crimping tool! You really don't need to. Once again, there are various compatible crimping tools available - I don't mean fake ones that are pretending to be Molex ones, I mean general cheapish multipurpose crimping tools. I got this set five years ago largely for the tool and it's still going: https://www.amazon.co.uk/dp/B07QNPZDTW - is it as ergonomic and as nice to use as a proper Molex one? No. Would I trust the crimps it made with highish voltages or currents? No. Is it 10% of the price of the official one and fine for low-power stuff? Yurp.

This helps me a lot! Being in the US, I will need to find an alternative to this generic tool that ships here, but this gives me a good idea of what I am looking for. I still think though the best thing to do might be to get a KK396 pre-terminated male to male cable, cutting one of the ends off, then soldering that to the inside of the PSU. Besides the product you showed me from the UK though, I have yet to find that sort of thing pre-terminated here on eBay or anywhere else, so I am not really sure how I would get something like that. I will keep researching in the meantime, but do you know of where on the likes of eBay I could get a pre-terminated KK396 end with wires custom made?
I have seen it before, but I haven't further researched them.

 

[cheesestraws]

male to male cable

Female to female. The male connector for these is the board-side one.

Besides the product you showed me from the UK though, I have yet to find that sort of thing pre-terminated here on eBay or anywhere else, so I am not really sure how I would get something like that.

OK, so if someone sends you a link to a product on a site from another country, the trick is to look for the manufacturer and the manufacturer's part number. Here, on the RS page, you can see the brand is 'Molex', so it's reasonably likely to be able to be found internationally. And next to where it says 'Brand: Molex', it says 'Mfr. Part No.: 219665-1042'.

If you find a decent supplier in your country (in this case, I'll use digikey as an example), you can just type "Molex 219665-1042" into the search box and, with luck, it'll come up, thus: https://www.digikey.com/en/products/detail/molex/2196651042/16104910 And from here you can see that the relevant category on the digikey website is 'Rectangular cable assemblies' so even if this isn't precisely the right one, then you can browse that category to find something more useful. The same trick will work on, e.g., Mouser.

 

[jazzius]

Female to female. The male connector for these is the board-side one.

The gendering is not always what you think it is. I had it backwards haha. It makes more sense that way anyway.

And from here you can see that the relevant category on the digikey website is 'Rectangular cable assemblies' so even if this isn't precisely the right one, then you can browse that category to find something more useful. The same trick will work on, e.g., Mouser.

Actually, I tried this while I was waiting on your reply! Since the LC II uses a weird 7 Pin connector which is not made, I was able to find this 4 pin and this 3 pin to compensate.

I even was able to find them on Mouser here and here.

Thanks for the guidance! It would have taken WAY to long for me to figure this out if it wasn’t for this thread!
I will post here again with an update if everything works out!

 

[jazzius]

With respect to the adapter, turn on 3 and 4, and leave the rest turned off. Your monitor should give you a 640x480 image, like what my old Dell gave me with my old LC III, as seen below.

I know I am giving you this update kind of late, but I did a while ago try the different dip switch settings on my video adapter, and it made zero difference on any of my monitors, where it was detected, but nothing would sync to it. However, I would like to ask based on your pictures, what specific Model of Dell Ultrasharp is that? From what I have seen from other posts, they are better about syncing to these unusual machines, and they usually don't cost too much, so I just might get one...

 

[volvo242gt]

I know I am giving you this update kind of late, but I did a while ago try the different dip switch settings on my video adapter, and it made zero difference on any of my monitors, where it was detected, but nothing would sync to it. However, I would like to ask based on your pictures, what specific Model of Dell Ultrasharp is that? From what I have seen from other posts, they are better about syncing to these unusual machines, and they usually don't cost too much, so I just might get one...

It is the 1908FP. Used it as the main monitor on my old Mac Pro, as well as on the G4 Digital Audio that it replaced.