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Fixing a power connector?


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You might try some right angle header pins. 


I used to know what type of connectors these were, but I've forgotten.  I believe they were originally used in some kind of phone back in the 1980s, and they weren't necessarily for power.  I think they might have connected some kind of handset or modem, but I'm not sure.  The 7800 uses a 9V power supply, so it might be easier just to replace it with a more conventional connector



These are the pins I'm talking about.  You can pull them loose from their plastic, and might be able to insert them into connector you have.


Edited by CMR
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1 hour ago, slx said:

It will probably save some trouble (and allow use of a cheaper PSU) to replace it with a conventional connector. Just make sure to affix a sticker with the correct voltage/polarity. 

I always change the power socket, this type fits perfectly on the existing pads and very tightly fits the gap I the back panel, put a cable tie through the existing mount holes in the PCB over the new socket.  



Also change the ferrite from the positive connection into a 1N5817 diode, with the cathode away from the pin on the connector.  Polarity protection.


@jham55I've got some of the 7800 power connectors, if you are in the UK, you can have one.

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38 minutes ago, jham55 said:

I don’t live in the uk but I’d gladly pay for  it if you can send it! 

Where do you live then roughly? I've got a few donor parts boards and I think one of them still has a good connector on it I can remove for you?


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10 hours ago, jham55 said:

Is that too far? Let me know what you would like for it!

My apologies, but I don't have a spare connector. I thought I did but after looking through my spare donor parts boards, none of them have the connector. So I must have used it for another 7800 repair, or sent it to someone already. I do apologize for that.


So the best option currently is to try and install a standard barrel jack in place of the original. I've this a few a few times, and another option although not as elegant. Is that you could purchase just a pigtail of the connector on wire and then solder the wiring directly to the board with the small length of cord and the adapter plug on the end. This way, if you fine an actual 7800 power DC jack in the future, you can de-solder the wiring and replace. I've done that for a few clients over the years although it isn't requested nearly as much these days.



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The power connector that @marauder666 linked to above can also be had from both Digikey and Mouser here in the US. Runs about $1.20 each from those locations. Here is the Mouser link which, I normally use Mouser only because they are just a little over 4 hours from where I live and so even 1st class postage gets to me in a day or two.




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3 hours ago, jham55 said:

So I solder this onto the board? What kind of adapter would I get? 

Post #21 on that thread has photo's on how to install it. I use a bit of solid core for the ground connection through the board, keeps it strong. You also might need to file the case very slightly as they vary, but it'll be very close. The case, zip tie and ground connection make the socket surprisingly strong. The power wire is just a wire from the other connection.


PSU wants to be 9v with a 2.1mm centre positive barrel jack. We use these: https://uk.rs-online.com/web/p/desktop-power-supplies/7212092/?relevancy-data There might be something like that available locally for you.




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6 hours ago, juansolo said:

PSU wants to be 9v with a 2.1mm centre positive barrel jack. We use these: https://uk.rs-online.com/web/p/desktop-power-supplies/7212092/?relevancy-data There might be something like that available locally for you.

Center positive? Hmm...that explains the difference in our wiring when I did one of these over a year back. For us here in the states, it is easier to use a Sega style PSU for something like this, bu they are wired center negative so I had to epoxy the connector upside down to the main board and then ran 22awg solid cord from the terminal tabs to needed points on the main board when I did this. Had I been willing to wire it for a different polarity, then I could have nearly made it a drop in replacement.




Can't see in the pics but I believe the grey wire was soldered to an empty VIA right here on the ground plane behind it, and the purple was the + voltage soldered at the base of the ferrite bead location just before the main filter cap. Although in the pic, you can see that I had already replaced out the bead with a diode for polarity protection.


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