HM 4.2.4 schematic image missing from wiki/picassa


 
You can fix your board for sure, just need to add wire where the trace is broken. Give more info about what traces broke, or better yet post some pics and I will help you figure out how to repair it.
 
To give you some encouragement I made up this image to show how few connections there are to Q3 (the green one is on the component side of the board) and how easy it will be to repair a broken trace from it.
Q3.jpg

As you can see, the connections are few... So if you clean up the damaged part of the board, remove any fragmented remnants of the damaged trace, it will be very simple to use a piece of wire to replace the broken trace. It's not rocket science, the purple lines on the board (traces) are just wires that go from point A to point B...
 
Hey folks, I cooled off a bit, took some pictures. My board isn't pretty. I'm pretty sure i ripped up that 12v trace coming from the power jack to the third pin of Q3. When I try and power up my HM, I get no display. So I'm not sure what else I may have harmed.

G8Qn4UI.jpg


What gauge wire should I get to jump the traces? Best practices when doing so?

Thank you.
 
The first thing you want to do is clean off the board, I can't see what is going on in that pic due to all the flux and debris left behind from your soldering. Use some isopropyl alcohol and a soft brush (old tooth brush if nothing else is available) to clean the board, then take another pic.
Next, use a razor to cut that broken 12V trace where it is peeled up so it isn't hanging there to short out on something, leave only the part of the trace that is firmly attached to the board.
I took a quick look at the board pics on OSHPark, there are only two traces coming from the 12V power jack, both on the solder side of the board. One seems to just power the buzzer, the other goes to Q3. The screen printing covers the trace in places so it is hard to see, but I think the 12V goes to Q3 then over to the top of D3, where it goes to the OKI to provide power the rest of the board. So I think when you replace that broken 12V trace the rest of the board will start to work again. I will have more time to look at the board and tell you for sure this evening.
As for what wire to use, I would use some solid core wire, stranded wire is hard to keep from fraying and shorting out other things. There's not too much current here, so it doesn't need to be very thick wire, I tend to use solid core wire out of a CAT5 cable because I have it handy, you can use a light gauge solid hookup wire as John has suggested.
As rough as your board may seem at this point, I think you are a quick cleanup and a jumper wire away from making it work...
 
John Bostwick said:
You want it(wire gauge) as small as possible 20-22awg should be fine
Click to expand...

RalphTrimble said:
The first thing you want to do is clean off the board, I can't see what is going on in that pic due to all the flux and debris left behind from your soldering. Use some isopropyl alcohol and a soft brush (old tooth brush if nothing else is available) to clean the board, then take another pic.
Next, use a razor to cut that broken 12V trace where it is peeled up so it isn't hanging there to short out on something, leave only the part of the trace that is firmly attached to the board.
I took a quick look at the board pics on OSHPark, there are only two traces coming from the 12V power jack, both on the solder side of the board. One seems to just power the buzzer, the other goes to Q3. The screen printing covers the trace in places so it is hard to see, but I think the 12V goes to Q3 then over to the top of D3, where it goes to the OKI to provide power the rest of the board. So I think when you replace that broken 12V trace the rest of the board will start to work again. I will have more time to look at the board and tell you for sure this evening.
As for what wire to use, I would use some solid core wire, stranded wire is hard to keep from fraying and shorting out other things. There's not too much current here, so it doesn't need to be very thick wire, I tend to use solid core wire out of a CAT5 cable because I have it handy, you can use a light gauge solid hookup wire as John has suggested.
As rough as your board may seem at this point, I think you are a quick cleanup and a jumper wire away from making it work...
Click to expand...

I'll give the cleaning a try but in the past I can't seem to get the yellow stuff off no matter how hard I scrub. That inevitable leads to me digging at it with my finger nails and then further scoring the board. :( I also have a can of CRC electronics cleaner - which doesn't seem to be any better than the isopropyl alcohol. If you right click the image and select open in new tab or window you will get the full 4k resolution which you can zoom into. I find that to be very helpful.

I will post new pics after I try and clean up the board some. As far as soldering the jumper wire in place; how do I make that contact? Should I scrape off the coating on the board to reveal the trace first or is there a better method?

Thanks!
 
If you live near a Fry's, you can get Puretronics Contact Cleaner and Lubricator. That stuff will take all the flux right off the board
 
Try to trim all the long leads, especially around the button. The resistors around the button, some have pretty long solder joints.

Take you soldering iron and heat each and every solder joint. Add solder until you have pads covered and the joint looks like a pyramid or a chocolate hersey kiss. If you see any stray solder on the board. Take your soldering iron and gently remove the solder
 
as for how to add the jumper wire(s)... Sometimes if just the circle around the hole is broken you can scrape the coating off the trace and bridge solder to it, but in this case the trace is broken further away so I would recommend that you run the jumper wire all the way from the 12V solder joint on the power jack to the 12V pin on Q3, this will give you a more rugged repair.
As for cleanup of the board, the most important thing is that the debris does not short things out, so use your meter in continuity mode to check the three legs of Q3, if they are all isolated from one another then I would just run the jumper from the 12V pin of the power jack to the 12V pin of Q3 (the right pin when looking at the solder side of the board). If you find shorts then you will have to scrape the board clean to remove whatever is causing the bridge. After you install the jumper check continuity again to make sure the legs are still isolated, and also check continuity from Q3 to the next component(s) down the line (as shown in the diagram I posted recently) to make sure all of the traces are intact. If you find continuity missing on any other traces then add another jumper wire there, again, going from solder joint to solder joint, don't bother with trying to solder to a broken trace.
I think it's just the 12V trace that is broken (hard to tell from that pic), so I think the board will work after you install that jumper, but just make sure you check for shorts before you power the board and burn something up...
 
Last edited:
You must log in or register to reply here.

 

Back
Top