HDM Z1 Battery Replacement

[Ephraim]

While Traveling last month, I had a rude awakening. We were boon docking in our trailer and I used to use a Resperonics System One with the power supply modified for 12V and plugged into the trailer with an Anderson Connector. the System One was part of the recall and I had just received a Dreamstation as the replacement. In the system one, I sys imply cut the 12V side of the power supply and inserted Anderson plugs so that I could run it off of the power supply or the trailer 12V system. I hadn't modified the Dreamstation yet, but brought everything along on the trip to do so. I dutifully cut the cord only to discover that Resperonics now uses a third wire which connects to a transponder inside the power supply to keep people like me from doing exactly that. After a few ill thoughts towards Phillips, I retrieved the HDM Z1 from its cabinet where I keep it as an emergency backup. Sadly, it was in handicap mode. It was not remembering the settings and would not let me change them. It was also throwing a Code 33. A quick Internet search revealed that it was most likely the internal lithium battery was depleted. With that, I went to the second backup plan which is much less desirable. I reassembled the Dreamstation power supply and ran an inverter all night long which was tough on the battery, but we made it.

Back in civilization, I was appalled that HDM wants north of $500 to repair the Z1. Uh, no thanks. I'd just buy a new unit at that price. So what else is there to do but repair it myself. I see other threads where people have the same frustration as me so here is a record of the repair. It took me about an hour to complete but it probably isn't considered an easy beginner job. There are also some specialized tools that you will need such as a Dremel tool with a tiny cutoff wheel, a high quality soldering iron capable of working on really tiny things (A Walmart special will probably cause more damage that it fixes), and some very fine wire. I used 22Ga wire, but I think I would have been happier with 24 or 26Ga.

So here goes:

Step 1:

Remove the filter cap and turn the unit over onto its front. You will see 5 small Phillips screws. Remove all 5. Note that there are three long and two short. The long ones go in the top three holes and the shorter ones go in the bottom two holes. don't mix them up.

   

Step 2:

Slide the clear intake tube out and separate the two halves of the shell. The silicone port where your hose adaptor plugs in will have to be pushed through the back shell. Just flex the edge and push it through. Do not pull the halves apart forcefully. The back shell must release the tube to separate them. You can see the ridge/groove in this picture where it snaps into the shell. just flex it and push it through.

   

Step 3:

Remove the 4 small screws holding the blower and electronics in place. You should be able to just lift it out of the shell.

   

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[Ephraim]

Step 4:

Carefully remove the plug from the top edge of the circuit board that attaches the blower, flip the circuit board over and carefully remove the display board from the main circuit board. You can flip the display board over backwards to get a good look at the connector. Note that the edges of the connector must be pulled up to free the cable from its clamping action. When that is done, you will see the Panasonic BR1225 lithium battery that is the culprit. I ordered a set of 6 batteries on Amazon for $12. I figured I'd get more than one just in case I killed the battery while soldering to it.

   

Step 5:

This is the most hazardous step. Using the Dremel with a cutoff wheel, you must carefully cut the tabs that are welded onto the battery. Cut the top one first and then you will be able to reposition the battery to cut the bottom one. The tiny cutoff wheel just barely fits between the other components. Take it slow and brace both your hands at the wrist on your bench to eliminate shaking. It's a very tight fit and if that cutoff wheel touches and kills any other component on the board, you are screwed. 

   

Step 6: 

Once the battery is out of the way, you can use the Dremel or some very sharp wire cutters to clean up the tabs left on the board. Do not remove them completely as you will attach your wire to these. I left them as small nubs that I could solder to. Note that the circuit board is actually labeled as to which lead is + and which is -.

   

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[Ephraim]

Step 7:

Prepare the battery. Small things are tough to solder without overheating them. When you are joining things, it's even harder. I've found that it is best to pre-tin both the wire and the battery as that can be done very quickly. then join the two surfaces being soldered. Make sure you let the battery cool down completely between each time you touch it with a soldering iron and do not spend too much time applying heat. If the solder isn't sticking, back off of it, let it cool down and apply some non-acidic rosin core flux. then try it again. A little goes a long way. Here you can see where I pre-tinned a spot on the battery. I'm using flux core solder designed for this. It's about 20 Ga in diameter so very fine. Don't try this with that 1/8" solder as you will apply way too much. put a pre-tinned spot of solder on both sides of the battery.

   

Step 8:

Prepare your connection wire. both ends of the wire are stripped and tinned. You can see here where the wire I used is probably too large, but it's what I had on hand. Each piece is only about an inch long. I used zip board that was separated. I highly recommend two different colors of wire so you can keep them straight. Bad things happen if you get the battery in backwards.

   

Step 9:

Attach the pre-tinned wire to the pre-tinned spot on the battery. If you are using different colored wires, make sure you know which side is going to the + and which is going to the -.

   

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[Ephraim]

Step 10:

Flip the battery over and attach the other wire to the other side. Make sure that the free ends of the wires do not touch each other.

   

Step 11:

Cut about 1.5 inches of electrical tape and carefully wrap the battery so that no bare metal is showing. Press the ends together tightly with your fingers. You do not want this battery touching anything else inside the case.

   

Step 12:

Now carefully solder the + wire to the + terminal on the PC board and the - wire to the - terminal. You should have something that looks similar to this:

   

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[Ephraim]

Step 13:

place a piece of double sticky foam tape on the battery. I used 3M outdoor tape as it's pretty strong unlike the cheap generic white stuff you get at the hardware store. Cheap foam tape tends to degrade over time (Phillips recall anyone?). The 3M outdoor rated tape performs really well and is probably overkill for this, but again, it's what I had on hand.

   

Step 14:

Carefully bend the wires and press the battery down onto the board so the foam tape grabs the board. You will need to flatten the bends in the wire so that they do not interfere with the display board.

   

Step 15:

Once the battery is secure, reattach the display board cable. Make sure the rim of the PC board connector is pulled up, insert the cable and then press the rim back down to clamp the cable. Make sure the cable is inserted squarely and all the way. If not, pull the rim of the connector up, reposition the cable and then push the rim back down. At this time, you must also place the button rubber pads into place. Note the 4 pins in the case that fit into the four holes on the pads. You need this securely in place as you are going to flip the case upside down and if all 4 pins/holes are not in place, the buttons fall out and you start again.

   

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[Ephraim]

Step 16:

Fold the display board back over and place the mounting groove onto the button board. the top of the board has two plastic legs that must fit in two tiny holes on the PC board. If you don't get thees legs into the holes, it won't fit right. This is where you may notice the new battery leads interfering. Gently bend them so that the two boards fit together like in this picture without having to hold them in place.

   

Step 17:

Now you need to mate the circuit board into the case. Despite how you see it in this picture, you must hold the circuitboard so that the display is on top (otherwise the display just fall off and dangles by its cable. Flip the case face up (gently, or the buttons fall out) and lower the case onto the circuit board so that it lines up in its nesting place. Assuming you got it back together, flip it back over face down while holding the circuit board in place and it should look like this:

   

Step 18:

Carefully line the blower motor and circuit board cover up and place it in the case as well. Don't forget the hose brace when you put the lower two screws in.

   

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[Ephraim]

Step 19:

You're almost home free at this point. all the difficult work is done and you are just reassembling the case now. I found the easiest way to do this is to partially insert the rubber fitting into the back half of the case and then line the two pieces up. It will look something like this picture.

   

You can then use a small screwdriver or small needle nose pliers to carefully grab the edges of the rubber boot and pull them through the hole. I found it easier to use small needle nose pliers and just grab the very edge that is almost ready to pop in place. Just work you way around the edge being careful not to damage the rubber.

   

Step 20:

Once that is in place, you just need to mount the blower motor holder. Note that the case has three pins and the silicone holder has three corresponding holes. You can't open the case very far without damaging the rubber fitting on the other end so you have to hold just about like you see here.

   

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[Ephraim]

Once the blower motor holder is inserted into the case, the easiest way to align it to to rotate it to the correct position as shown here. lift up on the rubber piece that is closest to the edge and line the single pin up with the hole in the rubber.

   

The holder will then drop down onto the other two pins perfectly

   

You can then position the two halves of the case back together easily. Put the 5 screws back into the back cover. the three top screw are the long ones, the two shorter ones go on the bottom. Don't forget to slide the clear inlet tube back into place. The rotation doesn't really matter, but it must be fully inserted.

   

You've now repaired your device and it will work normally. 

I have not been able to reprogram the date/time though as it is no longer supported and that function apparently has to be set using the firmware upgrade software. HDM has apparently separated the firmware upgrade from the data software so unless you have older software, there is no way to set it that I know of. It still works without that though.

One other thing you probably discovered if you did this is why HDM charges so much for the repair. I'd probably charge a similar amount as well. it makes sense that the original battery is soldered in place as medical devices are held to a higher standard than consumer devices, but ick!

Good luck!

[nocreek]

Thanks for this thread. I've got my taken apart and waiting for the battery to arrive. I ordered a BR-1225/HCN which has the solder tabs welded on it, so should be an exact fit for the board.

[thx1025]

Really great tutorial and I appreciate it. 

One question (and perhaps I missed this): is it too much of a risk to remove the entire battery with its tabs and replace it with another instead of cutting with the Dremel and soldering on wires? 

I found the Panasonic BR-1225 with the tabs already soldered on (product is listed as BR-1225/HCN) 
I wondered if un-soldering (is that a real word?) and soldering in a complete battery with tabs is possible. Thanks in advance!