Maha MH-C9000 Disassembled

[EngrPaul]

Sheesh. Haven't I done enough by ripping apart my new charger before using it even once so you can see it's guts? Now you want me to disembowel the display just so you can see where the wires go? I'd have to be crazy to do that.

SORRY! I honestly wasn't suggesting you go further.

I was thinking about an LED replacement that may be necessary some time down the road.

Just the other week I replaced the near-death LED's in my Philips clock radio. There was 3 x 3mm LED's along the one edge of the optic panel. They were easy to replace.

Now with this flat panel, I don't know how I would proceed. I suppose it's not like the panel can't be read without backlighting...

 

[Mike abcd]

Can you comment on the quality of the switches used for user input? Like many, my well worn BC-900 has developed "switch bounce" that makes it a pain to use. I'm hoping the C-9000 will stand up to long term use a lot better.

Mike

 

[EngrPaul]

Those switches look (from the pictures) very standard and of good quality, with my experience with that type of component.

I bet you could easily grab a few from Digikey when the time comes.

 

[Billson]

it would also do my dishes :nana:

It probably could if you could find a way to fit your dishes in it.

 

[dekelsey61]

Hi Evillithiumman,
On the PCB board What are the 2 black round things that have like a hard wax around them and is just behind the Ac plug-in and between the 2nd+3rd slots. Those 2 things are what I believe gets the charger so hot during the charge cycle. You can feel the heat right at that spot during the charge. Sorry for my lack of knowledge. Thank you.
Dan

Here's the inside of the MH C9000 charger. It contains three subassemblies - the PCB, the LCD display and the one piece switch actuator:

 

[Fizz753]

Hi Evillithiumman,
On the PCB board What are the 2 black round things that have like a hard wax around them and is just behind the Ac plug-in and between the 2nd+3rd slots. Those 2 things are what I believe gets the charger so hot during the charge cycle. You can feel the heat right at that spot during the charge. Sorry for my lack of knowledge. Thank you.
Dan

Those appear to be a couple of capacitors.

 

[EngrPaul]

Perhaps the heat comes from the opposite side of the board, not the caps.

 

[thomas1268]

the keys, display and control method are better than bc-900, keys are good feel.

 

[LuxLuthor]

I'm worried that after showing those great pix that Evil Lithium Man didn't get it all put back together right! I wouldn't have.

 

[tacoal]

Hi EvilLithiumMan,

Could you provide high resolution pics? the pics you posted has little details on the circuitry.

However, I can see there are only 3 electrolytic capacitor. it is reasonable to suggest the voltage on the battery is sawtooth type since each channel doesn't have a capacitor for smoothing it.

 

[radellaf]

The LCD carries backlight power and multiplexed data over a 2 wire connection?

That doesn't sound usual. I've just been designing something with a small LCD and they all have that backlight power connector, but anywhere from 26 to 34 connections between the LCD driver (on the display) and the micro controller on the main PCB.

So, any good tap-off points for 5 or 12 to run a small fan?

 

[Bones]

The LCD carries backlight power and multiplexed data over a 2 wire connection?

That doesn't sound usual. I've just been designing something with a small LCD and they all have that backlight power connector, but anywhere from 26 to 34 connections between the LCD driver (on the display) and the micro controller on the main PCB.

So, any good tap-off points for 5 or 12 to run a small fan?

I think the LCD connections are somehow conducted by the dark grey strip in the center of this image:

http://www.candlepowerforums.com ... post1757733

It's made of a flexible material with what feels like a rubber coating on both sides.

The center is black with no obvious connection points, but it sits between the smoked lens and the long row of connecters shown on the left side of the circuit board in the first image of this post:

http://www.candlepowerforums.com ... post1756783

When I reassembled my MH-C9000 for the first time, the display only showed about half the information until I disassembled it again and carefully positioned the strip against the lower wall of the black frame holding the display assembly.

That placement ensures that the lower edge of the strip sits directly over the long row of connectors on the circuit board.

Insofar as tap-off points for an internal fan, you should be able to pick up 12 volts from the solder points shown on the bottom of the circuit board directly below the DC-in plug.

It's a hack I've been debating as well.

 

[waiwak]

I think the LCD connections are somehow conducted by the dark grey strip in the center of this image:

http://www.candlepowerforums.com ... post1757733

It's made of a flexible material with what feels like a rubber coating on both sides.

That's called a zebra strip. It's layers of a bunch of conductors (carbon impregnated rubber) and insulators (rubber). It's cheaper and easier to use than two sets of connectors and a ribbon cable, and works fine for low current connections, such as an LCD display.

 

[radellaf]

Oh, those, I hate those, it can be so difficult to get good contact after you take them apart.

The display I was working with, from Optrex, has a "FPC" connector on it and the polyamide flex-circuit ribbon is permanently connected to the display. On that one, though, the LCD controller is mounted on the display glass... the one on the Maha may be running the LCD's raw connections to a controller on the circuit board.

Driving LCDs is weird. Takes 5 different voltages from +3 or so to abouts -11. Then you have to run this multi-stepped waveform to the pixels, I think to keep them from "freezing" in place as would happen if you just put 11V across them.
With the chip-on-glass controller, you just have address and data lines, and write to it like RAM (mostly).

 

[Burgess]

Thank you for your efforts, EvilLithiumMan. :thumbsup:


And thanks to all for the info, insights, and comments. :twothumbs


CPF certainly has some sharp people here !

:wow:
_

 

[hopkins]

Nah! I bet ELM took pics as he began disassembling this highly complex piece
of electronics. He'll just reference them to put it back together as I would.
Good pics ELM !

 

[Bones]

I think the LCD connections are somehow conducted by the dark grey strip in the center of this image:

http://www.candlepowerforums.com ... post1757733

It's made of a flexible material with what feels like a rubber coating on both sides.

That's called a zebra strip. It's layers of a bunch of conductors (carbon impregnated rubber) and insulators (rubber). It's cheaper and easier to use than two sets of connectors and a ribbon cable, and works fine for low current connections, such as an LCD display.

Thanks waiwak, I was becoming convinced the 'Wizard One' might really have some 'magical' properties. Oh well, I suppose it's better to be disillusioned and educated than the converse...

 

[rizky_p]

i used to have hobby charger that refused to discharge most likely damaged and i dont understand electronics, on charger like Wizard One, which componen that dump the energy when discharging?

thanks.

 

[Probedude]

i used to have hobby charger that refused to discharge most likely damaged and i dont understand electronics, on charger like Wizard One, which componen that dump the energy when discharging?

thanks.

Usually some resistors are switched into the circuit or the transistors/mosfets themselves are used to dissipate the battery power. I don't see any large size resistors on there so the mosfets themselves must dump the heat into the PCB plane.

 

[drmaxx]

Off topic:

I don't have much bandwidth and my damn roomate spends 25 hours a day downloading DVD's. I've considered beating him to death, but have decided against it because:

1 - It's not right.
2 - I'd be the only suspect.
3 - I need his retirement check to help with the rent.

Instead of having to find excuses not to beat your roommate you could tell him to limit the max. upload bandwith for his torrent client (I guess that's what he's doing...). This helps a lot to keep the connection usable.