NCE cab display upgrades

[Hiroe]

I had an NCE cab with a shattered screen that I've been forgetting to send back for about a decade now. I ended up just ordering a display in and fixing it myself, and the outcome was so strikingly better that I went ahead and upgraded my other cabs. It radically improves cab readability at a distance, and reduces eye strain in bad lighting. I'm really happy with how this turned out.

[mdltrn]

Looks great! Is the new display an NCE part or aftermarket?

[Hiroe]

it's a stock part from Digi-Key, part number 3444-AMC1602GR-B-B6WTDW-ND for the display, and part 478-601030-ND for the 10k trimpot.

[eja]

So tell us what is involved in doing the replacement.  Was it difficult, and 'tricks" of warnings.

[Hiroe]

I would not consider this project appropriate for anyone who doesn't have experience with circuit-board rework. If you're not comfortable with the risk that you might damage the mainboard irreparably and have to send it in for factory service (and possibly have them refuse to help you) then this project may not be for you.

The original display is soldered in on the header pins, which are then soldered into the NCE cab mainboard. You need to be quick enough with the iron to reflow the header pins on the display end fast enough to walk the display board off of them without damaging the mainboard, working the iron back and forth across the pads on the display reflowing each pin as you pry the boards 3/4 apart from the far end and 1/4 apart from the near end. (Some older displays used wire leads for pins 15-16, these can be removed from the display at any point during the process.) Once the old display is off, don't expect to salvage it. You'll also then need to upside-down re-tin each of the header pins left on the mainboard to clean them of any remaining excess solder/dross, straighten any that got bent with fine pliers, and test-fit the new display onto the pin row (do not solder). Re-tin-clean and re-straighten any pins necessary until the display fits cleanly. Then take the display off and set aside.

To prep the mainboard for the contrast pot, you will need to remove pin 3 from the header. The pins in the header are numbered 15-16-1-2-3-4->>14, so it is the fifth pin in from the end (unless the old display has wire leads for 15-16, in which case it's the third pin in from the end on the header strip. Flip the mainboard over to show the back side, use fine pliers to grasp pin 3 firmly, and use your iron to wet+re-flow the pad on the back for pin three while gently pulling on it with the pliers, until you can pull it out of the pad and header strip in one motion. Once it's out, cut the header strip plastic out of the way of the pin three via on the top side, re-tin the via to fill it, and scrape/tin the trace coming off of pin 1 towards the voltage-divider circuit that feeds pin 3.

To install the contrast adjustment pot, fold the leg tips flat with the plane of the board, and use fine pliers to straighten any kinks and flatten them to land on trace tops. tin each flattened leg tip, and place pot legs 1 and 3 to land on the board over the pin 3 header via and the pin 1 trace towards the voltage divider. solder both, then tin the upper leg of pin 2 on the pot. Settle the display down on the remaining header pins, solder it to each, and use a length of trimmed-off resistor lead (or fine copper wire) to connect the pot pin 2 to the display pin 3 pad. Then put the throttle casing back together on the boards and test the assembly by powering the cab up. If everything looks good, adjust the contrast, put the screws back in and you're done.

[eja]

Thank you for the details....

ed

[Cajonpassfan]

Nice. So does the new brighter display draw more battery power or affect its charge?
Otto K.

[Hiroe]

Nice. So does the new brighter display draw more battery power or affect its charge?
Otto K.

Not that I've seen any evidence of. I don't have the current draw specs of the original display, and I'll have to wait for someone to bring me another one to convert before I can meter it out on the power supply and compare it before-and-after.

[peteski]

I like that new display!

Few years ago I also made a similar upgrade to my Power Cab's display.  I found the display at a surplus electronic vendor.



Mine has blue letters on white background.  The camera didn't render the colors correctly. It is not light blue but just a standard cool white color white LEDs have.



I installed the small contrast adjustment SMD trimmer pot on the main PC board.

But looking at yours, I do like the white lettering on the dark background.  I might have to upgrade my upgrade!

[GGNInNScale]

Really nice. Thanks for the details.  I will boost my PowerCab now!

[Hiroe]

Nice. So does the new brighter display draw more battery power or affect its charge?
Otto K.

I finally got another cab to convert, and had the chance to check it's current draw before and after.
Before: draw of about 60ma
After: draw of about 29ma

If this is accurate, your battery life on radio cabs should about double.

[peteski]

Is that the total draw of all the circuitry measured at the battery terminal, or just the display unit current draw?

[Hiroe]

It's measured at the dc wall wart for the throttle network power supply, when plugged into a powered plate by itself. 

[peteski]

It's measured at the dc wall wart for the throttle network power supply, when plugged into a powered plate by itself.

While the reduced draw is surprising, I guess it makes sense.  I believe the original backlight unit has an array of several old-school (not very efficient) yellow-green LEDs, where the white backlight unit likely has either single or a pair of white LEDs on just one or possibly both ends.  White LEDs emit much more light at much lower current than those yellow-green LEDs.

[Cajonpassfan]

I finally got another cab to convert, and had the chance to check it's current draw before and after.
Before: draw of about 60ma
After: draw of about 29ma

If this is accurate, your battery life on radio cabs should about double.

Well that alone would make it worthwhile!
Otto K