Bose Acoustic Wave System II No LCD Display

[mlipovitch]

Seems I can't find out a lot about this issue-have the Acoustic Wave II system everything functions perfectly except for the LCD display..only the green backlite is on! No function display whatsoever. Checked for the obvious-broken ribbon connector to switch/display panel (continuity check across all ribbon connections are fine), cracked/dull slder connections around LCD area and surrounding components (chip caps, eletrolytics, etc.). Can't find anything obvious, so suspect a power supply issue? Power supply unit removes from the bottom (5 screws) and unplugs from main chassis, but I can't tell what voltages or outputs I should look for lacking a schematic of any sort..none are posted anywhere.

Next was to try shotgun approach and test power supply electrolytics and some on the main system board using my ESR meter suspecting one of the solid caps may have died or is drying out. Although some of the lower value caps exhibit a high ESR, nothing seemed out the ordinary here either-couldn't find a completely open cap or one with ESR so out of whack it warrantied replacement. Again, without schematic of any sort just shooting in the dark on this one since none of the obvious smacked me upside the head. Thanks for the read, maybe someone else here has repaired a similar problem on one of these and could point me in the right direction! (PS this was a thrift store purchase, so I'm only out about $8 bucks..but accepted the challenge)!
Marc

 

[shrtrnd]

First thing I'd check is the display driver integrated circuit.
If you're unsure which one it is, Google the part numbers on the IC to identify it. If it's inexpensive, I'd try replacing it to see if that solves your problem.

 

[mlipovitch]

Not sure which one it is...most likely the one behind the button and LCD panel I would guess..again I'd be shotgunning as I dont have any diagrams or pinouts for the IC not sure exactly what to check maybe start with Vcc off pin 1 or something see if its getting any voltage? Plus most of the IC's in there are SMD's wouldn't even know where to begin sourcing them.

 

[bsco]

I had some Bose equipment a while back.....and I am the tech for our local music store...Bose would not give me the time of day.....I could not get anything from them....We had to ship the items back...so you won't get any help from Bose even if it is not under warranty........I would agree with shrtnd.....If you have a scope, you could try checking the data lines to the display to see if there is any activity...if you have a logic probe you can also use that as well....and as suggested, try to google some of the chip numbers to see what comes up....who knows...you might find some data sheets.......The power supply board might have the output voltages silk screened on it next to a connector maybe....or try measuring the output voltages on the output connector if you can gain access to it just to see what is or isn't there......

 

[73's de Edd]

Sir mlipovitch . . . . .

Having 6 units of that Sound Wave lineage being in our family, and starting with my unit being number one back in circa 2000, maybe I can reverse
engineer some of their circuitry info for you.
Let me start with the connector to the " Panaplex" display and have you see what voltages are currently being present on yours.

Starting with the one model I expect to be the closest to yours:

The display connector, J4, is fed from a 'fotty 'fo pin flatpack . . . possibly being silk screened with info on the PCB proper, to its side, as U201.
With it being a derivative of the "Rota Mola" MC68HC705CB family of u/p's using its custom programmed internal ROM.
The wiring interfacing to the display is via J4 which has a 24 pin count..
With your MAIN point of interest now being pin 1 and 2 of J4 as being the supply line of AC to the displays loooooong struuuuuuung out filament.
Expect a low voltage AC level across those pins, after the set has been powered up.
Go back to a power down condition and inspect the J4 connector and search out J4 for its pin 7 and that will be serving as your NEGATIVE DC
metering probe connection . . . .. or . . .how you clazee Amellicans say . . . . . GROUND.

You then probe pin 3 and you will just KNOW all is well if you find a MINUS 21 volts on it, for all of the displays segments.
The next test point is iffy, in accordance to switch functions , but see if you do find approx +10VDC on pin 6
The last of our voltages will be pin 4 for +5VDC


Thassssssit . . . . .tell us what you find.

(MAN ! . . . . .those "thangs" surely do sound WONDERFUL, considering their speaker/baffling volumetric constraints)


73's de Edd

 

[mlipovitch]

Thanks for the reply Edd;
I will check out the voltages you suggest and see if they are there or not, and if not try to back track where they originate. Not sure of one point though-you suggest a filament voltage, but this is an LCD display panel (didn't think there is a filament in such an animal)? I'm still suspecting something power supply derived is missing, although that end of it may be on the motherboard itself. Thanks also to the other replies, although I especially appreciate Ed's insights-more of what I was looking for as well as anyone who has successfully repaired one of these. I will not contact Bose as I know they guard their proprietary circuits like it was a national security issue!
M

 

[73's de Edd]

.


Sir mlilpovitch. . . . .

Well hecks . . . .and I thought that I "dun gud" with just having your initial "car" and "Mercedes" info to work with, without further telling us the

model and year and more exacting specifics.

If your system is not using the deluxe " Panaplexed " display unit, it then must be using the LED model, downgraded to capture the

market and sell like hotcakes in Dollar and thrift stores.

I just initially submitted what circuitry I was finding in my top line units.

Come ye forth now and give us the complete model number of the unit and any PCB IC numbering or U assignments of the display
unit .

Any actual part numbers from the display IC or LED panel, if being there.

Then I will investigate to see if any of my units . . .or accessible ones . . .are being of your units design.

73's de Edd

.

 

[davenn]

If your system is not using the deluxe " Panaplexed " display unit, it then must be using the LED model,

He said it was LCD NOT LED

 

[mlipovitch]

Hey all;
Sorry for the confusion it is a model # ?? Don't see a model # anywhere-I've uploaded a few pics to see if anything other than Acoustic Wave II makes sense.I'll have to rip it back apart to get some model #'s off some of the custom IC's in there, I didn't write anything down from the first disassembly..next I'll post a few pics of the internals to see if that stirs up a memory or two...Again thanks for all the help (not sure what a "Panaplex" display is either)??

 

[Wolfpup]

had anybody made progress on this problem ? I have the same unit with the same display. problem my unit will get a display for the first 20 secs when the unit is unplugged and cold then fades away.