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MDAC - Front Buttons Not Working?

Stuart Frazer

Stuart Frazer

pfm Member
I have just bought a used MDAC which was sold on the basis that the remote wasn't working. I've powered it up and the remote seems to work fine, which is good. However, the Menu, Filter and Sel buttons on the front panel do not work. The main volume control works fine, but the MDAC is stuck in variable preamp mode when I want a fixed output. I can't seem to change that without the front panel buttons.

I've rolled back the Firmware to v0.90 but that hasn't sorted it. I cannot seem to reset the MDAC without the front panel 'sel' buttons as they aren't responding.

Is there another way to reset it, or perhaps I need to delve inside to check for lose connections? Any ideas?
 
I’m trying to recall, I think you need to undo the screws on the sides to release the front panel. You’ll need to then pull it away carefully to not put stress on the connector. Don’t take this for granted though as it’s ages since I took mine apart!
 
paulski said:
I’m trying to recall, I think you need to undo the screws on the sides to release the front panel. You’ll need to then pull it away carefully to not put stress on the connector. Don’t take this for granted though as it’s ages since I took mine apart!
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Thanks, I've also posted a message on the Lakewest Facebook page, so hopefully, John W or someone will reply at some stage.
 
I hope you solve your problems. It's a great DAC; better than the current flavour of the week DACs I've compared it with. Westlake has said that the DAC set at 0dB in variable mode is identical to fixed mode.
 
Stuart Frazer said:
Thanks, that was one issue that had crossed my mind. Is it easy to internally access the MDAC?
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It's pretty easy. The front and rear panels are held in place by screws on the sides. Remove these screws (8 in total), then gently pull out the front panel. There will be an inch-wide ribbon cable running along the left side of the case and connecting to the front panel PCB. Carefully disconnect it from the socket. Now you can pull out the rear panel along with the main PCB. Carefully reseat the other end of the ribbon cable, then reverse the steps to put it all back together.

While you have it open, check the electrolytic capacitors for damage (leaks or bulging). They're known to go bad with age.
 
The Torx screws can be tight if they have not been undone before, insert Torx bit and gentle tap with hammer if so.
 
switch cleaner? eg Halfords cheap at about £4 leaves no residue. I have used it on many domestic appliances to good effect. many "switches" these days are those rubber type "buttons" that act on a circuit board rather than self cleaning metal on metal that build up "debris" through use - remotes typical in that respect. air pollution does'nt help. The hard problem is to flood the switch to flush muck away
 
sq225917 said:
If the remote works then the front panel isn't unplugged...
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The remote seems to work fine. So I guess it isn’t the ribbon, unless it partially detached or something similar. I had a message from John Westlake via Facebook who stated that it wasn’t a common issue, but he could fix it if I sent him the front panel.

mercalia said:
switch cleaner? eg Halfords cheap at about £4 leaves no residue. I have used it on many domestic appliances to good effect. many "switches" these days are those rubber type "buttons" that act on a circuit board rather than self cleaning metal on metal that build up "debris" through use - remotes typical in that respect. air pollution does'nt help. The hard problem is to flood the switch to flush muck away
Click to expand...

I can maybe give this a try once I access the internals. I just find it strange that all 4 buttons aren’t working, but the volume control / button is. I was hoping those 4 buttons were on a separate ribbon cable or such which was detached in transit.
 
The front buttons are membrane switches, the volume pot is a optical multiway rotary, there's nothing to clean and no access to do it.

It's either a front panel clock or mcu fault.
 
sq225917 said:
The front buttons are membrane switches, the volume pot is a optical multiway rotary, there's nothing to clean and no access to do it.

It's either a front panel clock or mcu fault.
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"membrane switches" thats what the ones I am referring to are called?
 
Yeh, a moulded rubber cover over a one or more circuit board mounted contact switches, not the sort you want to get wet, even with volatiles
 
sq225917 said:
Yeh, a moulded rubber cover over a one or more circuit board mounted contact switches, not the sort you want to get wet, even with volatiles
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hmm the ones I am referring to you find typically in remotes where you have a circuit board then the key (press) in some way completes the ( open) circuit ( tracks by bridging them) - becuase it is some kind of conductive material? These after a time start to play up presumably due to contamination from the rubber button leaving residue or some think else? Using a residue less switch cleaner is a good idea with these I think.
 
The only way to do it is to separate the rubber and pcb and wash the rubber and clean the pcb.
 
The switches are of this general type (not that exact model):
Omron-B3F-1022.jpg


They can't be cleaned, but they can be replaced if you find a suitable part.
 
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