Sony RDR-HX710 HDD/DVD recorder dim display

I take it that it is 'evenly' dim ? Have you checked the negative supply volts ? Should be around -29v. You can check it between chassis, and the filament pins at one or other end of the display panel (the AC filament supply is normally 'floated' on the DC supply, so it's a convenient place to check it). I'm not sure how the voltage is derived on that model, but often, it comes from a voltage multiplier or an AC coupled transformer winding. In either case, it is usually the coupling electrolytics that cause the voltage to be low. I have also seen Sony use AC coupling on the filament supply. One particular tape deck of theirs, used to suffer regularly from the caps failing and making the display dim. Unfortunately, if the problem wasn't caught early enough, it used to do damage to the panel itself. If it is a switch mode power supply, it will be derived direct from a winding on the switching transformer.

Just as a slightly separate thought - the machine hasn't got a fluorescent display "dim" or "off" function in the user software, has it ? I've been caught by that more than once ... :-)

Arfa

Thanks for the advice.

I checked this voltage earlier and if my memory serves me correctly, it was around -17v. I will have to check that voltage again. There was a small transformer on the PCB that looks like it is used to generate this voltage and it had a 22 micro 50v cap on the output, which I changed.

-Jan

I have never seen the supply to a VFD panel on any piece of kit, to be as low as -17v. -29v is much more the 'norm', so I would say that is definitely the reason that the display is dim. 22uF seems a bit low for the smoothing cap if that is what it is. Either way, if that is an independant supply just for the VFD, it shouldn't be too complicated and hard to troubleshoot for why it is low. Any safety resistors on the board that may have gone high ? Leaky diode maybe ? Regulator transistor, zener ? Tried a 'scope on it to look for ripple ? (bearing in mind of course that if you check at the filament pins, it will have 1 - 3v of AC 'ripple' on it from the filament supply)

Arfa

That would be a good thing to check. I have a couple Sony A/V components that dim the display in its setup.

Yes, I did check this possibility too, no such luck ;-)

-Jan