Display problem with Pass X1

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After having built a couple of Pass DIY amps, my friends got enthusiastic too about the sound of Pass amplifiers.
Recently a friend bought a second-hand Pass X 1 preamp from 2004.
He is overjoyed with the sound. However after the acquisition we found a small defect in the preamp; the display is badly readable from a distance of two meters or more. Furthermore the left side of the display is less bright than the rest.
Yesterday we compared the display with the same amp from another friend. It turned out that the display is not as bright and clear as it should be.
I attach a photo of the display.
Meanwhile my friend got some information from the Dutch distributor. Repair would cost about 500 USD, and that seems a costly affair for an only 6 year old amp.
My question is: Does anyone have experience with this? Having some experience in DIY, could I try to mend it myself?
Any advice welcome!
 

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It looks like a VFD from the picture (Vacuum Fluorescent Display) and faults fall into a couple of categories.

The display itself can suffer from low emmision giving dull uneven illumination. Sometimes this can actually improve if it's caused by lack of use, the duller segments recovering if left illuminated.

Is the display clean ? and the polarising tinted window clean on the inside... because that makes a big difference if not. They attract atmospheric dirt easily.

Power supply problems... the displays use a negative rail of around -28 volts. Dried up caps can be a real issue here depending how that supply is derived. Any ripple on the supply can cause illumination problems too.

Looking closely at the pictures I suspect the display may be low emmision because there is noticeable brightning in horizontal lines which coincides with the heaters in the display.
Whether the dull segments would recover with use is impossible to say.
 
Looking closely at the pictures I suspect the display may be low emmision because there is noticeable brightning in horizontal lines which coincides with the heaters in the display.
Whether the dull segments would recover with use is impossible to say.

Hi Mooly and thanh1973,

Thank you both for your suggestions!.
We have had the display on for some while now, but it hasn't really improved, so I guess it's not low emission...

I will try the power supply. It would help if I knew how much voltage it should supply to the display..., but I am too shy to ask Papa :eek:

Has there ever been a service manual for the X1?
 
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