Help needed in repairing Squeezebox Classic VFD

[rmgvs]

My question is simple and complex at the same time. I have spent several days searching on the internet and not found what I looked for.

It is about a Squeezebox Classic (V3 etcetera). Everything works fine except for the VFD display. I can pretty sure point to what causes the non-functioning of the display but am not able to pinpoint it to the exact location on the pcb (due to a lack of circuit diagrams for the V3, a shame since the player is not longer sold anymore, nor repaired for that matter, it seems like the SB's are seen as throw-away articles ...).

Sean Adams has made a block diagram of the different voltages of the SB3. It starts with the external powerplug (switched 5V). Inside this delivers 3v3 and 1v2 for IO, wireless, logic, CPU and headphone.

After the 5V it goes to a switcher and a multiplier too, where 11 VAC and 55 VDC are 'made' for the display and 14 VDC for the opamps and DAC. All these voltages are not available in my SB3 (I know what causes the failure but skip this for brevity).

It's easy to make a new 14 VDC for the opamp and DAC. There is one resistor of 100 Ohms (R45 on my pcb): take this out and apply an external 12-14 Volts at the big cap J2 and done. I'm amazed that this mod is not done more often by audiophiles. It has to be much better than all those expensive regulated 5V power supplies at the outside because anyhow after that there will be another switched component and other maybe no so audiophile stuff.

So after that everthing works as should except for the display. Now two options are open:

1. I can make another external power supply that delevers 11 VAC and 55 VDC. Question: which pins of the VFD are for what voltages? And: is there a simple circuit available that delivers both voltages starting from a small 12 vac transformer (ie some kind of Cockcroft-Whalton circuit that already had been used in the existing circuit)?

2. (This is the preferable option) I don't know where to start. The VFD is allright. It's only about the supply of proper voltages. Because the initial 5V is allright, the problem has to be in the internal switcher and/or the voltage multiplier (and/or in a connecting component for example a resistor that connects the stages). So (after 6 years of existence and ten thousand hours of worldwide modding these things) who can tell me which component on the board is the switcher and which is the multiplier (this must be the string of diodes D9-D13 with associated caps?). And what is the most probable component of break down due to a temporary burst in (too much) current?

Thinking along with me will be appreciated. These SB's are way too good to throw away after 3-5 years of operation.

[rmgvs]

I'm still waiting for some light into the matter.

In the mean time I've not stood still. I have 'mastered' net-udap which was brought to the Squeezebox community as a Perl-based tool to install the SB Receiver without needing a remote controller.

The tool works for a number of other SB's too. Normally there is no need to work with udap since all other SB's have screens to do what is needed. But not in my case where the screen has no power and refuses to shine.

I figured out how to feed all necessary settings into the Classic. I first made a script into a text-editor so that I could experiment easily. With copy and past I move all commands to the udap-tool, reset the Classic and in the end it worked.

Next I disabled the normal remote because this is confusing without screen.

Conclusion: now I have some kind of Duet-receiver without screen that looks at the outside like a Classic. It can be controlled with Iphone and Ipad etc.

But all ideas about getting the screen alive I welcome.