Myryad Z140 Tuner with no display

Today on the workbench a special brand, Myryad. It’s a FM Tuner with RDS.
The defect is that the display does not illuminate anymore. The tuner does work and produces sound, so it’s only the display that is not working somehow.

No light what so ever, lets look what’s inside

Nice layout of the PCB with sections of the several block from a block diagram, like the VFD (Vacuum Fluorescent Display) power supply

I measured the voltage of the VFD power supply that is usually an AC or high negative voltage and is connected to the outer most pins of any VFD display. The meter reads 2,7V.
For my tast to low for a display like this. Because there was no voltage indication anywhere and no service manual or schematics at hand, I didn’t really had anything to go with.

As I took a closer look at the power supply I discovered something that I already was expecting.

One of the two 220uF capacitors didn’t look so healthy anymore. I took it out and it was very obvious that this capacitor is gone.

The capacitor completely lost its capacity. For what I can tell without the schematics this is a voltage doubler circuit. The first capacitor in this circuit will fail sooner or later because of heavy use.
Just to be sure, I replaced both 220uF capacitors.

Reassembled the PCB and fired the tuner up. Done!

 

 

Philips CD880 buttons unresponsive

One of Philips flagships… the CD880 with an impressive selected DAC chip: TDA1541A S1 (Single Crown).

Its malfunction is that most switches on the front don’t work anymore and that open/eject is functioning erratically. Another thing is that the lightbulbs for the illuminated bars need to be replaced.

The CD open/close issues are caused by very bad conductance of the switches indicating the position of the drawer. An easy cleanup solved this issue.

The same is the case on most of the operation buttons on the front panel. These have very high resistance when pushed in all the way.
First is to disassemble the player and disconnect the front panel.

Next is to disassemble the front panel

Eject switch and left site light bulb.


Display needs cleaning, so that can be don as well.


The glue of the red display filter came loose.

Bug check: failed

Found a bug in the cd player… a real one but it had died a long time ago.

 

So there are a lot of switches on the front PCB, several measured high resistance.
Best solution is to replace all those switches.

I bought a bag of those. The height of the switches is very important. This cd player requires the lowest button height of 4.3 mm.

The desoldering iron, flux, cutting pliers and flat screwdriver and piece by piece the PCB lost their faulty switches.

After a lot of work the new switches were in and all was working again.