This time he brings me a small desktop Roberts radio. I like Roberts stuff, it's nicely made and sounds reasonable.
"Goes quiet on medium wave"
OK... let's take a look....
The first battle is to get the thing apart.
First, remove the two philips screws on the edge of the back, on the left and right. Then remove the slotted screw in the centre.
Once you've done this, slide the card back upward and it'll pop out at the bottom with some gentle persuasion. Disconnect the green aerial wire from the board. Now unscrew the five silver philips screws from the bottom. Remove the power supply first, followed by the chassis.
Gently push the nozzle and direct the liquid at the suspect component.
Be careful when using it around higher voltages, as water will condense on the cold component. Never spray it on a hot valve, you'll crack the glass.
I started by cooling the board in areas to narrow down the search. I used a hot air gun to warm it back up again to cause the fault to reappear.
I narrowed the fault down to two caps, or maybe the
BC548 transistor. I changed the caps and the fault remained clear! The replacements are pictured.
There was no physical sign of failure of the capacitors.
Another job done!