Roberts RM40 Reborn.

[G6Tanuki]

A friend was after a radio/bluetooth speaker for her new kitchen; it had to do FM and be Bluetooth-comptible - I originally suggested modding one of the little micro-hi-fi things but she said no. Then I showed her my Roberts RM40 which she liked, except for the wooden end-cheeks [which wouldn't go with her kitchen which is very much marble, olive-green, glass, quartz, brushed-stainless in the 21st-century idiom].

A plan was hatched. I had a scrap RM40 acquired as a non-worker. Powering it up, it hummed horribly. One diode in the supply was O/C, and the grey plastic-sleeved electrolytic had lost capacitance.
New 4700uF 35V electrolytic and four new diodes got rid of the hum, to reveal a horribly crackly volume control. Switch-cleaner silenced the crackles, bt they returned after a few days. A new control fixed it permanently.

The original tuning only went up to 104MHz; a tweak of the two pots on the voltage-regulator board pushed the power supply rail up by 400mV and the upper end of the tuning to over 108MHz so GHR was now tunable. A further tweak stretched the tuning out by pushing Radio2 off the bottom of the scale. The RM40 has the little red slidey things on the scale so it's easy to mark the positions of the wanted stations despite the calibration of the scale no longer being accurate.

Bluetooth: Dead easy on the RM40 - it has an "AUX" button on the front and a 5-pin DIN socket on the back; a generic Bluetooth module wired to the inside of the AUX socket via a pair of 100-Ohm equalising resistors and all was joy sweetness and phone-pairing.

As standard the RM40 has no scale-lights; I fixed this with four nice high-intensity white LEDs mounted on little slivers of Veroboard; similarly I replaced the original power-on neon [which had faded to near-invisibility] with a high-intensity blue LED fed from the DC supply.

Meantime, my friend had cleaned up the case and given the wooden end-trims a coat of suitable olive-green paint to match the rest of the kitchen.

Reassembled and reinstalled, it all works fine! Only problem being that the bit-of-wire-threaded-through-holes-in-the-rear-cover FM antenna is, as expected, rather useless when the radio is pushed up against a rather thick brick wall, so you get the dreaded people-moving-around-in-the-room-causing-mush issue. Her electrician is going to put a length of coax down the cooker-hood channeling so I can tru a dipole in the attic.

All things considered, my friend now has a nicely 'modtro' kitchen radio/bluetooth-speaker that fits on a 4-inch-high shelf and through which she can play her Spotify playlists.