Roberts RD60 DAB/FM radio repair with service manual

[rh100605]

I recently bought a job lot of DAB radios, the first was a Roberts RIC 1 which only worked when pressure was applied to the side of the Mullard  LP1175 Xtal IF can which had an open circuit primary. I depressed myself by looking inside only to find that the hard glue holding the tri-fillar winding bridged the ferrite and paxolin base. It had cracked. In my opinion irreparable.

The second radio was a Roberts RD60 with the normal covering falling off. It powered up with no sound and the display kept returning to the same point.
Looking on the Vintage Radio site I found a very helpful member who offered a pdf of the service manual. With his approval I have copied the service manual here. It is splt into two files due to the EEV forum  upload limits.

To remove the electronics you have to remove the handle. The ends of the handle have pins that go though the sides of the case and are held by circlips. Push off the circlips , pull out the pins and then remove the threaded inserts in the sides of the case.

I removed the aerial and power inputs from the back and then the speakers leads. Then, with difficulty, removed the electronics. I removed the smaller screening cases over the two switching regulators and found +5 and 3.3 but the 1.2v was at 0.6v. Also the reset line was held at 1.4v.

I removed IC8 － ABLIC S-8550AA-M5T1G and measured the resistance between 1.2v and ground as over 3K so it was worth replacing the chip. The reset chip IC10 － NCP803 2.93V now showed reset at 3.3v so the switching regulator had been pulling that down too (and probably up during reset).

I bought a new regulator from Mouser UK and fitted the sot23-5 package. I used a microscope to do this. The radio then came back to life. Now to recover it.