RA17 page 5

Maybe I should have set about the PSU and Audio Stage compartment first for the simple reason that if the PSU has a fault in it, then it follows that everything else is going to suffer. So in my quest to resolve the terrible sounding audio, I turned my attention to the exceedingly grotty looking PSU compartment which, I have to admit, looked like it had been used as a barbeque!. The recommendation in the EMER is to ‘up’ the power rating of the large resistor just right of centre (R119A, 10K, 10W) which dissipates just over 10W when the receiver is set in ‘Stand-By’ mode. I never leave the RA17 in that mode so I opted to leave it be in the mean time. Most of the damage appeared to have been caused by over-cooking of the small vitreous enamel wire-wound resistor in the centre (R136, 47R, 3W). I replaced it with a

4W carbon resistor which so far has not exhibited ANY signs of stress or heating. The chassis cleaned up remarkably well simply by giving it a scrub with ‘Flux-Off’. The two electrolytics were duly replaced as were all the carbon composite resistors. So far I have not replaced the main PSU smoothing capacitors . . . Initially because I was not able to obtain a 32uF+32uF capacitor. Instead I have a couple of 47uF capacitors that I am prepared to glue together . However, the integrity of the HT supply is good (no hum) so I will defer replacement for the moment. I switched the RA17 back on fully expecting the audio to now be free from distortion . . . But sadly it was still as distorted as ever. Then I hit on the idea of connecting an external loudspeaker to one of the sets of rear- panel output terminals. To my astonishment, the audio on this ‘other’ loudspeaker was completely free from distortion. A quick rummage through my box of small loudspeakers yielded one that was almost exactly the right size. I have no idea where it came from. The mounting holes needed to have rivets drilled out and then filed very slightly in order to fit it. Hey-Presto! . . . distorted audio problem resolved! I can only surmise that corrosion may have built up between the pole pieces in the original Goodmans unit and was interfering with the travel of the voice-coil.