I currently have seven R505's Andrew, and they all work thanks very much for asking. I don't like them to sit long, otherwise what's the point? Ta - Paul in.
@@Andrewausfa Shelf Kings now Andrew 😉 I don't have any. Tell me where to find them and I will send a radio rescue team out to break the chains that bind them.
Thanks Paul ! I have a confidence issue in repairing (replacing transistors in) a Roberts R606, so it's good to see an example of how someone competent does it. So I see that a solder sucker can be used even when the under (solder) -side of the circuit board is facing upwards (I had wondered if I had to get under it facing downwards for gravity assist which would be awkward of course). My main issue is remembering which underside solder-points correspond to which components (and specific component leads) on the topside. I tried making a translucent image in Gimp (free photoshop-ish software) but maybe old-school tracing paper is more practical. Also my eyesight dynamic range is not what it used to be, and paper has the advantage that it can be held/viewed at the same distance as the circuit board (unlike a computer screen / tablet). Any thoughts / tips?
@@Codeeze Thanks Paul, it was really helpful. And now (after having replaced most of the audio-stage transistors) my radio (actually a Roberts R606MB) is at last fixed! (working well)
Hi mate I have a r505 that worked brilliantly now all of a sudden it just make a small "click" sound when I switch it on. I have changed the battery for a new one and tested the speaker using a known good one. Do you think it's likely to be the capacitors on mine as well or something else?
It could well be the capacitors, but equally (and to my experience) it suggests it could also be the output transistors gone short. If you have a schematic to hand, the capacitors are C38 / C40 / C42 and the output transistors are TR11-AC187 / TR12-AC188
The power supply rail generates ultrasonic oscillations that vary in amplitude at a low frequency due to the power supply voltage sagging as oscillations build up. C40, the open circuit cap caused this.
I assume that the capacitors are stopping the resistor limited power rails being modulated by the power amp. Not something that you want, unless you like a radio that's got a bad case of wind :). Another radio saved 😀
Nice work Paul and another great job.great to watch.nice and simple
Thanks Andy! - I like nice and simple. There's obviously more to it, but this just shows that 2 caps changed can make a radio breathe again
Nice repair. Sad to think of all those radios out there on shelves untouched.
Simon, you just like to fondle them :-D
@@zx8401ztv Got to fondle something!
They're just waiting for their moment Simon. A minute...
Yeah...
Chalk up another great one! Nice radio singing again.
I like singing. Especially my own, in the shower...
It's fully done now, looks and sounds like new. Thanks for watching Barry.
Another radio saved from landfill. Nice job Paul. Watch out for flying knobs!
I'm always on guard when you're around... Thanks for watching Victor
@@Codeeze....safety never sleeps.
I have had that capacitor fail on many Roberts Sets. Seems to be a common one…….
On the R505, it's either C38, C40, or C42 - sometimes the outputs have gone short, and need separating from the chassis
A Bwown Woberts Wadio with Bottom Burps. And flying knobs. Super!
Shots fired across the port bow. Thanks for watching George
How many R505s do you have and how many work? Ta - Andrew
I currently have seven R505's Andrew, and they all work thanks very much for asking. I don't like them to sit long, otherwise what's the point? Ta - Paul in.
@@Codeeze Yes sad to see an old radio as a shelf queen.
@@Andrewausfa Shelf Kings now Andrew 😉
I don't have any. Tell me where to find them and I will send a radio rescue team out to break the chains that bind them.
Motor boat sent on its way with two caps. Nice one.
Thanks! I reckon I could have got away with just the one cap change to make it work...
Thanks Paul ! I have a confidence issue in repairing (replacing transistors in) a Roberts R606, so it's good to see an example of how someone competent does it. So I see that a solder sucker can be used even when the under (solder) -side of the circuit board is facing upwards (I had wondered if I had to get under it facing downwards for gravity assist which would be awkward of course). My main issue is remembering which underside solder-points correspond to which components (and specific component leads) on the topside. I tried making a translucent image in Gimp (free photoshop-ish software) but maybe old-school tracing paper is more practical. Also my eyesight dynamic range is not what it used to be, and paper has the advantage that it can be held/viewed at the same distance as the circuit board (unlike a computer screen / tablet). Any thoughts / tips?
My email is on my 'About Me' tab (viewable from a PC)
Send me a message, and I'll ping you a copy of the original schematic which should help 👍
@@Codeeze Thanks Paul, it was really helpful. And now (after having replaced most of the audio-stage transistors) my radio (actually a Roberts R606MB) is at last fixed! (working well)
Hi mate I have a r505 that worked brilliantly now all of a sudden it just make a small "click" sound when I switch it on. I have changed the battery for a new one and tested the speaker using a known good one. Do you think it's likely to be the capacitors on mine as well or something else?
It could well be the capacitors, but equally (and to my experience) it suggests it could also be the output transistors gone short. If you have a schematic to hand, the capacitors are C38 / C40 / C42 and the output transistors are TR11-AC187 / TR12-AC188
Ooh, the last thing you need is your nob flying off. 😛 Another radio saved.
Indeed! What wasn't clear in the video, is that it took me 25 minutes to find the beggar!
Love it!
Me too!
That was short and sweet 👍😆
I think it's the future. Get in, get it done. Next! - Thanks for watching Terry
Serious motor boating !
Looking up motorboating on google now. Very interesting..
@@SoddingaboutSi I take it you didn't find 'Parasitic Oscillation' then Simon?... or did you? 😛
The power supply rail generates ultrasonic oscillations that vary in amplitude at a low frequency due to the power supply voltage sagging as oscillations build up. C40, the open circuit cap caused this.
Nice one thank you (:
Thanks for the Thanks and for watching Darren!
Nice video.... try to add extra new solder before you suck... will work better
I usually do, I was just lazy... 🤣
I assume that the capacitors are stopping the resistor limited power rails being modulated by the power amp.
Not something that you want, unless you like a radio that's got a bad case of wind :).
Another radio saved 😀
Unexpected open circuit capacitor. Pesky things. You'd think by now there'd be a Nuclear option...