Wish my repairs were that easy! I had one of these sets in a workshop I was working in once, Stole it from the front shop and I wish I had taken it when I left that place!
Hello Paul, I have one of these R250 radios and can not get FM. I have looked at your videos and put switch cleaner on the buttons but no luck. Have you any suggestions? I find your videos really helpful thanks.
I have an R250 that is dead. However, mine has a different PCB/circuit to yours. In place of the TDA 7231 it has a 2201X01 which I can't find anywhere. I'm not sure if that is the problem though, none of the caps appear to have blown and the IC isn't burnt. There doesn't appear to be a schematic available either.
There isn't a schematic available - not for the 2201X01 version at least... Check the audio input pin vs audio output pin (3 and 5 from memory but do check) - if signal in, but not out then your IC is blown. I do have some of those IC's here in my spares, but they are so very hard to find... It’s still possible to repair the radio using a substitute LM386N-4 with a little tweak to pin 7 and 8. Just Google the recommended circuit configuration to see the difference. Pins 1-6 are the same and no change is necessary. These IC's cost very little so not an expensive repair if you have the tools, patience & time.
@@Codeeze I have replaced the S1A2201X01 with an LM386N and yes, it works after doing some changes. It didn't take a great deal of work either. So thanks for the tip, it saved a few quid and a long wait for the original IC to come from China. Now all I need is a faceplate, door latch and an aerial - or scrap radio with these bits intact.
I do wonder of Roberts used center negative just so that if people used a non roberts psu they would blow the audio chip. Although i do think the standard 9v for guitar effects is the same negative centre.
That is indeed how the story goes... Customer buys more expensive OEM psu, or risks it with a cheaper alternative... and... Roberts get to charge for a repair, and a stock psu... So long as the psu is 9v centre negative, and around 4-500mA, a pedal psu would work just fine - I've used them. Thanks for watching, and the comment.
Hi can I ask you what voltage are the capacitors and the Tda 7231 is there anything in particular I need to look out for when making a purchase, can I also as if you sell any of the parts, thank you.
The standard factory capacitors are 'usually' rated at 16v. I replace them with 25v rated capacitors as my own standard practice. The TDA7231 Audio IC is still available from China (on eBay) - although with those ones I have found them to be 'hit and miss' - they sometimes work, they sometimes don't. I bought a bulk amount some time ago, of genuine IC's, from a UK source, so I have a healthy stock for my own future repairs.
@@Codeeze thank you so much, can I just ask you one more thing, on both the 1000 and the 470 what is the capacitance for each one as I want to be sure I buy the right ones, thank you.
@@dublinbred Before you go ahead - double check the audio IC to make sure that you do in fact need a TDA 7231. In rare circumstances, some R250's and R550's used a 2201X01 - I wouldn't want you buying the wrong one! As for the capacitors, the 'usual suspects' capacitance is as you have it, 470µF and 1000µF, and as I said previously, I use a minimum of 25v on each. Another thing to mention is to take care with the polarity of these capacitors, make sure by taking photographs before you remove any - then you have a reference. Lastly, when soldering in the new IC, make sure not to create any solder bridges between the pins. Best of luck, and please do let me know how you get on 🤞
Indeed Michael, usually caused by reversed polarity from a PSU. Centre pin on these, and many other Roberts sets is negative. Sometimes I see even worse where a greater voltage than required has been used - gets messy!
It's a shame that roberts used a barrel type socket, it allows any fool to plug in the wrong supply. I'm amazed the chips in the r.f section didn't die, maybe a power filtering R/C circuit stopped too much current flowing?. A fuse and a reverse polarity diode would have been kind of roberts.
Roberts did this I'm sure for commercial reasons. Centre pin negative meant that back in the day, if you needed a PSU for your radio, it was only available from Roberts... Popping in a penny diode would mean that sales from PSU's would plummet... along with the repair costs for reversed polarity...
Nice easy repair. When I replace audio power amp chips like this one I prefer not to use a socket as the pcb traces act as a heatsink. Socketting them reduces the ability to carry away heat. Probably not an issue in this set though.
It's one of the only radios where I would use a socket when doing this repair. Having previously measured active temperatures, the heat across the IC surface rarely makes it above ambient. The IC (TDA7231) Rth j-amb is 80C and Rth j-pins is 15C. One side of the IC is all ground, so this dissipates the tiny amounts of heat still quite well.
Another R250 saved from the tip. Nice fix. I’ve started putting diodes in these type of sets to stop it happening again. Cheers Graham
Wish my repairs were that easy! I had one of these sets in a workshop I was working in once, Stole it from the front shop and I wish I had taken it when I left that place!
Will be watching later. Looking forward to more R200 fun too
Thanks Brett. More on the R200 shortly. I hope you enjoy!
Poptastic campaters. Would you like chips with that sir?
Hello Paul, I have one of these R250 radios and can not get FM. I have looked at your videos and put switch cleaner on the buttons but no luck. Have you any suggestions? I find your videos really helpful thanks.
How many times do we all start making a video and screws, connectors, bolts etc don't want to budge?! Lots of times :) Nice repair Paul.
Easy repairs rarely are... only because of video 😉
Thanks for watching Andrew
I have an R250 that is dead. However, mine has a different PCB/circuit to yours. In place of the TDA 7231 it has a 2201X01 which I can't find anywhere. I'm not sure if that is the problem though, none of the caps appear to have blown and the IC isn't burnt. There doesn't appear to be a schematic available either.
There isn't a schematic available - not for the 2201X01 version at least...
Check the audio input pin vs audio output pin (3 and 5 from memory but do check) - if signal in, but not out then your IC is blown.
I do have some of those IC's here in my spares, but they are so very hard to find...
It’s still possible to repair the radio using a substitute LM386N-4 with a little tweak to pin 7 and 8. Just Google the recommended circuit configuration to see the difference. Pins 1-6 are the same and no change is necessary. These IC's cost very little so not an expensive repair if you have the tools, patience & time.
@@Codeeze Thanks for the info, it will be useful I am sure.
@@Codeeze I have replaced the S1A2201X01 with an LM386N and yes, it works after doing some changes. It didn't take a great deal of work either. So thanks for the tip, it saved a few quid and a long wait for the original IC to come from China. Now all I need is a faceplate, door latch and an aerial - or scrap radio with these bits intact.
I do wonder of Roberts used center negative just so that if people used a non roberts psu they would blow the audio chip. Although i do think the standard 9v for guitar effects is the same negative centre.
That is indeed how the story goes... Customer buys more expensive OEM psu, or risks it with a cheaper alternative... and... Roberts get to charge for a repair, and a stock psu...
So long as the psu is 9v centre negative, and around 4-500mA, a pedal psu would work just fine - I've used them.
Thanks for watching, and the comment.
Very neat and tidy!
Hi can I ask you what voltage are the capacitors and the Tda 7231 is there anything in particular I need to look out for when making a purchase, can I also as if you sell any of the parts, thank you.
The standard factory capacitors are 'usually' rated at 16v. I replace them with 25v rated capacitors as my own standard practice.
The TDA7231 Audio IC is still available from China (on eBay) - although with those ones I have found them to be 'hit and miss' - they sometimes work, they sometimes don't.
I bought a bulk amount some time ago, of genuine IC's, from a UK source, so I have a healthy stock for my own future repairs.
@@Codeeze I much appreciate your getting back to me, do you have a link to the page I can purchase them on, thanks.
@@dublinbred UK seller: www.ebay.co.uk/itm/200964391556
China: www.ebay.co.uk/itm/153025480721
@@Codeeze thank you so much, can I just ask you one more thing, on both the 1000 and the 470 what is the capacitance for each one as I want to be sure I buy the right ones, thank you.
@@dublinbred Before you go ahead - double check the audio IC to make sure that you do in fact need a TDA 7231. In rare circumstances, some R250's and R550's used a 2201X01 - I wouldn't want you buying the wrong one!
As for the capacitors, the 'usual suspects' capacitance is as you have it, 470µF and 1000µF, and as I said previously, I use a minimum of 25v on each. Another thing to mention is to take care with the polarity of these capacitors, make sure by taking photographs before you remove any - then you have a reference.
Lastly, when soldering in the new IC, make sure not to create any solder bridges between the pins.
Best of luck, and please do let me know how you get on 🤞
Easy peasy. See you on the next.
Thanks Terry, most of these come to me with the same problem, so they are straight forward to resolve. Thanks for watching, and stay tuned for more!
Have those parts failed because of reverse polarity of the external power supply being none standard? or just the age thing?
Indeed Michael, usually caused by reversed polarity from a PSU. Centre pin on these, and many other Roberts sets is negative. Sometimes I see even worse where a greater voltage than required has been used - gets messy!
You make it look so easy (:
It is easy! The hardest part is doing the video! - Thanks for watching and stay tuned for more!
It's a shame that roberts used a barrel type socket, it allows any fool to plug in the wrong supply.
I'm amazed the chips in the r.f section didn't die, maybe a power filtering R/C circuit stopped too much current flowing?.
A fuse and a reverse polarity diode would have been kind of roberts.
Roberts did this I'm sure for commercial reasons. Centre pin negative meant that back in the day, if you needed a PSU for your radio, it was only available from Roberts... Popping in a penny diode would mean that sales from PSU's would plummet... along with the repair costs for reversed polarity...
@@Codeeze I wonder if that was the reason the sinclair zx spectrum computer had the reversed power socket as well.
Sneaky none standard.
Nice easy repair. When I replace audio power amp chips like this one I prefer not to use a socket as the pcb traces act as a heatsink. Socketting them reduces the ability to carry away heat. Probably not an issue in this set though.
It's one of the only radios where I would use a socket when doing this repair. Having previously measured active temperatures, the heat across the IC surface rarely makes it above ambient. The IC (TDA7231) Rth j-amb is 80C and Rth j-pins is 15C. One side of the IC is all ground, so this dissipates the tiny amounts of heat still quite well.