Need help identifying a blown capacitor on a Cambridge Soundwork radio/cd 765i. It is located on the main PCB, which has the display and front controls (volume, tuning, etc. There is no marking on the capacitor unless it was blown off. The PC board labels it as “VC201” which I assumed meant Variable Capacitor and the remnants look like a trim capacitor. The blown cap had 2 flat pins that were soldered into holes about 5mm apart. The cap was also about 5mm diameter with one side flattened and only about 5-6 mm high.
Several persons on an audio tech forum believe it was a super cap and I should replace it with:
However I am not sure that is correct because there is a 5.5v 49uF supercap already on the board labeled as “CB201”, which I assumed means “Capacitor Battery”.
So if the blown cap is a trim capacitor, I have no idea what to replace it with, how to adjust it nor know its function. (I cannot find any schematics for Cambridge Soundworks). Here are some pictures that may help:
the blown cap
the entire board (front display and controls on other side)
This looks more like an encased trimmer cap such as GKG5R015
They use color code to determine value vs markings.
It is hard to tell from the pictures if the color is off or if there are a lot of parts with heat damage so it could be a guess as to Blue or Green and if that will solve your problem vs something else that causes a surge to this part.
I did verify that CB201 is a supercap; 470mF (0.47F) @ 5.5v. The audio tech forum suggestion is slightly smaller capacity at 47mF (0.047F). 283-KR-5R5H474-R-ND | 4688-CB5R5474HF-ZJP-ND are a couple of our products that would replace CB201 if you decide to replace that one too along with the actual blown component following Robert_Fay recommendation.
Thanks to both of you. I am fairly confident that it is a trimmer cap and most likely for the AM Antenna. It is connected to pin 97 of the AP909 IC which specs say is a general input. I looked at the schematics for the Bose Wave radio and they have a similar circuit in which they used a pF20 for an AM antenna to ground. Mine, based upon the color, might be a pF30, so I ordered both of them. I also did some reading about AM antenna circuits and I don’t think it will make any difference which I use. As for adjusting it, since I do not have an oscilloscope, I will just go with the quality of AM reception via the speakers. Fortunately we do not use AM very much so it would not be too critical. Again, thanks.
BTW, ever hear of Decon capacitors? With the exception of the supercap which was Starcap and whoever made the trimmer, all other caps within the radio were made by Decon. The radio was built around 2008. Should I be worried about “cheap” cap failure?
Not familiar with them, but found that Decon is the brand name of Dongguan Win Shine.
Looking around Google, there are a few mentions of them related to the capacitor plague, which was roughly from 2002 - 2009, but I don’t know if they were actually part of that or not.