Quote from: Jasz2 on October 09, 2016, 08:48:32 AMQuote from: phatt on October 09, 2016, 07:33:10 AM
Hum,,, 220uF seems a bit low. Replacement might be a little tricky and potentially destructive unless you are familiar with surface mounted components and Lead free solder.
You can raise that value without upsetting the PCB by simply adding more capacitors, see pic;
Now of course I'm just guessing the polarity and position of the parts so it's up to you to make certain which is which. just remember that the positive terminal of the capacitor goes to the pos rail and negative terminal goes to neg rail.
The junction in the middle of the two added caps will of course go to common. A couple of 470uF caps will raise the value to 690uF which should be enough. This saves you having to mess with the PCB and can be easy removed if it does not work. :tu:
One thing that does bother me is the 16Volt rating of the caps which is very close to the working voltage. Only .5 volt headroom. ouch!!
Others here will know far more about the limits but a rule of thumb, caps must be higher than the working voltage by 10~20%
in this case 15.5 + 10% = 17.2. So those caps are working on the limit.
If you feel confident I'd replace the originals with 680uF 25 Volt caps.
Even 1,000uF will be ok if they fit.
Mass production procedures often use parts that are just on the limit, just long enough to get past the warranty time. :grr
I replaced the original caps with 680uF 25 Volt caps, and there is absolutely no change to the hum at all.