NAD C320BEE repair possibly bad capacitors

[Alfieh]

hey Im very new to repairing electronics with capacitors as well as using a multimeter so I need so help/guidance fixing this issue

recently I was handed a family members old NAD C320BEE that they had in their loft for storage for a few years but when powered on it went into power safety mode due to a problem on the protection circuit somewhere before it went into storage I was told it worked fine I found lots of people online talking about how the capasitors are known to be pretty bad in this model and can cause this issue the only problem being I don't have much experience sorting this so I thought it might be a good opportunity to learn I found the online schematics for the board although I don't really know how to read them and tried checking some power levels around the board the power from the power supply mini board seemed correct but the +18 and -18 rail seemed to be incorrect from what I could figure out so I tried to check the capacitance of a lot of the capasitors on the board and I'm not too sure if I've found the issue or not the following capacitors stood out more than the rest but lots were slightly out of spec so I'm not sure how to take it if they need replacing or not:

C431 0.75mf instead of 10uf
C430 13.36mf instead of 10uf
C12 111.4uf instead of 47uf
C326 and c325 0.46mf instead of 47uf
C421 580mf instead of 4.7uf
C49 104900uf instead of 47uf
C47 860uf instead of 47uf
C413 and c414 350uf instead of 220uf
C48 1280mf instead of 47uf
C410 170uf instead of 47uf
C342 250uf instead of 47uf
C425 1.8mf instead of 2.2mf
C436 is 0.25mf instead of 100uf
C324 is 10.74mf instead of 47uf
C323 is 450uf instead of 47uf
C44 is 610uf instead of 220uf
C43 is 1.43mf instead of 220uf
C26 is OL on max settings should be 220uf
C25 is 18.4mf instead of 220uf
C15 is 13.6mf instead of 220uf
C16 is 14.26mf instead of 220uf

as I said I'm not experienced at all with this type of stuff so would be really appreciated for any guidance that you could give I'm not sure how big of an error of margin I should give c410 doesn't seem too far off but its still 3x over what it should be so should it be replaced or is it an issue further back down the line that is making this capacitor seem broken I'm not sure and don't really know where I should go

TL;DR
I need help fixing a NAD C320BEE but don't have much experience with electronics and don't know what to do

[CapLeaker]

So what are you getting on the positive and negative 18v rails? Some of your measurements are skewed because you measured them in circuit. So you probably measured multiple capacitors without understanding what the circuit does.
Here is a rule if something you think is off: When in doubt, take it out! Or lift a leg and measure it again out of circuit. Keep in mind a hot capacitor will always read better than at room temperature. If a capacitor is off 10% of the original rating, it is a non concern for me. Even at 20% off the circuit shouldn't be affected, but I'd change it out after I know why this thing isn't working.
Having a reading of 3x the value you should have on a cap, you measured something else and again it depends on the circuit. Don't focus on where is too much capacitance, rather on where there isn't enough and the ESR value on capacitors is like what a health gauge is on batteries depending on internal resistance and chemistry.

Usually if an amp is in protect mode it has problems inside the PA stage. First things first: Find all the power rails and see that they are correct.

Sometimes it is easier to follow the block diagram first, before you dive right into the schematics.

[Alfieh]

thanks for coming to help ill try tomorrow on taking off some of the capasitors that are too low and and measure their voltage and capacitance to see if they still seem weird
I apologise but I'm having trouble knowing if the +18 and -18 rails are correct as I'm not even sure if I'm measuring them off the right point when I measure off the v+ and ground as well as v- and ground the voltage is quite low but if I power the amp off and on again it seems to jump up then slowly decrease the voltage so I'm not sure what is happening but from another form I found people were saying to measure l11 and l21 for the +/-18 rail but both show up as 0v atm so I'm not sure if that's correct or if its because its in power safety mode

[CapLeaker]

Measure the + 18V and - 18V at C49 and C410 capacitors. Look at your schematic.

[ric000]

non è facile riparare un amplificatore per un profano ci servono diversi strumenti come misurare i componenti misurare le tensioni di alimentazione tantissime cose per me forse sbagli a misurare i condesatori dei video che ti possono aiutare https://www.youtube.com/results?sear...=the+river+lab
io sono italiano ......