That isn't exactly true I don't think.
In a situation where you have just serviced the PSU - like I have done to both my CS80's, replaced all caps and the IC's etc... you don't really want to be switching on not knowing if there are any over-voltages. So therefore the 'on-the-bench' setting up is vital!
This allows you to check to see the PSU is indeed still functioning - and to set all voltages accurately.
Once happy - then it is time to re-install the PSU, remove those jumpers - and then monitor the voltages with all circuit boards connected (as you say) and again adjust voltages but this time measuring at the points specified in the service manual. ie: not on the PSU itself but a certian key positions that take into account distances from the PSU and also cabling etc.
Please service tech's, do correct me if am wrong here. I am no tech as such, just picked up what I know from either here or other sites I follow.
Cheers,
TOM
--- In yamahacs80@yahoogroups.com, Csaba Zvekan <czvekan@...> wrote:
>
> Hi Fernando,
>
> The PSU should and can only be calibrated/troubleshooted under load meaning connected with all other boards. What exactly is your problem ? What voltages do you read ? And compare them with the service manual . If something is off and can not be adjusted we can see further down.
>
> Kind Regards
>
> Csaba
>
>
> On Mar 2, 2011, at 9:40 AM, Fernando Zarone wrote:
>
> > A question.
> > If something is wrong in the PSU of CS-80, how to check why all of the CC voltages are faulty from the origin? Usually one separates the PSU unit from the machine and checks where it is bad. In the service manual (p. 59 if I don't get wrong) it is alerted not to detach the connectors from the PSU, for the risk of damaging the whole.
> > So, how to check the PSU unit?
> > Moreover, if both two fuses are ok, is there any other component protecting the system ?
> >
> > Thanks
> > Fernando
> >