Nakamichi Stasis PA-5E MkII

EspenE

Member
2003-06-13 9:01 am
Oslo
I have a Nakamichi PA-5E MkII.
The mains power fuse blows the second I switch the amplifier on.

I cannot see anything wrong inside the amp: no burned components, no appearent cold solder joints.

Do anyone have any idea on how I should proceed on this?

Thanks, Espen
 

VHF man

Member
2007-05-21 2:34 am
If there are internal fuses on the +/- rails for each channel then replace them with 10W 47-100 ohm resistors - on both channels. That will allow you to measure and compare quiescent currents. If the mains fuse still blows then you probably have a short cct bridge rectifier. You should be able to check the BR's in cct with a DMM.

A blown bridge is pretty common with an old amp.
 
If there are internal fuses on the +/- rails for each channel then replace them with 10W 47-100 ohm resistors - on both channels. That will allow you to measure and compare quiescent currents. If the mains fuse still blows then you probably have a short cct bridge rectifier. You should be able to check the BR's in cct with a DMM.

A blown bridge is pretty common with an old amp.

Really? I find that to be a pretty rare failure - at least in the US.

 
I have a Nakamichi PA-5E MkII.
The mains power fuse blows the second I switch the amplifier on.

I cannot see anything wrong inside the amp: no burned components, no appearent cold solder joints.

Do anyone have any idea on how I should proceed on this?

Thanks, Espen

Could be

The mains transformer,
Shorted bridge or diodes,
Shorted output transistors,
shorted filter caps (usually quite rare),

regards
Trev