Pioneer SX-434 - fuse keeps blowing - #8

Can't remember off the top of my head but does the 424 use an amplifier block or discreet transistors?

But yeah, something is drawing too much current. In my experience it is usually a rectifier bridge, filter capacitor, or output transistor or amplifier block. The power transformer is only suspect upon the previous mentioned things being good. Power transformer failure is rare so that is why I suspect it (if at all) last.
 
Can't remember off the top of my head but does the 424 use an amplifier block or discreet transistors?

But yeah, something is drawing too much current. In my experience it is usually a rectifier bridge, filter capacitor, or output transistor or amplifier block. The power transformer is only suspect upon the previous mentioned things being good. Power transformer failure is rare so that is why I suspect it (if at all) last.
discrete transistors . b1+ is derived from a single diode and a couple of transistors etc for regulation . there are many things that might be shorted . i would start at supply looking for shorted caps etc . i might disconnect the wire going to amp board first . then see if current draw drops .
 
Yeah, I think simply testing the transistors with a meter would be a lot less complicated. 9 times out of 10 at least in my experience, it has been an output transistor. I might even go as far as saying 99 times out of 100.

I have had shorted diodes, rectifiers, filter capacitors, and power transformers but I automatically go for the output transistors first when I see blown or blackened fuses.
 
Could you have the circuit board wiring post number confused with the fuse number?
I am a newbee myself, so perhaps one of the more experienced members could help with this.
I think you might have reported fuse 8 blowing, when it is really fuse 6, because you were looking at the post number, not the fuse number.
I have an SX-434 that was given to me, and it blows fused 5 and 6. So far I have been too chicken to dive into it, but I have done some research.
I have noticed that the fuses on the power supply board are not labelled, but the wiring posts that are right next to the fuses are labelled very clearly.
I believe that post 7 is connected to fuse 5, post 8 to fuse 6, post 9 to fuse 8, and post 10 to fuse 7.
I will try to upload a pic of the power supply board (from the web) and one of a portion of the schematic to show what I mean.
If I have this all wrong, will somebody please set me straight. This is the kind of thing that can really throw us newbees.
 

Attachments

  • Pioneer SX-434 Schematic Clip - Power Supply Fuses.png
    Pioneer SX-434 Schematic Clip - Power Supply Fuses.png
    236.1 KB · Views: 29
  • Pioneer SX-434 Power Supply Board AWR-062.PNG
    Pioneer SX-434 Power Supply Board AWR-062.PNG
    712.4 KB · Views: 31
Back
Top Bottom