Reply To: Beomaster 4500 – one channel only

#6238
Llurkio
BRONZE Member
  • Topics Started 4
  • Total Posts 10

Thanks Christian for those words of encouragement – it helps to know I’ve got people ‘looking over my shoulder’.

Luckily I have a ‘scope so that made tracing the fault easier.
The IC3 (STK4151V) replacement has already be ordered, as is the recommended (by Christian) tape, I’ve also ordered replacement transistors (BC546, BC547, BC557) bewteen IC3 and the speaker connectors (they only cost pennies !), but don’t know if I should replace these, I’m wondering if they were likely to be “spiked” and destroyed ? I could remove them for testing, but then I just as well put new ones back in !
Glass control panel has already been cleaned up and ready for re-fixing, awaiting new tape !
One final question regarding 4 x diodes which make up a bridge rectifier, (D10, D17, D19, D27), these have been running so hot, they’ve discoloured the PCB, my guess is that they might be a bit “tired”, I was thinking about replacing these with some higher rated diodes AND mounting them with longer ‘legs’ so the body of the diodes are away from the PCB for a bit of ‘air cooling’, – or is the PCB supposed to act as a heatsink ? I’ve got some UF5404 rectifier diodes (left over from a previous repair), would these be a suitable alternative, given that they’re rated at 3a and high(er) frequency, my logic is that these diodes wouldn’t have to work so hard?
Any thoughts anyone ?
Tim