'Nice to get a freebie like that - so long as the parts aren't old carbon resistors and 30+ year old caps. I have had a few offers of parts collections over the years but most proved to be unsuitable for audio use.
Just clarify something for me. Is your bulb limiter wired in series or across the mains supply? If it is bright all the time, it will likely be just acting as an independent load across the mains supply, like any other lamp in the home. As a limiter, all current to the amplifier must pass through the bulb and since the bulb can in this case be wired in series with or across the supply Active and Neutral leads, there is room for error.
The bulb brightness should vary with how much current the whole receiver is drawing.
i.e. A flash of inrush current when you power up, a dimming to almost nothing with no audio output and a gradual rise of brightness that pulses with the audio peaks as volume is increased toward full power (when speaker loads are connected, that is).
Before the 180R resitors burned, the bulb should have been glowing but quite dim afterward. You haven't mentioned the bulb activity, so I'm curious as to what you have there, particularly since it should now be protecting your amplifier from these faults.
Just clarify something for me. Is your bulb limiter wired in series or across the mains supply? If it is bright all the time, it will likely be just acting as an independent load across the mains supply, like any other lamp in the home. As a limiter, all current to the amplifier must pass through the bulb and since the bulb can in this case be wired in series with or across the supply Active and Neutral leads, there is room for error.
The bulb brightness should vary with how much current the whole receiver is drawing.
i.e. A flash of inrush current when you power up, a dimming to almost nothing with no audio output and a gradual rise of brightness that pulses with the audio peaks as volume is increased toward full power (when speaker loads are connected, that is).
Before the 180R resitors burned, the bulb should have been glowing but quite dim afterward. You haven't mentioned the bulb activity, so I'm curious as to what you have there, particularly since it should now be protecting your amplifier from these faults.
Hi Ian yes it's in series live across the switch then the bulb holder, neutral in a block and earth in a block the bulb does seem to go bright and a bit duller, I was given a diagram on the forum so I think it's ok ? Ps you watching the rugby
OK - the "bit duller" should be "quite a bit duller" unless the tuner is switched on and indicator lamps glowing. Let's see what measuring the Vbe voltage drops (and of course C-E shorts) shows up unless you have already checked the ~ 0.7V expected there for all good transistors.
O/T
I haven't watched the Rugby since 2 other codes here, Rugby League a week ago and Australian Rules Football (a variation of Gaelic Football) this week, have both had their grand final matches. Popular interest and saturation promotions have dominated local TV so unless we pay for Foxtel distributions, we can miss the RU World Cup coverage, other than highlights. Still, there have certainly been some great matches and upsets with this huge pool of teams now competing. You are certainly in the box seat there.
O/T
I haven't watched the Rugby since 2 other codes here, Rugby League a week ago and Australian Rules Football (a variation of Gaelic Football) this week, have both had their grand final matches. Popular interest and saturation promotions have dominated local TV so unless we pay for Foxtel distributions, we can miss the RU World Cup coverage, other than highlights. Still, there have certainly been some great matches and upsets with this huge pool of teams now competing. You are certainly in the box seat there.
I must admit I'm not the biggest rugby fan but been watching the World Cup, it's free here same as football World Cup, big tournaments have been kept free access for everyone, a good thing and were out Typical. The amp - I had the tuner on so may be that's why the bulb stayed lit, it was all going well until I started adjusting centre voltage on left and right channel (8 ohm ) that went well, moved test meter to pin 403 and 404 adjusted that went well moved to pins 405 and 406 and q412 blew ? Is it wise to leave the current limiter on while working on the amp and adjusting it, thanks again
Sorry can you recommend modern replacement for 2sd669a - 2sb549a - and bd139 thanks
Sorry can you recommend modern replacement for 2sd669a - 2sb549a - and bd139 thanks
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