Hi Michael, that is a very nice video about repairing an amp. I really like the approach you have to getting access to the parts you need to replace. Also clearly indicated as with the Akai tape deck. I would like to give my two cents on the trouble shooting and the funny little circuit that gave you this trouble. I used to repair a lot of audio in the 80's. It was my college job where I was working for a radio and TV repair shop. I would not say I would have gotten faster to the end result but my laziness would result in a different approach. In other words, before touching that hard to reach place I would double check if it was needed. The first thing that comes to mind is that if you have two channels doing the same thing, it has to be a common problem. It turned out the case, one transistor controlling two channels. Secondly, on crackling faults and doggy Japanese transistors, you can find so much with cold spray. So I would recommend you ordering a can of that, since you are having this as hobby. Or by (carefully) heating it with your solder iron. Doggy transistors will strongly react to temperature changes and you may need cold or heat to make it either better or worse and thus confirming a bad part. As for the transistor it self, it is not speaker protection. This amp has output capacitors that block DC current so no speaker protection is needed. It looks like it is a soft clip control. That makes sense with a low power amplifier that does not have unlimited headroom. So if you play it loud, it will pull the input signal slightly to ground avoiding that you fry the amplifier by playing it too hard. (I guess they also did not have great confidence in the intended users of this amp, which I think was also a correct assessment). Sorry for the rant, I hope it was useful none the less.

Hiya Michael. I love mending things generally but I know absolutely nothing about electronics. However I found your video fascinating and rivetting. And bravo for saving an amp from the scrap heap which is where it would have ended up no doubt. It's tragic to think how many amps have been binned due to a faulty transistor or other tiny component. Thank goodness there are still people like you out there. Cheers 🙂

Ahhh same transistors on my Kenwood KA 2000 Mike! This is great, thanks for these vids!

Hi Michael ! You're guest starring on the latest video review from VWestlife !! 🙂 Cheers !!

Great Stuff Michael When I Fixed The Noise in My Sansui AU101 Amp I Replaced All The Transistors in The Pre Amp Board With 2SC1815s To Future Proof It (makes sense as more of the transistors could turn bad a few years down the line) Thanks For Uploading Michael P.S. You Got To Love That Frying Bacon Sound he he !! Regards mike.

Good video mate. Liked it 😊

hi i put little covers on the transsister legs as it will move over time in side the amp i seen this is alot of very old decks i worked on pro audio gear like the soundcraft 760 ace's brannel reel to reel decks nice to see you show all the tec info some don't like to do this i will say the big tape are better for your money long run have the space is a pain bob

Excellent, thanks.

no if the legs are black that is corrosion tarnish silver not paint, and can cause failure to the component and should be cleaned off Q-Tip and some isopropanol. it looks more like a global feedback circuit

Thanks Michael. I now got some clues into tackling the popping noise on my Pioneer VSX 433. Mine started doing this for the first 2 to 3 minutes initially. It now has go to a point where it does this for ~ 30 minutes until you could hear good music. BWW, where do you find schematic diagrams for such an old amplifier?

Hi Michael, Tricky one, It's common to both channels so could be the preamp power supply rails injecting noise into the circuit.. Is it possible to isolate the preamp from the power amp? Time to buy an oscilloscope maybe.. Great video..