There are a few threads about the Technics version of this, all with a similar issue, but I think mine is in the early stages. I have the Panasonic version, bought recently second-hand. I think the two versions are electronically identical.
It looks perfect, barely used. When I first switched it on it immediately switched itself off again, with a relay clicking sound. I fiddled with the interconnecting cables and it worked... but after leaving it overnight with mains power off, the same thing happened again. Here's what I've worked out:
1. When the amp has been left off for a while (hours), it won't switch out of Standby mode until it's had mains power for about two minutes: almost as though it's charging up (capacitors?).
2. It then works fine, but the display of the tuner module and to a lesser extent the amp module flicker at what could be AC frequency. The tape and CD module displays are rock solid.
3. If left permanently connected to the mains, the problem is not apparent, though I think it will get worse and the amp will start cutting out as other users have described.
4. The issue remains even if just the amp and tuner are connected together; no speakers, tape deck or CD. It's not possible to isolate the amp entirely as the tuner holds the power button to get out of standby.
5. Even in standby mode the amp is quite warm, so much so that I wouldn't use this as an alarm clock due to waste of power. That might just be 1992 engineering, but might be due to the fault.
6. There is a mild burning smell. Initially I thought that might just be dust, though I have cleaned the unit. Now I think otherwise...
See photos attached (the fourth is of the tuner), in particular the burn areas. It's perhaps not coincidental that these seem to be around diodes.
So, capacitor failure in the rectifier circuit? Or something else? I've ordered replacement capacitors for the larger ones because they're cheap, but those big caps look to be in perfect condition.
Weirdly, the tape, CD and tuner modules each take a 23VAC supply from the amp itself, so each needs its own transformer and rectifier circuit. Seems very wasteful.
Any thoughts?
Thanks.
It looks perfect, barely used. When I first switched it on it immediately switched itself off again, with a relay clicking sound. I fiddled with the interconnecting cables and it worked... but after leaving it overnight with mains power off, the same thing happened again. Here's what I've worked out:
1. When the amp has been left off for a while (hours), it won't switch out of Standby mode until it's had mains power for about two minutes: almost as though it's charging up (capacitors?).
2. It then works fine, but the display of the tuner module and to a lesser extent the amp module flicker at what could be AC frequency. The tape and CD module displays are rock solid.
3. If left permanently connected to the mains, the problem is not apparent, though I think it will get worse and the amp will start cutting out as other users have described.
4. The issue remains even if just the amp and tuner are connected together; no speakers, tape deck or CD. It's not possible to isolate the amp entirely as the tuner holds the power button to get out of standby.
5. Even in standby mode the amp is quite warm, so much so that I wouldn't use this as an alarm clock due to waste of power. That might just be 1992 engineering, but might be due to the fault.
6. There is a mild burning smell. Initially I thought that might just be dust, though I have cleaned the unit. Now I think otherwise...
See photos attached (the fourth is of the tuner), in particular the burn areas. It's perhaps not coincidental that these seem to be around diodes.
So, capacitor failure in the rectifier circuit? Or something else? I've ordered replacement capacitors for the larger ones because they're cheap, but those big caps look to be in perfect condition.
Weirdly, the tape, CD and tuner modules each take a 23VAC supply from the amp itself, so each needs its own transformer and rectifier circuit. Seems very wasteful.
Any thoughts?
Thanks.