This compact HiFi system shows error "F61" on display as soon as it's turned on, and then it shuts off at once. It's a quad amp with High-Low separated outputs, with a very expensive and hard to find RSN315H42C AMP IC.
From Service Manual one can read that F61 error is related to power amp (DC detected in output...), but from own experience with Panasonic audio equipment I know that it can be a problem with cooling fan too. I've found similar issues with SA-AK250, SE-CH770, SE-CA1080... and it's never just a single cause, as SM insists it's only "Power Amp output abnormal". Easy to check: just disconnect cooling fan, raise volume up to -14dB and F61 triggers immediately. It's a 2 wire 12VDC fan, but the driver circuit is able to detect its presence and if its turning or not. Common in Panasonic.
The odd thing is that after partial disassembling, F61 error disappears and audio output is normal. Cooling fan seems fine. After some tests i decide to reassembly it and return to the customer, but then problem shows up again! Then I discover that it only fails when CD loader/changer is connected. F61 related to CD? WTF?
Checking this part with detail I detect that CD spindle/sled/focus/tracking driver IC7003 (AN8739SB) has been getting hot for years, as the PCB is "browning" below it. Most importantly, CD +7.5V is barely 3V. C7614 (CapXon 100uF/6,3V, close to IC7003) shows abnormaly high ESR and decoloration due to heating, but it's not directly related to +7,5V. C7334 (Panasonic 220uF/10V) is related to +7,5V but it doesn't look bad. I replace both anyway, with no change in voltage. I isolate +7,5V from IC7003 and voltage doesn't improve. Down to the power supply I get to D5805 and D5807 (1N4003S). D5805 has 9V OK, but D5807 has 9V on Anode and just 3V on Catode. Replace it and +7,5V is OK, CD works and no F61 anymore.
I'll test if for some days before returning it to customer, because I'm afraid that it won't last. Why CD motors driver gets so hot? Panasonic/Matsushita CD/DVD spindle / sled motors aren't the best ones and I've had to replace quite a few.
BTW, I found (at yoreparo.com) an interesting trick to replace a faulty RSN315H42C. As this IC is really expensive and scarce, there's a chance to replace it with a less hard to find RSN314H41A. First one has 18 pins, while second has 14 pins, but same pitch. As these Panasonic ICs are undocumented, one can only rely on schematics from equipment that uses them. It turns out that pins 1-2 and 17-18 from RSN315H42C are ±VCC clones, while pins 3-16 are identical to RSN314H41A pins 1-14. So the trick is to insert the latter in 3-16 holes. As this IC is smaller than the original, perhaps you'll have to drill new mounting holes for screwing it to the heatsink. Surprisingly enough, in the SA-AK330 case, these holes are already made from factory!
From Service Manual one can read that F61 error is related to power amp (DC detected in output...), but from own experience with Panasonic audio equipment I know that it can be a problem with cooling fan too. I've found similar issues with SA-AK250, SE-CH770, SE-CA1080... and it's never just a single cause, as SM insists it's only "Power Amp output abnormal". Easy to check: just disconnect cooling fan, raise volume up to -14dB and F61 triggers immediately. It's a 2 wire 12VDC fan, but the driver circuit is able to detect its presence and if its turning or not. Common in Panasonic.
The odd thing is that after partial disassembling, F61 error disappears and audio output is normal. Cooling fan seems fine. After some tests i decide to reassembly it and return to the customer, but then problem shows up again! Then I discover that it only fails when CD loader/changer is connected. F61 related to CD? WTF?
Checking this part with detail I detect that CD spindle/sled/focus/tracking driver IC7003 (AN8739SB) has been getting hot for years, as the PCB is "browning" below it. Most importantly, CD +7.5V is barely 3V. C7614 (CapXon 100uF/6,3V, close to IC7003) shows abnormaly high ESR and decoloration due to heating, but it's not directly related to +7,5V. C7334 (Panasonic 220uF/10V) is related to +7,5V but it doesn't look bad. I replace both anyway, with no change in voltage. I isolate +7,5V from IC7003 and voltage doesn't improve. Down to the power supply I get to D5805 and D5807 (1N4003S). D5805 has 9V OK, but D5807 has 9V on Anode and just 3V on Catode. Replace it and +7,5V is OK, CD works and no F61 anymore.
I'll test if for some days before returning it to customer, because I'm afraid that it won't last. Why CD motors driver gets so hot? Panasonic/Matsushita CD/DVD spindle / sled motors aren't the best ones and I've had to replace quite a few.
BTW, I found (at yoreparo.com) an interesting trick to replace a faulty RSN315H42C. As this IC is really expensive and scarce, there's a chance to replace it with a less hard to find RSN314H41A. First one has 18 pins, while second has 14 pins, but same pitch. As these Panasonic ICs are undocumented, one can only rely on schematics from equipment that uses them. It turns out that pins 1-2 and 17-18 from RSN315H42C are ±VCC clones, while pins 3-16 are identical to RSN314H41A pins 1-14. So the trick is to insert the latter in 3-16 holes. As this IC is smaller than the original, perhaps you'll have to drill new mounting holes for screwing it to the heatsink. Surprisingly enough, in the SA-AK330 case, these holes are already made from factory!
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