Finally, after however old it its, my PM4 is ready for some capacitors, I hope, was listen to it the other day then when it had warmed up lost the bass on the lefthand speaker. Anyway, most of the capacitors I can see are just old nippon chemican general purpose but there are a couple that I'm not sure about.
1. there are some red Elna for audio 10µF 35v on the circuit diagram they look like they are in the signal path so putting some Nichicon Muse ES bi-polars would be a better option.
2. there are some light navy Blue Elnas marked RE that seam to be used for decoupling power rails in the preamp and the Power supply to ground (0V). I guess this is because they are better quality with better ESR an leakage characteristics than the standard nippon and micron? so any decent modern cap will do
3. in the preamp there is a small un marked 10µF 16v? i guess same as above.
The circuit diagrams are attached and the capacitors in question have been circled in the relevant colours. Any advice on these capacitors, what capacitors I should use in this amp and any thing to watch out for/upgrade will be much appreciated.
almost forgot any pointers on setting the dc off set and quasient current. the manual I have has the figures but its written in Japanese. I guess I need to set the off-set with the speaker load disconnected and a volt meter over the speaker terminals. with the quasient current i guess i tun the variable resistors to zero connect a 8 ohm load then wait for the amp to warm up then connect to the to the test points. However the manuals shows two values for class A (350mV then 320mV) and class B (10mV then 13mV). I'm guessing i set it to 350mv/10mv then after a while it should settle to 320mv/13mV?
Thanks
Tom
1. there are some red Elna for audio 10µF 35v on the circuit diagram they look like they are in the signal path so putting some Nichicon Muse ES bi-polars would be a better option.
2. there are some light navy Blue Elnas marked RE that seam to be used for decoupling power rails in the preamp and the Power supply to ground (0V). I guess this is because they are better quality with better ESR an leakage characteristics than the standard nippon and micron? so any decent modern cap will do
3. in the preamp there is a small un marked 10µF 16v? i guess same as above.
The circuit diagrams are attached and the capacitors in question have been circled in the relevant colours. Any advice on these capacitors, what capacitors I should use in this amp and any thing to watch out for/upgrade will be much appreciated.
almost forgot any pointers on setting the dc off set and quasient current. the manual I have has the figures but its written in Japanese. I guess I need to set the off-set with the speaker load disconnected and a volt meter over the speaker terminals. with the quasient current i guess i tun the variable resistors to zero connect a 8 ohm load then wait for the amp to warm up then connect to the to the test points. However the manuals shows two values for class A (350mV then 320mV) and class B (10mV then 13mV). I'm guessing i set it to 350mv/10mv then after a while it should settle to 320mv/13mV?
Thanks
Tom
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