Marantz PM-750 DC recap tolerance marking help

[ReisDaddy]

Hello guys,

I make my storry short, i fall in love to this underrated Marantz PM-750dc phillips era, for me its a sleeper, to my ears it sound amazing, warm, not to bright, i think its flat, its just so pleasing.
So i plan to recap.

Sorry to ask maybe for you guys its dumb question, and already search in this forum, i cannot find exact answer.
I posted the capacitor in question, its C801, Electrolytic 4.7uF 50v.





The problem is when the stuff is arrived, the measurement is 5.5uf (New Panasonic FC 4.7uf 50v), i bought 4, and all is same 5.5-5.6 uf.
When i ask chatGPT it is still in the tolerance, but in service manual it has exclamation mark (!).
Should i bought another one? because im in remote area, to buy just a piece of caps the shipping cost is higher. Unless it is very important.

It is in power lane i guess.

Thank you

 

[SkxawngGirl]

This cap is located after the rectifiers so it will be exposed to some AC ripple voltage, and I'm thinking the schematic exclamation is referring to this. In other words, a replacement capacitor should be tolerant of some reverse bias.
Apparently there are Nichicon FG, and Panasonic FC lines, so I am not sure what cap you have.

 

[ReisDaddy]

@SkxawngGirl Sorry, maybe im not clear, i mean i did buy Panasonic FC 4.7uF 50v as in the part list, but the measurement of that new Panasonic with my digital multimeter is 5.5uF instead of 4.7uF. Its almost 20% tolerance. I never get capacitor that far from marking.

 

[SkxawngGirl]

Yes, I understand. Still, my online search did not find a FC capacitor line from Nichicon, but there is a FC line from Panasonic. The odd markings and wide tolerance on your caps makes me wonder about the quality and origin of your replacements. We suggest primarily buying from quality stores like Digikey or Mouser.

 

[ReisDaddy]

Sorry my mistake, typo. I bought Panasonic FC instead of Nichicon FC. Edited.

 

[SkxawngGirl]

According to the data sheet, your new caps can handle up to 18uA of ripple. Unless your mains circuit has some HF noise on it, replacement is not critical.

 

[Athers-Aud]

According to the data sheet, your new caps can handle up to 18uA of ripple. Unless your mains circuit has some HF noise on it, replacement is not critical.

I am so glad to see someone examining datasheets for ripple current in electrolytics...and ripple rejection in a circuit

...many dont and we have to reverse the work some complete tit has done causing issues.
Also these smakheads putting polarised where "BP" or "NP"'s should go .... nice

...and inside this period of Marantz ... it's good practice to replace ALL those delightfully aged fusible resistors that typically drift 200% away from their values. .

 

[ReisDaddy]

Before recap is done, when im setting bias for right channel as service manual, sometimes i heard relay clicking. But nothing happened. Success the bias. Then i use DBT as usual wall is 220v DBT is 100w bulb, sometimes i still hear relay clicking, and nothing happened. The recap was success without any problem.

Then i start setting bias again, this time without DBT. Then a capacitor is glowing and smoking in R748. Then i put back the DBT, bulb glowing but its still smoking? Then i pull R748 and turn the device on, DBT glowing then R742 is smoking.

As far as i know the DBT prevent excessive current? Should i replace to lower the bulb to 40w? Or go higher? If higher, no one selling more than 100w.

Then i try to disconnect all powerline except the power to relay, it is clicking now. I think the problem is in power line for main amp.

But how can i do any diagnose while the resistor keep smoking when i use DBT?