Marantz PM75 Idle current adjust

[dj_holmes]

Hi, looking for help. Service manual states injecting 6-8mv into the test points. Never came across such a thing! Any help greatly appreciated!

 

[rayma]

Poor translation. They mean measure, not apply.

 

[dj_holmes]

but it clearly states apply 6-8mv?

 

[huggygood]

It's a mistake, you should read 6 to 8 mV between TP1-TP2 and TP3-TP4

 

[dj_holmes]

Thanks the replies but the plot thickens! After a bit of research I found the copy Philips amplifier fa888. See attached it states 19.4mv!

 

[rayma]

Many possible reasons for different bias choice. Different size heat sinks, desire for lower distortion specs, etc.

 

[Vunce]

Thanks the replies but the plot thickens! After a bit of research I found the copy Philips amplifier fa888. See attached it states 19.4mv!

19.4mA

 

[dj_holmes]

19.4mA

Sorry typo.

Clearly I'm struggling LOL. Basically anything between 6-8mv is fine then? Thanks

 

[Vunce]

Yes.
I own the Philips version of the PM75, nice component. Checking the bias and inspecting capacitors has been on my to-do list for a while, but more fun stuff always seems to cut the line, LOL.

 

[dj_holmes]

Well its turns out its already 6mv LOL. I will tell you however the test 3-4 is wrong! You have to go on the other side and copy the setup, nearest test pin and furthest test pin!

I have tried to compare the difference and the Marantz is definitely better, I like the fact also that the large power capacitors are not on the mainboard!

Thank you everyone for your contribution!

 

[dj_holmes]

Idle current is good now but DC is 88mv on each channel. Any advice please?