Audio Marantz PM500

[Tha fios agaibh]

I would pull pull and check cf07 and cf09.
They feed the opamp inputs and might be effecting when the amp switches on.

Great point @73's de Edd about using metal film resistors. I was looking to see if there was a key to explain what that "!" symbol means.
The voltage rating of cf11 is 25v. I believe it's borderline since it normal sees 22v. I might replace it with a 35v rating or even a 50v if it'll fit.

 

[eytonbranhan]

wooo ! I have a lot of difficulties to understand that :
The information given in the page 12 are not the same that on the pages 34 and 35 !

In the page 12, CF09 is a 100µF /10V.
In the pages 34 and 35, CF09 is not in the diagram and instead there is CF08 with same values.

The capacitors I really have on the PF00 are :
- CF07 : at the seventh pin of QF01 is a 100µF / 10V (OK)
- CF09 : at the sixth pin of QF01 is a 10µF / 25V (WTF ?)
In the diagram of the page 12, CF09 should be at the seventh pin of QF02 !
In the diagram of the pages 12, 34 and 35, there is no capacitor at the sixth pin of QF01 !

Anyway, I visually checked these components and they don't seem dead.
I also replaced CF07 by CF08 and CF09 by CF10 (same values).

Result : same problem of violent fried sounds from the left speaker when RF21-1 is high enough

About CF11, should I really need to replace it by a 35 or 50V capacitor ?

 

[eytonbranhan]

I just swapped RF21 and RF22 : same problem, no change

 

[eytonbranhan]

I just swapped JH07 and JH08 and now the problem is on the right speaker ! Preamp ?

 

[Tha fios agaibh]

Me too. This stuff can get convoluted when you have to flip through multiple pages.
Sometimes their are multiple components listed with the same component name.

I think the difference has to do with the different model options. I haven't looked thoroughly at the pdf, but parts are showing the pm700 only, while others are covering the pm500 and pm700. Different amp wattage I presume.

This was a good working unit for you until it died on you, right?
If so, I would trust what values and topography you have. Print the pdf as a reference and mark up your drawings to reflect what you see.

I was thinking it was working fine except for volume levels.
Can you describe this "fried sound" in more detail? Perhaps the eq section is fine but the amp is struggling delivering the added wattage needed when the low frequency (cr21) pot is cranked up?

Does the main volume have an impact on this noise? Or, different input sources?

Edit: I just read you post about jh07,8 swap.
Awesome, It looks like you're narrowing in on it!

I'll look at that section tomorrow, It's dinner time.

 

[eytonbranhan]

Hello guys !

About the service manual and the PM500 and PM700 differences, I think you're right !

This was a good working unit for you until it died on you, right?
If so, I would trust what values and topography you have. Print the pdf as a reference and mark up your drawings to reflect what you see.

Yes but I used it with a Marantz EQ-20 and didn't notice that the EQ of the PM500 was dead, maybe since a lot of time.

I was thinking it was working fine except for volume levels.
Can you describe this "fried sound" in more detail? Perhaps the eq section is fine but the amp is struggling delivering the added wattage needed when the low frequency (cr21) pot is cranked up?

Now that the problem is on the right speaker (when the RF21 fader is at the top), it's like the sound was suddenly very high and the volume to the maximum. It's so loud that I can't let it like that even for more than one single second, it's very violent.

When I disconnect the right speaker, I don't hear this phenomenon anymore but by cons I hear something very strange that seems to come from the amp itself and not from the speakers.

It sounds like a whistling, very high pitched. Like a magnetic resonance for a step-by-step motor. Someone told me that it can come from the L701 and L702 components but I have not checked again since.

Anyway, this weekend, I will try to find the cause of this, I think it's in the preamp section because the fact of swapping JH07 and JH08 moved the problem to the right speaker.

What's your opinion about all that ?
What's your ideas and advices ?

Thank you in advance !

 

[bertus]

Hello,

Where are these JH parts in the schematic?
Can you post a snaphot from the manual?

It sound like the channel with the faulty parts starts to oscillate.

Bertus

 

[eytonbranhan]

Page 35 :

 

[bertus]

Hello,

Then you only swapped the input signal connections.
There are no parts involved, that clears the part of changing channels.
Swap them back.
There must be something wrong in the electronics.

Bertus

 

[Tha fios agaibh]

It would be convenient if this pdf was searchable like newer pdf files.

Swapping Jh07,8 swaps L with R input to the pm700 (I thought you had the pm500?) so the problem is before the amp.

 

[Tha fios agaibh]

Where does Jh03,4 from the ph00 board come from?

 

[Tha fios agaibh]

Ok, I see it comes from pf00. Where we started.

This could be michrophonic distortion from a bad trace or something.

 

[Tha fios agaibh]

Have you taken a close up look with a bright light at the back of the board.

A cracked solder joint could be the culprit.

 

[Tha fios agaibh]

Try moving the left slider pot just before the point of distortion and then try slightly flexing the board or gently probing components with the eraser end of a pencil.

 

[Tha fios agaibh]

A solder joint can look fine at first glance, but actually be fractured making a poor connection.

 

[Tha fios agaibh]

Have you tried swapping opamps Qf01 and Qf02?
Trouble seems to be in this vicinity.

 

[eytonbranhan]

It would be convenient if this pdf was searchable like newer pdf files.

Swapping Jh07,8 swaps L with R input to the pm700 (I thought you had the pm500?) so the problem is before the amp.

yes I totally agree for the pdf files.

yes I have a PM500 but it swaps also with it, page 34 and page 35, no ?

 

[eytonbranhan]

Have you taken a close up look with a bright light at the back of the board.

A cracked solder joint could be the culprit.

I redid all the welds of PF00, PH00, PF01 and PG00 but not the other boards.

 

[eytonbranhan]

Trouble seems to be in this vicinity.

No but i will do that this evening !

 

[Tha fios agaibh]

About CF11, should I really need to replace it by a 35 or 50V capacitor ?

It's probably fine since there's others with the same 25v rating and seemed to have survived. Example, caps Ce17,18 are rated 25v and has 23v across it. Not much leeway there.
Capacitors are usually rated at least twice the voltage they see.

I would double check that your ps voltage rails are still ok (+- 25v) and check opamps Qe01 and 2 pins 4,8 are supplied with about 19 to 24v.

Good luck.