Marantz PM66KI amp.

[toman_9]

No I couldn't as I ordered wrong transistors...
I wanted to see whether at least one channel works..
But it seem that one has also a problem , dunno what..

 

[Fidelity Audio]

did you remove the bias transistor? its the little one on the heat sink between the two output transistors, this will defo be faulty.

If it still trips off remove all the transistors I mentioned in earlier posts,

INFACT remove and change them anyway as some of them will have been blasted with +40V.

 

[Netlist]

If the protection circuit has a distortion detection it will soon be activated without output transistors because the amp now has limited power.

/Hugo

 

[chicco_36]

So,
Which one is better :

2SA1941 or 2SA1265 ?
2SC5198 or 2SC3102 ?

If you can, go for 2SA1943 and 2SC5200, best from Toshiba IMHO.

Chicco

 

[toman_9]

Thanks Chicco!
I will order those transistors as well
And see what differene they make.

Thanks Hugo, I think that explains why the protection relay goes off.

Hi rowemeister,

I am interested in your power supply design.
Which TX have you used, was it expensive ?
Also do you plan to update your rectifier schematics ? From the topic comments it is a bit hard to follow.
Cheers..

 

[toman_9]

Hi guys!

Bad news... I have changed all the caps that you named and turn the amp on and after a while one of the caps exploded

I think the power supply is OK. But don't know what else can go wrong...

 

[hotscot]

I'm trying to get my PM66KI working...
All the voltages in the circuit seem to check out until near the output where the resistor that's part of the Zobel network heats up, really burning hot on one channel. R771 on the schematic.

It's been suggested to me that the amp is oscillating.

 

[anatech]

Alan <disembodied deep voice>

Use the 'scope Alan ..... use the 'scope

-Chris

 

[hotscot]

I know Chris I saw this thread and was just wondering if they had anything in common.

..but I think I need to take some time and learn some stuff first.

So..a scope...I could use that to follow a signal all the way through?
Are they expensive?

 

[anatech]

Hi Alan,
Yes, you can follow the signal straight through.

The price is relative to your expectations. They are cheap as heck compared to what I've paid for them over the years. A 20 MHz dual trace model will serve you well. They normally come with probes.

I would recommend Leader, Kenwood, Hitachi, B&K. There are more. Try not to buy the very cheapest brand.

-Chris

 

[toman_9]

Hi Hotscot ,

I have a very low-end multi-meter that can display signals up to 200 kHz, It is realtively cheap and if you want to follow the signal for audio signals it can do the job. (Voltcraft gdm 704)

Hi Anatech,

I am strating loose my hope and already started to think alternatives like buying another amp or buy separate kits (so that I can understand what is going on) to fit in the case.

The first option is easy...
Second could be a better option as I can have a better sound for the same price... At the moment I can make use of the PM-66's case, heat sinks, and the power supply (with its HQ Elna cps), all I would need is a pre amp,and 2 mono end stages...

However I still think that this amp could be repaired... But I have no idea where to start... Ok I know the power supply is working...
I was thinking of sperating the pre and power amp parts to see whether the pre amp is working, but have no idea how to do it.

Is there anyone out there with more experience. ????

 

[anatech]

Hi Tim,
Use your finger near the input stage or volume control to inject a hum. Do you have main in and pre out jacks on the back?

-Chris

 

[toman_9]

Hi Chris,

No I am afraid this am does not have a pre-amp out
There is AN7062 IC for the pre amp, which I couldn't understand all the circutry around it...

I think I will first remove the power amp transistors (the pair) and probe the pre amp stage first... and hope it doesn't explode again

 

[anatech]

Hi Tim,
Touch the input caps with your finger.

-Chris

 

[toman_9]

HI Chris,

Thanks for the tip, however I have already removed the the end stage as the transistors blew up and were causing shorts.
Now I will order new sets of transistors ( I should have ordered more pairs at the beginnnig... doh

 

[bekim]

Hi guys,

I receive marantz pm-66KI for repair, and I just wanna know is there any difference with 6010 or 66 model without KI on schematics...?
I have schema for 6010 and prior starting repairing if someone can answer to me I'll be happy or can send to me 66KI schema if you have on bekimh@gmail.com

thanx

 

[Fidelity Audio]

Hi guys,

I receive marantz pm-66KI for repair, and I just wanna know is there any difference with 6010 or 66 model without KI on schematics...?
I have schema for 6010 and prior starting repairing if someone can answer to me I'll be happy or can send to me 66KI schema if you have on bekimh@gmail.com

thanx

I believe the output is the same.
I'll send sch to you

 

[prasad1964]

Re: Marantz Circuit

Would LOve to have the schematic. I am Using Marantz PM44SE MarkII. This also has a AN7062 as driver. I would like to make some tweaks. In combination I am Using Marnatz CD52 MarkII CD player and Speaker off Course not so branded Berhinger Studion Monitors.

My mail ID prasad1964@yahoo.com

Thanks and best regards

Prasad

 

[Fidelity Audio]

Sent

Brent

 

[jimh0612]

power cord replacement

Hi guys I had the "no sound but LED on" problem which was the blown R802.
Now I've opened it up I've got the modding bug and want to change the power cord for an IEC socket and upmarket power cord.
If I add an earth point, connected to the chassis/case and then connected to the ground planes of the PCB's will I get an earth loop.
I've tried to read threads on the subject but it seems very complicated.
Also want to do it when I mod my CD63KI.
Hepl appreciated.