Marantz 2275 rebuild

[bitomaxsp]

I was just reading from the beginning and was thinking this could be solution for my problems and now such finish. Please update us if you resurrect some boards, specially P800.

I have P800 ok.

 

[bitomaxsp]

I digitized PE01 from original board that i have. And then Made layout of elements from the manual.
I am going to use it as reference to reproduce correct schematic and new PCB.
Schematic that we all have in our manual is wrong

 

[bitomaxsp]

Finally P700 arrived this morning.
I am going to do a trace check again to make sure its ok. Btw they are also design for Marantz 140. Since pcb is essentially the same.

Also i did pcbs a bit bigger in height than original for better laylout. Will see if it could be an issue, but my modeling showed it shouldn’t

 

[bitomaxsp]

Put it on to radiator. PCB naturally has the same size as radiator didn’t plan it

 

[bitomaxsp]

Moving resistors is very tedious process. I have checked their nominals when i did schematic. Check was done by measuring each individually.

Now i desolder one, put on to new pcb. One by one. Then i do check agaist the list that nominal matches.

Moat of the resistor arr ok, but i have checged some of them.

R716/717: they are supply. Originally 1.5W. But they were very hot when i did load testing. Replasin them with 2W. [CPF21K5000FKE14]

R718/719: replaced to precise one with low ppm 680 0.1% 15 PPM [RN60D6800FB14]

R725/726/736/737: 100R 0.1% 1/4W 15 PPM [H8100RBYA]

 

[bitomaxsp]

Slowly going to the end. H709 is replaced and it doesn’t have metal back, so i can achieve better thermal coupling with H713. But there is a clearance now so i need a spacer. Will figure something out.

 

[bitomaxsp]

I just soldered it and plugged in. No transistors replaced except mentioned above. Relay seem to click. There is noise when i put full volume (as it was before). Waiting till it will get hot to adjust bias

 

[bitomaxsp]

I am amazed. It worked! Everything was able to adjust to the required level. DC offset is 0mv. Bias 10mv. It is so nice to adjust with multi turn pots.
Now when I am certain that layout is correct (evidence based approach, otherwise it wouldn't play the sound) i will replace some transistors and diodes.
Clean the PCB and test again.

After that i'll plug it in the audio interface and compare with original one in another channel.

 

[dankik]

Looks like you re-designed the board with copper on the component side (or am I missing something). Is there an advantage to doing this? It seems like now you need to rely on plated vias for solder connections and rework runs the risk of breaking the via holes.

 

[bitomaxsp]

"re-designed the board with copper on the component side" - you are right. No advantage except there is a solid ground plane.

 

[bitomaxsp]

Finally fully assembled with all new components.
Old one is C709 and H711,H712.

Thermal coupling of H709, H710 is done using copper foil 0.1mm to H713.
H701/702 was matched using Vbe transistor matcher i build earlier 2 year ago.

I'll post parts list later when I hear this beast will be playing

 

[dennislarock]

WOW!!!!!!!!!!!!!!!

I just joined AudioKarma as I need to rebuild my Marantz 2275 and this is the first thread that I've read!!!!

ABSOLUTELY AWESOME WORK... bitomaxsp!!!! I did download the the Lamp Holder .stl file... THANK YOU, SIR!

​

 

[bitomaxsp]

P700s are assembled and are playing really well. I want to do some measurements, but i have no time.
Meanwhile, i am routing PE01. There is nothing to show yet, since original schematic full of error and simply doesn't match the PCB in the amp. So i made trace layout and component layout and reconstructing schematic from original PCB instead. As soon as I have something to show, i'll post it here.

 

[Jonstigator]

That is amazing! Why not just replace resistors?

 

[bitomaxsp]

That is amazing! Why not just replace resistors?

I see no point. I measured their values, all good. it could be done later if needed. Packaging and spacing are standard ones.

 

[bitomaxsp]

Traces obtained by taking picture of the PCBs bottom and cleaning it later with photo editor. Width of the board is 238mm.

 

[bitomaxsp]

Elements layer obtained from schematic. Cleaned it up a little. As you may notice, it is not in match with traces, but gives good enough understanding of components placement.

 

[tranguru]

Hi

What footprint did you use for J709 -


I am building a new pre amp and buffer boards for a 1250.
it also has single and double 6 pin and 12 pin pushbuttons.

for the moment I use pads - but I need to position them very precisely - I am using a caliper to measure the exact positions.

I also asked this on the KICAD forum - no answer yet.

Help needed finding correct footprint for old Marantz amplifier

Hi team, I want to build a new PCB for a Marantz 1250 amplifier. The previous broke the board in many places. I am looking for the optimal footprint for : double base horizontal pin (for lack of a better word) pushbuttons see attached pictures. I used...

forum.kicad.info

 

[tranguru]

this is current status:



I am still adjusting the positions and pad diameters.
the button positions and pin connector are critical as they must fit with other parts.

I tried to underlay the picture of the PCB picture from the service manual - scaling has been a challenge

let me know your thoughts/ideas.

Thanks
Robin

 

[bitomaxsp]

Hi

What footprint did you use for J709 -


I am building a new pre amp and buffer boards for a 1250.
it also has single and double 6 pin and 12 pin pushbuttons.

for the moment I use pads - but I need to position them very precisely - I am using a caliper to measure the exact positions.

I also asked this on the KICAD forum - no answer yet.

Help needed finding correct footprint for old Marantz amplifier

Hi team, I want to build a new PCB for a Marantz 1250 amplifier. The previous broke the board in many places. I am looking for the optimal footprint for : double base horizontal pin (for lack of a better word) pushbuttons see attached pictures. I used...

forum.kicad.info

I did J709 myself. If you want, i can share it with you. No a big deal