Marantz 1060 : complete overhaul

[Bert 1100]

Hello again,
This is my first 1060, bought off our local auction site, knowing it was defective. This time it wasn't an easy fix....
It turns out the amp board had been badly hacked in attempted repairs, the rest is fine and untouched.
See this thread about how I built a whole new P700 amp board :
http://audiokarma.org/forums/index....th-butchered-p700-amp-board-questions.727129/

So, now I know it is all working properly I am starting on a full cleanup and refurb.
As usual I'll be using Silmic II caps, but this time I'm tempted to use a 4-pole for the main cap. Probably Jensen, we'll see....
I'll also be choosing something very nice for the speaker coupling caps.

The amp was reasonably clean on the outside, but the inside is quite grimy, with a layer of greasy dirt with nicotine, and smells not nice....
So after some thinking I decided to disassemble it as much as possible, or as much as I dared....

The disassembling is done, the cleaning has yet to start...

The amp as received : in reasonably good shape...



The inside : from close up it looks much worse !



New parts for the P700 board



Board done !

temporarily in place for testing : all works nicely, happy



Hmm, what am I getting into
It's starting to look frightening...


All out ! Actually few wires were unsoldered...and all that were are numbered, except the very obvious ones..



Yuck !






This will be a slow project, I'm not spending more than a few hours a week on it.....

Oh, how do I interpret the date stamp on that last photo : 49. 7. 3 ?? week 49 of 1973 ?
Strangely the serial number plate is missing...

 

[Bert 1100]

OK, the washing is done : I have some industrial cleaner (no solvents, used in food industry) I spray on, a bit of brushing or sponge work, and a good rinse off with a hose, yes... Of course no soaking of the transformer !
It does a really good job of washing everything off with no effort. But it needs to be rinsed off, as it just makes the dirt and nicotine and grease water-soluble...the water comes out a nasty brown color...

Any idea about those numbers ? stamp = 49. 7. 3 on the top side of the chassis, and the number 522684 stamped on the bottom of the chassis. (the serial number plate is missing)

Other question : on the P800 power supply board, can I replace the 330uf cap with the same 470uf as the bigger one on that board ? why, just because I happen to have two 470uf 63V in stock, but no 330uf...
I know I can go up in capacitance and voltage for the main power supply, but here ?

A clean chassis !


Just after the rinse..
I used compressed air to blow out any water left in the pots and switches.


The P.S. board before


And after, no scrubbing, just spray and rinse


Part of the phono board


Tone board





I will recap the power supply board before putting it back in because it is on its own, but the rest will go back in before parts are changed, I don't want to flex wires back and forth too many times, and also I can check things are working in between doing the different boards.

 

[runningdog]

Wow!

 

[ton4eff]

No problem at all with 470uf 63V. I would go a step up with C803 to 680uf also.

 

[Bert 1100]

Great, thanks !

 

[airtime]

That's an amazing job!!!!

Strange how I when I was younger I liked to look at naked girly pictures. Now I like looking at a good rebuild.

Keep the pictures coming. Great work!!!!

 

[Steven Tate]

Great work! Can't wait to see it all put back together.

 

[ton4eff]

To avoid scratching the board when removing the old glue, I use a piece of cotton, soaked in acetone. Just placing it above the glue for about 10min. It's not dangerous for the board and silkscreen, but don't touch anything else. It may remove the color bars from the resistors.

 

[Bert 1100]

Strange how I when I was younger I liked to look at naked girly pictures. Now I like looking at a good rebuild.

Yes a good rebuild is very nice to look at....but girly pictures also are !

Ton4eff, yes I'll do the acetone trick. never tried it before.

 

[bryans12v]

Frame off restoration, very nice! That does look like a lot of work. Keep an eye on those wire>board connections for fragile wires that may have weakened.

You're in it this deep it may be worth cutting them and pushing new ends through.

 

[Bert 1100]

What's good is that there are no solid wires, all multi-strand, they much less prone to breaking than those wire-wrapped type connections with solid wire...

 

[Bert 1100]

Got a little done today : installed new binding posts, quite easy with the back panel out. The posts are Pomona 6883, not the prettiest but solid and cheap .
Installing is easy : drill out the existing screw holes to 12mm (need the special drill bit for sheet metal) and cut out a bit of the plastic mounting plate so it fits in the rectangular opening - see photo
Also got the PS board done : Silmic II and ultrafast diodes.

 

[tyeeslayer]

Nice work!!!

 

[Bert 1100]

A little progress :
It's now coming back together slowly.
I've added an IEC type mains connector.
I was trying to decide between a Mundorf 4-pole (MLytic AG+) or a Jensen 4-pole main cap (both in 10'000uf 80V). After finding out the Jensen costs THREE times as much as the Mundorf, I decided to go with the cheaper option... the coupling caps will also be Mundorf (MLytic AG, 4700uf 63V)





And yes, I will be replacing the paper / cardboard pieces glued on the chassis that protect the boards from shorting accidentally on the chassis panels....

 

[gslikker]

great!

 

[CohibaJoe]

...I've done 2 of these....I just may over the Winter start another 1.....Very Nice Work!!!

 

[Bert 1100]

OK, it's back together and working !!!!
I was a little nervous at the first turn on (DBT) but it was all fine.
The pre and phono board are untouched yet, but it now has the mundorf caps and Silmic II on the PS board. Also a fast / soft recovery bridge rectifier.
After the first small listen on my test speakers (small bookshelf type) , it seems to be promising !
I still need to glue back on the card bits that prevent shorts from boards to chassis, deal with the power light, glue the plastic part back into the buttons where they came out....

QUESTION : I now have a main DC supply of 69.3V DC (power amp board) So I want to adjust the DC balance on the output before the caps to half that, at 34.65V DC (I don't have an oscilloscope)
But with the pots (R723 / 724) at max. resistance (100K) I get just above 31V DC. Is it a problem or not at all ? Should I maybe change the pots to 200K ?
The idle adjusts very nicely and seems to be stable.

Voltage selector is set for 240V AC, my line voltage was 236 V AC.

To the pre board I get 28.7V DC and to the phono board 36.5V DC. these are not adjustable.

Oh, and an other question : with the fast / soft recovery diode bridge, should I keep the two supressor caps that were on the old rectifier ?

Some pics :


Caps, old and new



The two coupling caps are on with their glue rings. I will add clamps when I get some, they were out of stock when I ordered the Mundorfs.




The new 22 Amp rectifier


the back of the IEC mains connector, with optional rubber boot protection



first ON measuring the main cap voltage








Going now to continue on this project !

 

[Bert 1100]

 

[Bert 1100]

Bump
Anybody about the questions in post #17 ? Thanks in advance !

Bert.

 

[Steven Tate]

I wish I could help you. All I can do is compliment your work. It looks stunning. Someone will be along, I'm sure, who can help you with an informed answer to your question.