GUIDANCE NEEDED to mod - MARANTZ SA 7001

[Thomo]

I've also added another +3.3v super-reg for those clock IC's, this is mounted to the under-side of the servo board and is supplied by the same 5v reg as the c3 clock.

Lee.

[6h5c]

Hi Lee,

Nice work! I'm hoping to get some work done soon, I already have part of the OS-CONs here . Waiting for the rest to arrive and then I can take the board out. I ordered some LT1963A regulators to replace the BA033 stuff that's on the board.

Did some tinkering with the clock schematic yesterday. It's not so easy to get rid of the extra divider and buffer IC. There are some inversions in the clock signal that have to be corrected. For example, Marantz used the inverted Q output (NOT-Q) of the 7474 instead of the 'normal' Q. This is because the signal is inverted again later on when it is switched by a NAND-gate. So it appears I will have to re-route some traces. Just have to see if that's possible in practise.

Ray

[Thomo]

Hi Ray. That's a lot of work there! Why not simply remove the logic from the c2 and use the SA7001 logic that's already present?

Even better will be a c3, it's a huge step up over the c2. Funny really, the c2 was already massively better than any clock I've ever tried.

Lee.

[6h5c]

Hi Lee,

The on-board logic of the 7001 is what I want to get rid of. The only frequency that's needed is 16.9MHz (if you glue the filter switch to GND), so the second flipflop-divider can go, plus some NAND logic behind it that switches between the two freq.

I'd rather go the other way and use an external clock with divider, or trim down the on-board logic and use that. Less logic = less jitter.

Regards,

Ray

[dennusch]

I would like a bit more gain from the SA7001. Can i double the gain bij doubling r641 from 120 to 240 ohm? R641 seems to be a feedbackresistor to me. Maximum output will become 4v.

[UV101]

Thought I'd join you all!!!

Just added an SA7001 to my arsenal. Just had a listen in bog std form and its much better than I was expecting (was expecting to turn it off straight away and head for the bench!!!) I'll start with a few cap swap outs and see where we get too!

[UV101]

Didn't stay standard very long ;-)
From this


To this!!!
Various BG FKs and Std and some large mundorf smothers. 3 5v regs and 3.3v replaced. I can tell this definitely has potential.

[6h5c]

Yes, it's absolutely a player with potential and it's very tweakable. Nice work!

Got my SMD caps in this weekend and making plans to attack the SACD board that's under the mech.

Regards,

Ray

[UV101]

Did a bit more this evening. Added a 12v and 8v reg. I also noticed with the std transformer (non KI) that the servo rail per reg was dropping nearly 1v under load. Clearly the winding is barely up to the job. I also noticed that my 5v regs were running a bit low. This was caused as I need about 5v drop out with these regs and the supply was about 8v which is a little low. I decided to isolate the original mains transformer from the board for pins 1 to 5 which are the ac8 and ac11 windings. I replaced the ac8 with a 2x9v 15va which is about 1.6A which happily is supplying all the 5v regs, 3.3v and vref. I was more concerned with the main servo 8v and 12v supply which seemed woefully inadequate. The ac11 rails are now powered from a 12v 30va transformer 2.5A.

The results at this point are staggering. I've not been this excited about a player in ages. Hopefully the new clock and a few more caps will arrive over the next few days so I can further release the potential.

[Thomo]

Nice work there Ian.

I've investigated a bit further into what I've done re. transformers.

I've added an extra tx for the display and front panel, isolating the original psu for the servo 5v only.

I've also added a 15va 2x9v for the dac to isolate the dac supply from the servo psu too.

I've been planning to investigate the 8v (I think) servo winding for sagging as I think mine drops a little, although it does stabilise quickly.

Cheers, Lee.