GUIDANCE NEEDED to mod - MARANTZ SA 7001 - Page 5 - diyAudio
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Old 11th August 2012, 02:26 PM   #41
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Quote:
Originally Posted by stvnharr View Post
Thanks Lee.
Where do you install the second clock, the 16.9mhz. one?

Steve
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Old 11th August 2012, 02:57 PM   #42
Thomo is offline Thomo  United Kingdom
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Hi Steve, sorry I didn't reply I've been very busy and not had time to check the thread properly.

I haven't actually fitted that clock yet, but it is definitely something that will be done and I see no reason for it not to work.

Cheers, Lee.
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Old 11th August 2012, 08:57 PM   #43
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Originally Posted by Thomo View Post
Hi Steve, sorry I didn't reply I've been very busy and not had time to check the thread properly.

I haven't actually fitted that clock yet, but it is definitely something that will be done and I see no reason for it not to work.

Cheers, Lee.
Hi Lee,
After writing the above post I started looking in the service manuals for the 7001 and 8260 to find where the clock selector IC's were located. I then got out a spare board I have and tried to find the IC's, and did.
All I can say is that this mod is WAY above my level.
I can successfully replace the X101 oscillator with leads to a clock, but that's about it.
To do your mod, I'd have to closely look at what Brent did on his SA11.
Steve
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Old 12th August 2012, 11:54 AM   #44
Thomo is offline Thomo  United Kingdom
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Hi Steve.

It's not too hard to do I think. Just a case of removing the first clock buffer IC, and feeding the relevant clocks into the input of the second IC.

The SA11 is a different animal and uses a custom FPGA (I think) to control the clock lines. This IC is mounted on the mainboard and is not fitted to the Sony servo board under the mech.

The trickiest part I can see will be physically soldering coax cables to such a small contact area. Plenty of hotglue and sticky pad required methinks

Lee.
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Old 12th August 2012, 02:11 PM   #45
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Hi Lee,
Yes the SA11 arrangement is completely different. Yes, hot glue and securing the skinny wires to the small pins is critical for this. Good Luck.

Steve
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Old 15th August 2012, 01:13 PM   #46
6h5c is offline 6h5c  Netherlands
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Hi Lee,

I had a look at the schematic this week, and the frequencies going to the DAC are 16.9 and 8.47MHz, not 33.8 and 16.9. The master clock is divided by two twice, and then selected by IC735. So in theory, you need a third clock to cover all frequencies . Luckily the 8.47MHz isn't used if you tie the filter switch to GND permanently, and only 16.9MHz is fed to the DAC. That means you can get rid of IC735 as well.

However... I don't think adding a second clock will work. The decoder and DVD processor also use the 33.8MHz master clock, and data transfer to the DAC must be synchronous with this master clock. If you add a second 16.9MHz clock instead of using the divided master, this will probably lead to trouble. Both clocks will run out-of-sync. One thing you could do is use one C2 and use the divided output instead of IC734.

Ray
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Last edited by 6h5c; 15th August 2012 at 01:29 PM.
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Old 15th August 2012, 01:53 PM   #47
Thomo is offline Thomo  United Kingdom
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aha that is a good point. And to be honest, I was going from memory about the dac's clock frequencies (never a great idea I know).

I'll settle for improving those IC's and power supply arrangements for now then.

In the sa11 Marantz have used that FPGA chip to get around this problem somehow, I need to look at that in more detail then i think.

Lee.
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Old 15th August 2012, 09:23 PM   #48
6h5c is offline 6h5c  Netherlands
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Yes, this stuff is getting more and more complex, with all these large chips that each need their own working frequency. The SA11 has an external clock input, so that could be a starting point. Anyway, there's always some master XO or crystal that can be replaced .

I'm going for removal of IC735
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Old 16th August 2012, 09:41 AM   #49
Thomo is offline Thomo  United Kingdom
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Great stuff, let us know how you get on Ray.

It looks like it'll be next week before I get to work on mine again

Itching to get more mods done.
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Old 23rd August 2012, 02:06 PM   #50
Thomo is offline Thomo  United Kingdom
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Just thought I'd post an update on the latest mods I've just made.

I replaced the c2 with a c3. This is also supplied via an additional 5v super-reg. I got very big improvements in openness, detail and much better dynamics. Bass is now more powerful, treble is cleaner and there's a lot more air and space around instruments.

I'm surprised by just how big the improvements are to be honest.

Lee.
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