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Got Fleas?

Hi Ant,

You need to run it at 3.3v output. Go back over your CD6003 thread, there is info there from myself and Martin.

Unless you have other ideas?



Ideas?.... I had a good look at the scematic and there are 2 regs for the XO IC supply, 1 x 3.3v quite a distance away for IC output which splits to 1.8v kia reg for the IC supply.

In a rush.

More detail later.
 
You may recall that there are 2 supply inputs to the XO chip - one @ 3.3v and another @ 1.8. The easiest way is the lift the inductor just before the 1.8v reg and plumb in your flea there. That way the main 3.3v suply to the XO chip is coming from the Flea and the 1.8v reg is also getting a nie clean supply from the Flea too.

Another way would be to use 2 Fleas set at 3.3v and 1.8v but the above is the easiest way.

I'll be around after 10:30PM so if your up gimme a call :)
 
You may recall that there are 2 supply inputs to the XO chip - one @ 3.3v and another @ 1.8. The easiest way is the lift the inductor just before the 1.8v reg and plumb in your flea there. That way the main 3.3v suply to the XO chip is coming from the Flea and the 1.8v reg is also getting a nie clean supply from the Flea too.

Another way would be to use 2 Fleas set at 3.3v and 1.8v but the above is the easiest way.

I'll be around after 10:30PM so if your up gimme a call :)


Cheers Mike,

Sure, I remember that. I just assumed it'd be more important to feed a clean 1.8v supply to the IC as that's the 'workings' of the XO/VCXO circuit where as the 3.3v is for the IC output.

I was thinking the kia 1.8v reg was the noisy component and if the flea was situ'd before (inductor), the kia would still be in the circuit generating it's own noise feeding the IC XO/VCXO or am I wrong:confused:


Thanks
 
Hello folks, just a quick question.....

Has anyone out there a BOM from Mouser/Farnel or CPC for Rays DIY flea?




Ta,
Ant
 
Friends, someone will install in a Marantz DV6600?, which requires modifications needs?
Best regards
Osvaldo

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I'm sorry. Got a question. Can anybody explain to me something. How's even possible for a opamp to hold stable with that large capacitive load on its output without series isolating resistor? I just don't get it.

Thanks.
 
Magic ;)

It's not driving an AC signal into the cap, which would be the worst case, and above a handful of Hz the opamp is running at unity gain. This cap actually supplies the dominant pole to stabilise the whole operation (usuing the inherent open-loop output z of the opamp, which is in the range of 5-10ohms).

Make the cap very much smaller, or much more resistive (eg add a lot of artificial ESR) and the thing actually goes unstable - I played a lot with this in testing. But 4.7 to 10uF of tantalum, or an oscon, or a small film cap of 1-3u3 is just fine :)
 
Thanks for your answer. I'm planning on making my own pcb layout since I'm not using Tent's XO but a SMD one form a different manufacturer.
 
Hi,

Hope someone can help.

Just built 2 fleas, one with the "extra power" option and it's working fine.

The other which is standard to drive a tent xo is giving me 11.9 volts and I can't see where it's wrong.

On the 7812 I'm getting I = 17.6, G = 1.9, O = 13.8.

On the opamp
2=3.8
3=3.7
6=11.9
7=13.7

Output at clock = 9.8. I can see that this is double what it should be and is likely caused by the input on pin 2. But I can't see what is causing pin 2 to be so high given that I'm getting the correct 1.9 from the G on the 7812. The resistors all check out ok.

Any one help please?

Thanks


pete
 
Seem to have solved it now.

Went over most of the solder joints with a hot iron and the voltages now seem ok. Odd thing though, I still see higher voltages momentarily (same level as before) when I touch the probe but then it settles down to proper voltage readings. Maybe a poor earth somewhere?

Pete
 
Can you measure the voltage across the pair of 1R SMD 0805 resistors on the back of the board. Use millivolt scale. This will give an indication of oscillation.

The load here with the Tent Xo should be around 5 to perhaps 10mV equating to 10 to 20mA
More than 10mV here is cause for concern and usually indicates a naughty Flea, some stern words would then be required.


Pins 2 & 3 should measure the same, so looks like your meter may have some error.

The output should be absolutely rock steady, holding or prodding around should not cause any voltage rise.
 
Yes, put it in two working cd48s now and both cases disc refuses to spin even on start up, no toc and I just get error. Diagnosis gives radial error maybe the oscillator is faulty.
 
Chivvy - is the one the doesn't appear to work running off an existing internal supply rail in the player, ie the flea only gets power when you turn the player on?

The flea has some fairly long filter time contants onboard and the clock must start up early for a CD player to run/ take charge of the servos. That's another reason to use a separate transformer, so the clock can remain powered when the player is 'off'. You can shorten the time constants to test if this is the problem - swap the 10k resistors for 1K and try again - just tack 1K in parallel with each 10K part to test.
 
Hi Martin,

the flea's running on a seperate tx so it's powered up before the player is switched on.

The flea itself seems to be fine and I can trace the clock output to the crin pin on the 7345. Unfortunately I can't check that the oscillator is ok.

Pete
 
Martin/All:
Probably missed this somewhere in this thread ... but can one somehow CLEANLY adapt the Flea to PC-PSU-friendly 15v? That 18v min. "requirement" is a tough one to implement in my latest diy gear ... which are mostly PC sound-card based.
Thx!
 


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