[b0bb]

I removed CCHD957 and check the circuit, I found that the suppose to be regulator component may be not a regulator, it's pin out is not compatible with TPS7A20, this caused the pin1 of VCXO voltage almost short circuit to 4.8V (not sure why not 5V, some where drop the 5V to 4.8V), it is also abuse TPS7A20, connect it's 3.3V output to 4.8V. Do you have idea what component it should be? I think I cannot get it back after I swapped it out and replaced with TPS7A20.

The chip on my SU-2 has the following marking: T1IS

The part is TL331IDBVR.
Digikey has them in stock

 

[joenetic]

The chip on my SU-2 has the following marking: T1IS

The part is TL331IDBVR.
Digikey has them in stock

Thanks! The circuit connects it's output to it's negative input, also connect others circuit, positive inout reference is 3.3V. Next time to mod components, I should check the marking if it is reasonable.

 

[joenetic]

I just tested SU2 without 45Mhz VCXO and comparator, run internal clock, SU2 works fine, prove that it is not using VCXO when using internet clock. What else you want to test?

 

[joenetic]

I tested SU2 with external 10Mhz clock, it is as expected, doesn't work.

 

[b0bb]

I just tested SU2 without 45Mhz VCXO and comparator, run internal clock, SU2 works fine, prove that it is not using VCXO when using internet clock. What else you want to test?

That is all. Thanks.

 

[joenetic]

That is all. Thanks.

I got my SU2 turely work with external 10Mhz clock now after I solder the comparator on PCB tonight
VCXO voltage control voltage around 1.67V when running 45Mhz VCXO, 1.68V when running 49Mhz VCXO.
The sound is much detail now better than my DigiOne much more, when ran Crystek before, the sound quality is little bit better than DigiOne, it is great, success upgrade.
I am looking for good clock cable, I bought two low price clock cable, one is Sommer SC Classic MK II, one is Canare 5DFB, Canare is cheaper but it is slight better in detail.
Another good guy told me Harmonic Technology Digital Copper III 50 ohm is super in another forum, anyone use this cable and any comment ?

 

[joenetic]

@b0bb do you know in the attached photo component? I found external 10Mhz clock enter this IC component, then from another pin through 33ohm into FPGA.

 

[b0bb]

@b0bb do you know in the attached photo component? I found external 10Mhz clock enter this IC component, then from another pin through 33ohm into FPGA.

Probably a Rohm BD4932 voltage detector.
This is a part of a crude sinewave to squarewave converter, this part is normally intended for generating microcontroller reset signals.
https://fscdn.rohm.com/en/products/databook/datasheet/ic/power/voltage_detector/bd48xxg-e.pdf

Jitter accuracy of your external clock is dependent on how consistently this part operates.
2% amplitude accuracy or 20000ppm variance, not exactly reference class.

 

[joenetic]

You are superb! From the pin out function, it is not BD4932 because actual IC pin 5 seems to be output, but BD49XX pin 5 is NC or VCC, but your guess is make sense!

 

[b0bb]

You are superb! From the pin out function, it is not BD4932 because actual IC pin 5 seems to be output, but BD49XX pin 5 is NC or VCC, but your guess is make sense!

The FN marking is the Rohm part, as far as how it is actually used, doing that work is up to you if you want to explore further.

 

[joenetic]

You are superb! From the pin out function, it is not BD4932 because actual IC pin 5 seems to be output, but BD49XX pin 5 is NC or VCC, but your guess is make sense

The FN marking is the Rohm part, as far as how it is actually used, that work up to you if you want to explore further.

Unless there has others pin out, actual IC and spec pin out are not match, so I guess they are not the same, you see the spec shows the silk screen pattern also not same as actual IC. However if use this kind of IC for sin to square wave conversion, it is really bad design.

 

[b0bb]

You are superb! From the pin out function, it is not BD4932 because actual IC pin 5 seems to be output, but BD49XX pin 5 is NC or VCC, but your guess is make sense

Unless there has others pin out, actual IC and spec pin out are not match, so I guess they are not the same, you see the spec shows the silk screen pattern also not same as actual IC. However if use this kind of IC for sin to square wave conversion, it is really bad design.

Those are the details you need to work out for yourself, the SMD marking books do not list anything else

 

[joenetic]

Those are the details you need to work out for yourself, the SMD marking books do not list anything else

Thanks for your help!

 

[joenetic]

Those are the details you need to work out for yourself, the SMD marking books do not list anything else

I think I just found it, it should be FIN1002M5X, a LVDS differential receiver.

 

[b0bb]

I think I just found it, it should be FIN1002M5X, a LVDS differential receiver.

I think I just found it, it should be FIN1002M5X, a LVDS differential receiver.

This would be worse than the first option, LVDS are digital signals, a sinewave is an analog signal.
The FIN1002 outputs a LVTTL digital signal, in effect this is the sine to square converter.

To make matters worse, the coax clock input is single ended / unbalanced not diffrential. LVDS works best with a differential input