Hello,
I want to build the coax output circuit (D) found on page 22 of the attached service manual of Pioneer PD-S507 CD player. My unit does not have coax out; I want to add this circuit so I can connect it to my DAC's coax in (toslink is already occupied).
L334 is listed as PTL1003 but I can't find this pulse transformer anywhere or any info on it.
I'm not good with digital circuits and would appreciate your help where to find such transformer or what specs should an equivalent have.
Also, logic converter IC331 TC74HCU04Ax is not available at Mouser or DigiKey. I can get TC74HC04Ax. It seems to be the same. Would you know how these 2 differ and if they are interchangeable in this circuit?
Thanks,
Bill
I want to build the coax output circuit (D) found on page 22 of the attached service manual of Pioneer PD-S507 CD player. My unit does not have coax out; I want to add this circuit so I can connect it to my DAC's coax in (toslink is already occupied).
L334 is listed as PTL1003 but I can't find this pulse transformer anywhere or any info on it.
I'm not good with digital circuits and would appreciate your help where to find such transformer or what specs should an equivalent have.
Also, logic converter IC331 TC74HCU04Ax is not available at Mouser or DigiKey. I can get TC74HC04Ax. It seems to be the same. Would you know how these 2 differ and if they are interchangeable in this circuit?
Thanks,
Bill
There's no need to copy the Pioneer circuit exactly, it looks like the PTL1003 is a step-down trafo but with a suitable attenuator at the input, a 1:1 pulse trafo would be substitutable. I've used PE65612 before in such applications :
https://www.aliexpress.com/item/1005003511932585.html?spm=a2g0o.productlist.main.3.1be0r8q1r8q1TX&algo_pvid=065a345f-dfc1-4f21-9929-aa383270de62&algo_exp_id=065a345f-dfc1-4f21-9929-aa383270de62-1&pdp_npi=3@dis!USD!2.17!2.17!!!!!@211bf04a16841173967162174d07a0!12000026117755027!sea!HK!2609685283&curPageLogUid=GCkmop2jec6j
Here's the recommended S/PDIF output circuit from CS8401A datasheet :
The 374ohm is less easy to source, I'd go for 360ohm. 90.9ohm is in effect, 91ohm. I'd keep the caps in series with the inverter outputs shown in the service manual and put them prior to the 360R resistor above. 74HC04 can be used here in place of 74HCU04 without issues I think. Any manufacturer's logic will work fine, no need to limit yourself to Toshiba brand.
https://www.aliexpress.com/item/1005003511932585.html?spm=a2g0o.productlist.main.3.1be0r8q1r8q1TX&algo_pvid=065a345f-dfc1-4f21-9929-aa383270de62&algo_exp_id=065a345f-dfc1-4f21-9929-aa383270de62-1&pdp_npi=3@dis!USD!2.17!2.17!!!!!@211bf04a16841173967162174d07a0!12000026117755027!sea!HK!2609685283&curPageLogUid=GCkmop2jec6j
Here's the recommended S/PDIF output circuit from CS8401A datasheet :
The 374ohm is less easy to source, I'd go for 360ohm. 90.9ohm is in effect, 91ohm. I'd keep the caps in series with the inverter outputs shown in the service manual and put them prior to the 360R resistor above. 74HC04 can be used here in place of 74HCU04 without issues I think. Any manufacturer's logic will work fine, no need to limit yourself to Toshiba brand.
Don't forget to add a 75ohm resistor across the RCA jack side.
In this particular incidence, the 75ohm resistance which defines the output impedance is already in-circuit in the form of the parallel combination of 91R and 360R resistors. So no additional 75R is called for.
abraxalito, the Pioneer circuit has a 75R in series with the coax output (R333). Do I not need to include R333 albeit 91R and 360R being on the primary side? And one more question, do the primary and secondary of the PT need to be in phase?
In the Pioneer circuit the trafo is driven directly by the logic gates (via the series cap). Thus there's a need for the 75R resistor to set the output impedance. If it were on the primary side it would need a different (higher) value as the trafo must step-down the signal. But on the CS8401A circuit the impedance is set on the primary side and the trafo's 1:1. So 75R on the primary side becomes 75R on the secondary, reflected 1:1 by the trafo.
As regards phase, the S/PDIF signal isn't phase sensitive so no attention to phase is required. I would though apply the input and take the output from the same side (say the 'dot' marked sides) as the parasitics of the trafo will be lower in this config.
As regards phase, the S/PDIF signal isn't phase sensitive so no attention to phase is required. I would though apply the input and take the output from the same side (say the 'dot' marked sides) as the parasitics of the trafo will be lower in this config.
This is SPDIF Output, which I used few times. Works very good.
IC is 74HCT86 for 5V power supply and 3.3v signal. Possible to use 3.3v power supply and 74HC, 74LVC gates, but R1=R2=R4=110R.
T1 - Ethernet transformer, I used H1102NL, H2260NL, E2023 from Pulse.
(check the transormer's pinout, some parts must be turned 180deg).
IC is 74HCT86 for 5V power supply and 3.3v signal. Possible to use 3.3v power supply and 74HC, 74LVC gates, but R1=R2=R4=110R.
T1 - Ethernet transformer, I used H1102NL, H2260NL, E2023 from Pulse.
(check the transormer's pinout, some parts must be turned 180deg).