Optimized PSU questions

[alchemist]

Hello,

 

I will get a brown C64 today, which will complete my set of 4xcores, 4x6581 and 4x8580.

 

I will use the optimized PSU set-up, and some things are not yet clear for me:

- the 7805 are dropped because the PSU provides stable 5V

- there is a 7809 to stabilize the 9VAC output, and combined with the 5VAC output, it provides 5VDC and 14VDC

- the "Optimized PSU" document don't mention the MBHP_SID 78xx : do I need to put one 78xx by MBHP_SID, or can I use one 7809 for the 8580, then link the power to the three others, and the same for the 7812, or is it better to have all MBHP_SID their own 78xx to avoid ground loops?

 

Kind regards,

Xavier.

[alchemist]

Since I've got a C64, I have one more question : I see there is a large voltage conversion circuit on the right of the C64 motherboard, with even a 7805. Does it mean I need to stabilize the 5VDC or is that 7805 there only to be sure the voltage is stable ?

[Janis1279]

Hello,

 

I will get a brown C64 today, which will complete my set of 4xcores, 4x6581 and 4x8580.

 

I will use the optimized PSU set-up, and some things are not yet clear for me:

- the 7805 are dropped because the PSU provides stable 5V

- there is a 7809 to stabilize the 9VAC output, and combined with the 5VAC output, it provides 5VDC and 14VDC

- the "Optimized PSU" document don't mention the MBHP_SID 78xx : do I need to put one 78xx by MBHP_SID, or can I use one 7809 for the 8580, then link the power to the three others, and the same for the 7812, or is it better to have all MBHP_SID their own 78xx to avoid ground loops?

 

Kind regards,

Xavier.

Hi,

 

For the 8580 you need to use one 7809 and for the 6581 you need to use one 7812. The inputs of both voltage regulators are connected together to +14VDC rail. It is possible to use the common heat sink, as ground pins of the regulators are connected together,  too.

 

Regards,

Janis

[alchemist]

Thank you for the reply !

 

Xavier.