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optimized c64 psu - f***in AWESOME!!!


kokoon

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well, i have the normal PSU and it sounds like this: http://www.mrvelcrofastener.com/sid/humina.wav - i think it's terrible, can it be just because the PSU isn't the "optimized" type? the hum clearlty changes when switchin the filter on/off to oscillators, doesn't get more silent or loud but just different.

but if i make the optimised PSU do i need to make changes to CORE or SID module?

cheers

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it's all written in the pdf that's linked on the ucapps.de sid module page.

the difference is HUGE. no background hum at all! the sid quirks still remain (hanging notes, funnny filter switching behavior you mentioned) but still - it's absolutely usable now! especially the 8580.

you *absolutely* have to do this mod!

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oh yes, it says: "(3) the 7805 regulators of the core modules have been removed. The Input/Output line

of this IC has been shortened so that C5 of the core module (ca. 1000 uF is ok)

is directly connected to the +5V input"

this is also shown in the diagram.

but what about the 7809? "(2) a 7809 removes the AC part of the SID module supply voltage. Without this

additional voltage regulator you may hear a 50/60 Hz humming sound at the SID output"

the SID module will remain the same? atleast there's no changes in the diagram....

cheers

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but what about the 7809? "(2) a 7809 removes the AC part of the SID module supply voltage. Without this

additional voltage regulator you may hear a 50/60 Hz humming sound at the SID output"

the SID module will remain the same? atleast there's no changes in the diagram....

Yes, the SID modules remain the same. (Well.. unused audio inputs are shown as grounded and the last SID module has a cap added between +5VDC and GND contacts)

The schematic shows 9VAC from the C64 powersupply first rectified to DC (by B40C800), filtered by additional caps and that 7809 regulator has it's "common" pin connected to +5VDC so the output referenced to ground is 14VDC. And this is then regulated down by SID modules.

Bye, Moebius

p.s. Soo nice to see you here, Mr. Velcro ;)

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i'm a total n00b, this midibox sid is my first soldering ever but i already managed to almost finish it. and i got the optimized psu right in the first try :)

i just did everything exactly like it says in that pdf. though it took me a hour or so to place it all on the breadbord (or whatever it's called - the plain board with a grid of holes and copper rings/circles around them) - not on the stripboard.

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  • 1 month later...

okay, i have had too big gap from where i didn't have time anymore to build the SIDbox... but now i want to get it finished finally! :D

changing to optimized PSU seems easy to do, but i want to make sure couple of things (avoiding more mistakes):

J1 of core module is unconnected with optimized PSU, that's that?

in optimized PSU there's no GROUND as was in the original PSU - what about audio out? it should still have ground connected too should it?

is there any options for the B40C800 in case i can't find the component?

many thanks!

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J1 of core module is unconnected with optimized PSU, that's that?

Yes. You connect +5VDC to the core/SID J2. (mind the polarity) - leave the regulator out from the core... ect.

in optimized PSU there's no GROUND as was in the original PSU - what about audio out? it should still have ground connected too should it?

The Ground is there, but it's just not marked as ground but Vs. And yes, audio out needs Ground connection.

is there any options for the B40C800 in case i can't find the component?

I'd say any bridge rectifier should work. Or 4 x 1N400* series diodes (1N4001<->1N4007)

Bye, Moebius

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and where do you solder the cap on #3 of the pdf? 5v and what else?

Just solder it like on the unmodified (original) core module! There is no difference beside the bridging of pins 1 and 3 of the 7805 (leave the 7805 out).

so what all extra do you need to buy?

All parts on the left side:

1 x B40C800 rectifier

2 x 2200uF/16V electolytic cap

1 x 100nF cap

1 x 330nF cap

1 x 7809

1 x 220 Ohm resistor

Reuse the swith and power plug from the C64!

Raphael

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Just solder it like on the unmodified (original) core module! There is no difference beside the bridging of pins 1 and 3 of the 7805 (leave the 7805 out).

All parts on the left side:

1 x B40C800 rectifier

2 x 2200uF/16V electolytic cap

1 x 100nF cap

1 x 330nF cap

1 x 7809

1 x 220 Ohm resistor (only if you want to use a LED as power indicator)

Reuse the swith and power plug from the C64!

Raphael

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Just solder it like on the unmodified (original) core module! There is no difference beside the bridging of pins 1 and 3 of the 7805 (leave the 7805 out).

All parts on the left side:

1 x B40C800 rectifier

2 x 2200uF/16V electolytic cap

1 x 100nF cap

1 x 330nF cap

1 x 7809

1 x 220 Ohm resistor

Reuse the swith and power plug from the C64!

Raphael

plus 1 x 2200/25uF isn't it? (between  B40C800 and 330nF between the PDF)?

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