Commodore 64 Power-Supply Protector (C64 Saver): Difference between revisions
Created page with "<templatestyles src="Template:StyledTable/styles.css" /> {{Infobox hardware | name = Commodore 64 Power-Supply Protector | image = 250px | caption = A popular open-hardware implementation of the '''C64 Saver''' | developer = Ray Carlsen (original design)<br />community derivatives (OpenC64Saver, SaV64, SaRuMan-64, C64 Saver 2, etc.) | type = External over-voltage / over-current protection adapter | firs..." |
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{{Infobox hardware | {{Infobox hardware | ||
| name = Commodore 64 Power-Supply Protector | | name = Commodore 64 Power-Supply Protector | ||
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| operating_voltage = +5 V DC (monitored) • 9 VAC passthrough | | operating_voltage = +5 V DC (monitored) • 9 VAC passthrough | ||
| application = Commodore 64 / 64C / SX-64 / VIC-20 CR and any CBM 8-bit that uses the 7-pin DIN power connector | | application = Commodore 64 / 64C / SX-64 / VIC-20 CR and any CBM 8-bit that uses the 7-pin DIN power connector | ||
}} | }}The '''Commodore 64 Power-Supply Protector'''—best-known by Ray Carlsen’s original name '''“C64 Saver”'''—is a small plug-through safety adapter that sits between a vintage Commodore power brick and the computer. | ||
The '''Commodore 64 Power-Supply Protector'''—best-known by Ray Carlsen’s original name '''“C64 Saver”'''—is a small plug-through safety adapter that sits between a vintage Commodore power brick and the computer. | |||
Its only mission is to '''sacrifice itself if the +5 V rail from the ageing “epoxy-potted” supply drifts above a safe level''', instantly disconnecting the load and saving irreplaceable MOS chips such as the VIC-II, SID, CIA and RAM. | Its only mission is to '''sacrifice itself if the +5 V rail from the ageing “epoxy-potted” supply drifts above a safe level''', instantly disconnecting the load and saving irreplaceable MOS chips such as the VIC-II, SID, CIA and RAM. | ||
== | == Why a Protector Is Needed == | ||
Original Commodore “brick” PSUs were cost-reduced, epoxy-potted switchers with no serviceable parts or active regulation feedback. | Original Commodore “brick” PSUs were cost-reduced, epoxy-potted switchers with no serviceable parts or active regulation feedback. | ||
With age the internal linear regulator or crowbar diode can short, driving the +5 V DC rail to 7–12 V—high enough to destroy ICs within seconds. Modern collectors therefore avoid the stock PSU '''unless''' a C64 Saver-class device is in-line. | With age the internal linear regulator or crowbar diode can short, driving the +5 V DC rail to 7–12 V—high enough to destroy ICs within seconds. Modern collectors therefore avoid the stock PSU '''unless''' a C64 Saver-class device is in-line. | ||
== | == Operating Principle == | ||
{| class="wikitable styled-table" style="width: | {| class="wikitable styled-table" style="width:70%; text-align:center;" | ||
! Function block !! Component example !! Description | ! Function block !! Component example !! Description | ||
|- | |- | ||
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*OpenC64Saver* introduces reverse-polarity protection, replaces the SCR with a low-R<sub>DS(on)</sub> MOSFET for cooler running, and adds a precision trim-pot for exact trip voltage set-up. | *OpenC64Saver* introduces reverse-polarity protection, replaces the SCR with a low-R<sub>DS(on)</sub> MOSFET for cooler running, and adds a precision trim-pot for exact trip voltage set-up. | ||
== | == Design Evolution == | ||
{| class="wikitable styled-table" | {| class="wikitable styled-table" text-align:center;" | ||
! Variant !! Year !! Key features !! Trip point (nom.) | ! Variant !! Year !! Key features !! Trip point (nom.) | ||
|- | |- | ||
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All variants honour Carlsen’s open-distribution request that the design remain non-proprietary for the benefit of the community. | All variants honour Carlsen’s open-distribution request that the design remain non-proprietary for the benefit of the community. | ||
== | == Typical Bill of Materials (through-hole C64 Saver 2.3) == | ||
{| class="wikitable styled-table" | {| class="wikitable styled-table" text-align:center;" | ||
! Qty. !! Reference !! Part | ! Qty. !! Reference !! Part | ||
|- | |- | ||
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|} | |} | ||
== | == Installation == | ||
# Power '''off''' and unplug the PSU. | # Power '''off''' and unplug the PSU. | ||
# Connect the PSU’s 7-pin DIN plug into the '''male''' side of the Saver. | # Connect the PSU’s 7-pin DIN plug into the '''male''' side of the Saver. | ||
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The device draws under 5 mA and introduces ≈ 15 mΩ series resistance, insignificant even for sensitive Ultimate-64 boards. | The device draws under 5 mA and introduces ≈ 15 mΩ series resistance, insignificant even for sensitive Ultimate-64 boards. | ||
== | == Testing the Trip Circuit (Bench) == | ||
* Dial a bench supply to 5.0 V and feed the Saver through the DIN pins (+5 V → pin 2, GND → pin 5). | * Dial a bench supply to 5.0 V and feed the Saver through the DIN pins (+5 V → pin 2, GND → pin 5). | ||
* Increase voltage slowly; at 5.3–5.5 V the LED flips to red and the output collapses to ≈ 0 V. | * Increase voltage slowly; at 5.3–5.5 V the LED flips to red and the output collapses to ≈ 0 V. | ||
* Remove input power for 5 s to reset the latch. | * Remove input power for 5 s to reset the latch. | ||
== | == Limitations == | ||
* '''Does not regulate ripple'''—a PSU with excessive 50/60 Hz ripple under 5.2 V will still pass. | * '''Does not regulate ripple'''—a PSU with excessive 50/60 Hz ripple under 5.2 V will still pass. | ||
* '''No 9 VAC protection'''; an internal short in the PSU transformer can still inject noise or excessive VAC. | * '''No 9 VAC protection'''; an internal short in the PSU transformer can still inject noise or excessive VAC. | ||
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* If the SCR version trips it may blow the PSU’s internal fuse; replace that fuse before re-testing. | * If the SCR version trips it may blow the PSU’s internal fuse; replace that fuse before re-testing. | ||
== | == Where to Buy or Build == | ||
* '''DIY PCB/gerbers:''' OpenC64Saver repository (KiCad + BOM). | * '''DIY PCB/gerbers:''' OpenC64Saver repository (KiCad + BOM). | ||
* '''Kits / assembled:''' SharewarePlus SaV64 series, RETRO Innovations, and many eBay/Tindie sellers. | * '''Kits / assembled:''' SharewarePlus SaV64 series, RETRO Innovations, and many eBay/Tindie sellers. | ||
* '''Integrated solutions:''' All Ray Carlsen modern PSUs ship with an internal Saver circuit plus precision linear regulation. | * '''Integrated solutions:''' All Ray Carlsen modern PSUs ship with an internal Saver circuit plus precision linear regulation. | ||
== | == Related Pages == | ||
* [[Commodore 64 Power Supply Guide]] – failure modes of the original bricks | * [[Commodore 64 Power Supply Guide]] – failure modes of the original bricks | ||
* [[Commodore 64 Capacitor Replacement Guide]] | * [[Commodore 64 Capacitor Replacement Guide]] | ||
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[[Category:Commodore Systems]] | [[Category:Commodore Systems]] | ||
[[Category:Commodore Maintenance Guides]] | [[Category:Commodore Maintenance Guides]] | ||
[[Category: Commodore 64 Modifications and Enhancements]] | |||
