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+--- Thread: Need a replacement Bridge Rectifier Varo VMO8 (/thread-21334.html)
Need a replacement Bridge Rectifier Varo VMO8 - JoeG - 02-21-2024 12:48 AM
Hello:
I'm working on a Commodore 64 that has what appears to be a homemade bridge rectifier. The C64 only displays a black screen. The Dead Test / Diagnostic cartridge does not boot. I have so far identified that the 5V rail is not getting to the side of the board where the CPU, SID, ROMs, RAM, and other chips reside. I've checked the power supply, the power switch, and the fuse with a multimeter. All look good. I've worked on several black screen C64's, and this is the first that has present a voltage distribution issue.
The only source I have found so far for the Bridge Rectifier Varo VMO8 (as stated in the C64 Service Manual is on this ebay link: https://www.ebay.com/itm/155486745102
One of my similar C64 boards has a S2VB (and other numbers on it) bridge rectifier installed. I don't know what the other numbers mean (please see photo)
Having little knowledge about these components, I'm not sure if I can trust that these have the right specifications for the C64.
Can someone help me either say "these ebay ones look like the might work", or help me find a a S2VB (and other relevant numbers) or equivalent replacement? I'm at a loss here.
Thank you!
Joe
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RE: Need a replacement Bridge Rectifier Varo VMO8 - cruff - 02-21-2024 02:19 AM
Well a search for "Varo VM08" turns up https://www.electronicsurplus.com/varo-vm08-diode-fwb-50v-1amp, which means any bridge rectifier (or discrete diodes) that have the same specs should work.
RE: Need a replacement Bridge Rectifier Varo VMO8 - JoeG - 02-21-2024 02:39 AM
Thank you. I found that site as well earlier, but didn't read the specifications like I should have. They don't have any in stock. So I will order the ones from ebay and see what I end up with.
Thank you!
Joe
RE: Need a replacement Bridge Rectifier Varo VMO8 - teenix - 02-21-2024 09:25 AM
The CR4 bridge rectifier I assume is supplying the 7805 5V 1A regulator. If so a W04 (1.5A 400V) regulator should do, about $US1.
cheers
Tony