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Museum of the Game® & International Arcade Museum® Forums
Need some technical help to educate me on this TO-3 hybrid 5v voltage regulator. I'm not completely sure how this part is meant to behave. Here is the situation.
I am replacing this part in my Super Don Quixote power supply but the entire circuit and heat sink is missing and all Universal schematics suck so I'm winging this a bit.
I fabricated this a bit by using a spare heat sink I had from a roached Williams PS but voltages (+5v) are still not right.
I purchased the VR off eBay, actually bought two, and they are NOS. In circuit both act the same, both output 11v when they are meant to be fixed 5v. The input is 12v
I already built my own breadboard 5v regulator circuit using a 7805 and it works fine so it's this UA78H05 and associated circuit that I need to sort out.
I did find that the original application calls for two tantalum caps and a ceramic resistor also to be in circuit (see image), but I have not added those yet so perhaps that's my issue.
Question 1: will installing these components bring the output voltage down to 5v?
Question 2: does the VR need a load to bring the output voltage down to the fixed 5v?
I want to ensure I have this circuit correct before connecting any boards and I also want to make sure that this VR is not bad. They do look legit.