[sdiy] Korg SDD-3000 5 volt supply problems

Tristan tu at alphalink.com.au
Fri Nov 16 09:51:17 CET 2018


On Fri, Nov 16th, 2018 at 6:46 PM, Gordonjcp <gordonjcp at gjcp.net> wrote:

> On Thu, Nov 15, 2018 at 07:12:10PM +1000, Adam Inglis wrote:
> > With 7.8 ohm resistance, the 5 volt rail was pretty steady. With 6.7 ohms,
> the bench voltage shut down. So about 700mA seems to be the breaking point.
> > 
> 
> That's not right.  7805, TO220 package?  That shouldn't even be close to
> shutting down at 700mA, unless you mean that the bench PSU is giving up
> before the 7805?

Doesn't that rather depend on the size of the heatsink? 

10V into a 7805 at 700mA is 3.5W dissipated in the regulator.

/Tristan



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