Science Of Cambridge MK14 Replica build

[HigashiJun]

Replace with a Traco?

+1

[rubber_jonnie]

Replace with a Traco?

+1

It's on order

[HigashiJun]

Good to hear that !

I had a Traco in my Oric Atmos and it was night and day compared to the old and burning hot LM.

[PhilC]

Out of interest, which traco do you guys use? A lot of the 7805 equivalents only do 0.5 - 1.0 amp which is fine for a spectrum but not for other stuff.

[HigashiJun]

Out of interest, which traco do you guys use? A lot of the 7805 equivalents only do 0.5 - 1.0 amp which is fine for a spectrum but not for other stuff.

I had a TSN 1-2450A in my Atmos.

And yes, it was 1 amp.

[PhilC]

Thanks @HigashiJun

[rubber_jonnie]

The one I've ordered is 1 amp, the Mk14 takes around 1/2 amp.

TSR 1-2450A

[rubber_jonnie]

So, the Traco is installed in the MK14 now:

IMG20240802100430.jpg (183.02 KiB) Viewed 901 times

And the thermals look good:

20240802-135305.jpg (10.87 KiB) Viewed 901 times

The Traco is running at 39.4C and the item at 56.6C in front of it is one of the two Tesla PROMs holding the SCIOS operating system. With the 7805 installed with a large heatsink I was getting about double the temp of the Traco, and also I'm pulling about 100mA less with the Traco too, so definitely a good call to swap it out.

[stephen_usher]

I would put an oscilloscope on the +5V rail as these switching DC-DC converters may produce ripple.

[rubber_jonnie]

I would put an oscilloscope on the +5V rail as these switching DC-DC converters may produce ripple.

Maybe later on, just at the barbers for a trim

EDIT - I'm seeing a mean ripple value of about 15mV, probably helps having a 1000uF capacitor on the input side.