PSU comparison

[1980s_john]

Hi,

I recently bought a pair of PSUs for my 800XL, both 230V for use in the UK. One is a CO 70046-01 rated at 1.0A @ 5V, the other CO 61763-34 rated 1.5A @ 5V (or 7.5VA). the later was the original type supplied with the 800XL, the former was for the 65XE but seems to work with the 800XL. Both are completely potted internally so impossible to repair or recap, but I tested them both out with dummy loads to see how they performed.

 

The CO 61763-34 went from 5.19V with no load down to 4.9V at 1.5A, and was at 5.01V at 0.96A.

 

The CO 70046-01 went from 5.02V at no load down to 4.88V at 1.01A.  I couldn't get exactly 1A as I was using fixed resistors.

 

I saved the results in Excel and plotted the results, both gave very nearly straight lines so not good regulation or high internal resistance. The CO 61763-34 had worse regulation (or higher internal resistance) as shown by the steeper gradient on the line, but it is the one I am keeping. I will need to check the voltage in the future as I understand these can go higher as they fail, I can see why replacement PSUs are the way to go.

Atari PSU.xlsx

Regards,

John

[TGB1718]

12 hours ago, 1980s_john said:

I can see why replacement PSUs are the way to go.

I think most people replace these PSU mainly because of their size or they don't get one when they purchase it,

I believe they are very reliable and even given their age are still unlikely to fail.

 

From the readings/graphs you show, I would say they are in excellent condition. well within their given tolerance

of 5VDC +/- 5%