{"id":1254,"date":"2016-09-22T04:54:30","date_gmt":"2016-09-22T04:54:30","guid":{"rendered":"http:\/\/avitech.com.au\/?page_id=1254"},"modified":"2018-04-03T11:24:13","modified_gmt":"2018-04-03T11:24:13","slug":"dct11-em-evaluation-module","status":"publish","type":"page","link":"https:\/\/avitech.com.au\/?page_id=1254","title":{"rendered":"DEC DCT11-EM Evaluation Module"},"content":{"rendered":"

Here are some pictures of the DEC T11 microprocessor trainer that I have.<\/p>\n

It has a power supply fault. With a little luck it will otherwise work OK.<\/p>\n

Power supply fault<\/h4>\n

I have found the problem with the power supply. Mounted on the outside of the wooden box is an LM338K. This is a variable voltage regulator in a T03 package. It is supposed to regulate by maintaining a 1.25V differential between Vadj and Vo. When I have the evaluation module disconnected (so there is no load), the LM338K operates as expected (Vi=12.7V, Vo=5.24V, Vadj=4.03V). But when the evaluation module is connected, the current draw is 0.72A and the voltages are as follows: Vi=11.0V, Vo=3.97V and Vadj=3.03V). Note that with the load connected, there is only 0.94V between Vadj and Vo. So something is broken inside the LM338K – it is unable to ramp up the output voltage to maintain the required 1.25V differential.<\/p>\n

So I have ordered a replacement LM338K from China on 3 April 2018.<\/p>\n

Manuals<\/h4>\n

Here are some links to relevant manuals:<\/p>\n

DCT11-EM Evaluation Module User’s Guide<\/a><\/span><\/p>\n

u\/T11 User’s Guide<\/a><\/span><\/p>\n

Gallery<\/h4>\n