SM 74 - 5 volts problem - SAK2 , SSK1, SSK2

Having 5 volts problem in my SM 74 press. My tech has manually adjusted one of the boards to give out the needed 5 volts ( in the electrical panel beside the feeder) so that the SAK2 board can give out the values / position of the motors of the press on the Cptronic display - ( Test SSK1 and SSK2 to see the values on the Cptronic display). I would know that there is the said 5 volts problem when the feeder has the all sorts of error - paper does not go through the press, paper stops as it is about to go in the first unit and when I check the Cptronic display all the values of the SSK1 and SSK2 is "0" But the problem keeps on happening and my tech has to adjust manually again the what he says is the 5 volts. I am not a tech guy just sort of repeating what my tech is telling me. He suspect the SAK2 board is the problem, have another used SAK2 board which he tried out, the outcome is the same. If the 5 volts problem happens the indicator lights of the two SSK boards goes out also. Hope anyone can point out to me where the problem is so that I would know what board to check, what board gives the 5 volts. Thanks in advance. You can also email me at pressmachines@yahoo.com

 

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Hi sir:

You must test the power supply for SAK2:

A) The +5Vdc is very critical, example if you measure 5.3Vdc is defective, of course this coming voltage IS from electronic board NTK5 (repair or replace)

B) Measure +24Vdc for SAK2: the same if you are measure 24.3 is defective, repair or replace, of course this coming voltage is from Electronic board NTK24(repair or replace)

In short SAK2, maybe is NOT defective because the voltages is coming from Electronic Boards NTK24+NTK5

Of course the CPU coming in SAK2, need the +5vdc correctly +Clock MHZ(test if is working)

 

Possibly one of the LTK 500 power supply boards. You may exchange them from slot to slot, as they are all similar.

 

Thank you all for your inputs

 

Problem solve. Check the NT85 as per your advice, one NT85 has 2 capacitor leaks. Thank you!