trying to identifying parts - Page 1
Forum section: electronics / repair

author: spetros
author_rank: Contributor
timestamp: May 07, 2024, 04:52:46 pm
content: Hello.I am trying to repair an old vintage machine but there are two parts that i cannot find info about them.The first is a capacitor ? but i can not find info how to read it . and the second is a unknown part that is located at the gate of a SCR.Any info will be very helpful.Thank you.

author: fzabkar
author_rank: Super Contributor
timestamp: May 07, 2024, 05:42:03 pm
content: "U56" = 0.56uF = 560nF ceramic capacitor ??

author: spetros
author_rank: Contributor
timestamp: May 07, 2024, 06:12:10 pm
content: Thank you for your answer.I have test it with my component tester and it says 56p but i am not sure if it correct.Its my first time that i see this marking.

author: pcprogrammer
author_rank: Super Contributor
timestamp: May 07, 2024, 06:36:34 pm
content: Quote from: fzabkar on May 07, 2024, 05:42:03 pmJudging by the size of the capacitor I doubt it to be 560nF, but maybe if we know more about the device it is in, we can provide better answers.The component with the 10nS marking is strange. S normally stands for siemens which is the unit of conductance. That would make it a high value resistor R = 1 / S. 100M Ohm which is very high.

author: BlownUpCapacitor
author_rank: Frequent Contributor
timestamp: May 07, 2024, 06:37:13 pm
content: the UF notation on the capacitor might be a company logo. The U might just be tolerance. 56 is the capacitance. A ceramic cap with just 56 on it usually signifies 56pF.

author: spetros
author_rank: Contributor
timestamp: May 07, 2024, 07:31:42 pm
content: Thank you for your answers.I Attach a part of the schematic that i made ( You can see the strange capacitor and the strange 10nS component )

author: spetros
author_rank: Contributor
timestamp: May 07, 2024, 07:33:23 pm
content: The machine is a Ultrasonic Concrete Tester , Model num E46 from CONTROLS Italy.It is a vintage machine

author: pcprogrammer
author_rank: Super Contributor
timestamp: May 07, 2024, 07:42:54 pm
content: Looks like the CD4001 is used as an oscillator to drive the primary side of a transformer to make a higher voltage and drive the ultrasonic output, so the capacitor might well be the 56pF you measured. Have you checked if the oscillator is still running?The other part between ground and the thyristor, I can't think of what it would be or do.

author: spetros
author_rank: Contributor
timestamp: May 07, 2024, 07:47:14 pm
content: Yes the oscillator is running . The problem is somewhere else.I am near to find it. I want to know the values of this components so i can add them on my schematic.about the black thing i am confused too.Now i am drawing the SCR driving circuit and i will post it.Thank you again for your answers.

author: spetros
author_rank: Contributor
timestamp: May 07, 2024, 07:52:10 pm
content: As i can see the output ( Q2 pin 4 ) of a 74LS290 ( Decade and 4-Bit Binary Counter ) goes to this black part and drives the SCR

author: madires
author_rank: Super Contributor
timestamp: May 07, 2024, 08:24:51 pm
content: 10nS is a 10nF cap with a tolerance of -20% up to +50%. U56 should be 56pF but the U in front of the value doesn't make much sense (maybe some vendor specific code). A U after the value would mean a tolerance of -0% up to +80%.