Hi everyone,
I need help identifying the two circled components on the circuit board as shown in attached picture. Any help is appreciated.

Thanks.

 

Hi everyone,
I need help identifying the two circled components on the circuit board as shown in attached picture. Any help is appreciated.

Thanks.

1 looks like a thick film resistor, it could be one of any number of types from basic resistor to thermistor etc. 2 looks like an RF choke.

 

2 could also be a simple wire link for use as test point.

 

2 could also be a simple wire link for use as test point.

Some capacitors look like that - guesses aren't always right.

The "zero Ohm resistors" usually look like, well..............err; resistors.

 

It looks to me like a hybrid IC with multiple chips/components mounted to a single substrate.

 

The legend on the PCB should help. The screw terminal next to the 3 pin hybrid board says "Isolated". The axial thingy says W2. W is often a designator for wire. Is there any legend on the other side of the PCB? What about the back of the 3 pin hybrid board?

For the 3 pin board, I would trace the lines to see what it's connected to. If it goes to any of the clock or data terminal pins, then it's an active device.

Also, what is this board from? That might help understanding it.

 

W2: A zero ohm resistor - jumper. They don't need a 2-sided board.

The other component, whatever it is, it likely to measure the temperature of the terminal block. To do CJC (Cold Junction Compensation), you need to know the temperature of the block. It might be a large area thermister.

The markings on the other component may provide a clue.

 

W2: A zero ohm resistor - jumper. They don't need a 2-sided board.

The other component, whatever it is, it likely to measure the temperature of the terminal block. To do CJC (Cold Junction Compensation), you need to know the temperature of the block. It might be a large area thermister.

The markings on the other component may provide a clue.

Bingo! I was wondering what CJC meant. I agree, it's probably a thermistor.

 

It looks to me like a hybrid IC with multiple chips/components mounted to a single substrate.

Looks like just a SMD transistor and thick film resistor - but some thick film circuits use both sides.

COB hybrids aren't exactly rare either.

 

Hi,
The board is part of a DP41 programmable temperature display panel (kinda like vintage ). I was trying to get a better understanding of how the thing works. It was in a box with the device, its components and then this board. It was previously used for temperature measurement on some equipment, not sure. Date says its was last calibrated in 1990.

 

Do see if you can read any letters or numbers on the IC next to the terminal block. That may provide another clue.

In order to do CJC, you need the current temperature of the block. The block should ideally be isothermal. You don't want drafts to influence the temperature of the block.

You have to do a reverse lookup by temperature to get the mV value of that temperature for the thermocouple type in question. You also need the mV value of the reading of the thermocouple.

 

I think that's the reason the thermistor was on that vertical board right next to the terminal.

 

Yes, but what are the numbers on the smaller black component? They will be difficult to see and be crypic. e.g. Y1