Hi Joe, I am measuring the transistors in circuit, I have not removed any of the components from the pcb.
So you are saying to disconnect each transistor and check them individually? Thanks!
Electron Kinetics Eagle 2C amplifier problem
- Thread starter MarioP2020
- Start date
So you are saying to disconnect each transistor and check them individually? Thanks!
I see very similar postings in other forums concerning this specific problem. I'll assume it's the TS under a different name.
Since the 7A schematic is useless, you should take good pictures of both sides of the PCB, i.e. Left side front, left side back and same for the right side. The next step is for you to compile a listing of all the components, by Name and value.
This will aid you in drawing the schematic you will need to fix your equipment.
Since the 7A schematic is useless, you should take good pictures of both sides of the PCB, i.e. Left side front, left side back and same for the right side. The next step is for you to compile a listing of all the components, by Name and value.
This will aid you in drawing the schematic you will need to fix your equipment.
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I've never actually drawn out a circuit schematic of this size, so not certain how I could? I would have to remove the 2 big main caps and disconnect the transformer wiring to the pcb in order to detach the PCB. I will have to do this eventually, as to de-solder/replace any bad part/s.
Do you think I should just replace all caps, perhaps the transistors as well, would solve my problem? Thanks again!
Without a diagram it's going to be hard work to fix it, this transistor needs testing out of circuit for shorted B /E, if it's ok then something else across the b/e is pulling down, your only option is to compare it to chan A.
I see. So I should remove the PCB from the chassis and de-solder that transistor to check it? I have another DMM that allows me to measure transistors. I guess I can use it to check them?
I have a CHY 20 multimeter like this one: https://www.tme.eu/en/details/chy20/portable-digital-multimeters/chy-firemate/
I also have a Fluke 177 True RMS multimeter.
I purchased a program a while back called DATS for my computer. It does have a generator as well as an oscilloscope. Not sure if I could use any of these functions?
Just lift the base or the emitter off the track and test on Diode with your Fluke meter.
Hi Dave! So you want me to remove the transistor you believe to be shorted first? Once I take the PCB out, I imagine it will be easier to trouble shoot?
Sorry for the delay in my reply, been rather busy the past week. I'm fairly confident that this older PCB should have good copper traces on the board, so it should be fairly easy to remove these parts. I know on some PCB's, the copper traces are very thin and it can break free if your not careful when de-soldering..lol
I understand. So when you say to use the diode setting on the DMM, what will I be checking for? Never have done this before, but I am willing to learn. Thanks again!
The transistor is like two junctions .... E-B and B-C. You will be measuring the forward and reverse by reversing the leads. In the forward mode, the NPN would have the negative meter lead on the emitter and the positive lead on the base. The reading should be around 0.700 for a silicon transistor. The leads would be reversed and your meter should read open (sometimes it's 1.999 or OL) . Whatever the meter reads in shen you hold the leads apart, not connected to anything, on the diode test function is an open.
The B-C junction is reversed bias compared to the E-C junction. In you measure E-C it should be Open in both directions.
The B-C junction is reversed bias compared to the E-C junction. In you measure E-C it should be Open in both directions.
Hi Joe! I will get to taking this amp down as soon as I get caught up with some work I must get done. I'll post back here when I have taken the PCB out and de-solder that transistor. Thanks again for your help!
Mario
