thanks, I picked it up in a job lot. I used to have a fluke 100MHz analog 4ch scope, but I think this might be better. It is amazingly clear even at 120MHz. If only I had space to keep some of the things like this.
Hello sir, I bought a Promax OD 540 oscilloscope at low cost. But it doesn't work. When power on, all led lights up. Constantly alarming, can't find any manual on the oscilloscope. Looking forward to your advice.
Information on promax is very limited, you might find something using a lower model in the range e.g. od-512 or what i think is closely related od-514/515/545. Also take a look around and see if you can find anything that looks similar i.e. rebadged and check on EEVBLOG forum. Without a service manual it can be a needle in a haystack. I should always start with a voltage check as far as possible. Get hooked up and power on, look at the voltages early and see if any drop when it gets to the point it stops. Hopefully you wiill find a separate power section with voltages marked, you can however pick up pretty reliable voltage test points by finding a suitable ground and testing voltages on logic ICs, operational amplifiers etc. Obviously also check any front panel cables etc in the hope it is something simple. I have seen stopping durng power on for several reasons - from power that drops part way through starting caused by overload from another fault, power borderline with old capacitors, excessive ripple as that device powers on, So voltages even if just to get a solid assurance for later checks. And if possible the quality of those power supplies e.g. massive ripple. Check the processor (if it has one) is actually clocking and running before and after it stops. You may have seen in several videos that I do a voltage check on yout the power supply with everythig else disconnected, then if that works I connect up and test the power again - because the power supply will often protect itself if there is fault elsewhere. Not always practical but perhaps there are sub-assemblies that might be disconnected to see if that helps it narrow tha search. Is it perhaps failing when it attempts to power on the CRT, which might point to a power fault in that area which could be difficult and dangerous without a manual . But really it is a case of trying to understand roughly what is what - input amplifiers to choppers then a delay line, then to y-amplifiers for the plates. The first amplifiers also branch off to the trigger circuits which in turn control the sweep circuits. Once you have a reaosnable amount of comfort you can start trying to isolate sections to narrow the fault. But it can be a long and frustrating process. You might find it helpfult to get a service manual for anything similar from a similar time not because it will be exactly right but because there will be similarities, particularly at the block diagram level. Good luck!
Not much about this scope on the Internet, so hope this helps people
Excellent demonstrations and teaching. I learned so much! Thank you!
Thanks, Sometimes I like to try and cover how I approach things, not just do the repair, although I worry how much time it adds.
Nice Scope.
thanks, I picked it up in a job lot. I used to have a fluke 100MHz analog 4ch scope, but I think this might be better. It is amazingly clear even at 120MHz.
If only I had space to keep some of the things like this.
Hello sir, I bought a Promax OD 540 oscilloscope at low cost. But it doesn't work. When power on, all led lights up. Constantly alarming, can't find any manual on the oscilloscope. Looking forward to your advice.
Information on promax is very limited, you might find something using a lower model in the range e.g. od-512 or what i think is closely related od-514/515/545. Also take a look around and see if you can find anything that looks similar i.e. rebadged and check on EEVBLOG forum. Without a service manual it can be a needle in a haystack.
I should always start with a voltage check as far as possible. Get hooked up and power on, look at the voltages early and see if any drop when it gets to the point it stops. Hopefully you wiill find a separate power section with voltages marked, you can however pick up pretty reliable voltage test points by finding a suitable ground and testing voltages on logic ICs, operational amplifiers etc.
Obviously also check any front panel cables etc in the hope it is something simple.
I have seen stopping durng power on for several reasons - from power that drops part way through starting caused by overload from another fault, power borderline with old capacitors, excessive ripple as that device powers on, So voltages even if just to get a solid assurance for later checks. And if possible the quality of those power supplies e.g. massive ripple. Check the processor (if it has one) is actually clocking and running before and after it stops.
You may have seen in several videos that I do a voltage check on yout the power supply with everythig else disconnected, then if that works I connect up and test the power again - because the power supply will often protect itself if there is fault elsewhere. Not always practical but perhaps there are sub-assemblies that might be disconnected to see if that helps it narrow tha search. Is it perhaps failing when it attempts to power on the CRT, which might point to a power fault in that area which could be difficult and dangerous without a manual .
But really it is a case of trying to understand roughly what is what - input amplifiers to choppers then a delay line, then to y-amplifiers for the plates. The first amplifiers also branch off to the trigger circuits which in turn control the sweep circuits. Once you have a reaosnable amount of comfort you can start trying to isolate sections to narrow the fault. But it can be a long and frustrating process. You might find it helpfult to get a service manual for anything similar from a similar time not because it will be exactly right but because there will be similarities, particularly at the block diagram level.
Good luck!