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ROLAND VP-540 Will not power up
- Thread starter Adam Edge
- Start date
there is not simply one component that fails.
you need a service manual (and a bit of EXPERIENCE at this sort of thing)
i have often found bad solder connections and "feed throughs" from layer to layer on the boards.
damonc21 is probably the expert on these machines,
the most important question for mes how to keep the printheads functional while the boad is repaired/replaced?
haha im not falling for it
I have manual and some know how.
BTW what are you getting fixed on your board? Simply way to keep heads moist and fresh while board is being repaired is to do head soak. Refill cap tops every couple of days.
man I asked you if you have repaired no power issue you said yes so I asked which parts(s) did you have to replace, instead of giving me a clear answer you went on about this and that lol. You either haven't fixed no power issue or you are holding back haha. At least AI doesn't say it knows the answer and then holds back lolIt's about as true as what AI has told youThey have basically said replace 90% of the components on the board, which is fine, but still won't fix your problem
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I have had to replace different parts depending on what the problem is. There is no one definitive answer on what causes a lack of power. This is why you need to trace the whole board power signals to find out where it is failing. If you can't do this yourself, then you need to get someone to physically look at the board.
To do this you need to understand schematics and circuits and how components work with each other. It isn't as simple as just testing one component and saying 'that one is bad' and replacing it.
To do this you need to understand schematics and circuits and how components work with each other. It isn't as simple as just testing one component and saying 'that one is bad' and replacing it.
On most boards I have worked on it has been different components fail. Unfortunately there isn't any one that is more likely to be the problem, which is why tracking the fault isn't simple.
As a basic start ;
1) With your IR camera, check for obvious shorts
2) Check electrolytic capacitors for shorts, and also ESR value
3) With your oscilloscope check clock signals to chips, and supply voltages
4) Test any voltage supply ICs
If you are lucky the first component you test could be the one causing it, but it can also be one resistor is blown or has drifted too far out
As a basic start ;
1) With your IR camera, check for obvious shorts
2) Check electrolytic capacitors for shorts, and also ESR value
3) With your oscilloscope check clock signals to chips, and supply voltages
4) Test any voltage supply ICs
If you are lucky the first component you test could be the one causing it, but it can also be one resistor is blown or has drifted too far out
Jim Hancock
Old School Technician
As a former US Navy electronics technician from the days of tubes, I would say this. Back in the day, when each component was an individual part, and schematics had each individual part showing, troubleshooting electronics was a matter of skill and logic in determining which component was the faulty component. Today's electronics are a whole different ballgame, where a single chip on a board may contain many different circuits, which back in the day, would have been an entire chassis with discrete components. In addition, the chips showing in the schematics, which I believe Roland is the only company that actually supplies schematics, the chips are impossible to troubleshoot without knowing what signals and voltages are on what pins, and also the need for advanced equipment, such as IR cameras and an oscilloscope as damonCA21 has mentioned. The VP-540 mainboard is known to be a problematic board. You can check fuses and output transistors with a multimeter and look for bulging tops on capacitors, but beyond that, it's what we techs call "easter egging", which means you guess what part may be bad, without any real logic. It's not simple. Good luck!
Not to mention these days the schematics companies supply often don't actually match the board :/. which just makes it even more annoying. Then you get ICs with a number on them that doesn't exist when you google it!
There is no shortcut to doing actual troubleshooting.
someone needs to tske the service manual, a dvm and perhaps an oscilloscope to decide WHAT IS NOT THERE. no one can tell you with so little info why your machine is dead.
take the service manual & verify if all the “always on” voltages are coming out of the power supply.
press the power button& see if there is activity at the cpu.
see if the switched voltages come up.
NO ONE can tell you why your machine is dead without some troubleshooting
Interesting...
But it is, as the seasoned guys tell you. It could be a bad solder joint or even worse a crack in a PCB track or even mor likely in a layer to layer connection.
I hold a EE degree and even with a scope, it's just guesswork.
You can check the onboard voltage regulators and so on.
BTW the drivers for the heads are no MOSFETs, but bipolar transistors.
But it is, as the seasoned guys tell you. It could be a bad solder joint or even worse a crack in a PCB track or even mor likely in a layer to layer connection.
I hold a EE degree and even with a scope, it's just guesswork.
You can check the onboard voltage regulators and so on.
BTW the drivers for the heads are no MOSFETs, but bipolar transistors.
Which ones were they?
Totally agree, I also have a degree in EE and circuit design and 9 times out of 10 it is slogging through the circuit and testing and diagnosing
for the layer to layer connections, the best thing is to have the board put through one of those ovens the repair depots use for the nvidia chipsets that go intermittent
i no longer have access to one
these were the best way to do the repair without risk of damage to the board
THE PROBLEM IS, the roland service manual is sorely lacking, it givies you enough info to troubleshoot to the point where you would replace the board, not do a component level repair
every issue is different, you will have to do the following and find the fault on your board
As a basic start ;
1) With your IR camera, check for obvious shorts
2) Check electrolytic capacitors for shorts, and also ESR value
3) With your oscilloscope check clock signals to chips, and supply voltages
4) Test any voltage supply ICs
If you are lucky the first component you test could be the one causing it, but it can also be one resistor is blown or has drifted too far out
ahahahahaha just kidding, replace R14 and C126