Need Help!- meldas YM 2B

[cadcamsolutions]

Hi dear friends , I have a Mazak model VQC and it has a mitsubishi meldas YM2B control , when I start the machine it seems to boot up fine , but I can not see anything on the display , I can watch a red led on the stop bottom and when a press the start bottom the led turn on, it only reamain on when is pressed. Does any body can help me to find out wheather is the crt board or the display itself ?.

Thanks in advanced.

[onthebumper]

It's probably something in the control or one of the CRT boards. When the CRT goes out the machine will still come up ready and you can move the machine in manual. If you look at the control unit in the electrical cabinet what boards have LED's lit and which LED's are lit (MCU, WDER, etc)?

[chippy1]

You probably have a 24 volt short. I'm assuming that you turn the breaker on to the machine. Everything seems fine. Then you press the NC on button and then when released the NC off led turn back on. If this is so, you need to remove the cables on your I/o PCB's in the electrical cabinet. These would be the FX53, FX63, FX763, FX773 which ever ones you have, remove the cables and then try again. If the NC come up, then start putting the cables back on until the NC does the same thing. At that point you need a schematic to figure out what is all on the cable. You can then check with a meter to ground to figure out the short.

Good Luck

Chippy

[Leelund]

Chippy, don't the PSU have a red and green power indicator and if you have a short doesn't it go red instead of green?

[chippy1]

Hi Leelund,

Typically the older power supplies such as the PD14 or PD14C-1 may or may not have an LED, but it doesn't show Green and then Red when there is a short. These power supplies are used in the FX series controls for Mitsubishi. However, the PD21 which is for the M300 series control does. Also this can be confusing though too. Yes, if a 24V short occures, the LED will go red on the PD21, but if the incoming voltage is over 100Volts AC such as 120VAC which is normal for US without a transformer that doesn't have tap for 100VAC 50hz vs. 60hz line then you will also get a red led on the PD21. Which puts the power supply into overload. Although I have seen the PD21 run in overload forever when the power supply has 120VAC incoming.

Hope this helps,

Chippy