[rbleth51]

Hello all. I ahve posted before about this machine control (Hitachi Seiki Hitec Turn 20 w/Fanuc 10TF). Most recently I posted trying to figure out what kind of fuses I had that were blown and needed replacing. That issue has been resolved and the fuses are replaced.

So the next problem has now croped up. The control does not seem to fully power up now after replacing the fuses. Upon pressing the green control Power On button I get the following result:

The hydraulic motor seems to come on, the familiar relay clicks and clunks all seem to occur in the cabinets and things light up, all as normal/before the fuse blow. The CRT lights up/comes on, but does not display anything. This behavior is different. The machine functioned completely before the fuse blow. Pressing the Standby button has no effect on anything. Before more relay engagements would be heard and maybe some more fans would come on.\

Looking at the PCB (not sure correct name for it - master, etc.) with the 7 segment LED on it also shows a different behavior. Prior to the fure problem it would display a couple of numbers (don't remeber what numbers) and stop with I beleive 1 displayed. Now it simply displays A (at least I think that is what it is, all segements are lit except for the bottom most)

Does any one have any idea how to proceed from here? Is there even a way to proceed? I wonder is some alarm has to be reset/cleared before the control will fully power back up. But for all I know this could indicate some components are fried.

The fuse blow occured when someone was testing the function of the spindle overide knob. We suspect that a short occured in the contacts behind the knob.

Any help/advice is greatly appreciated. Have a great evening.

Best Wishes,
Rob

[cncdiag]

Check the fuses on the front panel power supply

[Al_The_Man]

Looking at the PCB (not sure correct name for it - master, etc.) with the 7 segment LED on it also shows a different behavior. Prior to the fure problem it would display a couple of numbers (don't remeber what numbers) and stop with I beleive 1 displayed. Now it simply displays A (at least I think that is what it is, all segements are lit except for the bottom most)

Sounds like you might have a couple of problems, the A in the display is primarily one of the COP fibre optic cables faulty, check for disconnection or damage, or a remote board not working.
Al.

[rbleth51]

Check the fuses on the front panel power supply

Thanks for responding so quickly. These are the fuses I was reffering to having changed. I should have linked to the thread where I asked about them. I forget how easy it is to do that. LOL

However, you were correct. Both fuses that had blown previously were now blown again. I assumed they were fine as previously when they blew the CRT did nothing, no light up, no flicker, nothing, just stayed dark and unpowered. After I changed the fuses it lit up. However it did not display anything, but I could tell it was powered up and running. So I assumed my fuses that I had just changed were fine. That is what I get for assuming.

I guess I did not rectify the problem that caused them to blow in the first place, or more serious damage was done when they blew the first time. I will have to dig deeper.


The orignal blow occured while the spindle speed overide know was being used. My associate was concered that the shop electrical service was not going to be able to handle the phase converter running and the spindle speed changing drastically at the same time. He thought it would be too much load. So he was using the spindle speed overide knob and turning it very fast from one extreme to another.

No breakers tripped and the lights did not seem to dip at all so we hoped that the electrical service was fine (as in able to supply enough current). We figured that the big stack of contacts behind the overide know must have shorted some how (as in a chip got into some how or a loose contact moved, etc.) I inspected it and could not see an obvious problem.

Does sound like something anyone has seen before? Any more ideas/thoughts? Thanks.

-Rob

[rbleth51]

Alright. I have done some checking. I double and triple checked for bare wires, chaffed wires, and shorts in general. I found none. So after doing that I replaced the second set of blown fuses (1st-orignal set, 2nd-replacement set). I powered machine and crossed my fingers. That didn't work. I was greated with a distinct pop. I powered down and investigated.

The fuses were both intact. But imediatley I noticed something else. All of this is taking place on the MDI/CRT power supply board. The fuses are all loacted there. One of the resistors on the board is most definately blown. All the magic smoke and black stuff has been let out. In the process the the body was wrecked enough that I cannot ID its value by the bands.

It is labled R17 on the board. Does anyone have any idea what value this resistor is? The part number for the board is as follows:

A20B-1001-0160/03A

There may be many more problems than just this. But I at least know this one is bad. LOL It is in an easy spot to change out to. Thanks again for any help. This place is great for help for guys like me. I trully apreciate it.

Best Wishes,
Rob

[bborb]

Can you tell what wattage the resistor is?
1/8 _ 1/4 _ 1/2 watt?
You sometimes can tell by the physical size.
Does it look like a regular carbon resistor?

[rbleth51]

Can you tell what wattage the resistor is?
1/8 _ 1/4 _ 1/2 watt?
You sometimes can tell by the physical size.
Does it look like a regular carbon resistor?

Unfortunately I don't know enough about resistors to know if it is a plain carbon resistor or not. But it does look like most small resistors I have seen. Here is a picture of it on the board:



It is a little lest than 0.250" (1/4") long not counting the leads protruding from the body.

Here is where it is on the board. May help with the scale of it all.



Thanks again. I hope changing this out may get the board going again. Sure would like to do it for the price if a small resistor rather than around $500 for the whole board.

-Rob

[Al_The_Man]

It's quite possible that is a symptom, not the cause, IOW you probabally have a situation that caused the resistor to blow, they very rarely burn up on their own.
Al.

[cncdiag]

The resistor is 18ohm 1/4w 1%tol
We have the power supply in stock if you need one or we can repair yours.
CNC Diagnostic LLC
813-983-1870

[rbleth51]

It's quite possible that is a symptom, not the cause, IOW you probabally have a situation that caused the resistor to blow, they very rarely burn up on their own.
Al.

That is exactly what I am thinking. But I have no idea where to start looking for the bigger "situation"/problem that caused the blown fuses and resisitor.

Where does the power come into this card anyway? I can see no obvious place. Maybe the multi pin "Honda" style connector?

And the search goes on. LOL

Thanks.

-Rob

[Al_The_Man]

Where does the power come into this card anyway? I can see no obvious place.

The power into the power supply usually is CP11 220vac input.
Al.

[rbleth51]

The power into the power supply usually is CP11 220vac input.
Al.

I can not see a CP11 on the board. There is a CP11 in a separate cabinet on a large black aluminum encased board that plugs into the board with the 7 segment LED. Does the power going into the MDI/CRT power supply board originate from here?

The MDI/CRT power supply card that I have has 3 connecting points. One is a small blue 20 pin connector that a Honda connector plugs into, one is a brown 6 pin connector with much larger pins and the last are blades labeled R and S that female spade connectors plug onto.

Any idea which of the the power to the board may come in on? I am thinking it has to be the R and S as they run to the On and Off push buttons for the control. But I have no idea.

I would like to see what the power fed to the board looks like. I wonder if it is too high due to the phase converter and the old components finally gave out. Probably not, but worth a look before I junk the control and retrofit it.

It is likely a short somewhere farther down the chain in the MDI system, but I have no idea. Could a problem in the CRT cause something like this? It was working before, but just barely. It appears as if the actual CRT is powered separately from the MDI/CRT power supply board. But given the name of the board (MDI/CRT) one would assume that it does power the CRT. But it looks as if that is done separately, before the MDI/CRT board.

Any thoughts?

Thanks.

-Rob

[Al_The_Man]

R & S are the label for the ac power and are normally 200vac.
My mistake CP11 is the main power supply connector
Al.

[rbleth51]

R & S are the label for the ac power and are normally 200vac.
My mistake CP11 is the main power supply connector
Al.

Very nice, thank you. I was hoping that something like that was the case. So I should see 200VAC across R and S with a meter?

-Rob

[rbleth51]

The resistor is 18ohm 1/4w 1%tol
We have the power supply in stock if you need one or we can repair yours.
CNC Diagnostic LLC
813-983-1870

I would like to try to repair the board myself first. My main concern is the same as stated by AL. That is to say that this was just a symptom and not the cause. I don't want to have a board repaired or buy a new only to have it cooked again due to some other, as yet, unfound problem.

Is the resistor a "carbon composistion" resistor or a "carbon film" resistor? I looked around over on the Mouser website and those are the 2 catagories they list with Carbon.

How important is the tolerance value? Most of what I have seen only goes as low as 5%.


And just to be sure the value 18ohm is just ohms, not kohms right?

Thanks.

-Rob

[Al_The_Man]

Principally Fanuc used R & S for the 200v, BTW they usually state voltage tolerance to be withing ±10%.
Resistor composition is mostly carbon film now, the cheaper carbon composition tend to change over time when ran near or just above the wattage tolerance.
Al.