Anybody replaced a Mits VFD with anything else?

I was just wondering if anyone has replaced their FR-SE or otherwise with a plain old 1200.00 VFD (Hitachi)? Its not something I need to do at the moment...... but reading about Captdaves dilemma, and recalling the 4800.00 flat rate fee that Mitsubishi wanted to repair my drive when I thought it might need it.......just makes me think a substitute could work.

I've just installed a few VFD's and induction motors at a local business to replace DC motors, and noticed that most VFD's have the needed inputs and outputs to interface with the Mazatrol.

A few years back, I replaced the toasted VFD on my former employers Onsrud 20HP spindle with a Hitachi (don't recall the exact model) VFD, at a cost savings of around 1500.00. The machine functions exactly as original and is still running perfectly.

Its been a while since I looked at the ladder for my machine, but I cant recall anything that would seem to be an insurmountable impediment.

Anybody done this already?

Mike

The original FR-SE drive is a regenerative drive, meaning it sinks power back into the mains when braking instead of wasting it as heat through a resistor heating element.

I have wondered about this too, but never had any issues with my FR-SE and it is coming up on it's 27th birthday.

I was advised years ago that slowing down the accel and decel settings (DIP switches) helps the VFD to live a lot longer as this reduces the instantaneous MAX current draw upon spindle startup and shutdown. This does not limit the spindle torque or HP output. The machine just takes a few extra seconds to wind up. This also has the benefit of reducing the electrical bill--specifically the peak demand charges for those of us actually paying for the juice to run the machine.

I wonder what amount of savings is to be had from Regenerative versus Dynamic braking on a typical lathe application?

I followed that ramping advice, too......although I have not yet really done anything with my machine yet, I'm sure it will extend the life. Mines 27 years old, too, but it appears it was set on the quickest accel for most of its life.

Mike

Mike,

I would imagine you could replace a Mits drive with an Hitachi or other brand. The big difficulty would be getting all the small wires identified and connected to the new drive. I would imagine you would have to cut the original connectors off the ribbon cables, and make custom connections between your machine and the new drive.

A viable solution is to keep the Mits drive, and use a combination of self-repair and factory repair to get it back in service. If you are somewhat mechanically/electrically inclined, you can replace all the big base transistors on the drive yourself. These transistors can be sourced new via Ebay from several sources. A QT15 has 6 of them, and can be had for 300 or so for all of them.

The SF-CA main circuit board, and SF-PW power supply can be sent to Mitsubishi Electric Automation in Chicago for testing. If both are OK, Mits will charge you a couple hundred for testing. If they need repair, the SF-CA is about $800, the SF-PW is about $500.

Catman Greg

Thankfully, my drive is working for now.

I think Mazak connectors are from Honda. They can be had pretty easily. I sourced some for a Studer grinder i worked on, and was able to integrate a new control into the existing wiring with new replacement connectors on the control end.

I was just curious if anyone had done it already on the forum.

I'll keep my fingers crossed that my drive will hang in there for now.

Mike

I nailed down a few intermittant problems in an FR-SE about a year ago. If there's enough interest I can describe them in more detail but for now, here's what I remember:

1.) Too much current is drawn thru some wires and connectors on the control boards. The +5V on the boards intermittantly drops and weird things happen. A solution is to add a couple of extra wires.

2.) The 100 uF and 220 uF capacitors in the driver stage develop increased series resistance and/or decrease in value and need to be replaced.

3.) The current sensors get flakey and the power supply starts to trip for no reason. $60 for a new sensor from MEAU - no more start or regen faults.

Cheers,

Duak,

Myself and others on here try to learn all we can about these Mits drives. Any more detail would be appreciated!

Greg

I've found my notes on the FR-SE drive I worked on. I wish I had written more down. It's not mine so I can't pull it apart and take pictures so you'll have to go with my description. Replacing some parts will require the proper tools and a bit of expertise. It's not rocket science but don't try this unless you've some experience with PCB repair. You'll need a soldering iron, solder and a solder sucker (Soldapullit) in addition to pliers, sidecutters, screwdrivers, etc. A good DMM is also handy.

1.) +5V instability: all the DC power for the various DC voltages comes from the Power supply module through pin and leaf connectors. These are tin plated and can oxidize or the the leaf spring can get weak if overheated. The MEAU tech I talked to was aware of the problem and performs a similar repair if needed.

I pulled the PCB stack and power supply out of the drive and did the work on the bench. The two boards connect with each other by flexible cables and by pin connectors. All +5V has to pass through one connector pin. I made up a couple of jumpers with ring terminals on one end, one red and one black. The wires were 22 gauge and about 3" long. I soldered the free end of the jumpers to the connector pins on the board that doesn't have the two screw terminals in the upper left corner. The ring terminals will go under these screw terminals when the boards are put back together. The red wire connected to +5V on both boards while the black wire connected to GND on both boards.

There's about a dozen screws holding the boards to the frame. I think some were under the power supply cover. Separate the PCB from the power supply by lifting it up. The pins will slide out the the connectors. I used contact cleaner and cotton swabs on the pins to clean off any oxidation before putting things back together.

2.) flakey capacitors: the MEAU tech confirmed some internet lore that the 100 uF and 220 uF capacitors in the driver stage can degrade. Some of the capacitors on this board had already been replaced. These are in the area of the board that has the twelve hybrid modules (black or brown gizmos about 1 by 2 by 1/2"). The capacitors in question are to the left of these modules. I have a DMM that can measure the capacitance in place. At least one of each type on this board was bad. I pretty much replaced them all with parts of the same value and with a higher voltage, something like 25 V. I recall that MEAU used 16 V parts which is close to the 14 or so volts on the parts when operating. I got the replacements either from my personal collection or a local industrial supplier. Digikey(.com) is good supplier and can get replacements to you the next day. I don't think MEAU used any particularly special parts as they really weren't available at the time. Just pick a good quality replacement (Nichicon, Panasonic) possibly with a higher temperature rating and/or a lower ESR value.

3.) The drive would sometimes have trouble starting or, if it did start, would throw a #12 (regen) fault when decelerating. Going through the adjustment procedure in the manual (available on MEAU's site) made me think the trimpots (the variable resistors on the board) were flakey. I eventually figured out that the current sensor that is mounted on the capacitor bank buss bars in the main chassis was NFG. I pulled the current sensor out, figured out which pin was which and bench tested it. I found that its output had almost nothing to do with its input. You'll have to get the exact part from MEAU as it is calibrated for the HP rating of the drive. Similar sensors are used elsewhere in the drive so if you're having trouble with setting currents, it might be due to the current sensor.

Hope this makes sense. I should be able to clarify or answer questions if need be.

Cheers,

Duane

Thanks Duane,

That's good stuff to know.

Mike