Blog
Delta Inverter Repair
Andy Martin
Tuesday 17th June 2025
It isn't always just about fixing a fault, it's taking the time and effort to work with a customer to ensure the item goes back to site and works for a long time to come.
Take this Delta Electronics inverter, its nothing out the ordinary. A decent 11kW variable speed drive, well made and reliable. Have a look inside it - it has quality Nichicon branded capacitors, the boards are conformally coated and the power interconnections are all quality metal components. The more eagle eyed amongst you may see something which isn't quite right, and you would be correct in noticing an area of the board is extremely burnt.
The customer rang me this morning, a little perplexed as this drive was brand new off the shelf and upon fitting it blew instantaneously, belching out smoke into the panel. Obviously this isn't what should happen, and the first thing we think is its either defective from new, or there is an external issue. My money is usually on an external issue as these inverters have a great reputation for reliability.
Upon discussing this issue, we took a trip to site to have a look at the damaged inverter and also the panel. As soon as the door was opened I knew exactly what had happened. Connected to this inverter is a DC bus brake chopper unit. I couldn't be sure until I got my multimeter out but I could have bet my bottom dollar the resistance across the DC supply leads being low. It was. The chopper had gone short circuit resulting in the 36 ohm braking resistors permanently being connected across the DC bus. This meant that when the drive was powered on there was a massive stress on all the input circuitry which never disappeared, and sooner or later something has to give.
The inverter is back with us now for repair, and the braking module will be following. It took a little time out of my day to do this but the end result paid dividends and saved another new drive failing instantly on power up. It would have been easy enough to take the drive away, fix it and just ship it back but that isn't what we are about. In a few days this drive will be repaired and back on site, with 100% confidence it will work as expected.
Indramat DDS Servo Drive
Andy Martin
Monday 23rd June 2025
This Indramat DDS2.1-W150 is in the workshop this week with a F61 error which relates to an abnormality in the current drawn from the power stack.
These drives were massively advanced for their time when they came out and are still widely used today as axis drives in CNC machinery. They build on the basic performance of the TDM analogue drives adding in digital support for an endat encoder as well as communication control using plug in cards.
We dismantled the drive and found some components in the current sensing circuitry at fault and these are being refitted tomorrow. Once rebuilt we will connect this to a TVM power supply and run it up with its MDD servo motor.
We don’t just fix faults at Martronic, we fully test everything ensure you have no surprises when your repair comes back to site.
Siemens OP17 HMI
Andy Martin
Tuesday 1st July 2025
With any electronic devices we always recommend routine maintenance and servicing to avoid costly breakdowns. This can be a simple visual inspection, cleaning or replacement of common time degradable components.
This Siemens Operator Panel OP 17/DP12 6AV3617-1JC30-0AX2 is a classic example of being left to do its job since 1997 without any maintenance.
You would be right in thinking “What maintenance does a keypad screen really need?”, however when the covers are removed the implications of no maintenance become quickly apparent. This unit was behaving unpredictably and not accepting input of data from the keypad. The initial thought was maybe a failing keypad however this is functioning fine after testing each of the switches. The real issue is the result of a leaking supercapacitor. The function of this capacitor is to retain data in RAM when the machine is off, and ensure the time and date remains correct. This one isn’t behaving like a supercapacitor anymore, more like a super resistor being almost completely open circuit with no capacitance. During its final years it has leaked electrolyte over the PCB in turn damaging traces, vias and neighbouring components.
We have ordered some new capacitors and also replacement logic ICs which decode the keypad matrix data as the legs are all corroded. We are now cleaning the board and repairing the failed vias which connect the top of the board to the underside.
Once we are happy the repair is complete we will connect it to our Siemens PG and run a test program to ensure everything works.
If you have any concerns over your equipment why not let us visit site and offer free advice on critical assets? There isn’t much we haven’t seen and simply opening a panel door can usually be enough for us to put together a plan of high risk equipment.
