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What APS has learnt from fixing the 17,000 DC Power Supplies our Customers have destroyed!

Managing Director Paul Horner

‘To repair, refurbish and replace mission critical AC-DC Power Supplies and rectifiers for reliability conscious engineers worldwide’.

This was the mission that former design engineers from Farnell & Advance Power set out on way back in 2002 when they formed Advance Product Services Ltd (APS).

Managing Director Paul Horner recalls the journey from 1 to 17,000 repairs:

“I can’t quite believe we have just repaired our 17,000th PSU. The vast majority of these have been AC-DC power supplies which is what we specialise in, but we’ve also done dozens of custom or bespoke PSU designs and are now heavily involved in Electric Vehicle (EV) DC rapid charger maintenance.

Looking back over the years, I think the most difficult thing we ever repaired was, by pure coincidence, our first job! There were only 3 of us back then and I remember we had just launched the website in 2002 when we got an enquiry from the Czech Republic regarding an obsolete Farnell rectifier which had gone faulty.

When it arrived at the lab in the U.K. it had the typical aged electrolytic capacitors but there was also a second, more strange fault whereby it would shut down at >80% load.  Bizarrely, it did not exhibit the fault when a scope probe was connected to any of several nodes around the control circuit. This made it difficult to see what was happening dynamically and I remember it took days to fault find (and at a fixed repair charge)!

In the end, the problem was traced to HF noise interference upsetting the control circuit (the scope probe was effectively acting as a 25pF snubber) and the solution was to add a suppression cap to ground. It was only digging through the Farnell archives much later that found that this was actually an official design revision on later units. You kind of don’t expect to have to do that on your first job and we wondered what we had let ourselves in for!

The most bizarre thing we have ever repaired was probably a control panel for a JCB excavator. It’s not exactly something we advertise but when you are practised at fault finding to component level, most things are possible. The assembly had obviously been damp and had traces of silt in the enclosure which seemed a little odd. The repair turned out to be relatively straight forward but it wasn’t until the customer later told us that the operator had toppled the entire JCB into a lake that it all made sense. That must have been an interesting day at work.

Move on 18 years to 2020 and I think it is testament to our engineer’s abilities that we have so much repeat business from some of the most demanding clients in the UK such as EDF Energy and Highways Agency. They use us because of our unparalleled levels of quality and highly specialised skillset when it comes to DC power supply repairs, refurbishments and custom replacements.”



Brilliantly, Paul and the other Directors at APS had the foresight to keep a database of the causes of failure behind every single fault they repaired. Delving into this unique data set shows us exactly why power supplies fail. It identifies the most unreliable electronic components, points to design flaws and it shows us what is susceptible to user and environmental abuse.

Sounds like a great idea, but how do APS use this information to help you?

Prior knowledge and previous experience enables us to repair your PSUs quickly and economically. Your power supply or DC rectifier will be back up and running reliably in the shortest possible time. To find out if we have previous experience repairing your PSU model, click here to search our Repairs List.

Based on our extensive component reliability data, we can work with you to undertake planned refurbishment programs on critical power supplies. A new lease of life for ageing, obsolete supplies.

We have developed a range of new power supplies designed as straight forward like-for-like replacements for popular obsolete models from Farnell, Advance and other manufacturers. They deigned to have the same physical characteristics and the same or better electrical specifications. They are a simple trouble free replacement for you.

For some Customers, an ‘off the shelf’ option does not exist, but a solution MUST be found. To your specification, we are able to design, develop and manufacture a new power supply to suit your exact needs and industry standards, even in small volumes.

To read more about how we might help you, Click Here