Expensive Products - Low-Quality (internal) 3rd-Party SMPS ... Why? - Page 1
Forum section: electronics / general

author: gbrettell
author_rank: Contributor
timestamp: January 28, 2015, 10:56:29 pm
content: I'm curious why companies such as Polycom Conferencing units, Crestron Controllers, Crown Amplifiers, & ETC Lighting Boards (& probably many more) use internal 3rd party switch mode power supplies?I've been doing electronic repairs on a wide variety of A/V equipment for quite some time now and it seems as though there is a trend for companies to use these modular open-frame SMPS inside their designs instead of designing their own power supply. These 3rd-party power supplies are almost always the cause of product failures (in my experience). Mostly bad capacitors.I think it's a shame ... when I open a unit to service, I typically see a high-quality main PCB (from the Mfg), then ... next to their board is a piece-of-junk low-quality power supply made by someone else.I'm sure it is all about cost/profit ... but what about the reputation of the company ... don't they care? When a product fails, the consumer looks to the brand name on the face of the product to blame.

author: dannyf
author_rank: Super Contributor
timestamp: January 28, 2015, 11:02:53 pm
content: I don't blame them - power supplies are THE highest cost item in a power amp. So as long as consumers are looking for el cheapo amps, manufacturers will continue to produce el cheapo amps.BTW, smps in a (class B) power amp is very difficult to design. the trend now is to produce a smps that is a class D amplifier - a power supply whose output is controlled by an audio signal.

author: coppice
author_rank: Super Contributor
timestamp: January 29, 2015, 01:49:35 am
content: Designing an SMPS is one of the dark arts. Few people can do it well, and even the ones who do make mistakes sometimes. People generally use a power supply with a track record, because they DO care about their products. These third party supplies probably are the biggest cause of failure in many products, but power supplies are the only high stress item in most modern electronics products, and that's where you would expect the failures to occur. If you think third party supplies are bad, you should see what happens when most engineers try to make their own.

author: LabSpokane
author_rank: Super Contributor
timestamp: January 29, 2015, 05:41:37 am
content: Switch mode power supplies should be designed by those who specialize in the art.As for the decision by manufacturers, it is driven by the NRE and certification cost. It's almost always cheaper to buy a pre-certified supply by the time the NRE, overhead, documentation, testing, and certification are paid for. You have to be selling serious volume to amortize out the dev costs on a power supply.As for choosing poor quality supplies, once again it's cost. I think it's the wrong decision, but for some there is a compelling reason to save that cost upfront and hope that it lasts through warranty. Another reason is just plain ignorance. Some engineers take spec sheets as the holy gospel and will spec in a shit supply without testing because the data sheet says it's wonderful.

author: Simon
author_rank: Unknown
timestamp: January 29, 2015, 12:52:53 pm
content: Marketing and sales departments will be scrutinizing costs and want to "sub out" where ever possible.If the products need CE marking etc you have a whole other host of problems as the PSU is the bit that WILL fail the test as opposed to the actual kit and you will have redesign after redesign.

author: Kjelt
author_rank: Super Contributor
timestamp: January 29, 2015, 12:59:44 pm
content: Engineers recommend good PSU like Delta/TDK-Lambda etc. etc. but on the BOM it says for instance SMPS 12V 1A.Then the purchasing dept. looks at the BOM and sees SMPS 12V 1Amp 100000 pieces and ask for offers from their recommended suppliers and than often the cheapest gets the deal, not always but than the purchasing dept. looks at the guarantee on the product, 1 or 2 years? The cheap PSU manufacturer also guarantees 2 years FINE deal done.Now if the manufacturer had to guarantee their product for 6 years than we would (over time) see other better products, because the manufacturer would get stuck with the repair/replacement bill

author: electr_peter
author_rank: Unknown
timestamp: January 29, 2015, 01:25:23 pm
content: As other forum users mentioned, designing your own PSU is difficult, costly and takes too much time. You also lose on quantity vs price.One other point - if during design phase design changes suddenly require 50% (or 200%) of previously implemented PSU power, you are screwed with in house built PSU. You cannot just reduce/increase size of PSU components - it is not how it works. By using externally supplied PSU you can freely alter available power for very little cost even at late project stages. (You:"We need more/less powerful PSU", PSU supplier: "No problem, check this model with number XXX").

author: dannyf
author_rank: Super Contributor
timestamp: January 29, 2015, 01:45:50 pm
content: QuoteClass D amps are essentially SMPS.Years ago, there was this new revolutionary Class D amp that every review site appraised. Except that it has a problem: it has a tendency to blow mosfets under low volume into a heavy load.When I mentioned that had the designer done some smps work, he would have figured out why quickly. He wasn't too happy about that,

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 29, 2015, 02:06:00 pm
content: If you are in the business of designing expensive products, it's a waste of your time reinventing the wheel when you can buy in something which, due to economies of scale, is probably cheaper than if you'd integrated it yourself, especially once you factor in approvals costs.

author: gbrettell
author_rank: Contributor
timestamp: January 30, 2015, 01:13:03 am
content: Thank you all for your replies ... it makes better sense to me now.The one product that baffles me the most though is the Polycom HDX 9000 (video conferencing system) with a price tag @ appx $15,000 ... inside is a low-quality SMPS. You'd think at that price they'd use a better power supply (even if it is made by a third party) ... and their service charges are high, as well (no matter what the failure is - flat rate). I ended up repairing the SMPS for less than $20 worth of capacitors ... Polycom wanted to charge the company that owns it $1,500 to repair the unit.I guess it is what it is ... thanks again for your replies.

author: LabSpokane
author_rank: Super Contributor
timestamp: January 30, 2015, 02:37:40 am
content: You just answered your own question. The power supply made it through warranty and Polycom got to double down on the repair.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 30, 2015, 08:22:37 pm
content: The questions of why a 3rd-party PSU, and why a cheap one are completely seperate.On a £15K item, there is no excuse to cheap out on what is usually the most likely part to fail, even if a good one is fitted.As mentioned it's quite possible that a good PSU was specced, then the bean-counters changed it bcause they are too stupid to know better.

author: LabSpokane
author_rank: Super Contributor
timestamp: January 30, 2015, 08:44:20 pm
content: Two different questions. Same answer.