Refusal to supply schematic diagrams for Tenma 72-8690A bench power supply

I'm not sure if you're aware but Tenma products are rebadged from other manufacturers. element14 doesn't have access to that information - only the original OEM has as it is their product and their design. You're better off trying to identify who the OEM is and seeing if they can provide information. Otherwise, you are on your own - you've had the warranty period which has passed, so the product has met its minimums. As far as products go, this is a very low-end product, so I wouldn't expect much support.

Otherwise, you're just going to have to rely on your own skills and expertise to repair it. If you can't - you can easily blow the whole cost in service technician hourly fees even before the cost of parts. Paying others to repair such low-cost devices rarely makes sense.

I've had issues with even first-tier brands as modern equipment frequently doesn't have available schematics or service manuals, and even if you could identify the bad assembly, they refuse to sell you replacement assemblies (and in some cases, to make the replacement module work, it requires calibration/reprogramming which only they can achieve). Right to repair is hardly universal or standard practice.

- Gough

You don't say what country you are in so I can't comment directly on 'Right to Repair' for you. In the UK there are no general rights to repair information.

I'd really like to see it - we have loads of silly rules and laws but not so many sensible ones !

As Gough has suggested you may be able to identify the box and find a schematic on the web.

The problem is widespread, if you buy a 40 year old HP instrument you can maintain it because full service info was published and is available. If you buy a modern scope you can pay the manufacturer a huge amount to fix it until they drop it (from maintenance support) and after that they expect you to bin it.

MK

Gough Lui said:

I'm not sure if you're aware but Tenma products are rebadged from other manufacturer

We could all certainly benefit from some sort of look up table that maps their rebadged names to their "original". I know some customers have done that for a range of the tenma products.

Looks like a GW Instek.

Looks more like this:

https://www.rapidonline.com/uni-t-utp3705s-0-32v-5a-dc-power-supply-2-channel-85-4048

Had a quick look on the web and couldn't find anything.

There are some repair blogs for very similar products on the web which might help the OP.

MK

Huh. From my searches it appears that only a user manual was ever supplied for this.

Unknown said:

How does that negative response reconcile with the "Right to Repair" laws/directives

The Right to Repair in the UK only covers specific equipment and I do not believe bench-top power supplies are covered.

https://www.legislation.gov.uk/ukdsi/2021/9780348222920

While it says 'external power supply' this is typically in conjunction with one of the supported devices, such as an electronic display.

It's also worth mentioning consumer law

https://www.legislation.gov.uk/ukpga/2015/15/section/23/enacted

But this is dependent on how you bought it when you bought it, and whether or not you bought it as a company versus as an individual. 

I'm not a lawyer and I do not speak for our online stores or their transactions with customers or how that's defined or how they define it and would have to be taken up with the online store support. My understanding is that consumer law tends to be effective to individuals and not business-to-business transactions which our online stores mainly operate as.

Many clones exist for this kind of PSU.

This looks like a possibility....

http://micromir.ucoz.ru/Scheme/Power/49.gif

That's a key point, often missed. Consumer rights that are automatic for consumer purchases are different to B2B transactions, where the fine print needs to be read, and all online stores are not consumer stores.

UK law considers it rightly unreasonable to have the same rights for B2B, because it would bring business transactions to a halt.