De Walt DC500 Vacuum Cleaner Component values

[Old Sparky]

I have been asked to repair a PSU circuit board from one of the above on which a varistor has burnt out, and a PTC thermistor may be suspect. The markings on the varistor were on the side that burned off (of course!) The Thermistor is marked
'WTR10D050', and measures about 6 ohms 'cold' These two components and a fuse are all in series with each other and with the live supply line to the Switch mode Power supply. I'm told the unit was accidentally connected to 230v, despite being designed for 110/120vac. No other components have suffered. With what value Varistor and Thermistor should I replace the faulty components? I cannot find a diagram on the web which shows the internal circuit and component values.

[Refugee]

I would power it up on a Variac and make sure the rest of it is O/K before going any further. It should crowbar the fuse out if it is any good.

[Yorkie]

You can get the exploded view, parts list etc from ServiceNet is the Official Site for Parts & Service for (In the USA) for DEWALT, Porter-Cable, Black & Decker, Bostitch, Proto and DeVilbiss here:

http://servicenet.dewalt.com/Products/Detail/DC500#

http://servicenet.dewalt.com/Products/De...gram/DC500

The parts that are jiggered is - I assume - on the AC/DC Converter PCB for which De Walt provide no service information as they don’t service or repair the PCBs of course – they just supply replacement board. Except that for the DC500, they don’t any longer, even assuming that it were it economical to buy and fit one, which is doubtful:

http://service.dewalt.co.uk/Products/Par...rtID=61652&BOMRegionID=1

It’s a long shot, but you could try contacting De Walt Service HQ in the UK, which is here and see if you can get through to someone friendly in the Technical Dept who might be able to give you a few pointers:

DEWALT
210 Bath Road
Slough, Berks. SL1 3YD
United Kingdom
reply@dewalt.com

They also say: "If you have a question please visit our Online Customer Service Centre": [www.2helpu.com]

'2helpu'? I fear that the term ‘help’ is one of those words in the English language that's been seriously devalued over time – like ‘Engineer’ for example, or terms such as 'my word is my bond'.

Not very helpful I'm afraid.

[Old Sparky]

Thanks for the info., David, but none of those links include either a circuit diagram or component parts list for the AC/DC converter PCB. I may contact DeWalt UK about this, though I doubt if I'll get the info. I need from them!

[Yorkie]

As with all control PCBs on such things as white goods, central heating boilers etc, there is unlikely to be a circuit diagram as they're not considered to be a serviceable unit - just 'replace on fail'. The labour cost of diagnosis and repair would far outweigh the cost of a new PCB. Very unhelpful to the likes of us, particularly as the 'mystery parts', will doubtless cost only coppers.

Good luck in your quest.

[Refugee]

I look up the chips and with luck there will be an application circuit to look at on the data sheet.
There will then be a bit of reverse engineering around the bits that have problems and the likely candidates can be replaced with OEM parts.
This is how VGA screens used to be fixed in the short time that the things were actually worth repairing.

[pwdrive]

Good luck with it all, I sometimes get asked to repair some mystery control boards, I just say no.
I'd rather pick my nose with a rock drill.

Lawrence.

[singlepentode69]

There are no circuit diagramed for anything these days bring back the wireless and electrical trader .
Regards
Robin