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Electronics => Repair => Topic started by: orbiter on February 15, 2014, 03:36:42 pm

Title: Parts help required please (Mastech MS5205 Repair)
Post by: orbiter on February 15, 2014, 03:36:42 pm
Hi All,

Could some of you guys help me with some parts numbers please as I'm getting rather stuck. I've tried looking on Farnell, Mouser etc for replacement OR equivalents AND on the following websites but I'm not having much luck with the SMD markings.. ( (

I'm trying to repair a reasonably new'ish Mastech MS5205 Insulation Tester which I've shorted out by accident. It initially blew a couple of SMD transistors Q20 and it's adjacent transistor (it also vaporized the track beneath the transistor which I have repaired temporarily for now)

The main issue is part numbers though. I could just buy a new unit for about £90 but I thought having a go at a repair on this would be more beneficial to me not being an EE in the diagnostics dept, especially as I don't have schematic either so :( If anyone does have a schematic that would be great :-+

Anyway the parts I'd like to know replacement numbers for if necessary are listed below, as I have most others. I don't mind at all spending £30+ odd quid on bits if needed as I love repairing SMD stuff down to 0402 (depending on accessibility.) I've posted a pic of the board in the hope of some help with replacements/equivalents.

8525 (u3)
8512 (u2)
80M (or maybe upside down W08)
A7W16 (the number 16 is written sideways on the transistor after the A7W)

Also how do I identify Diode D1 ?

( (

( (

Many Thanks for any assistance guys.

Title: Re: Parts help required please (Mastech MS5205 Repair)
Post by: MrAureliusR on February 15, 2014, 06:04:40 pm
A lot of those small SOT-23 packages use codes that don't represent the actual part number at all. Most cases you need to know the manufacturer, and often they'll have a reverse code lookup tool. Without knowing the manufacturer for those parts... man. It'll be near to impossible to figure out that way.

One solution would be to get a transistor tester, figure out what kind of transistor they are. If you have a schematic, then take a look at each one. Schematics also sometimes list exact part numbers. Also, try and find the BOM (bill of materials) as this will explicitly state the part number used for U1, D4, etc etc.

Good luck!
Title: Re: Parts help required please (Mastech MS5205 Repair)
Post by: orbiter on February 15, 2014, 09:07:58 pm
Understood mate.. 

As mentioned, I've not got a schematic for the Mastech MS5205 so I'm out of luck there. I do have a PEAK Atlas DCA Pro component analyser but trying to find similar spec parts would IMHO still be a huge PITA, even with the details the tester spits out.

If anyone does know any more details on detecting the required parts no's here please do chime in?

Thank you