Quote:
FlukeII:
Thanks for the very detailed report of the LC components! What initially made you suspect of the power supply diodes?
It wasn't so much the rectifier diodes on the board, it was the output transistors...the kit supplies black devices with the BD139 marking, PH and 91 presumably the counterfeiters idea of a date code...when I saw PH - only PHILIPS used to use this marking on it's on on TRIACs, SCRs and MOSFETs; with BJT's it always used to be PHxy - xy was the year - at least that's what i remember!
The trouble is the PHILIPS BD139 and BD140 devices, to the best of my knowledge, were only fabed in the Nederland’s and Germany, then packaged in the Nederland’s and Belgium e.g. the silicon wafer was cut and the transistors glued to the Collector terminal and the molded SOT32 package applied.
Having worked for PHILIPS at the time in 91 when we were using these parts, they only ever came in a light grey plastic housing with printed BD139 and the date code, say PH91 (yr 91), they were not using laser etching based markings until after the 90’s for devices and never on the BD139 and BD140s only made in EU. (Also, the factory would only do one production run per year and put excess into inventory - if you neded more, you had to wait to next year's production run - these were the days before the internet -- life was easy!!)
(When the ELCOMA section was broken up within PHILIPS and they formed NXP, they kept the production of the BD140 and BD139 devices the same - according to the local distributor)
So the dead give away was the packaging of these output transistors - they just don't look right.
Attached is a photo of genuine PHILIPS devices, made in 1995 and 2001 of the BD139 and BD140 (I can’t show a photo of the BD139-16 or BD140-14 as the AMP is at a friends house and a I can’t find the last 10 pcs of each in the spare room – it’s a mess with boxes everywhere…)
For the BD139-16 / BD140-16 the markings are identical except that there is the number 16 placed near the BD139/BD140 text, the same font size. e.g.BD139 16 or BD13916 - depending where the devices were packaged.
That wasn't enough I thought, so at work we tested the fT and hFE of these parts (supplied with the Lovely Cube kit), and while close to the ST parts performance, they were nothing like the original PHILIPS parts, therefore they can only be counterfeit IMO?
I suspect the kids putting these kits together were at primary school back in 91 when PHILIPS were making the BD139 and BD140s - so I suspect they have no idea what they are buying from their component suppliers, else they know exactly what they are doing and are too preoccupied chasing Deng Xiaopingi's vision: "...it's glorious to be rich..."!
PS. I would be really amazed if the counterfeiters can clone the original PHILIPS / NXP packaging material (epoxy resin), at PHILIPS they used to make their own resins from raw materials - that's why I'm sure the black BD139s and BD140s supplied in the kit are fake....