Comments on: Humax Set Top Box Fault Finding

By: Gautam

Gautam — Wed, 22 Aug 2018 06:11:31 +0000

Sir i purchase this book.iam headend owner and we have stb catvision and Surbhi.icannot able to repair STB.pls help

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By: Albert van Bemmelen

Albert van Bemmelen — Wed, 22 Jun 2016 21:53:44 +0000

In reply to Humberto.

Hi Humberto. Indeed often the first characters of the components typenumber look like different typenumber versions of in fact just the same SMD Component. MMBT or STK or 2N are probably all the same NPN Transistor. I found the STK4401 several times in the Humax PDF Service Manual file I mentioned in these Post to be used for switching through electronic videosignals for Scart VCR, Scart TV and other connectors.
(the f1-fox_service_manual_197.pdf)
I had bought the 2014 edition Turuta SMD-code Book previously but still it is impossible to find all codes that exist. Some codes I still couldn't find anywhere.

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By: Albert van Bemmelen

Albert van Bemmelen — Wed, 22 Jun 2016 14:26:03 +0000

In reply to Yogesh Panchal.

Understood Yogesh! Must be equal to the 2N4401. I am afraid that finding a matching Humax Tata Sky Box Service manual will be very difficult. But often it helps to google the number and version of the printed circuit board used to find the much needed info. While searching for Humax T41 CPU B/D rev1.0 I found this Humax Service Manual that also uses the kst4401 transistor you mentioned. See this link: http://monitor.espec.ws/files/f1-fox_service_manual_197.pdf
I hope this helps.

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By: Humberto

Humberto — Wed, 22 Jun 2016 14:12:33 +0000

Good repair Yogesh. Any published article is a source of information for readers. Congrats.

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By: Humberto

Humberto — Wed, 22 Jun 2016 14:09:42 +0000

In reply to Albert van Bemmelen.

Hi Albert and Yogesh, here's another type of 2x (2X M) https://docs.google.com/viewer?url=http://www.onsemi.com/pub/Collateral/MMBT4401LT1-D.PDF

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By: Yogesh Panchal

Yogesh Panchal — Wed, 22 Jun 2016 10:47:20 +0000

Albert,
Here is the Link for 2X transistor
http://www.s-manuals.com/pdf/datasheet/k/s/kst4401_fairchild.pdf

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By: Albert van Bemmelen

Albert van Bemmelen — Tue, 21 Jun 2016 16:47:10 +0000

In reply to Albert van Bemmelen.

Oops: the 2X instead the x2 is indeed only the 2N4401 type transistor.
I guess it is just a question of replacing the bad one. But with those often badly standardized or hidden
codes you never can be 100% sure.

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By: Albert van Bemmelen

Albert van Bemmelen — Tue, 21 Jun 2016 16:29:12 +0000

Yogesh are you sure the X2 is a npn transistor?
They could according to their SMD code also be Zeners? In case of BZX99 a 13V 0.3W, or in case of BZX84 a 30V 0.3W, or in case of BZV49 a 30V 1W zener?
(all being sot23) See also http://english.electronica-pt.com/smd-databook?ref=x2
I did look for Humax on ElektroTanya but only found a interesting PDF with name :
humax_oak-ii-large_5100_5300_5350_5400_5500_5550_5600_5700_ver-1.0_sm

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