420 Blowing Resister

[skinerd]

See the attached pic, R14110 goes directly to the gate of Q14100, so that transistor is probably shorted.

[skinerd]

Q14100 is probably shorted and needs changed....

[bigstraw]

chi,
one thing with electronics is you just can't go replacing burn out components without first checking to see if another problem led to it burning out.check the transistor like skinerd suggested and if it's shorted, then check the other components around it before you replacing anything

[zhakrin]

Q14100 is probably shorted and needs changed....


I have a 480 here with this part blown, what is the part spec for it so i can pick one up?


Zhak

[zhakrin]

I have a 480 here with this part blown, what is the part spec for it so i can pick one up?


Zhak

Found this off some webpage with regards to RCA 420 receivers found it interesting for part numbers:

QUESTION NO. P121302-9: RCA Direct TV receiver model DRD420RE. I need the values of R14113, R14103, R14110, R14112 CR14101, CR14102 and C14105.
r14113=100
r14103=2.4k
r14110=22, 1w
r14112=1k
cr14101,cr14102 & cr14103 1n4148,
c14105=.22 63v
sm-r14115=5.1k
sm-r14107=4.7k


check cr14104,cr14108,cr14106,cr14105 & for sure q14100,q14101,14102

[zhakrin]

Q14100 is probably shorted and needs changed....


Still looking to find a spec on this transistor so i can track one down. Its not listed on the scematic for some reason.

You have some sort of part number for this Skinerd?

zhak

[zhakrin]

It's Stmicroelectronics P4NB50FP. If it's shorted check Q14102 and Q14101 also.


yea Q14101 is blown. Q14102 appears fine but might be worth replacing as well.

Anyone have parts specs for these too?

Zhak

[zhakrin]

yea Q14101 is blown. Q14102 appears fine but might be worth replacing as well.

Anyone have parts specs for these too?

Zhak

Ok i have sourced the Q14101

Transistor (Q14101) – MPS8599 = NTE159

Anyone know if there's someplace closer to Toronto then california in which i can get them? My local electronics supply store here doesn't have.

http://www.allelectronics.com/cgi-bin/category.cgi?category=search&item=MPS8599&type=store


zhak

[loserbaby]

Same info I came up with, maybe a few more variations for replacements, but I don't know how exact tolerances need to be and what ones may not be so important. They obviously require the power ratings if so many of us have them blown but going bigger means you smoke some other part of the board. I have some aircraft avionics suppliers I'm looking into but I havn't found any direct crossovers yet??????? Our best resource would be old, parts or irrepairable receivers, I found that toshiba p/n in one of my 420's, so we know thats a good replacement.






INfo i found from the net searching, plz help verify. I DO NOT know if these are correct, but would like help to verify if they are indeed replacements that could help all of us. Please repond if you can verify or see any changes that we can remove or add.

Thanks,
GrumpyMan

"QUESTION NO. P111-7: RCA DRD221RD dss receiver. I need a cross reference on Q14110 (TO220 package) one number is K2862 and in another receiver (same component reference) it has several markings which include W926moroccoP4NB50 FP,or P4N850FP.
2SK2862 is a Toshiba Mosfet, rated 500 Volt, 3 Amp, and STP4NB50FP is a ST Micro Mosfet, rated 500 Volt, 2.5 Amp. Similar devices include 2SK2182, 2SK1245, 2SK3045, and IRFI820. B&D (xxx.bdent.com) is listing 2SK2182 and 2SK1245, and Digikey (xxx.digikey.com) is listing 2SK3045. Newark (xxx.newark.com) is listing IRFI830, a beefier device than IRFI820. If insulation hardware can be provided, plain IRF820 or IRF830 could be tried."

[loserbaby]

this cross came from a site mouser.com, it is nte2946 to replace (st)p4nb50fp also (2s)k2862. if any body has come up with better info on this pls help, I've got 1 DOA reciver that needs one.

[loserbaby]

not radio shack, I checked.

[skinerd]

(st)p4nb50fp is a special fast chopper, Radio Shk won't have it, order on line..

[loserbaby]

P/n 526-NTE2946 qty 1-pc @ 6.42 each, 2-pcs in stock. Per the NTE cross reference, this is a cross for ST Micro p/n P4NB50FP. The spec sheet for the above NTE item is available on our website .

Frank Barrett
Customer Service Representative
Mouser Electronics, Inc.

However they now have only 1 in stock since I just ordered mine.

[coolwind]

Hello Fellow members
I need to know what the value & watt on R14111 & R14112 Resistors are & also Q14101 & Q14102 pn are Q14101 i see is NTE 159 Is Q14102 the Same ???
TKS Coolwind

[skinerd]

Components on the Low Voltage Side of the Switcher.
--------------------------------------------------------------------

U14103 - LM7905 -5volt three terminal voltage regulator.
L14102 - 22uh 200ma choke.
CR14108 - ST BYW100-200 Fast Recovery Rectifier Diode.
CR14104 - ST BYW98-200 Fast Recovery Rectifier Diode.
Q24501 - TIP42A PNP Power Transistor (Must Use Insulator!).
Zener - This S.M. Zener diode is located either next to the LNB tuner assembly, or inside of it. DRD22x used S.M. 33V 500mw, and DRD4x0 used S.M. 24V 500mw. Any value from 24V to 35V at 400mw to 1W should work fine.



Components on the High Voltage Side of the Switcher.
---------------------------------------------------------------------

F14100 - 3 Amp 250V Axial Lead (Pigtail) Fast or SlowBlow fuse.
R14102 - 3.3 Ohm, 1W 5% Metal Film F.R.
R14113 - 100 Ohm, 1/4W 5% Metal Film F.R.
R14110 - 22 Ohm, 1/2W 5% Metal Film F.R.
R14112 - 1K Ohm, 1/4W 5% Metal Film F.R.
R14103 - 2.4k Ohm, 1/8W 5% Carbon or Metal Film Resistor.
Q14102 - MPSA06 or MPSA05 NPN Transistor.
Q14101 - MPS8599 PNP Transistor.
Q14100 - ST STP4NB50FP N-Channel Enhancement Power Mosfet.
CR14103 - 1N4148 S.M. Diode.

The following three capacitors usually do not fail unless they are literally burnt off the board by the flames from R14112 and R14110. I will list them here in case you need them.
---------------------------------------------------------------------
C14100 - .033uf 50vdc S.M. ceramic capacitor.
C14104 - .001uf 50vdc S.M. ceramic capacitor.
C14105 - .22uf 63vdc mylar capacitor.

[coolwind]

Thanks Bro
you always have the answers Dude I Owe ya 1 for sure ! Hope ya had a HAPPY HOLIDAY
Coolwind