[TechAssist] Re: Philips HOT BU2508DF Mis-labeled
- From: "Intrepid Video Support" <support@xxxxxxxxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>, <greentron@xxxxxxx>
- Date: Wed, 31 Mar 2004 09:57:47 -0500
If the resistance is too low, same thing.
Ideal resistance should be in the 60-70 ohm range.
Jeff Dougherty
Intrepid Video TV/VCR
263 S Front St
Steelton PA 17113
fax...717-564-4952
www.intrepid-video.com www.tech-repair.net
----- Original Message -----
From: <greentron@xxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Cc: "Corey Brazell" <cohbraz@xxxxxxxxxxxxxx>; <techassist@xxxxxxxxxxxxx>
Sent: Tuesday, March 30, 2004 10:42 PM
Subject: [TechAssist] Re: Philips HOT BU2508DF Mis-labeled
Those are counterfeit. Regardless of what other differences there are, they
will burn out quickly without
the resistor. The resistor damps parasitic oscillations and has to be as close
to the junction as
possible, which is why they are fabricated internally. No distributor
intentionally ships counterfeits but
we hear about this thing all the time. Some techs keep a list of the resistor
measurement for a given type
of hot and check all of the new stock against the list. If the resistor value
is more than 20% above the
nominal value, they know from experience that the hot wont last.
J Silverman
> That's what it said on PartSeeker, but when I ordered it, it subbed to that
> BU2508DF.
>
> Regardless, any BU2508DF should have the dampening diode and biasing
> resistor; I have several older BU2508DF that do and read 40 ohms. But,
> these new ones that I ordered that all have the same date code not have
> that resistor. There is around a 2 Meg Ohm resistance between Base and
> Emitter.
>
> So, I have two different BU2508DF transistors. Older ones that are correct,
> and newer ones that do not have the biasing resistor.
>
> Also, I just noticed that the new DF's don't look the same as the older
> ones. It looks like they have been re-stamped. The front of these look as
> if they have been fine-sanded to a smooth even surface and then stamped. My
> older DF's Have three round indentions on the front face. One in the middle
> near the bottom, and two toward the top near each side. These new ones are
> smooth all the way across. As a matter of fact, I have one that is stamped
> on both sides!
>
> Corey Brazell
> Audio Video Electronics
> 12169 SC Hwy 121
> Newberry SC 29108
>
>
> > [Original Message]
> > From: Intrepid Video Support <support@xxxxxxxxxxxxxxxxxx>
> > To: <techassist@xxxxxxxxxxxxx>
> > Date: 3/30/2004 3:29:48 PM
> > Subject: [TechAssist] Re: Philips HOT BU2508DF Mis-labeled
> >
> > Corey,
> > Thanks for the information, but that part number is for Philips S2055,
> 610597
> >
> > Jeff Dougherty
> > Intrepid Video TV/VCR
> > 263 S Front St
> > Steelton PA 17113
> > fax...717-564-4952
> > www.intrepid-video.com www.tech-repair.net
> >
> > ----- Original Message -----
> > From: "Corey Brazell" <cohbraz@xxxxxxxxxxxxxx>
> > To: <techassist@xxxxxxxxxxxxx>
> > Sent: Tuesday, March 30, 2004 1:07 PM
> > Subject: [TechAssist] Philips HOT BU2508DF Mis-labeled
> >
> >
> > I have received two separate shipments of these BU2508DF transistors from
> > Philips, and the transistors do not have the built-in Base-Emitter bias
> > resistor. They seem to be a BU2508AF. The transistors in both shipments
> > have the same date code: 0231 C2
> >
> > Philips is now running a Stock Check on these parts. They may also be
> under
> > part number 4835 130 47897.
> >
> > If you have any of these type HOTs, check them!
> >
> >
> > Corey Brazell
> > Audio Video Electronics
> > 12169 SC Hwy 121
> > Newberry SC 29108
> >
> >
> >
> >
> >
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