[TechAssist] Re: HOT subs in general question
- From: "J Silverman" <greentron@xxxxxxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Thu, 31 Jul 2003 14:17:15 -0400
The wattage rating is for the power dissipated during the turn-on and
turn-off switching. That power dissipation is much higher than the rating
because it is averaged over the whole cycle for heating purposes. There is
hardly any power dissipated during the on or off periods. If the transistor
is getting hot either there is not enough drive to get it on quickly or
there is not enough drive to shut it off quickly. There is also a problem if
there is too much drive. Too much turn on current can heat or damage the b/e
junction and too much turn off voltage can break down the b/e junction. If
it runs cool you know you are OK for operation. Wheather it survives
startup, shutdown, or the failure of something else is another matter.
Jerry Silverman
Greentron Inc
4 Newland Ave
Greenville SC 29609
864 232 3889
Fax 271 2080
mailto:greentron@xxxxxxx
----- Original Message -----
From: "Bil Green" <tv.vcrrepair@xxxxxxxxxxx>
To: "Jorge Camboni" <techassist@xxxxxxxxxxxxx>
Sent: Thursday, July 31, 2003 3:04 AM
Subject: [TechAssist] Re: HOT subs in general question
> The BUH717 is rated at 1700V. The 1500V HOTs may not last long.
> Hard to believe that Sony recommends a HOT replacement which
> does not have a damper diode (when the original one does).
>
> I recommend the D1884 through D1887 (no damper diodes) and
> D1878 through D1881 (have damper diodes) for most HOT subbing.
> You also need to have a Japanese transistor manual so you can
> look things up. If you buy these as original Sanyo, Toshiba,
> etc. you will find that they work for almost any HOT in
> direct view and PTVs.
>
> Saves lots of money and you rarely have to special order a
> HOT. Using a sub which has the same amp rating as the original
> is the key. More voltage and faster switching speeds is OK.
> Lower wattage rating is OK also. HOTs are off most of the time
> (~12us on, ~55us off).
>
>
> --
> Best regards,
>
> Bil Green
> 2001 TV VCR
> Mammoth Lakes, CA 93546
> 760-934-2001 mailto:tv.vcrrepair@xxxxxxxxxxx
>
> Wednesday, July 30, 2003, 7:07:23 PM, you wrote:
>
> JC> Hi Tony. You're using a 1881 subbing a BUH517
> JC> but the BUH517 HAS NO DAMPER. neither the C5148,
> JC> so you're adding another damper to the circuit (and it works!!)
> JC> which is not the best way, i believe, In those cases you should
> JC> use D1885/86/87. Strangely enough, Sony reccomends subbing
> JC> d1941 (damperless) for c4927 (damper included)
> JC> I had not noticed any difference between 1879 and 1881 if the 79
> JC> stands the current. (it will in most cases). According to Sanyo, there
> JC> is no difference between 78/79/80/81 excepting the current rates
> JC> and the power handling. FT (gain/bandwith product) is the same,
> JC> so dc beta is.
>
> JC> Jorge
>
> JC> At 07:14 p.m. 30/07/03 -0500, you wrote:
> >>Hey Phil I have been using the D1880 and 1881 for many subs, They do
seem to
> >>keep the temp down and last longer. must haves in my book BUH517, C4927,
> >>C5148 ( I dont like using subs on sony to many bad memorys.)
> >>
> >>Tony Saracco
> >>TCS ELECTRONICS
> >>Elgin , IL 60120
> >>847-695-1928
> >>tcselectronics@xxxxxxxxxxxxxxxx
> >>----- Original Message -----
> >>From: "Philip Bader" <tjanphyl@xxxxxxxxxxxxxxx>
> >>To: <techassist@xxxxxxxxxxxxx>
> >>Sent: Wednesday, July 30, 2003 12:30 PM
> >>Subject: [TechAssist] HOT subs in general question
> >>
> >>
> >> > A tech friend says if he cannot get, or ID an HOT he will sub a
> >> > 2SD1881. Says thiis 1881 seems to be a general heavy transistor for
at
> >> > least test/estimate purposes.
> >> > Yesterday he had a Sharp with bad HOT 2SD2586.No subs avail. OEM a
week
> >> > away.
> >> > Used an 1881 and ran cool.
> >> > I want to improve my TV HOT selection bin. Is there a certain
selection
> >> > that are "must haves"?
> >> > Phil Bader
> >> > --
> >> > Philip Bader
> >> > Jan Phyl TV Inc. (estab. 1976)
> >> > 3420 Recker Hwy. Winter Haven, Fl. 33880
> >> > Fax (863) 299-8821
> >> > email: tjanphyl@xxxxxxxxxxxxxxx
> >> >
> >> >
>
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>
>
> JC> Jorge Camboni, GY Electronics, Richardson, TX
>
> JC>
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