[TechAssist] Re: HOT subs in general question
- From: Bil Green <tv.vcrrepair@xxxxxxxxxxx>
- To: J Silverman <techassist@xxxxxxxxxxxxx>
- Date: Thu, 31 Jul 2003 13:01:29 -0700
I mentioned that the HOT wattage rating is not critical. An engineer from
ECG told me that years ago, and it works for me. I have subbed HOTs
that were rated at 150W with a 50W and there were no problems.
--
Best regards,
Bil Green
2001 TV VCR
Mammoth Lakes, CA 93546
760-934-2001 mailto:tv.vcrrepair@xxxxxxxxxxx
Thursday, July 31, 2003, 11:17:15 AM, you wrote:
JS> The wattage rating is for the power dissipated during the turn-on and
JS> turn-off switching. That power dissipation is much higher than the rating
JS> because it is averaged over the whole cycle for heating purposes. There is
JS> hardly any power dissipated during the on or off periods. If the transistor
JS> is getting hot either there is not enough drive to get it on quickly or
JS> there is not enough drive to shut it off quickly. There is also a problem if
JS> there is too much drive. Too much turn on current can heat or damage the b/e
JS> junction and too much turn off voltage can break down the b/e junction. If
JS> it runs cool you know you are OK for operation. Wheather it survives
JS> startup, shutdown, or the failure of something else is another matter.
JS> Jerry Silverman
JS> Greentron Inc
JS> 4 Newland Ave
JS> Greenville SC 29609
JS> 864 232 3889
JS> Fax 271 2080
JS> mailto:greentron@xxxxxxx
JS> ----- Original Message -----
JS> From: "Bil Green" <tv.vcrrepair@xxxxxxxxxxx>
JS> To: "Jorge Camboni" <techassist@xxxxxxxxxxxxx>
JS> Sent: Thursday, July 31, 2003 3:04 AM
JS> 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
JS> 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
JS> at
>> >> > least test/estimate purposes.
>> >> > Yesterday he had a Sharp with bad HOT 2SD2586.No subs avail. OEM a
JS> week
>> >> > away.
>> >> > Used an 1881 and ran cool.
>> >> > I want to improve my TV HOT selection bin. Is there a certain
JS> 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
>> >> >
>> >> >
>>
>>>**************************************************************************
JS> **
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>>
>>>**************************************************************************
JS> ***
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>>
>>
>> JC> Jorge Camboni, GY Electronics, Richardson, TX
>>
>> JC>
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