[TechAssist] Re: Q601, 602 voltages too high--measuring AC/DC voltages
- From: Wayne Vanaman <Wayne@xxxxxxxxxxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Sat, 29 Jan 2005 06:55:49 -0600
When you are measuring switch-mode supplies with a DMM there are several
variables. What is the frequency response of the meter? What is the
shape of the waveform? How is the meter sampling?
I dropped in to visit another shop once. He was working on a CTC169
with a vertical problem, using a Fluke 87 DMM. The SCR measured about
3V instead of the expected 12 (or so), but the picture was fine. I
pulled out a Fluke 77 and the voltage measured "correctly". We found
that the Fluke 87 could be manually ranged and the voltage would be
different on different ranges.
I have since tried many different meters measuring AC waveforms on a DC
scale and found that "your mileage may vary".
The best measurement of an AC waveform is done with a 'scope. In the
case of these Sonys, the duty cycle should be 50%, and that is the most
important thing with these supplies.
Wayne Vanaman
Omega Electronics
6904 W Fairfield Dr
Pensacola, Fl. 32506-3310
Wayne@xxxxxxxxxxxxxxxxxxxxx
WWW.PensacolaTVRepair.Com
850-456-5995 voice
850-458-6369 fax
Larry E wrote:
> Al, the B+ on the secondary is right on and the transistors are not running
> hot so I`m
> going to run it tomorrow for half a day, if it passes that test I`m going to
> ship it, I
> don`t know if the print is correct or not, I`ve worked on a few of these
> supplies
> but always worried about the heat so I don`t think I`ve ever actually
> measured the
> voltages before, I guess I`ll find out tomorrow, Larry E
>
> Larry Eastman
> American TV & Electronics
> Crystal River, Fl. 34428
> ----- Original Message -----
> From: "al m" <ampm@xxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Friday, January 28, 2005 6:06 PM
> Subject: [TechAssist] Re: Sony KV32TS36 AA-1 Q601, 602 voltages too high
>
>
>
>>Are you sure the print is right?
>>Al Marquardt
>>ampm@xxxxxxx
>>Al Marquardt Electronic Repair
>>206 W Main
>>Girardville Pa. 17935
>>----- Original Message -----
>>From: "Larry E" <videotech@xxxxxxxxxxxx>
>>To: <techassist@xxxxxxxxxxxxx>
>>Sent: Friday, January 28, 2005 3:28 PM
>>Subject: [TechAssist] Re: Sony KV32TS36 AA-1 Q601, 602 voltages too high
>>
>>
>>
>>>Phil I used the better "P" version (originals were "M"), as stated
>>>heatsink
>>>is warm
>>>not hot after 1 hour of running, there has to be something causing this
>>>set
>>>of transistors
>>>(which are notorious for failing as we all know) to run 30 volts higher
>>>than
>>>normal,
>>>what`s really got me is why is B+ correct???? Larry E
>>>
>>>Larry Eastman
>>>American TV & Electronics
>>>Crystal River, Fl. 34428
>>>----- Original Message -----
>>>From: "Phil Bader" <tjanphyl@xxxxxxxxxxxxxxx>
>>>To: <techassist@xxxxxxxxxxxxx>
>>>Sent: Friday, January 28, 2005 3:10 PM
>>>Subject: [TechAssist] Re: Sony KV32TS36 AA-1 Q601, 602 voltages too high
>>>
>>>
>>>
>>>>Also: Did you use OEM Sony transistors?
>>>>I find the "acid test" for those power suplies is whether Q601,602
>>>>are=20
>>>>running comfortably warm, or does the heat sink burn your finger.
>
> (the=20
>
>>>>two-second test)
>>>>If just warm,and the set has good picture,width, regulation from
>
> light=20
>
>>>>to dark scenes,etc, I wouldn't borrow trouble. Be happy! Don't worry,
>>>>mon=
>>>>!
>>>>Phil Bader
>>>>
>>>>Gemini Computer & TV wrote:
>>>>
>>>>
>>>>>Larry,
>>>>>I hate to ask this but are you using the proper ground? Is the set
>>>>>worki=
>>>>
>>>>ng.
>>>>
>>>>>Those supplies are rather unforgiving if something is wrong which is
>>>>>wha=
>>>>
>>>>t
>>>>
>>>>>made me ask my original question!
>>>>>
>>>>>Bob Waterman, CET=AE #RI-28
>>>>>Master Technician License #9109
>>>>>Service Manager / Parts Manager
>>>>>Gemini Computer, TV, & Security Alarms
>>>>>(508)695-7302
>>>>>(508)695-7769 FAX
>>>>>geminitv@xxxxxxxxxxx
>>>>>
>>>>>
>>>>>----- Original Message -----=20
>>>>>From: "Larry E" <videotech@xxxxxxxxxxxx>
>>>>>To: <techassist@xxxxxxxxxxxxx>
>>>>>Sent: Friday, January 28, 2005 2:59 PM
>>>>>Subject: [TechAssist] Sony KV32TS36 AA-1 Q601, 602 voltages too high
>>>>>
>>>>>
>>>>>=20
>>>>>
>>>>>
>>>>>>Hi Guys, this KV32TS36 came in dead R607 and Q601,602 replaced, all 3
>>>>>> =20
>>>>>>
>>>>>
>>>>>VDR`s checked good, HOT good, powered up set with variac B+ 133.8 but
>>>>>voltages on Q601 & 602 are too
>>>>>=20
>>>>>
>>>>>
>>>>>>high, print says Q601 should be 164 e&b, 319 on collector, Q602
>>>>>>should=
>>>>
>>>>>> =20
>>>>>>
>>>>>
>>>>>be, E not shown,
>>>>>=20
>>>>>
>>>>>
>>>>>>b -.2 c 164 I have the following;
>>>>>>Q601 e&b 193.5 c 305
>>>>>>Q602 e .002 b-.172 c193.5
>>>>>>set has been running for an hour and heat sink of Q601&2 is pretty
>>>>>>warm=
>>>>
>>>>>> =20
>>>>>>
>>>>>
>>>>>but not real hot,
>>>>>=20
>>>>>
>>>>>
>>>>>>any ideas? I have resoldered all bad joints including hdt,
>
> regulators,
>
>>>>>> =20
>>>>>>
>>>>>
>>>>>vertical IC, etc.
>>>>>=20
>>>>>
>>>>>
>>>>>>thanks in advance, Larry E
>>>>>>Larry Eastman
>>>>>>American TV & Electronics
>>>>>>Crystal River, Fl. 34428
>>>>>>
>>>>>>
>>>>
>>>-----------------------------------------------------------------------=
>>>
>>>>---
>>>>
>>>>>> =20
>>>>>>
>>>>>
>>>>>---
>>>>>=20
>>>>>
>>>>>
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>>>>>> =20
>>>>>>
>>>>>
>>>>>
>>>>>
>>------------------------------------------------------------------------=
>>
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>>>>
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>>>>>
>>>>>=20
>>>>>
>>>>
>>>>--=20
>>>>
>>>>Philip Bader
>>>>Jan Phyl TV Inc. (estab. 1976)
>>>>3420 Recker Hwy. Winter Haven, Fl. 33880
>>>>Fax (863) 299-8821
>>>>email: tjanphyl@xxxxxxxxxxxxxxx
>>>>
>>>>
>>>>
>>>>
>>>>--
>>>>No virus found in this outgoing message.
>>>>Checked by AVG Anti-Virus.
>>>>Version: 7.0.300 / Virus Database: 265.7.3 - Release Date: 1/24/2005
>>>>
>>>>
>>
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