electronics, repairs, service manuals and datasheets discussion community for the repairs professionals and technicians
FAQSearchMembersGroupsRegisterProfilePM'sLogin/Out
power failure
Goto page Previous  1, 2
 
Post new topic   This topic is locked: you cannot edit posts or make replies.    Electronic equipment repair and service manual search discussion Forum Index -> Equipment Repairs
View previous topic :: View next topic  
Author Message
Guest






PostPosted: Fri Aug 05, 2005 1:03 pm    Post subject: Reply with quote

so it could be the control IC, can u give me some ideas about that IC's function & it's cause's when it is faulty.

And in the 1st Item the secondary side is shorted but which parts are more likely to be shorted in the secondary side.
Back to top
Guest






PostPosted: Wed Aug 10, 2005 10:12 am    Post subject: Reply with quote

so it could be the control IC, can u give me some ideas about that IC's function & it's cause's when it is faulty.

And in the 1st Item the secondary side is shorted but which parts are more likely to be shorted in the secondary side.
Back to top
Al_Dodge_Bundy



Joined: 05 Apr 2005
Posts: 93
Location: Netherlands

PostPosted: Wed Aug 10, 2005 1:02 pm    Post subject: Reply with quote

1st item) Because you don't seem to have any high voltage, I'll would start by checking the HOT (large transitor/fet near the flyback trafo) for shorts. And also check other semiconductors, like diodes and transitors in this cicruit.

2nd item) If you have 300 V over the large capacitor, and already replaced the small capacitors, you could try to find the resistors which are used to "supply" the controller IC. These high resistant (+/- 100KOhm) sometimes go bad, and should be placed between the 300 V line and Vss input of the controller IC.

Another way to check if the controller IC has supply voltage is to download the datasheet of the IC (don't know which type is used in yours) an look for the Vss input pin in this diagram.
Supply voltage is around 15 Volt ussualy (but can also be checked in the datasheet).

The controller IC "generates" a small pulse signal, which is supplied to a switching-transitor, which converts the small puls to a higher one, so the transformer in this primairy power supply circuit can generate a few supply voltages to the secundairy circuits.

If the IC has no supply voltage (bad resistor, or missing 300 V), or no start puls, it will not generate a small puls signal.

They are most of the times very cheap, so just replacing them should not be a big problem.

If you can't find the "supply voltage-pin" on the controller IC, please give me the partnumber of this IC, and I'll have a look.

Grtz Mark
Back to top
View user's profile Send private message
Guest






PostPosted: Thu Aug 11, 2005 3:28 pm    Post subject: Reply with quote

Hi Mark thanks for ur clear & wide advice, I realy appriciate it.

1st Item, I had power ok. but no sound & picture,i got only fast tick tick sound that increases or deacrease if i change the volume. So If the horizinat transistir ( the HOT ) is failed can I decrease or increase the tick tick sound by change of volume ? I am doing this. So what can make the TV have no sound & picture , just fast tick tick sound only with power ok.

2nd Item. yes I have checked all the resistors ( high resistors & the fusable resistors, I have changed the capacitors & also the power transistor, but nothing happens. so my guess is either the control Ic or the autocoupler ( with 4 legs - 2 in primary & 2 in secondary ) are failed.
So what do u think , help me plz & i will check the Vcc through the datasheet of the ic
Back to top
Guest






PostPosted: Wed Aug 17, 2005 12:10 pm    Post subject: Reply with quote

Hi Mark thanks for ur clear & wide advice, I realy appriciate it.

1st Item, I had power ok. but no sound & picture,i got only fast tick tick sound that increases or deacrease if i change the volume. So If the horizinat transistir ( the HOT ) is failed can I decrease or increase the tick tick sound by change of volume ? I am doing this. So what can make the TV have no sound & picture , just fast tick tick sound only with power ok.

2nd Item. yes I have checked all the resistors ( high resistors & the fusable resistors, I have changed the capacitors & also the power transistor, but nothing happens. so my guess is either the control Ic or the autocoupler ( with 4 legs - 2 in primary & 2 in secondary ) are failed.
So what do u think , help me plz & i will check the Vcc through the datasheet of the ic
Back to top
Guest






PostPosted: Wed Aug 24, 2005 9:56 am    Post subject: Reply with quote

Hi thanks for ur clear & wide advice, I realy appriciate it.

1st Item, I had power ok. but no sound & picture,i got only fast tick tick sound that increases or deacrease if i change the volume. So If the horizinat transistir ( the HOT ) is failed can I decrease or increase the tick tick sound by change of volume ? I am doing this. So what can make the TV have no sound & picture , just fast tick tick sound only with power ok.

2nd Item. yes I have checked all the resistors ( high resistors & the fusable resistors, I have changed the capacitors & also the power transistor, but nothing happens. so my guess is either the control Ic or the autocoupler ( with 4 legs - 2 in primary & 2 in secondary ) are failed.
So what do u think , help me plz & i will check the Vcc through the datasheet of the ic
Back to top
Guest






PostPosted: Sat Sep 03, 2005 11:10 am    Post subject: Reply with quote

Hi thanks for ur clear & wide advice, I realy appriciate it.

1st Item, I had power ok. but no sound & picture,i got only fast tick tick sound that increases or deacrease if i change the volume. So If the horizinat transistir ( the HOT ) is failed can I decrease or increase the tick tick sound by change of volume ? I am doing this. So what can make the TV have no sound & picture , just fast tick tick sound only with power ok.

2nd Item. yes I have checked all the resistors ( high resistors & the fusable resistors, I have changed the capacitors & also the power transistor, but nothing happens. so my guess is either the control Ic or the autocoupler ( with 4 legs - 2 in primary & 2 in secondary ) are failed.
So what do u think , help me plz & i will check the Vcc through the datasheet of the ic
Back to top
JORDAN-JOR
Guest





PostPosted: Sat Oct 29, 2005 7:42 am    Post subject: Re: power failure Reply with quote

Anonymous wrote:
what's the cause for letting no power in the secondary side of an SMPS power supply. there is power in the primary side but no power in secondary. The SMPS has a transistor , controller IC and an autocoupler . I guessed one of those may be faulty which are in the primary. Anyway please help me what can be the cause.
Back to top
Display posts from previous:   
Post new topic   This topic is locked: you cannot edit posts or make replies.    Electronic equipment repair and service manual search discussion Forum Index -> Equipment Repairs All times are GMT
Goto page Previous  1, 2
Page 2 of 2

 
Jump to:  
You can post new topics in this forum
You can reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Електроника София - Service Manuals Free Download - Prikachi - Service Diagrams

Free TV Schematics Download - HARDW.net - Pinout Master - Jabse Search - Jabse.InK  - Pulsator

Connector Pinout Forum - Новини - SnimkiOt.com - безплатен DNS - Whois разузнаване - Poblizo.com : пътешествия