HY9 is a Zener for ? voltage

[capwizard]

Hello, I am not try to give you guys A hard time.

I am troubleshooting A INSIGNIA NS-29D310NA15, One board TV (PCB: TP.MS3393.PB703), under $100 TV, I ordered the PCB at US $34.42.

Yes, I can change the PCB and fix this TV in 5 mins, but I want to fix the original problem otherwise Im gonna learn nothing.

Question : HY9 is a Zener for ? voltage

I use Haier 32" service manual fix this INSIGNIA 29" TV. From pic2, my guess is (HY9) a sot-23 9v Zener!

PS: I can use poormans LED tester to test another good parts (zener).............

[budm]

Re: HY9 is a Zener for ? voltage

Well, if you at least start a new thread in the TV section with make, model, pictures and any service manual you have plus what is the TV or the power supply board not doing will be a good start.
i doubt that it will be 9V ZENER since it is for clamping the running Voltage from the SMPS transformer.
What is the UB101? You can get the spec sheet and look at the MAX VCC the IC can handle then you will have some idea what the Zener Voltage will be.
BTW, why do you think that Zener bad? It is for protection so the the circuit will work without it.
it sounds like you are just looking all over the places without trying to narrowing down to the suspected section of the circuit, if we know what Voltages have or not have then you can narrow down the search. I will not even try to removing all throwing in the parts yet at this point since you can create new problems.

[capwizard]

Re: HY9 is a Zener for ? voltage

Yes I will, but now I need to know what the part HY9 means ?

[budm]

Re: HY9 is a Zener for ? voltage

Yes I will but now I need to know what the part HY9 is ?

Why?
What is the required VCC to run that SMPS IC? IC spec? Is it shorted or low resistance reading?
read my post 2.

[capwizard]

Re: HY9 is a Zener for ? voltage

SMPS IC : UB101 It is the LD7573
https://www.badcaps.net/forum/showthread.php?t=60813

Recommended Operating Conditions

-----------------------------Item Min. Max. Unit
Supply Voltage Vcc (LD7535) 11 25 V
Supply Voltage Vcc (LD7535A) 11 18 V
Switching Frequency 50 130 KHz
Startup Resistor Value 1.2 4.4 MΩ

[gabiz_ro]

Re: HY9 is a Zener for ? voltage

Such kind of zenner protection will have voltage,few or more,greater than UB101 start-up voltage and lower than UB101 maxim Vcc Voltage.
Ex.
Start-up Vcc is 10V
Max Vcc is 18V
Then I use 15V zenner diode to protect IC

That was just an example.
Not related to IC presented here.
Apologise.
Until I post my message,have few phone calls,looking for smd code etc and messages 2-3-4-5 appears.

[budm]

Re: HY9 is a Zener for ? voltage

Well, I wish you stay with one thread instead starting the new thread working on the same board.
You do not want a repeat of this: https://www.badcaps.net/forum/showthread.php?t=60332, do you?

[budm]

Re: HY9 is a Zener for ? voltage

UVLO (ON) is 16V typ, not 10V.
10V is the shutdown Voltage once the IC is running when it reaches the start up Voltage (16V) then as long as the Vcc does not go down to 10V then it will be running, or above 21V for A' version, 28V for non 'A'
Read the Application information and look at Fig 3.
Max Vcc is not 18V:

Recommended Operating Conditions
Item Min. Max. Unit
Supply Voltage Vcc (LD7535) 11 25 V
Supply Voltage Vcc (LD7535A) 11 18 V
Switching Frequency 50 130 KHz
Startup Resistor Value 1.2 4.4 MΩ

OVP is:
LD7535 --- 28.0V ± 1.5V.
􀁺 LD7535A --- 21.0V ± 1.5V.

Max VCC is:
Absolute Maximum Ratings
Supply Voltage VCC 30V

Info are there in the spec sheet.

[capwizard]

Re: HY9 is a Zener for ? voltage

gabiz_ro Good idea ! Maybe I can omit it, I try now see what's happening!

[budm]

Re: HY9 is a Zener for ? voltage

gabiz_ro Good idea ! Maybe I can omit it, I try now see what's happening!

Please read the spec sheet, that info given is wrong, it is not 10V.

[budm]

Re: HY9 is a Zener for ? voltage

Such kind of zenner protection will have voltage,few or more,greater than UB101 start-up voltage and lower than UB101 maxim Vcc Voltage.
Ex.
Start-up Vcc is 10V
Max Vcc is 18V
Then I use 15V zenner diode to protect IC

Sorry, that are wrong information, please read the spec sheet again. Please figure out how to read the spec sheet.

[gabiz_ro]

Re: HY9 is a Zener for ? voltage

Until I post new message,new messages appears.
At that time didn't know about what IC is in discussion.

It was just an example.

All values are changed when you know about what IC is talking.

You may note that I say greater than UB101 start-up voltage,but at that time didn't know what is UB101

You may omit that zenner and all still working fine in some cases.But risky,IC could be damaged.

[budm]

Re: HY9 is a Zener for ? voltage

Post 2: 'BTW, why do you think that Zener bad? It is for protection so the the circuit will work without it."
I also already ask if the Zener is bad or not.

[budm]

Re: HY9 is a Zener for ? voltage

gabiz_ro Good idea ! Maybe I can omit it, I try now see what's happening!

Knowing you will do that is kind of funny. Remember you were removing transistors from the circuit without understanding what is going on?

[capwizard]

Re: HY9 is a Zener for ? voltage

gabiz_ro..................... .........." Then I use 15V zener diode to protect IC"

HY9 it is A 15v Zener diode. Not 9v

I omit it , the power supply works................yes .............

[budm]

Re: HY9 is a Zener for ? voltage

Once the VCC reaches the 16V startup Voltage, then it can drop down to be any where as long as above 10V, you should look at the VCC pin when first power is apply to see what the VCC using peak hold.
OVP for 'A' 21V
UVP = 10V
Recommended running V is 18V (A).

[capwizard]

Re: HY9 is a Zener for ? voltage

"Once the VCC reaches the 16V startup Voltage"

I will put A 15 Zener diode, Thank you, budm.

[gabiz_ro]

Re: HY9 is a Zener for ? voltage

Using a lower voltage zenner can overburden RB110 or RB114-RB115 or even damage new zenner.
Best way is to use one few volts lower than absolute maximum voltage

15V is not enough,few exception,maybe depending on IC or zenner diode.(in real diode is 15.6V and IC could start at 15.5 but that is like lottery,zenner may have 14.9 and IC start at 16.3V so no way to start)

Few HY zenner diodes found was 18V

[budm]

Re: HY9 is a Zener for ? voltage

"Once the VCC reaches the 16V startup Voltage"

I will put A 15 Zener diode, Thank you, budm.

After all the explanations, I gave up.

[capwizard]

Re: HY9 is a Zener for ? voltage

Thank you, gabiz ro ,This kind of power supply on a lots of Chinese small size, one board TV. Actually is not worth you time to repair if you can get a PCB for $20, but the knowledge is priceless.

PS: I spend 2 days to fix it. It's not worth my time but I am extremely happy. 3 parts changed to fix this PCB. ( It covers a lot of brand name TVs EX: SEIKI SE39HE02 MAIN BOARD N14070237 TP.MS3393.PB713 at pic3.)

PS: look at pic2 right side PCB EEprom is gone because I try to dump it.............