• Marshall stanmore II Identify value of resistors in power supply

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#1 Marshall stanmore II Identify value of resistors in power supply


Napisal/-a Zemog 9 Julij 2024, 09:55
I have the Marshall Stanmore II bluetooth speaker with power supply part number DSO602-240250-17417. The diode bridge is damaged and shorted, and has damaged other parts of the circuit. After cleaning and sanitizing, I cannot clearly identify the value of resistors R8, R9 and R10, especially R9.
R8 and R10 appear to be 10 ohms (marked 100) but R9?

Can somebody help me ?

Slika

Re: Marshall stanmore II Identify value of resistors in power supply


Napisal/-a Google Adsense [BOT] 9 Julij 2024, 09:55

#2 Re: Marshall stanmore II Identify value of resistors in power supply


Napisal/-a matic 10 Julij 2024, 13:25
Hello!

Please, post a clear picture of primary side of the power supply from both sides of the board.

#3 Re: Marshall stanmore II Identify value of resistors in power supply


Napisal/-a Zemog 10 Julij 2024, 18:51
Slika

Slika

Slika

Is it ok?

#4 Re: Marshall stanmore II Identify value of resistors in power supply


Napisal/-a matic 11 Julij 2024, 07:32
These three resistors are shunts to sense the current flowing through the transistor Q1.
What is the marking of chip U1?

#5 Re: Marshall stanmore II Identify value of resistors in power supply


Napisal/-a Zemog 11 Julij 2024, 11:44
matic napisal/-a:¿Cuál es la marca del chip U1?


GR8874

#6 Re: Marshall stanmore II Identify value of resistors in power supply


Napisal/-a matic 11 Julij 2024, 13:30
Replace all three resistors R8, R9, R10 with a value 1Ω/1%, package 1206.

Also check the resistor R11 (470Ω) and measure the resistance between pin 4 and pin 6 of chip U1 (it should be high - in kΩ range or greater).

#7 Re: Marshall stanmore II Identify value of resistors in power supply


Napisal/-a Zemog 11 Julij 2024, 18:37
matic napisal/-a:Reemplace las tres resistencias R8, R9, R10 con un valor de 1Ω/1%, paquete 1206


Could I place the 3 1.2Ω resistors? The supplier has them of that value, but not 1Ω
Will it influence?

#8 Re: Marshall stanmore II Identify value of resistors in power supply


Napisal/-a matic 11 Julij 2024, 19:09
No, you couldn't.
The value of these resistors is critical and should be within a few % tolerance. At 1.2Ω resistors, the tolerance is 20%, which is not acceptable.

The option is to use three pieces of 1.2Ω resistors and an additional one piece of 2Ω (or 2.2Ω) resistor, which you solder on the top of resistor R9.

Note that the tolerance of used resistors must be 1% (the classic resistors with a tolerance of 5% are not acceptable here).

#9 Re: Marshall stanmore II Identify value of resistors in power supply


Napisal/-a Zemog 15 Julij 2024, 13:00
matic napisal/-a:También verifique la resistencia R11 (470Ω) y mida la resistencia entre los pines 4 y 6 del chip U1 (debe ser alta, en el rango de kΩ). o mayor).


The value of R11 is correct.

The resistance between pins 4 and 6 of U1 (with the chip soldered on the board) is 2k, can this be considered valid?

Q1 (svf10n60f) was also damaged and is shorted

#10 Re: Marshall stanmore II Identify value of resistors in power supply


Napisal/-a matic 16 Julij 2024, 09:10
Zemog napisal/-a:The resistance between pins 4 and 6 of U1 (with the chip soldered on the board) is 2k, can this be considered valid?
That's probably fine, so the chip U1 probably survived.

Zemog napisal/-a:Q1 (svf10n60f) was also damaged and is shorted
That's expected and is also a reason for the damage on resistors R8, R9, R10.
The fuse F1 is probably also damaged.

#11 Re: Marshall stanmore II Identify value of resistors in power supply


Napisal/-a Zemog 25 Julij 2024, 11:20
The 3 resistors go in parallel, right?
According to the first photo, although the track is damaged, it seems to me that they are in parallel, and I have repaired the track on both sides of the resistors.


Slika

#12 Re: Marshall stanmore II Identify value of resistors in power supply


Napisal/-a matic 26 Julij 2024, 10:47
Zemog napisal/-a:The 3 resistors go in parallel, right?
Yes, exactly.

#13 Re: Marshall stanmore II Identify value of resistors in power supply


Napisal/-a Zemog 1 Oktober 2024, 13:12
Hello, sorry for the delay but I have not been able to continue with this repair before.
After replacing the resistors and other damaged components, there is still no current at the output.

In the Drain of the 10N60 I now have 330V but in Gate and Source 0V.
Would it be logical to change U1 (GR8874)?

#14 Re: Marshall stanmore II Identify value of resistors in power supply


Napisal/-a matic 1 Oktober 2024, 20:30
- Measure the resistances to ground on pins 3, 5, 6, 8 of chip U1.
- Measure the voltage to ground on pin 8 of chip U1.

#15 Re: Marshall stanmore II Identify value of resistors in power supply


Napisal/-a Zemog 3 Oktober 2024, 19:04
matic napisal/-a:Medir las resistencias a tierra en los pines 3, 5, 6, 8 del chip U1

Pin 3 ... 7 Ohm4
Pin 5 ... 10k
Pin 6 ... 1,7k
Pin 8 ... More than 2 Mega ohms

matic napisal/-a:Mida la tensión a tierra en el pin 8 del chip U1

Pin 8 ... 311V

PD. Pin 6 (VCC) ... 0V

#16 Re: Marshall stanmore II Identify value of resistors in power supply


Napisal/-a matic 3 Oktober 2024, 20:08
Zemog napisal/-a:Pin 3 ... 7 Ohm4
What does it mean? Is it 7.4Ω or what?

#17 Re: Marshall stanmore II Identify value of resistors in power supply


Napisal/-a Zemog 4 Oktober 2024, 10:07
No, sorry! I missed the 4 without realizing it. It's 7 Ω

#18 Re: Marshall stanmore II Identify value of resistors in power supply  [REŠENO]


Napisal/-a matic 7 Oktober 2024, 08:49
Not fine. It should be 470Ω.

There are only two options:
You have replaced the resistor R11 with a wrong value, otherwise the chip U1 is damaged.

#19 Re: Marshall stanmore II Identify value of resistors in power supply


Napisal/-a Zemog 16 Oktober 2024, 13:12
matic napisal/-a:el chip U1 está dañado


U1 chip (GR8874) changed, and now the equipment is working. Thank you very much

Re: Marshall stanmore II Identify value of resistors in power supply


Napisal/-a Google Adsense [BOT] 16 Oktober 2024, 13:12

Kdo je na strani

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