RCF Art 715: Identifying L502 Choke & C76 Capacitor Values on PST417F PCB Board

Question

I need to identify two elements (their values) on the board (PST417F) from the above mentioned columns. One is a choke marked L502 and a capacitor marked C76. Will someone help?

yogi009 · Answer

Photo, buddy, clear photo of this plate (on both sides) ... it will be hard to remember.

Świr · Answer

Here you are (better my camera can't):

yogi009 · Answer

I see two outputs, either find the schematic (which may not be easy) or measure these items in the second column. Do you have access to capacitance and inductance measuring instruments? Expect this capacitor to be something a la 100nF, but it's shooting in the dark. However, it is better to measure.

Świr · Answer

The measurement from the second column is out of the question. Unless someone has better meters than mine. I need the value of these items preferably from a service shop. This capacitor is not 100nF. Unfortunately.

yogi009 · Answer

Have you tried to write a mail asking the manufacturer for a diagram? Crate didn't bother me with that.

Świr · Answer

Haven't tried - but a good suggestion. I'll try tomorrow.

Świr · Answer

Unfortunately - the Italians are silent.

yogi009 · Answer

Call me, it's better handled over the phone.

borys.stw · Answer

Hello, the question as above is only about one tiny element that has been lost to me. What is a coil, resistor or maybe a jumper? Thank you in advance for your help and best regards.

yogi009 · Answer

A colleague of neither pear nor parsley in someone else's thread puts in some photos? In addition, in the photo, both elements are in place.

borys.stw · Answer

I borrowed a photo to show the item that was lost. There is no need to set up a new topic.

yogi009 · Answer

I wonder if the forum rules also see the need.

borys.stw · Answer

One simple question, what is this item. The subject speaks of the device in question and the same problem that I have. So why should I set up another topic, how can I refresh it?

yogi009 · Answer

You mean the C130? The description suggests a capacitor. Give the markings of these mosfets, maybe the application will tell you something (I would always start with 100nF).

Added after 5 [minutes]:

Still slightly edited for better readability.

pikarel · Answer

The capacitor is marked with a black arrow and there should be no problems with identifying the type of element.
The marking of the element marked with a red arrow and the letters VR can mean a varistor, i.e. a varistor.
https://ec.kemet.com/varistor-mov-voltage-protection

yogi009 · Answer

And what capacity do you read from?

pikarel · Answer

A colleague clearly asked: and I answered the question exactly. Electronics is a science, not poetry.

yogi009 · Answer

You are literally right, but in practice it adds little to the topic.

borys.stw · Answer

Hello, I was able to determine that VR3 is a thermistor, but I do not know what resistance it should have and whether it is an NTC or PTC thermistor. Please help.

pikarel · Answer

It is located next to the rectifier circuit, so maybe it is an NTC with a value of single ohms, used to protect the diodes against too high a charging current of the capacitor. In the photo I cannot see if VR is connected to ground or to a thin path leading to the via, which is very important as it determines whether it is a varistor or a thermistor.

borys.stw · Answer

100% is a thermistor because on the other side is VR4 and it is a thermistor at the mains voltage input. One leg goes to the optocoupler emitter, the other leg goes towards the dsp and power amplifier. In the evening I will find out where exactly.

I measured this arrangement:
[url=https://obrazki.elektroda.pl/8624278200_1517861327.jpg]

kanmar · Answer

Hello. And how did it end with this rcf? Because it's the same for me.

Świr · Answer

I sent the amplifier to the man who handles it. He fixed it.

kanmar · Answer

You didn't ask what was damaged?

Świr · Answer

I just checked on an email. Repair description: Repair of the audio input circuit.

mediaitechnika · Answer

Hello colleagues ... I'm sorry, but allow me to join the discussion. I have a similar problem as above. friend. Does anyone have the parameters of this L502 choke from the system? Or maybe you have a service manual. Thank you in advance and best regards

hducanh118 · Answer

BLM21PG331SN1D

RCF Art 715: Identifying L502 Choke & C76 Capacitor Values on PST417F PCB Board

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