martes, 16 de agosto de 2011

un minicomponente


 ¿which is a mini component?

It is what is commonly known as a stereo. The term came into vogue in the lateeighties, because electronics brands entered the market very compact devicesin size (approx. 60-70cm long complete with horns) but with good sound quality. Also including cassette players (usually double), radio tuner and CD in the same apparatus. Unlike normal devices, which were large consoles where each unit issold separately and connected.

Material bajado de la página:

-Minicomponente protection circuits AIWA NSX-S111

As an example we will use the computer AIWA NSX-S111, which is formed by aclass AB amplifier with Darlington output transistors. Some models use transistor amplifiers aiwa, as in this case, but others use integrated circuits. More powerful computers also use class H amplifiers but the description of the types of audio amplifiers will see them another time.

The power amplifier is starting 20vcc + VP,-VP-20vcc.

The control manager is M38B59MFH-P109FP. That is for your I-hold terminal (pin 2) to note if there is a change from any of the protections.

O-power terminal (pin 18), which controls the relay that connects or disconnects+ VP-VP, the amplifier.

-Detector circuit AC (alternating current)

There are always power cuts, sometimes very continuous for several reasons.The weather, maintenance problems of the grid lines overloaded if an industrial area, and so on.

Cuts are known to cause voltage spikes that are very destructive to equipmentand can cause a variety of damage.

For this reason, amplifiers and audio equipment have this circuit.

- Description and operation of the circuit:

D108-109 D101-102 and form a bridge rectifier, using the same voltage usedfor the amplifier, with the difference that rectified through current limiting resistor.See D108-109 that are encapsulated in a single R115-R116 still the limitingcurrent.

D101-102 are the same diodes that rectify the-VP for the amplifier, but to deliver the negative half circuit through R117.

About R118 will have a voltage drop to Q107-Q108, driving, this causes tensionat the base of Q106 C113 is very low and almost downloaded. In this condition,while there is line voltage of ca. The collector of Q106 will be approximately5VDC. (See Figure 1)

Now if the line voltage were to be cut. C113 is charged by driving to Q106, dropping the voltage at collector of this, or I-hold.

In this situation, the control system changes the state of o-power, which controls the relay, opening it by cutting power to the amplifier. And the control systemgoes into standby. Remain on standby until it is the firing order and / or up to fix the damage that may have caused.

-Detector circuit DC (direct current or DC)

As its name implies, this circuit is designed to control the presence of current inthe audio output of the amplifier, because as mentioned above, the amplifier is very prone to damage from problems in the output. A bad speaker can cause a short circuit in the output transistors, and if not cut the power off immediately, the damage would be great all the circuits can damage the amplifier and to the source!.

- Description and operation of the circuit:

The bases of Q109-Q110 are connected to each output of the amplifiers throughR237-R238 100K each.

While the amplifier did not show any defect in its output value should not present any CD neither positive nor negative. In this condition, Q110 Q109, not lead.

If you have a defective component, such as a leaky transistor or short, there is an imbalance in the audio output voltage appearing, positive or negative. Havingcontinued this becomes the basis for charging Q110 Q109-C114, and producing the conduct of these Q107-Q108 blocking. under these conditions is loaded C113, Q106 leads to saturation and low collector voltage affecting theterminal I-hold. (see Figure 1)

In this condition the control system cuts power, changing the state of the terminal or-power, which leads to the circuit controlling the relay. And the bus goes into a wait state, but turning off the display completely. Remain in this condition until the problem is resolved.

- Overload detector circuit

If you connect a subwoofer that has a speaker with the coil rubbing, or connect more than one subwoofer in the audio output. It requires the amplifier to deliver more current than normal, running risks of the output transistors and the surrounding components.

To prevent the amplifiers harmed by excessive current, this circuit is linked between the output transistors and the terminal I-hold to cut the power to a problem with the load.

-Description and operation of the circuit:

Q215-Q216. detectors are overloaded. Q218, is responsible for changing the level of I-hold terminal to an excess current.

The bases of the detectors are connected to the collectors of Q213-Q214, which are TR output. And through R291-R292, are connected to the collector of Q218.

The emitters are connected to-VP.

The collectors are connected: a differential amplifiers of the two channels, a circuit that improves the current flow in the outputs, and the base of Q218. note the diagram that all these connections they are made through diodes and resistors. And finally the I-hold terminal is connected to the emitter of Q218 through R244.

When the amplifiers are operating normally, Q215-Q216 non-drivers. And remain in this state as tensions in their bases do not exceed 0.6 V.

Now if for some reason there is a higher power consumption in one of the amplifiers, the voltage at the base of Q215 or Q216, begins to rise, causing the conduct of any of these.

The difference between BE is produced by being connected in parallel with R249-R250. circulating current in these directly affect the voltage on the basis of the guards.

The conduct of one or both detectors (depending channel is damaged), Q218 does lead to changing the status of I-hold. thus the team through the change of state in o-power, cut off power amplifiers, and go into stand by. 
Operating the display only.

- Conclusion
As you will see when you know why a team does not start, there are several sections to be discarded. It's always good to ask the client what has happened before the computer inoperable. The data this contribution, we can target to detect where the problem is and / or review steps, we would have overlooked and, later going to fail.
Teams often harmed by:
- Connect over a baffle on the outputs. The equipment is protected from overcharging.
- Use baffles damaged.
- For a short circuit in the connection. Sometimes users in trouble let loose copper wire and end up playing anywhere! Causing a short in the output.
- By using less powerful speakers. In these cases if they require the team ends up being damaged and therefore the speaker, a short in the output.
- And I have played many teams with the output of the source and short. A reason that the customer had the wrong wiring of the home. I found out because wedeliver the equipment running and this again with the same damage right away! I went to the house and surprise! A very old facility, with many losses and phaseover!.
Well many may be the cause of faulty audio equipment, it is important to know how it works, and on that basis, we propose a diagnostic method, which we’ll refine with time and experience we gain.
Finally I say, as I mentioned earlier, that there are differences between brandsand models, but most teams have in amplifiers with these protections, so the report is valid when working with a team from another brand.

Material bajado de la página:

1 comentario:

  1. Me parece espectacular el blog... pero la letra esta muy pequeña... debiste usar arial 12, y el color de los títulos con un color que contraste con el fondo de la pagina¡