REPAIRING AND NOT THROWING AWAY

REPAIRING AND NOT THROWING AWAY

Richtige Fernseher haben Röhren!

Richtige Fernseher haben Röhren!

In Brief: On this site you will find pictures and technical information about Service Modes, Circuit Diagrams, Firmware Update procedure, Disassemble procedure, Universal remote control set-up codes, Troubleshooting and more....

If you go into the profession, you will obtain or have access to a variety of tech tips databases HERE IT IS Master Electronics Repair !.

These are an excellent investment where the saying: 'time-is-money' rules. However, to learn, you need to develop a general troubleshooting approach - a logical, methodical, method of narrowing down the problem. A tech tip database might suggest: 'Replace C536' for a particular symptom. This is good advice for a specific problem on one model. However, what you really want to understand is why C536 was the cause and how to pinpoint the culprit in general even if you don't have a service manual or schematic and your tech tip database doesn't have an entry for your sick TV or VCR.

While schematics are nice, you won't always have them or be able to justify the purchase for a one-of repair. Therefore, in many cases, some reverse engineering will be necessary. The time will be well spent since even if you don't see another instance of the same model in your entire lifetime, you will have learned something in the process that can be applied to other equipment problems.
As always, when you get stuck, checking out a tech-tips database may quickly identify your problem and solution.In that case, you can greatly simplify your troubleshooting or at least confirm a diagnosis before ordering parts.

Happy repairing!
Today, the West is headed for the abyss. For the ultimate fate of our disposable society is for that society itself to be disposed of. And this will happen sooner, rather than later.

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..............The bitterness of poor quality is remembered long after the sweetness of todays funny gadgets low price has faded from memory........ . . . . . .....
Don't forget the past, the end of the world is upon us! Pretty soon it will all turn to dust!

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All posts are presented here for informative, historical and educative purposes as applicable within fair use. NOTHING HERE IS FOR SALE !

Tuesday, 2 April 2019

JBL BP1200.1 - CAR AMPLIFIER - SCHEMATIC (CIRCUIT DIAGRAM)

JBL BP1200.1 - CAR AMPLIFIER - SCHEMATIC (Circuit Diagram)

JBL Power supply / Input – Crossover – Power Amplifier _ Schematic (Circuit Diagram)
SPECIFICATIONS
Number of Channels . . . . . . . . … 1
4 Ohms . . . . . . . . . . . . . . . . . . …… 600W
2 Ohms . . . . . . . . . . . . . . . . . ………1200W
T.H.D. @ 4 Ohms rated Power . .  0.10%
Frequency Response . . . . . . . . . . 10Hz ~ 320 Hz
Signal to noise Ratio . . . . . . . . . . . >100dB
Maximum Current Draw . …………114A
Fuse size. . . . . . . . . . . . . . . ………… 40A x 3
Input Sensitivity. . …….. . . . . . . . .250mV ~ 4V
Minimum Speaker Impedance…1 ohm
External Dimensions
Length . . . . . . . . . . . . ……………….14 13/16 (376mm)
Width . . . . . . . . . . . . . . . . . . . . . . 10 3/16 (274mm)
Depth . . . . . . . . . . . . . . . . . . . . . . 2 11/16 (68mm)
Under certain large signal conditions during intense bass passages, the unit will go into protection. These amplifiers are behaving as designed. As the unit is driven into hard clipping, the protection circuit found in BP Series amps was engineered to protect your loudspeakers from being destroyed by a severely clipped output signal. This can be remedied easily by turning the volume down somewhat on your music source.  In the event you receive a BP series amplifier with the complaint: “Under a large signal input, with music that is composed of high-level bass, the amplifier mutes for 2-3 seconds, and then returns to normal operation”, the following modification will effectively increase the amount of clipping that is allowed to occur before the protection circuit engages by increasing the threshold at which the amplifier mutes - for the benefit of customers who use the amps in SPL competition, or for customers who insist on driving the amplifiers into this potentially hazardous zone.
1  Turn the amplifier upside-down and remove the Phillips screws holding the bottom cover on.
2  Locate and change R510 from 47K to 4.7K ohms 1/5W (JBL part# RE212047200).
3  Locate and change R511 from 22K to 2.2K ohms 1/4W (JBL part# QAF0450-222).
4  If it is not already present, add new part - 4.7uf 50v electrolytic capacitor (JLB part# EC070114760) in parallel with R511. Polarity: The negative side of the Capacitor must be connected to the junction of R510/R511, which can be discovered with an ohmmeter.
NOTE: Using the correct soldering techniques, you should be able to make these changes from the top of the PCB without its removal.
5) Replace bottom cover; test amplifier.
POWER SUPPLY SCHEMATIC
INPUT - CROSSOVER - POWER AMP
Posted By: FRANK at 02:09
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