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!

©2010, 2011, 2012, 2013, 2014 Frank Sharp - You do not have permission to copy photos and words from this blog, and any content may be never used it for auctions or commercial purposes, however feel free to post anything you see here with a courtesy link back, btw a link to the original post here , is mandatory.
All posts are presented here for informative, historical and educative purposes as applicable within fair use. NOTHING HERE IS FOR SALE !

Thursday 19 November 2020

JVC KDR440 CD RECEIVER, HOW TO ENTER SERVICE MODE AND SERVICE ADJUSTMENTS, SCHEMATIC DIAGRAM

KD-R440J, KD-R440JW, KD-R441E, KD-R441EN, KD-R441EU, KD-R441EY, KD-R442E, KD-R442EN, KD-R442EY, KD-R443E, KD-R443EN, KD-R443EY, KD-R444UI, KD-R445U, KD-R445UN,
KD-R446EU, KD-R446U, KD-R446UN, KD-R446UP, KD-R446UT, KD-R447EE, KD-R449E, KD-R449EE, KD-R449UR, KD-R540J, KD-R541E, KD-R541EN, KD-R541EY, KD-R547EE


Service Test mode

Default status immediately after the mode activation
Operating Key: [MENU] + [ |<< ] (7sec) Press and hold.

How to release each Test mode
• Reset
• Acc off
• Power off
• Panel Detach

Mode content
Syscon shall display the following information after entering this mode. The operation shown below shall be workable.


Service Information Clear Mode

Default status immediately after the mode activation
* The receiver is connected with the DC power supply (with the power supply turned off).
Operating Key: [BACK] + [POWER] Press and hold + DC power supply turned ON

How to release each Test mode
• Reset
• Acc off
• Power off
• Panel Detach

Mode content
After entering this mode, Syscon shall clear the information stored for service and output the result to the display tube.
CD will be ejected upon process ended.
Preset Frequencies and Tagging (HD models) information shall be cleared.

DC error information mode

Default status immediately after the mode activation
* The receiver is connected with the DC power supply (with the power supply turned off).
Operating Key: [MENU] + [ >>|] Press and hold + DC power supply turned ON

How to release each Test mode
• Reset
• Acc off
• Power off
• Panel Detach

Mode content
Syscon shall display the following information after entering this mode. The operation shown below shall be workable.

DC offset error description

DC offset detection circuit design
• Purpose:
To prevent breakdown, burning and emitting smoke from customer's car speaker when occur DC offset between speaker output "+" and "-".
• Target:
Detect DC offset, then stop the Power Amp operation and shift to specified condition.

Possible causes of DC offset at speaker output lines
(1) Mis-connection for speaker output for example touch to car body or battery line.
(2) Current leak of coupling capacitor for Power IC input.
(3) Current leak of Ac-GND capacitor for Power IC Ac-GND.
(4) Capacitor shorted of above parts due to foreign object.

To detect DC offset Error
• Mis-connection
- Short any one speaker out line to GND or Vcc
• Capacitor leak
- Parallel 330kΩ to either any one of coupling cap or Ac-GND cap (to simulate current leakage of capacitor)
- Shorted either any one of coupling cap or Ac-GND cap.

Manipulate after detect DC offset
• If detected error 10 consecutive times, and 10th error occurred in "Mis-connect detection period", judge as "Mis-connect".
• If detected error 10 consecutive times, and 10th error occurred in "Capacitor leak detection period", judge as "Capacitor leak ".
• If detected error 10 consecutive times, and 10th error occurred in "Other detection period" and detected another 10 errors consecutively, then judge as "Other".
• If judge as "Mis-connect". - turn off speaker output.

- display "MIS WIRING" > "CHK WIRING" > "THEN RESET" > "UNIT".
- key access disable except button of Eject, Reset and service mode
- record error in EEPROM "DC1 ERR"
- Set is able to be recovered by Reset button.

• If judge as "Capacitor leak ".
- turn off speaker output.
- display "WARNING" > "CHK WIRING" > "THEN RESET" >"UNIT".
- key access disable except button of Eject, Reset and service
mode
- record error in EEPROM "DC2 #" (# means counter number)
- Set can be recovered by pressing the Reset button before the capacitor leak error counter reach "DC2 4".
After that, only clear the counter back to "0" can recover the set.
• If judge as "Other" (manipulation same as mis-connect)

How to cancel DC offset error

Check to be sure the terminals of the speaker leads are covered with insulating tape properly, then reset the unit.
If an error message does not disappear even after a reset, there is a need for internal repair.

How to clear DC offset error recorded in EEPROM

DC Error Information Mode is started.
[MENU] + [ >>|] Press and hold + DC power supply turned ON
DC1 ERR > [ >>|] Press and hold.> DC1 OK
DC2 1-4 > [ |<<] Press and hold.> DC2 0

SCHEMATIC DIAGRAM