FET Audio | Hi-End Audio & Electronics DIY Electronics & Repair

Problem: cannot powerup.  digital L/R no output.

Cause: Cold solder joint at power amp driver transistors / Digital filter AL24 IC NG.

Actions:

1. Touch up all solder joint on power amp board (100%).
2. Add small heatsink onto driver transistors.
3. Replace digital filter by DF1704 (Denon DXP6001 cannot find).
4. Cleaning and anti-rust all metal parts.

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Is it laser issue?  Not really.  It is a good build DVD player by Arcam but use a Korean DVD rom with poor components – capacitors.

The main board and power supply board all use Japanese capacitor and audio grade!  What a waste for this WM8740 DAC also.

I take out the dvd rom and use a USB to parallel connector to put that into my computer but the rom cannot detect CD or DVD.  I am think it is the laser issue.  Later I observed one capacitor body a bit dirty and looks like chemical contamination.  I take it out and measure it, oh it cannot be measure at all!  totally dead.  Thus I start to take out few more capacitors and found most of them are almost dead or left 10-20% of capacitance value with high internal resistance.  So action is to change all the smd capacitor on the dvd rom.  After that the computer connector is able to read CD and DVD disc!!!

As usual, do clean up and touch up with paint pen on any rusty casing on the set.

Lesson Learnt, do not use Korean made spare part in your high end product!  they all use cheapy capacitors which can last 5-10 years only.

Still have a bit issue as some CD cannot be read when power up.  Only able to read after playing for 15 mins.  Anyway I have order a laser head for this CD rom drive and will replace it to see if better.

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Got this for $100 SGD with bad conditions and repair before by some unprofessional people. Power board use mix of power and driving transistors!  Missing big filter caps cover and metal support x 3 pcs!  PCB crack under the big cap due to movement.  This is really a old set and heavy beast. 

Repair done:

Remove all grease on pcb.

Clean and polish all the switches, then put contact oil to protect it.

Change all power and driver transistors to match pairs.

Clean and polish relay contact.

Repair crack pcb with wires, solder and solder mask.

Repair the wood board with wood wax.

Change the bias VR to 10 turn type for accurate adjustment.

Make metal support frame and cut big capacitor holder to secure it to prevent movement.

Finally all cleaning and painting of the cover to prevent rust.

Total repair many manhours!

Enjoy some pictures.

 

 

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