Lightning and CDP's don't mix - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 21st September 2007, 04:26 AM   #1
mmerig is offline mmerig  United States
diyAudio Member
 
Join Date: Jan 2005
Location: south east Idaho, Teton Basin
Default Lightning and CDP's don't mix

Recently, lightning struck the service wire to our house, and one of the casualties was our CD player. Using the sevice manual as a guide, I think I have isolated the problem to the DAC, as I can get a digital signal to another DAC and sound results. The power supply is fine, and DC off-set at the output is < 3 mV. So far I have only found and replaced one bad transistor; all others tested okay. I replaced 4 IC's that could have been damaged (I could not test them) that had something to do with the analog section, muting circuit, or DAC. The DAC itself is a Burr-Brown PCM1716. There is a faint sound if I turn up the volume all the way.

Could a damaged DAC still put out a little sound?

The DAC is surface mounted (soldered) with 28 very small leads. What would I need to replace this chip? is it feasible to do by hand?
  Reply With Quote
Old 1st October 2007, 09:02 PM   #2
diyAudio Member
 
Join Date: Nov 2004
Location: Germany
I would double check the output stage - have you replaced all the opamps involved? Then again, the PCM1716 seemingly is a voltage output DAC, i.e. has an I/V amp stage built in, which might well be blown.
  Reply With Quote
Old 1st October 2007, 11:24 PM   #3
rossl is offline rossl  United States
diyAudio Member
 
rossl's Avatar
 
Join Date: Nov 2004
Location: Central Ohio
Don't try to remove the IC with an ordinary soldering iron. You will damage the PCB.

Repair shops have a U-shaped soldering tool that heats all 28 pins at once. The tool has a vacuum accessory that lifts the IC once the solder on all 28 pins is melted.
  Reply With Quote
Old 2nd October 2007, 12:57 AM   #4
mmerig is offline mmerig  United States
diyAudio Member
 
Join Date: Jan 2005
Location: south east Idaho, Teton Basin
Thanks for the advice.

Since posting the original message, I found out what is involved in replacing the DAC chip, and I will not do it myself, as I figured I would probably ruin the PCB using ordinary tools, and it is not worth investing in special tools for just one chip.

As for the output stage, I checked all of the active devices in it and the muting circuit (transistors, opamps), and only found one bad transitor in the muting circuit. All of the voltage regulators in the powers supply are fine.

I think I will send it out for repair.
  Reply With Quote
Old 14th December 2007, 03:02 PM   #5
mmerig is offline mmerig  United States
diyAudio Member
 
Join Date: Jan 2005
Location: south east Idaho, Teton Basin
The ARCAM repair center found that the DAC chip was probably ok, but the "motherboard was corrupt", and it is not available anymore. The only chip I did not replace related to the DAC was a contoller. I figured it was okay as the transport and remote functioned fine, but part of this chip controls the DAC. The ARCAM repair folks tested the transport section and said it was good.

Anyway, I would like to install a DAC in the ARCAM case by using the existing regulated power supply and audio section. The unit has a provision for an upgrade DAC (not available either) so the connections are a little easier than cutting traces etc. The digital output is SPDIF and it goes through an isolating transformer. I plan on shielding the DAC unit.

Is there a basic problem with this approach? I have the repair manual and schematic, and will try the RAKK DAC if it fits. Does anyone know the dimensions of the original RAKK DAC?

I asked Kevin at K & K Audio about this, and he recommended against installing one and suggested I buy the Mk II DAC, PS, and line stage and build an external DAC. This could be simpler, but much more expensive.

What do I have to lose by trying to patch in a DAC? The main difference between this and an external box seems to be location.
  Reply With Quote
Old 14th December 2007, 03:30 PM   #6
diyAudio Member
 
analog_sa's Avatar
 
Join Date: Aug 2002
Location: Sofia
I wouldn't take the "corrupt motherboard" diagnosis very seriously. Have someone else look at it. Maybe someone from this board in your area?

Installing a complete external dac inside the CDP case is certainly possible but from my POV it's simply wrong. External dacs have spdif inputs and using those is (maybe) acceptable for an external dac but there is just no excuse to do it inside a CDP. Try to identify I2S signals and format for your dac and you'll stand a chance to end up with a good sounding CDP again.

Still, rather repair it than create a Frankenstein.
  Reply With Quote
Old 14th December 2007, 07:30 PM   #7
mmerig is offline mmerig  United States
diyAudio Member
 
Join Date: Jan 2005
Location: south east Idaho, Teton Basin
Thanks for the advice. The "corrupted motherboard" comment came from Charley Croan at ARCAM in the UK when the ARCAM repair center asked for help, so it may have some credence. I live in SE Idaho -- is there anyone on this board near me?

It may be difficult to get I2S signals out of the disc drive unit as the manual only mentions SPDIF coming out of the decoder.

What's the disadvantage of SPDIF compared to I2S?
  Reply With Quote
Old 15th December 2007, 03:57 AM   #8
diyAudio Member
 
Join Date: Aug 2005
Quote:
Originally posted by mmerig
The unit has a provision for an upgrade DAC (not available either) so the connections are a little easier than cutting traces etc. [/B]
Can you be more specific?
  Reply With Quote
Old 16th December 2007, 05:36 PM   #9
diyAudio Member
 
Join Date: Mar 2004
Location: UK
Hi,

What test equipment do you have to diagnose the problem ? An oscillosope and logic analyser would be useful !

When you say faint sound is that music or noise? If it's music then I'd look at the output stage again.

I'm not sure if anyone does a U bit to desolder all 28 pins in one go ? There are methods of removing SMT ICs using a pair of tweezers a very sharp knife and a soldering iron but they risk damage to the pcb and destruction of the IC. I'd use solder wick and a pair of tweezers myself but I wouldn't recommend it to someone who isn't confident with a soldering iron !

Cheers,

Jon
  Reply With Quote
Old 16th December 2007, 06:47 PM   #10
diyAudio Member
 
VoltSecond's Avatar
 
Join Date: Mar 2004
Location: USA
Default SMT replacement

It must be a special CD player to just not go out and buy a new one.

One of my buddies unsolders SMT ICs by adding a little solder blob to a pin and the while the solder is liquid bending the lead up with a fine but strong dental pick / tool.

I don't remember if he does the corner pins last or not.
__________________
Unplug it, discharge it, and measure it (twice) before you touch it.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Thunder and lightning Netlist Everything Else 9 22nd August 2006 05:39 AM
Grounding and Lightning jackinnj Everything Else 0 18th October 2004 11:32 AM
Thunder and lightning. In jleaman Everything Else 3 8th July 2003 07:12 AM
Lightning chris ma Everything Else 2 10th May 2003 03:49 PM
Lightning and power surges robertpear Everything Else 2 18th January 2001 01:49 PM


New To Site? Need Help?

All times are GMT. The time now is 02:41 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2