The Adcom GDA 600 modification thread

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  • Poee7RPoee7R Posts: 903
    edited May 2010
    Anyone have a lead on the .1 uf 50v stack metal film caps, or a replacement?

    Digikey is out of them at the moment.


    Dave
    Once again we meet at last.
  • FTGVFTGV Posts: 3,654
    edited May 2010
    If they have stock you can use the .12uf 50v or the .1uf 100v. part #P4526-ND or P4725-ND.
  • dacboydacboy Posts: 23
    edited May 2010
    FTGV wrote: »
    if they have stock you can use the .12uf 50v or the .1uf 100v. Part #p4526-nd or p4725-nd.


    .22 100v???
  • FTGVFTGV Posts: 3,654
    edited May 2010
    dacboy wrote: »
    .22 100v???
    You have some .22uf Panny stacked films and want to use them?Sure.
  • davide256davide256 Posts: 50
    edited May 2010
    ok, I'm in for the PS regulators, web site now showing sale price on the order so no headache there :D Hoping to eek out a little better definition in low base and low volume background sounds.
  • FTGVFTGV Posts: 3,654
    edited May 2010
    I did a mock up on perf board to help show an alternative mounting for the electrolytics and stacked films. I apologize for the poor photography.
    After removing bypass caps,C528,C529,C530,C531 bend the leads of the 'lytic's' (like in first pic)to fit the spacing of the removed caps.Then as shown in pic 2&3 solder the leads of the .1uf's to the 'lytics' so they are paralleled.It is preferable to keep the leads of the .1uf's as short as possible.In pic #4 I tried to duplicate the relative positions and proper polarity as they would actually be on the 600's PC board.The caps I used are bigger but you should get the idea.Alternatively you could install just the lytics on the top side as shown in pic #5 .Then simply solder the .1's to the same solder pads on the bottom side.Hope this is helpful.
  • george danielgeorge daniel Posts: 11,994
    edited May 2010
    Now it makes perfect sense,,thanks for the tutorial Fred--good on you.:)
    JC approves....he told me so. (F-1 nut)
  • FTGVFTGV Posts: 3,654
    edited May 2010
    davide256 wrote: »
    The cap value is documented in the schematic but the inductor doesn't show a value.
    OK that cap.It is there to shunt hi frequency noise to ground but will not affect SQ in any way as it's not in the signal path. I guess somewhere along the line it was suggested that they be removed but thats not necessary.
    davide256 wrote: »
    Hoping to eek out a little better definition in low base and low volume background sounds.
    I would expect any improvements to be in the areas of detailing and dynamics.Bass might tighten up but gain some slam.It will be interesting to hear your impressions after you gents get them installed.

    BTW.Good to see you got yours working correctly.
  • dacboydacboy Posts: 23
    edited May 2010
    FTGV wrote: »
    I did a mock up on perf board to help show an alternative mounting for the electrolytics and stacked films. I apologize for the poor photography.

    Thank you for doing this FTGV!!!!!
  • FTGVFTGV Posts: 3,654
    edited June 2010
    No reg's yet George?
  • george danielgeorge daniel Posts: 11,994
    edited June 2010
    Nope, should be here anyday.
    JC approves....he told me so. (F-1 nut)
  • heiney9heiney9 Posts: 24,125
    edited June 2010
    Nope, should be here anyday.

    Mine too
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass

    Pass Aleph 30 | EE Avant Pre | EE Mini Max Plus DAC | MIT Shotgun S3 | MIT Z P/C's | updated SDA 1C| SQ Box Touch/Welbourne Labs P/S- Tubes add soul!
  • davide256davide256 Posts: 50
    edited June 2010
    regs arrived arrived Monday, but I'm not sure I understand all the steps or where to measure the voltages yet...
  • Poee7RPoee7R Posts: 903
    edited June 2010
    Post #166 in this thread, Fred states what has to be removed and jumped in order to use them. As far as measuring them, they should both be at 15v, as to how to properly measure them... not sure on that yet.


    Dave
    Once again we meet at last.
  • FTGVFTGV Posts: 3,654
    edited June 2010
    davide256 wrote: »
    regs arrived arrived Monday, but I'm not sure I understand all the steps or where to measure the voltages yet...

    1)Remove R110,R111,R112,R113,C122,C123,CR101,CR109.

    2)Install wire jumper in R111 and R113 locations.

    3)Remove LM317(U100)and install 72017 positive regulator,making sure of correct pin orientation

    4)as above but remove LM337(U104) and install 72019.

    5)Those who have their opamp's socketed should remove both of them.If you don't have them socketed then I recommend that you disconnect the cable connecting the power supply to the main board.

    6)After installation of the regulators (and double checking everthing)power up and with a multi meter on the DC scale check the voltages on pin's 4 and 8 of the empty IC sockets.Pin 4 should read negative 15 volts DC and Pin 8 should be positive 15 volts DC.If the voltages are different adjust the little pot on the regulator until you get the correct voltages.Carefully reinstall your opamps and have listen.

    If you don't have your opamp's socketed (and with the cable to the main board disconnected) you will have to check the voltages at the regulator pins or near by on the power supply board.If the voltages check out then you can reconnect the cable.
  • george danielgeorge daniel Posts: 11,994
    edited June 2010
    I received mine yesterday,,if someone instals theirs ,please post an update, I'm having some vision issues and will not be able to perform this surgery until it is corrected.Thanks for the instructions Fred.
    JC approves....he told me so. (F-1 nut)
  • heiney9heiney9 Posts: 24,125
    edited June 2010
    FTGV wrote: »

    6)After installation of the regulators (and double checking everthing)power up and with a multi meter on the DC scale check the voltages on pin's 4 and 8 of the empty IC sockets.Pin 4 should read negative 15 volts DC and Pin 8 should be positive 15 volts DC.If the voltages are different adjust the little pot on the regulator until you get the correct voltages.Carefully reinstall your opamps and have listen.

    If you don't have your opamp's socketed (and with the cable to the main board disconnected) you will have to check the voltages at the regulator pins or near by on the power supply board.If the voltages check out then you can reconnect the cable.

    Question? When you say "Pin 4 should read negative 15 volts DC and Pin 8 should be positive 15 volts DC."

    Do you mean measure pin #4 of socket one to pin #4 of socket two and the same for pin 8?

    Thanks again Fred

    H9
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass

    Pass Aleph 30 | EE Avant Pre | EE Mini Max Plus DAC | MIT Shotgun S3 | MIT Z P/C's | updated SDA 1C| SQ Box Touch/Welbourne Labs P/S- Tubes add soul!
  • FTGVFTGV Posts: 3,654
    edited June 2010
    I'm having some vision issues and will not be able to perform this surgery until it is corrected.
    Sorry to hear that George,hopefully you can get it cleared up.
    heiney9 wrote: »
    Question? When you say "Pin 4 should read negative 15 volts DC and Pin 8 should be positive 15 volts DC."

    Do you mean measure pin #4 of socket one to pin #4 of socket two and the same for pin 8?
    With the black probe of the meter contacting ground,you would first put the red probe on pin 4 of the empty socket (should be -15) then move the red probe to pin 8 where it should be +15.Then check the other socket in the same manner.
  • heiney9heiney9 Posts: 24,125
    edited June 2010
    FTGV wrote: »
    With the black probe of the meter contacting ground,you would first put the red probe on pin 4 of the empty socket (should be -15) then move the red probe to pin 8 where it should be +15.Then check the other socket in the same manner.

    Of course, too early and no coffee............at first it just didn't compute :p
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass

    Pass Aleph 30 | EE Avant Pre | EE Mini Max Plus DAC | MIT Shotgun S3 | MIT Z P/C's | updated SDA 1C| SQ Box Touch/Welbourne Labs P/S- Tubes add soul!
  • george danielgeorge daniel Posts: 11,994
    edited June 2010
    Well lets hear it guys,,don't let a one eyed old man(me) down,,I'm sure that with Fred's guiding hand someone has already got their regulators installed.;)
    JC approves....he told me so. (F-1 nut)
  • davide256davide256 Posts: 50
    edited June 2010
    ok, got mine installed, a little bit crowded on the board but otherwise an easy task with FTGV's instructions. Initial listening impressions are that the wooly mammoth base has been tamed, but too tired at this point to listen for more. Will get some zz's and listen again tomorrow.
  • FTGVFTGV Posts: 3,654
    edited June 2010
    davide256 wrote: »
    ok, got mine installed, ....
    Great! I'm just curious did you need to do any adjustments to the pots to get them operating at 15 volts?
  • heiney9heiney9 Posts: 24,125
    edited June 2010
    Well lets hear it guys,,don't let a one eyed old man(me) down,,I'm sure that with Fred's guiding hand someone has already got their regulators installed.;)

    Haven't even received my parts yet! Good luck George.

    H9
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass

    Pass Aleph 30 | EE Avant Pre | EE Mini Max Plus DAC | MIT Shotgun S3 | MIT Z P/C's | updated SDA 1C| SQ Box Touch/Welbourne Labs P/S- Tubes add soul!
  • FTGVFTGV Posts: 3,654
    edited June 2010
    davide256 wrote: »
    ok, got mine installed, a little bit crowded on the board
    If it is not too much bother I'm sure George, Dave and dacboy would appreciate a pic or two.:)
  • george danielgeorge daniel Posts: 11,994
    edited June 2010
    how do you determine the polarity of the regulators? I've got 4 of these things,,, oops,, 2,,had to put my patch back on,,lol,,post some picks fellas':)
    JC approves....he told me so. (F-1 nut)
  • FTGVFTGV Posts: 3,654
    edited June 2010
    how do you determine the polarity of the regulators?
    http://www.partsconnexion.com/t/Index/burson_reg.php

    At the bottom of the link it shows the pin numbers and orientation. The positive reg is the 72017 (LM317)and the negative is the 72019(LM337).

    I've got 4 of these things,,, oops,, 2,,had to put my patch back on,,lol,,post some picks fellas':)
    LOL.:)
  • george danielgeorge daniel Posts: 11,994
    edited June 2010
    Okay-- components removed and jumpers in place.Since the regulators will not fit side by side unless I bend the pins,,I'll need some help here

    Is this the correct position for the lm 337 in the U 104 slot?(the one on the right.)?
    JC approves....he told me so. (F-1 nut)
  • FTGVFTGV Posts: 3,654
    edited June 2010
    Yes LM337 is designated U104.How tight is the fit?If you need to bend the pins do it carefully,a pair of needle nose pliers will be helpful.

    btw. I can't tell from the pics if the heatsinks on the Burson's are isolated from the transistors mounted to them, so I would make sure the two heatsinks don't touch each other.
  • george danielgeorge daniel Posts: 11,994
    edited June 2010
    I'm gonna have to bend the pins on one,,I did not mean to post the pic of both,,right now just the one on the right,,but I think that I can figure it out.
    JC approves....he told me so. (F-1 nut)
  • FTGVFTGV Posts: 3,654
    edited June 2010
    OK I see you added a pic.They are somewhat bigger than I thought they would be.You might have to get creative.Unless it was just for the pics it appears they should be oriented the other way.
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