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    SCA 35. What update mods should be done?

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    poconoman

    Posts : 106
    Join date : 2013-01-17

    Re: SCA 35. What update mods should be done?

    Post by poconoman on Sun Aug 04, 2013 10:21 am

    sailor wrote:peterh is giving good advise however in this case the whole power supply should be changed out as a unit not one part at a time. You have the new power supply board install it and follow the steps I gave in the above post. The solen replacement can wait. Please read these posts very carefully.

    Yes, the cans will be out and the EFB in. Roy's instructions are very nicely laid out.


    poconoman

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    Join date : 2013-01-17

    Re: SCA 35. What update mods should be done?

    Post by poconoman on Mon Aug 05, 2013 7:58 am

    Took out the cans and I'm labeling the wires. But my soldering iron suks. Ordered an AOYUE 9378 station. Tired of spending money on cheap, useless irons.

    poconoman

    Posts : 106
    Join date : 2013-01-17

    Re: SCA 35. What update mods should be done?

    Post by poconoman on Thu Aug 08, 2013 10:51 am

    The AOYUE 9378 arrived and went to work. Installed all the wires into the EFB, 100 ohm resistors and need to put in the 1k resistors. That should do it. Now, to check voltage, I use the multimeter and measure the tube sockets? Explain in detail what areas I should check and HOW to do it.

    Side note. The AOYUE 9378 is a god send. It heats up VERY quickly. I set it to 360c and it's there in 10 secs! Fantastic! And it comes with 10 extra tips of multiple sizes! Highly recommended!


    Last edited by poconoman on Thu Aug 08, 2013 3:04 pm; edited 1 time in total

    sailor

    Posts : 269
    Join date : 2011-04-04

    Re: SCA 35. What update mods should be done?

    Post by sailor on Thu Aug 08, 2013 2:07 pm

    First, before any more advice did you double check your wiring, install the correct fuses and did you make a copy of the manual?

    poconoman

    Posts : 106
    Join date : 2013-01-17

    Re: SCA 35. What update mods should be done?

    Post by poconoman on Thu Aug 08, 2013 3:02 pm

    sailor wrote:First, before any more advice did you double check your wiring, install the correct fuses and did you make a copy of the manual?
    I have the fuse, the manual and I'll triple check the wiring.

    Stay tuned.

    sailor

    Posts : 269
    Join date : 2011-04-04

    Re: SCA 35. What update mods should be done?

    Post by sailor on Thu Aug 08, 2013 6:36 pm

    I have never installed or used this EFB supply. I think it is the same as what David Gillespie sells so I pulled up that manual. If you are sure that you have wired it correctly and removed the original diodes from the chassis, and the fuse is the same amp. or less. Follow the EFB instruction for start up. If not sure follow the below instructions.
    Remove all tubes. Plug in turn on and test the high voltages at the tube pins. Can be done from the top. They should be reading high because the supply is not loaded with the tubes. If correct follow start up instructions in the EFB manual. Good luck!
    If you didn't fully understand please post before starting up. Please understand that this is only advise all decisions on what you do is your responsibility.

    poconoman

    Posts : 106
    Join date : 2013-01-17

    Re: SCA 35. What update mods should be done?

    Post by poconoman on Thu Aug 08, 2013 8:48 pm

    sailor wrote:I have never installed or used this EFB supply. I think it is the same as what David Gillespie sells so I pulled up that manual. If you are sure that you have wired it correctly and removed the original diodes from the chassis, and the fuse is the same amp. or less.  Follow the EFB instruction for start up. If not sure follow the below instructions.
    Remove all tubes. Plug in turn on and test the high voltages at the tube pins. Can be done from the top. They should be reading high because the supply is not loaded with the tubes.  If correct  follow start up instructions in the EFB manual.  Good luck!
    If you didn't fully understand please post before starting up. Please understand that this is only advise all decisions on what you do is your responsibility.
    The EFB is the Gillespie design. It's just tubes4hifi has them assembled. Yes, the diodes are removed and I have the correct fuse.

    The EFB is installed and I followed everything to the tee. Very easy. I'll take some pics.

    poconoman

    Posts : 106
    Join date : 2013-01-17

    Re: SCA 35. What update mods should be done?

    Post by poconoman on Thu Aug 08, 2013 9:26 pm












    poconoman

    Posts : 106
    Join date : 2013-01-17

    Re: SCA 35. What update mods should be done?

    Post by poconoman on Sun Aug 11, 2013 5:00 pm

    Ok, all the connections are done. Triple checked and all looks good. Now for biasing. The manual doesn't say anything about giving the amp load. Nothing about connecting speakers. I know when biasing, an amp has to be on a load. Is it a different case with the EFB?

    sailor

    Posts : 269
    Join date : 2011-04-04

    Re: SCA 35. What update mods should be done?

    Post by sailor on Sun Aug 11, 2013 5:22 pm

    Yes read the last pages of the EFB manual. The test points are on the EFB board and so is the pot that you must adjust. The original amp was self biosing and did not need adjusting but with the EFB you must set the bios according to the instructions. Tubes installed.

    poconoman

    Posts : 106
    Join date : 2013-01-17

    Re: SCA 35. What update mods should be done?

    Post by poconoman on Sun Aug 11, 2013 5:38 pm

    sailor wrote:Yes read the last pages of the EFB manual. The test points are on the EFB board and so is the pot that you must adjust. The original amp was self biosing and did not need adjusting but with the EFB you must set the bios according to the instructions. Tubes installed.
    Yes, I read the last pages and I understand the EFB needs to be biased, but my question is, connect speakers WHILE biasing or it's not needed? The bias instructions don't say either or. Please excuse me if I misunderstood you.

    sailor

    Posts : 269
    Join date : 2011-04-04

    Re: SCA 35. What update mods should be done?

    Post by sailor on Sun Aug 11, 2013 8:22 pm

    You can do either. I would hook them up and play some music after the bios is set. They need to be bios then say about 5 minutes of warm up with no music playing they should be rechecked. After you do the first bios check turn on your CD play you can go ahead and play the amp. Just stop the CD player when you do the second check. You want the tubes with no signal when you do the bios checks.

    peterh

    Posts : 679
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: SCA 35. What update mods should be done?

    Post by peterh on Mon Aug 12, 2013 3:38 am

    poconoman wrote:Ok, all the connections are done. Triple checked and all looks good. Now for biasing. The manual doesn't say anything about giving the amp load. Nothing about connecting speakers. I know when biasing, an amp has to be on a load. Is it a different case with the EFB?
    Always load a tubeamp on the output. Best is a resistor, speakers will do ( but things might get noicy :-), if
    nothing else available short the speaker terminals.

    poconoman

    Posts : 106
    Join date : 2013-01-17

    Re: SCA 35. What update mods should be done?

    Post by poconoman on Mon Aug 12, 2013 9:23 am

    peterh wrote:
    poconoman wrote:Ok, all the connections are done. Triple checked and all looks good. Now for biasing. The manual doesn't say anything about giving the amp load. Nothing about connecting speakers. I know when biasing, an amp has to be on a load. Is it a different case with the EFB?
    Always load a tubeamp on the output. Best is a resistor, speakers will do ( but things might get noicy :-), if
    nothing else available short the speaker terminals.
    To short with a resistor. One end on the 8 or 16 ohm tap and the other C? I have some resistors left from this project. The 100 and 1k.

    poconoman

    Posts : 106
    Join date : 2013-01-17

    Re: SCA 35. What update mods should be done?

    Post by poconoman on Mon Aug 12, 2013 9:25 am

    sailor wrote:You can do either. I would hook them up and play some music after the bios is set. They need to be bios then say about 5 minutes of warm up with no music playing they should be rechecked. After you do the first bios check turn on your CD play you can go ahead and play the amp. Just stop the CD player when you do the second check. You want the tubes with no signal when you do the bios checks.
    Thank you.

    peterh

    Posts : 679
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: SCA 35. What update mods should be done?

    Post by peterh on Mon Aug 12, 2013 9:37 am

    poconoman wrote:
    peterh wrote:
    poconoman wrote:Ok, all the connections are done. Triple checked and all looks good. Now for biasing. The manual doesn't say anything about giving the amp load. Nothing about connecting speakers. I know when biasing, an amp has to be on a load. Is it a different case with the EFB?
    Always load a tubeamp on the output. Best is a resistor, speakers will do ( but things might get noicy :-), if
    nothing else available short the speaker terminals.
    To short with a resistor. One end on the 8 or 16 ohm tap and the other C? I have some resistors left from this project. The 100 and 1k.
    8 ohm is the best, but even 100 ohm will protect some. Providong that the resistor does not explode from the power surge that might be emitted ( and that is exactly the case where a load is importent)

    poconoman

    Posts : 106
    Join date : 2013-01-17

    Re: SCA 35. What update mods should be done?

    Post by poconoman on Mon Aug 12, 2013 10:00 am

    peterh wrote:
    poconoman wrote:
    peterh wrote:
    poconoman wrote:Ok, all the connections are done. Triple checked and all looks good. Now for biasing. The manual doesn't say anything about giving the amp load. Nothing about connecting speakers. I know when biasing, an amp has to be on a load. Is it a different case with the EFB?
    Always load a tubeamp on the output. Best is a resistor, speakers will do ( but things might get noicy :-), if
    nothing else available short the speaker terminals.
    To short with a resistor. One end on the 8 or 16 ohm tap and the other C? I have some resistors left from this project. The 100 and 1k.
    8 ohm is the best, but even 100 ohm will protect some. Providong that the resistor does not explode from the power surge that might be emitted ( and that is exactly the case where a load is importent)
    You know what, this is too risky. I'll simply hook up speakers and play it safe.

    Thank you for your help.

    poconoman

    Posts : 106
    Join date : 2013-01-17

    Re: SCA 35. What update mods should be done?

    Post by poconoman on Mon Aug 12, 2013 6:00 pm

    The amp and the EFB work. I'm getting music on both channels, BUT the right channel distorts. Meaning, the highs and mids are there but the bass distorts. Another thing is that I can't get both channels to bias around .27. If I bias the left 27, the right is 19. So, I bias the right towards 27, but the left is in the 30's. I can't get them close to any value. What gives?

    Captain Coconut

    Posts : 213
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    Re: SCA 35. What update mods should be done?

    Post by Captain Coconut on Mon Aug 12, 2013 7:09 pm

    Try moving the tubes from one channel to the other and see if the readings follow the tubes.

    poconoman

    Posts : 106
    Join date : 2013-01-17

    Re: SCA 35. What update mods should be done?

    Post by poconoman on Mon Aug 12, 2013 8:42 pm

    Captain Coconut wrote:Try moving the tubes from one channel to the other and see if the readings follow the tubes.
    Good advice. I'll do that. Stay tuned.

    peterh

    Posts : 679
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: SCA 35. What update mods should be done?

    Post by peterh on Tue Aug 13, 2013 2:17 am

    poconoman wrote:The amp and the EFB work. I'm getting music on both channels, BUT the right channel distorts. Meaning, the highs and mids are there but the bass distorts. Another thing is that I can't get both channels to bias around .27. If I bias the left 27, the right is 19. So, I bias the right towards 27, but the left is in the 30's. I can't get them close to any value. What gives?
    Is it the same tubes ? How was the sound before you started EFB mod ?


    poconoman

    Posts : 106
    Join date : 2013-01-17

    Re: SCA 35. What update mods should be done?

    Post by poconoman on Tue Aug 13, 2013 7:59 am

    peterh wrote:
    poconoman wrote:The amp and the EFB work. I'm getting music on both channels, BUT the right channel distorts. Meaning, the highs and mids are there but the bass distorts. Another thing is that I can't get both channels to bias around .27. If I bias the left 27, the right is 19. So, I bias the right towards 27, but the left is in the 30's. I can't get them close to any value. What gives?
    Is it the same tubes ? How was the sound before you started EFB mod ?

    No sound because the cans were shot. I'll switch tubes and see if the bias changes.

    I think my right woofer is blown. The tweet works, but the woofer crackles. I got to switch speakers and see what happens. But so far, it sounds sweet.

    poconoman

    Posts : 106
    Join date : 2013-01-17

    Re: SCA 35. What update mods should be done?

    Post by poconoman on Tue Aug 13, 2013 8:22 am

    BTW, the el84 are three GE gray, oval plates and one WG. Looks oval and gray too. Don't know if the GE are matched.

    sailor

    Posts : 269
    Join date : 2011-04-04

    Re: SCA 35. What update mods should be done?

    Post by sailor on Tue Aug 13, 2013 10:09 am

    Captain Coconut advise is best. If you move the tubes to the other channels and the same tubes won't bios then you should buy a new matched quad of tubes. One of the great things about the EL84 is they are cheap. Sovtek is cheap and good sounding for about $40.00 for a matched quad set.

    poconoman

    Posts : 106
    Join date : 2013-01-17

    Re: SCA 35. What update mods should be done?

    Post by poconoman on Tue Aug 13, 2013 10:52 am

    sailor wrote:Captain Coconut advise is best. If you move the tubes to the other channels and the same tubes won't bios then you should buy a new matched quad of tubes. One of the great things about the EL84 is they are cheap. Sovtek is cheap and good sounding for about $40.00 for a matched quad set.
    I was hoping to use the vintage GE. But, I'll see what happens with moving the tubes.

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