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Vintage Synth Repair

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Thread

Moderator

Moderator

2010-06-27 by alvaroangelo

Scott (from Vermont) is our new Moderator.
Alvaro Angelo (Owner).

Re: Moderator

2010-06-27 by scituate_mass

to celebrate... some books I scanned.  If any authors want me to remove these links, please just tell me. 'm not aware that any of these authors are selling copies on their sites etc. I just think these are amazing books that many people would otherwise never see... 


I'm graduating soon and will lose my host. So download now!


http://umich.edu/~damont/FriendPearlmanPiggot1974.pdf

http://umich.edu/~damont/PowellPerformOnTheArpUncompressed.zip

http://umich.edu/~damont/Kehler.pdf

http://umich.edu/~damont/Horn.zip

http://umich.edu/~damont/Horn1984.pdf

http://umich.edu/~damont/PowellPerformOnTheArpUncompressed.zip

http://umich.edu/~damont/Strange1983_2nd_ed.pdf

http://umich.edu/~damont/Strange19721stEd.pdf

http://umich.edu/~damont/Klein1982.pdf



--- In vintagesynthrepair@yahoogroups.com, "alvaroangelo" <ALVAROANGELO@...> wrote:
Show quoted textHide quoted text
>
> Scott (from Vermont) is our new Moderator.
> Alvaro Angelo (Owner).
>

[vintagesynthrepair] Oberheim OB-X and Cmos 74 series + Autotune

2010-06-27 by Philip

Hi, I'm repairing a hopelessly faulty OB-X...I'm dealing with all the CPU and digital control side first....all the voice board faults secondly..

First question...it's packed with early cmos 74 series IE 74C174 etc...what are the best equivalents for these and other 74C types? 74HC? 40174 for example?

Second question: How long is the Autotune function supposed to run for? At the moment it stays on for about 2 seconds after button press...not that it seems to do much as it's hopelessly out of tune with various boards missing a VCO here and there...

Thanks, Philip.

Re: [vintagesynthrepair] Oberheim OB-X and Cmos 74 series + Autotune

2010-06-27 by GB

We have a bunch of "new" 74C at my work. They are still in the original rails, but were bought many years ago. If you give me a list of what you need. I can see what we have. Also, the sockets can get dirty, so sometimes even reseating the chips helps  or replacing the sockets with new double-wiping ones.

GB
Show quoted textHide quoted text
  ----- Original Message ----- 
  From: Philip 
  To: vintagesynthrepair@yahoogroups.com 
  Sent: Sunday, June 27, 2010 9:46 AM
  Subject: [vintagesynthrepair] Oberheim OB-X and Cmos 74 series + Autotune


    

  Hi, I'm repairing a hopelessly faulty OB-X...I'm dealing with all the CPU and digital control side first....all the voice board faults secondly.. 


  First question...it's packed with early cmos 74 series IE 74C174 etc...what are the best equivalents for these and other 74C types? 74HC? 40174 for example?


  Second question: How long is the Autotune function supposed to run for? At the moment it stays on for about 2 seconds after button press...not that it seems to do much as it's hopelessly out of tune with various boards missing a VCO here and there...


  Thanks, Philip.

Re: [vintagesynthrepair] Oberheim OB-X and Cmos 74 series + Autotune

2010-06-27 by Philip

Thanks, I'd like to find new equivalents if possible..I find those old CMOS ic's to be inherently flaky...so anyway I've gone for new 40174's as I need at least two to get the controls working properly again..




________________________________
From: GB <grantbt@...>
To: eggwheatis@...
Cc: vintagesynthrepair@yahoogroups.com
Sent: Sun, 27 June, 2010 17:55:51
Subject: Re: [vintagesynthrepair] Oberheim OB-X and Cmos 74 series + Autotune

 
We have a bunch of "new" 74C at my work. They are still in the original 
rails, but were bought many years ago. If you give me a list of what you need. I 
can see what we have. Also, the sockets can get dirty, so sometimes even 
reseating the chips helps  or replacing the sockets with new double-wiping 
ones.
 
GB
 
----- Original Message -----
Show quoted textHide quoted text
>From: Philip 
>To: vintagesynthrepair@yahoogroups.com 
>Sent: Sunday, June 27, 2010 9:46 AM
>Subject: [vintagesynthrepair] Oberheim 
>  OB-X and Cmos 74 series + Autotune
>
> 
>Hi, 
>  I'm repairing a hopelessly faulty OB-X...I'm dealing with all the CPU and 
>  digital control side first....all the voice board faults secondly.. 
> 
>
>
>First question...it' s packed with early cmos 74 series IE 74C174 
>  etc...what are the best equivalents for these and other 74C types? 74HC? 40174 
>  for example?
>
>
>Second question: How long is the Autotune function supposed to 
>  run for? At the moment it stays on for about 2 seconds after button 
>  press...not that it seems to do much as it's hopelessly out of tune with 
>  various boards missing a VCO here and there...
>
>
>Thanks, Philip.
>
>

Re: [vintagesynthrepair] Oberheim OB-X and Cmos 74 series + Autotune

2010-06-27 by Roger J

Most OBX have solder faults between the CPU board and the voice cards. So start there and re-solder all first. You may be surprised how many other problems are resolved. 

R

rom: Philip <eggwheatis@...>

To: GB <grantbt@...>
Cc: vintagesynthrepair@yahoogroups.com
Sent: Sun, June 27, 2010 10:23:13 AM
Subject: Re: [vintagesynthrepair] Oberheim OB-X and Cmos 74 series + Autotune

  
Thanks, I'd like to find new equivalents if possible..I find those old CMOSic's to be inherently flaky...so anyway I've gone for new 40174's as I need at least two to get the controls working properly again..




________________________________
From: GB <grantbt@jps. net>
To: eggwheatis@yahoo. com
Cc: vintagesynthrepair@ yahoogroups. com
Sent: Sun, 27 June, 2010 17:55:51
Subject: Re: [vintagesynthrepair ] Oberheim OB-X and Cmos 74 series + Autotune

 
We have a bunch of "new" 74C at my work. They are still in the original  rails, but were bought many years ago. If you give me a list of what you need. I  can see what we have. Also, the sockets can get dirty, so sometimes even reseating the chips helps  or replacing the sockets with new double-wiping  ones.
 
GB
 
----- Original Message -----
Show quoted textHide quoted text
>From: Philip 
>To: vintagesynthrepair@ yahoogroups. com 
>Sent: Sunday, June 27, 2010 9:46 AM
>Subject: [vintagesynthrepair ] Oberheim    OB-X and Cmos 74 series + Autotune
>
>  
>Hi,    I'm repairing a hopelessly faulty OB-X...I'm dealing with all the CPU and    digital control side first....all the voice board faults secondly.. 
>
>
>First question...it' s packed with early cmos 74 series IE 74C174    etc...what are the best equivalents for these and other 74C types? 74HC? 40174    for example?
>
>
>Second question: How long is the Autotune function supposed to    run for? At the moment it stays on for about 2 seconds after button    press...not that it seems to do much as it's hopelessly out of tune with    various boards missing a VCO here and there...
>
>
>Thanks, Philip.
>

Re: [vintagesynthrepair] Oberheim OB-X and Cmos 74 series + Autotune

2010-06-27 by Philip

Yes as I've discovered...well as soon as I saw all those molex pins I knew there would be trouble.. I re-soldered about twenty cracked joints..

I basically completely stripped it, re-soldered, re-capped..then started going through all the logic faults.




________________________________
From: Roger J <winking_n_nodding@...>
To: vintagesynthrepair@yahoogroups.com; GB <grantbt@...>
Cc: vintagesynthrepair@yahoogroups.com
Sent: Sun, 27 June, 2010 19:10:02
Subject: Re: [vintagesynthrepair] Oberheim OB-X and Cmos 74 series + Autotune

  
Most OBX have solder faults between the CPU board and the voice cards. So start there and re-solder all first. You may be surprised how many other problems are resolved. 

R

rom: Philip <eggwheatis@yahoo. com>

To: GB <grantbt@jps. net>
Cc: vintagesynthrepair@ yahoogroups. com
Sent: Sun, June 27, 2010 10:23:13 AM
Subject: Re: [vintagesynthrepair ] Oberheim OB-X and Cmos 74 series + Autotune

  
Thanks, I'd like to find new equivalents if possible..I find those old CMOS ic's to be inherently flaky...so anyway I've gone for new 40174's as I need at least two to get the controls working properly again..




________________________________
From: GB <grantbt@jps. net>
To: eggwheatis@yahoo. com
Cc: vintagesynthrepair@ yahoogroups. com
Sent: Sun, 27 June, 2010 17:55:51
Subject: Re: [vintagesynthrepair ] Oberheim OB-X and Cmos 74 series + Autotune

 
We have a bunch of "new" 74C at my work. They are still in the original rails, but were bought many years ago. If you give me a list of what you need. I can see what we have. Also, the sockets can get dirty, so sometimes even reseating the chips helps  or replacing the sockets with new double-wiping ones.

GB

----- Original Message -----
Show quoted textHide quoted text
>From: Philip 
>To: vintagesynthrepair@ yahoogroups. com 
>Sent: Sunday, June 27, 2010 9:46 AM
>Subject: [vintagesynthrepair ] Oberheim OB-X and Cmos 74 series + Autotune
>
>  
>Hi, I'm repairing a hopelessly faulty OB-X...I'm dealing with all the CPU and digital control side first....all the voice board faults secondly.. 
>
>
>First question...it' s packed with early cmos 74 series IE 74C174 etc...what are the best equivalents for these and other 74C types? 74HC? 40174 for example?
>
>
>Second question: How long is the Autotune function supposed to run for? At the moment it stays on for about 2 seconds after button press...not that it seems to do much as it's hopelessly out of tune with various boards missing a VCO here and there...
>
>
>Thanks, Philip.
>

Re: Moderator

2010-06-27 by narfman96

Hi Alvaro,

Thank you so much for doing this! 

Scott, Welcome to the wonderful world of Yahoo Moderators...

Fran
--- In vintagesynthrepair@yahoogroups.com, "alvaroangelo" <ALVAROANGELO@...> wrote:
Show quoted textHide quoted text
>
> Scott (from Vermont) is our new Moderator.
> Alvaro Angelo (Owner).
>

Re: [vintagesynthrepair] Re: Moderator

2010-06-27 by Frank Simon

AWESOME material!!!
Thanks
Maybe I'll be able to finally fix my Prophet 10 and Korg Trident Mk II with these guides.
Show quoted textHide quoted text
----- Original Message -----
Sent: Sunday, June 27, 2010 12:31 PM
Subject: [vintagesynthrepair] Re: Moderator

to celebrate... some books I scanned. If any authors want me to remove these links, please just tell me. 'm not aware that any of these authors are selling copies on their sites etc. I just think these are amazing books that many people would otherwise never see...

I'm graduating soon and will lose my host. So download now!

http://umich.edu/~damont/FriendPearlmanPiggot1974.pdf

http://umich.edu/~damont/PowellPerformOnTheArpUncompressed.zip

http://umich.edu/~damont/Kehler.pdf

http://umich.edu/~damont/Horn.zip

http://umich.edu/~damont/Horn1984.pdf

http://umich.edu/~damont/PowellPerformOnTheArpUncompressed.zip

http://umich.edu/~damont/Strange1983_2nd_ed.pdf

http://umich.edu/~damont/Strange19721stEd.pdf

http://umich.edu/~damont/Klein1982.pdf

--- In vintagesynthrepair@yahoogroups.com, "alvaroangelo" wrote:
>
> Scott (from Vermont) is our new Moderator.
> Alvaro Angelo (Owner).
>

Re: [vintagesynthrepair] Re: Moderator

2010-06-27 by Frank Simon

BTW Strange 1972 does not open for me.
----- Original Message -----
Sent: Sunday, June 27, 2010 12:31 PM
Subject: [vintagesynthrepair] Re: Moderator

to celebrate... some books I scanned. If any authors want me to remove these links, please just tell me. 'm not aware that any of these authors are selling copies on their sites etc. I just think these are amazing books that many people would otherwise never see...

I'm graduating soon and will lose my host. So download now!

http://umich.edu/~damont/FriendPearlmanPiggot1974.pdf

http://umich.edu/~damont/PowellPerformOnTheArpUncompressed.zip

http://umich.edu/~damont/Kehler.pdf

http://umich.edu/~damont/Horn.zip

http://umich.edu/~damont/Horn1984.pdf

http://umich.edu/~damont/PowellPerformOnTheArpUncompressed.zip

http://umich.edu/~damont/Strange1983_2nd_ed.pdf

http://umich.edu/~damont/Strange19721stEd.pdf

http://umich.edu/~damont/Klein1982.pdf

--- In vintagesynthrepair@yahoogroups.com, "alvaroangelo" wrote:
>
> Scott (from Vermont) is our new Moderator.
> Alvaro Angelo (Owner).
>

RE: [vintagesynthrepair] Re: Moderator

2010-06-28 by timothy kosiorek

My download of Strange 1972 comes up as a damaged PDF file and won't open either
Tim K.


direct link to my Ziing store.(lower prices)
direct link to my Bonanzle store.(lower prices)
direct link to my FEEbay store.
http://www.sonicelectronicmusic.com




To: vintagesynthrepair@yahoogroups.com
From: fsimon001@neo.rr.com
Date: Sun, 27 Jun 2010 18:47:24 -0400
Subject: Re: [vintagesynthrepair] Re: Moderator



BTW Strange 1972 does not open for me.
Show quoted textHide quoted text
----- Original Message -----
Sent: Sunday, June 27, 2010 12:31 PM
Subject: [vintagesynthrepair] Re: Moderator

to celebrate... some books I scanned. If any authors want me to remove these links, please just tell me. 'm not aware that any of these authors are selling copies on their sites etc. I just think these are amazing books that many people would otherwise never see...

I'm graduating soon and will lose my host. So download now!

http://umich.edu/~damont/FriendPearlmanPiggot1974.pdf

http://umich.edu/~damont/PowellPerformOnTheArpUncompressed.zip

http://umich.edu/~damont/Kehler.pdf

http://umich.edu/~damont/Horn.zip

http://umich.edu/~damont/Horn1984.pdf

http://umich.edu/~damont/PowellPerformOnTheArpUncompressed.zip

http://umich.edu/~damont/Strange1983_2nd_ed.pdf

http://umich.edu/~damont/Strange19721stEd.pdf

http://umich.edu/~damont/Klein1982.pdf

--- In vintagesynthrepair@yahoogroups.com, "alvaroangelo" wrote:
>
> Scott (from Vermont) is our new Moderator.
> Alvaro Angelo (Owner).
>




Re: [vintagesynthrepair] Re: Moderator

2010-06-28 by Sandra Garcia

opened for me

Sandra Garcia

--- On Sun, 6/27/10, Frank Simon <fsimon001@neo.rr.com> wrote:
Show quoted textHide quoted text
From: Frank Simon <fsimon001@...>
Subject: Re: [vintagesynthrepair] Re: Moderator
To: vintagesynthrepair@yahoogroups.com
Date: Sunday, June 27, 2010, 4:47 PM







 



  


    
      
      
      


BTW Strange 1972 does not open for me.
 

  ----- Original Message ----- 
  From: 
  scituate_mass 
  To: vintagesynthrepair@ yahoogroups. com 
  
  Sent: Sunday, June 27, 2010 12:31 
PM
  Subject: [vintagesynthrepair ] Re: 
  Moderator
  
  
  
  to celebrate... some books I scanned. If any authors want me to remove 
  these links, please just tell me. 'm not aware that any of these authors are 
  selling copies on their sites etc. I just think these are amazing books that 
  many people would otherwise never see... 

I'm graduating soon and will 
  lose my host. So download now!

http://umich. edu/~damont/ FriendPearlmanPi ggot1974. pdf

http://umich. edu/~damont/ PowellPerformOnT heArpUncompresse d.zip

http://umich. edu/~damont/ Kehler.pdf

http://umich. edu/~damont/ Horn.zip

http://umich. edu/~damont/ Horn1984. pdf

http://umich. edu/~damont/ PowellPerformOnT heArpUncompresse d.zip

http://umich. edu/~damont/ Strange1983_ 2nd_ed.pdf

http://umich. edu/~damont/ Strange19721stEd .pdf

http://umich. edu/~damont/ Klein1982. pdf

--- 
  In vintagesynthrepair@ yahoogroups. com, 
  "alvaroangelo" <ALVAROANGELO@ ...> wrote:
>
> Scott (from 
  Vermont) is our new Moderator.
> Alvaro Angelo 
  (Owner).
>

Re: [vintagesynthrepair] Oberheim OB-X and Cmos 74 series + Autotune

2010-06-28 by Roger J

There was an engineering change order/service bulletin that removed the newer series CMOS 74C part and replaced it with the older TTL 74 series part due to a fan out issue on the OB-8(or was it the OBXa) in the panel circuit. 

Only reason I mention it is that you could be "updating" but adding a problem. Just something to keep in mind. I am sure some of the guys will pipe up on the details that are a bit foggy in my brain this Monday.
R


________________________________
From: Philip <eggwheatis@...>
To: winking_n_nodding@...
Cc: vintagesynthrepair@yahoogroups.com
Sent: Sun, June 27, 2010 12:53:26 PM
Subject: Re: [vintagesynthrepair] Oberheim OB-X and Cmos 74 series + Autotune


Yes as I've discovered...well as soon as I saw all those molex pins I knew there would be trouble.. I re-soldered about twenty cracked joints..
 
I basically completely stripped it, re-soldered, re-capped..then started going through all the logic faults.




________________________________
 From: Roger J <winking_n_nodding@...>
To: vintagesynthrepair@yahoogroups.com; GB <grantbt@...>
Cc: vintagesynthrepair@yahoogroups.com
Sent: Sun, 27 June, 2010 19:10:02
Subject: Re: [vintagesynthrepair] Oberheim OB-X and Cmos 74 series + Autotune

 
Most OBX have solder faults between the CPU board and the voice cards. So start there and re-solder all first. You may be surprised how many other problems are resolved. 

R

rom: Philip <eggwheatis@yahoo. com>

To: GB <grantbt@jps. net>
Cc: vintagesynthrepair@ yahoogroups. com
Sent: Sun, June 27, 2010 10:23:13 AM
Subject: Re: [vintagesynthrepair ] Oberheim OB-X and Cmos 74 series + Autotune

  
Thanks, I'd like to find new equivalents if possible..I find those old CMOS ic's to be inherently flaky...so anyway I've gone for new 40174's as I need at least two to get the controls working properly again..




________________________________
 From: GB <grantbt@jps. net>
To: eggwheatis@yahoo. com
Cc: vintagesynthrepair@ yahoogroups. com
Sent: Sun, 27 June, 2010 17:55:51
Subject: Re: [vintagesynthrepair ] Oberheim OB-X and Cmos 74 series + Autotune

 
We have a bunch of "new" 74C at my work. They are still in the original rails, but were bought many years ago. If you give me a list of what you need. I can see what we have. Also, the sockets can get dirty, so sometimes even reseating the chips helps  or replacing the sockets with new double-wiping ones.
 
GB
 
----- Original Message -----
Show quoted textHide quoted text
>From: Philip 
>To: vintagesynthrepair@ yahoogroups. com 
>Sent: Sunday, June 27, 2010 9:46 AM
>Subject: [vintagesynthrepair ] Oberheim OB-X and Cmos 74 series + Autotune
>
>  
>Hi, I'm repairing a hopelessly faulty OB-X...I'm dealing with all the CPU and digital control side first....all the voice board faults secondly.. 
>
>
>
>First question...it' s packed with early cmos 74 series IE 74C174 etc...what are the best equivalents for these and other 74C types? 74HC? 40174 for example?
>
>
>Second question: How long is the Autotune function supposed to run for? At the moment it stays on for about 2 seconds after button press...not that it seems to do much as it's hopelessly out of tune with various boards missing a VCO here and there...
>
>
>Thanks, Philip.
>

Re: [vintagesynthrepair] Oberheim OB-X and Cmos 74 series + Autotune

2010-06-28 by arthurok

what about  using 74hct  ics    
amazingly  4000 series  cmos ics  are still  in  production
im not  sure about    small  scale  bipolar digital  ics
74hct  is supposed  to  be  fully  compatible  with  74ls   parts
"im  not  sure about   leaving  unused  inputs  floating
thats  a  big  no  -  no   when using    cmos parts    
someengineers   even   pulled  up   unused  ttl   inputs    using a resistor to  vcc
to  protect the  input  from  powersupply   overshoot.
Show quoted textHide quoted text
  ----- Original Message ----- 
  From: Roger J 
  To: Philip 
  Cc: vintagesynthrepair@yahoogroups.com 
  Sent: Monday, June 28, 2010 12:30 PM
  Subject: Re: [vintagesynthrepair] Oberheim OB-X and Cmos 74 series + Autotune


    

  There was an engineering change order/service bulletin that removed the newer series CMOS 74C part and replaced it with the older TTL 74 series part due to a fan out issue on the OB-8(or was it the OBXa) in the panel circuit. 

  Only reason I mention it is that you could be "updating" but adding a problem. Just something to keep in mind. I am sure some of the guys will pipe up on the details that are a bit foggy in my brain this Monday.
  R


------------------------------------------------------------------------------
  From: Philip <eggwheatis@...>
  To: winking_n_nodding@...
  Cc: vintagesynthrepair@yahoogroups.com
  Sent: Sun, June 27, 2010 12:53:26 PM
  Subject: Re: [vintagesynthrepair] Oberheim OB-X and Cmos 74 series + Autotune


  Yes as I've discovered...well as soon as I saw all those molex pins I knew there would be trouble.. I re-soldered about twenty cracked joints..

  I basically completely stripped it, re-soldered, re-capped..then started going through all the logic faults.




------------------------------------------------------------------------------
  From: Roger J <winking_n_nodding@...>
  To: vintagesynthrepair@yahoogroups.com; GB <grantbt@...>
  Cc: vintagesynthrepair@yahoogroups.com
  Sent: Sun, 27 June, 2010 19:10:02
  Subject: Re: [vintagesynthrepair] Oberheim OB-X and Cmos 74 series + Autotune

    

  Most OBX have solder faults between the CPU board and the voice cards. So start there and re-solder all first. You may be surprised how many other problems are resolved. 

  R

  rom: Philip <eggwheatis@yahoo. com>

  To: GB <grantbt@jps. net>
  Cc: vintagesynthrepair@ yahoogroups. com
  Sent: Sun, June 27, 2010 10:23:13 AM
  Subject: Re: [vintagesynthrepair ] Oberheim OB-X and Cmos 74 series + Autotune

    

  Thanks, I'd like to find new equivalents if possible..I find those old CMOS ic's to be inherently flaky...so anyway I've gone for new 40174's as I need at least two to get the controls working properly again..







------------------------------------------------------------------------------
  From: GB <grantbt@jps. net>
  To: eggwheatis@yahoo. com
  Cc: vintagesynthrepair@ yahoogroups. com
  Sent: Sun, 27 June, 2010 17:55:51
  Subject: Re: [vintagesynthrepair ] Oberheim OB-X and Cmos 74 series + Autotune

   
  We have a bunch of "new" 74C at my work. They are still in the original rails, but were bought many years ago. If you give me a list of what you need. I can see what we have. Also, the sockets can get dirty, so sometimes even reseating the chips helps  or replacing the sockets with new double-wiping ones.

  GB

    ----- Original Message ----- 
    From: Philip 
    To: vintagesynthrepair@ yahoogroups. com 
    Sent: Sunday, June 27, 2010 9:46 AM
    Subject: [vintagesynthrepair ] Oberheim OB-X and Cmos 74 series + Autotune


      

    Hi, I'm repairing a hopelessly faulty OB-X...I'm dealing with all the CPU and digital control side first....all the voice board faults secondly.. 


    First question...it' s packed with early cmos 74 series IE 74C174 etc...what are the best equivalents for these and other 74C types? 74HC? 40174 for example?


    Second question: How long is the Autotune function supposed to run for? At the moment it stays on for about 2 seconds after button press...not that it seems to do much as it's hopelessly out of tune with various boards missing a VCO here and there...


    Thanks, Philip.

Re: [vintagesynthrepair] Oberheim OB-X and Cmos 74 series + Autotune

2010-06-28 by Philip

Yes I've used HCT and in LS compatible situations..but im not looking for compatibility with LS this time..

Basically 74C is a cmos format with a 74 series pinout. So I guess looking at the readily available variations of the 74 series, HC would be ideal..maybe.



________________________________
From: arthurok <arthurok@...>
To: vintagesynthrepair@yahoogroups.com; Philip <eggwheatis@...>
Cc: vintagesynthrepair@yahoogroups.com
Sent: Mon, 28 June, 2010 21:08:10
Subject: Re: [vintagesynthrepair] Oberheim OB-X and Cmos 74 series + Autotune

 
what about  using 74hct  
ics    
amazingly  4000 series  cmos ics  
are still  in  production
im not  sure 
about    small  scale  bipolar digital  
ics
74hct  is supposed  to  be  
fully  compatible  with  74ls   parts
"im  not  sure about   
leaving  unused  inputs  floating
thats  a  big  no  -  
no   when using    cmos parts    
someengineers   even   
pulled  up   unused  ttl   
inputs    using a resistor to  vcc
to  protect the  input  from  
powersupply   overshoot.
----- Original Message ----- 
>From: Roger J 
>To: Philip 
>Cc: vintagesynthrepair@yahoogroups.com 
>Sent: Monday, June 28, 2010 12:30 
>PM
>Subject: Re: [vintagesynthrepair] 
>  Oberheim OB-X and Cmos 74 series + Autotune
>
> 
>There 
>  was an engineering change order/service bulletin that removed the newer series 
>  CMOS 74C part and replaced it with the older TTL 74 series part due to a fan 
>  out issue on the OB-8(or was it the OBXa) in the panel circuit. 
>
>Only 
>  reason I mention it is that you could be "updating" but adding a problem. Just 
>  something to keep in mind. I am sure some of the guys will pipe up on the 
>  details that are a bit foggy in my brain this Monday.
>R
>
>
________________________________
 From: Philip <eggwheatis@yahoo. com>
>To: >  winking_n_nodding@ yahoo.com
>Cc: >  vintagesynthrepair@ yahoogroups. com
>Sent: Sun, June 27, 2010 12:53:26 
>  PM
>Subject: Re: 
>  [vintagesynthrepair ] Oberheim OB-X and Cmos 74 series + 
>  Autotune
>
>
>Yes as I've discovered.. .well as soon as I saw all those molex pins 
>  I knew there would be trouble.. I re-soldered about twenty cracked 
>  joints..
> 
>I basically completely stripped it, re-soldered, re-capped..then started 
>  going through all the logic faults.
>
>
>
>
________________________________
 From: Roger J 
>  <winking_n_nodding@ yahoo.com>
>To: >  vintagesynthrepair@ yahoogroups. com; GB 
>  <grantbt@jps. net>
>Cc: >  vintagesynthrepair@ yahoogroups. com
>Sent: Sun, 27 June, 2010 
>  19:10:02
>Subject: Re: 
>  [vintagesynthrepair ] Oberheim OB-X and Cmos 74 series + 
>  Autotune
>
>  
>Most 
>  OBX have solder faults between the CPU board and the voice cards. So start 
>  there and re-solder all first. You may be surprised how many other problems 
>  are resolved. 
>
>R
>
>rom: Philip <eggwheatis@yahoo. 
>  com>
>
>To: GB 
>  <grantbt@jps. net>
>Cc: >  vintagesynthrepair@ yahoogroups. com
>Sent: Sun, June 27, 2010 10:23:13 
>  AM
>Subject: Re: 
>  [vintagesynthrepair ] Oberheim OB-X and Cmos 74 series + 
>  Autotune
>
>  
>Thanks, I'd like to find new equivalents if possible..I find those old 
>  CMOS ic's to be inherently flaky...so anyway I've gone for new 40174's as 
>  I need at least two to get the controls working properly again..
>
>
>
>
>
>
>
________________________________
Show quoted textHide quoted text
 From: GB <grantbt@jps. 
>  net>
>To: eggwheatis@yahoo. 
>  com
>Cc: vintagesynthrepair@ 
>  yahoogroups. com
>Sent: Sun, 
>  27 June, 2010 17:55:51
>Subject: Re: [vintagesynthrepair ] 
>  Oberheim OB-X and Cmos 74 series + Autotune
>
> 
> 
>We have a bunch of "new" 74C at my work. They are still in the original 
>  rails, but were bought many years ago. If you give me a list of what you need. 
>  I can see what we have. Also, the sockets can get dirty, so sometimes even 
>  reseating the chips helps  or replacing the sockets with new 
>  double-wiping ones.
> 
>GB
> 
>----- Original Message ----- 
>>From: Philip 
>>To: vintagesynthrepair@ 
>>    yahoogroups. com 
>>Sent: Sunday, June 27, 2010 9:46 
>>    AM
>>Subject: [vintagesynthrepair ] Oberheim 
>>    OB-X and Cmos 74 series + Autotune
>>
>>  
>>Hi, 
>>    I'm repairing a hopelessly faulty OB-X...I'm dealing with all the CPU and 
>>    digital control side first....all the voice board faults secondly.. 
>> 
>>
>>
>>First question...it' s packed with early cmos 74 series IE 74C174 
>>    etc...what are the best equivalents for these and other 74C types? 74HC? 
>>    40174 for example?
>>
>>
>>Second question: How long is the Autotune function supposed 
>>    to run for? At the moment it stays on for about 2 seconds after button 
>>    press...not that it seems to do much as it's hopelessly out of tune with 
>>    various boards missing a VCO here and there...
>>
>>
>>Thanks, Philip.
>>
>
>
>
>
>

Re: Moderator

2010-06-29 by scituate_mass

oops... I think I hit my server limit for uploads. I'll need to delete something and reupload it. I have a painfully slow connection right now but will post a new link when I get back to school in a couple of days. I also have a bunch of other books I scanned that I will post.

--- In vintagesynthrepair@yahoogroups.com, Sandra Garcia <createsjg@...> wrote:
Show quoted textHide quoted text
>
> opened for me
> 
> Sandra Garcia
> 
> --- On Sun, 6/27/10, Frank Simon <fsimon001@...> wrote:
> 
> From: Frank Simon <fsimon001@...>
> Subject: Re: [vintagesynthrepair] Re: Moderator
> To: vintagesynthrepair@yahoogroups.com
> Date: Sunday, June 27, 2010, 4:47 PM
> 
> 
> 
> 
> 
> 
> 
> Â 
> 
> 
> 
>   
> 
> 
>     
>       
>       
>       
> 
> 
> BTW Strange 1972 does not open for me.
> Â 
> 
>   ----- Original Message ----- 
>   From: 
>   scituate_mass 
>   To: vintagesynthrepair@ yahoogroups. com 
>   
>   Sent: Sunday, June 27, 2010 12:31 
> PM
>   Subject: [vintagesynthrepair ] Re: 
>   Moderator
>   
> Â  
>   
>   to celebrate... some books I scanned. If any authors want me to remove 
>   these links, please just tell me. 'm not aware that any of these authors are 
>   selling copies on their sites etc. I just think these are amazing books that 
>   many people would otherwise never see... 
> 
> I'm graduating soon and will 
>   lose my host. So download now!
> 
> http://umich. edu/~damont/ FriendPearlmanPi ggot1974. pdf
> 
> http://umich. edu/~damont/ PowellPerformOnT heArpUncompresse d.zip
> 
> http://umich. edu/~damont/ Kehler.pdf
> 
> http://umich. edu/~damont/ Horn.zip
> 
> http://umich. edu/~damont/ Horn1984. pdf
> 
> http://umich. edu/~damont/ PowellPerformOnT heArpUncompresse d.zip
> 
> http://umich. edu/~damont/ Strange1983_ 2nd_ed.pdf
> 
> http://umich. edu/~damont/ Strange19721stEd .pdf
> 
> http://umich. edu/~damont/ Klein1982. pdf
> 
> --- 
>   In vintagesynthrepair@ yahoogroups. com, 
>   "alvaroangelo" <ALVAROANGELO@ ...> wrote:
> >
> > Scott (from 
>   Vermont) is our new Moderator.
> > Alvaro Angelo 
>   (Owner).
> >
>

Re: Oberheim OB-X and Cmos 74 series + Autotune

2010-06-30 by Paul

Hi Guys,
My two-cents worth, if you are going to "update" it then 74HCT would be the ideal choice as it has the fanout required as well as lower power, therefore lower heat. I alwasy considered the 74C series to be a bit weak !
Flack invited if I have it wrong :o)
Cheers
Paul

Re: [vintagesynthrepair] Re: Oberheim OB-X and Cmos 74 series + Autotune

2010-06-30 by arthurok

74hct can only be used on a 5 ; vlt syslem
hc, c and 4000series can be operates at any thing between 3 and 15 vlts dc
Show quoted textHide quoted text
----- Original Message -----
From: Paul
Sent: Wednesday, June 30, 2010 1:15 PM
Subject: [vintagesynthrepair] Re: Oberheim OB-X and Cmos 74 series + Autotune

Hi Guys,
My two-cents worth, if you are going to "update" it then 74HCT would be the ideal choice as it has the fanout required as well as lower power, therefore lower heat. I alwasy considered the 74C series to be a bit weak !
Flack invited if I have it wrong :o)
Cheers
Paul

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