Vintage Synth Repair

The ripple is just the AC measurement on the line. The power supply rectifies the incoming AC to DC of course then drops the voltage.

You look at the power on the lines with the o-scope set to AC to see how well the rectifiers and capacitors are doing their job. The peak-to-peak value should be less than 15% of the DC value, hopefully a lot less. Like a 5 VDC line will probably have around 2 to 3 mV of ripple (that is, ± 1 to 1.5) in my experience. Others with more experience can probably give you a better numbers.

A quick and dirty method is to just check it with an meter set to AC, but you really need the scope to tell the tale and make sure you don't have one leg of the rectifier gone bad or something. and the ripple image is symmetric and, not cocked off to one side.


  ----- Original Message -----
  From: plat@...
  To: vintagesynthrepair@yahoogroups.com
  Sent: Thursday, December 26, 2013 5:48 PM
  Subject: Re: [vintagesynthrepair] Re: Jupiter 6 PSU.



  Hi Scott.

  Yes, it seems more discreet.

  There are no large 3 terminal regulators, however there is a D1406 Transistor , a thyristor 5P05M and 2 ic's ( IC1:Nec C3423C / IC2:Mitsubishi M5218L ).
  IC2 seems like it is for the 10v Ref but all the others belong to the 5v circuit , the +/- 15v is looking solid.

  Just found and ordered the D1406 and the M5218L , have not been able to find the NecC3423C.
  I replaced the thyristor 5P05M (was missing) with a BT151.

  I do have a scope but I am not sure how to measure DC ripple , I have read up on that but could not get it to work?

  I will check for loose solder joints and replace the caps.

  Thanks
  Arnar

  ----- Upprunaleg skilaboð -----
  Frá: "Scott Frye" <painintheamp@...>
  Til: vintagesynthrepair@yahoogroups.com
  Sent: Þriðjudagur, 24. Desember, 2013 13:49:32
  Efni: [vintagesynthrepair] Re: Jupiter 6 PSU.

  Yes, I would say it's the PSU. I dont have a diagram for it here but , in a rig with THAT much digital, the +5volts is either a LARGE three terminal regulator ( in a T0-3 case) , or something more discreet. Also, weak solder joints are a problem when a circuit asks for current. So, replace all electrolytic caps in the +5 supply, resolder any connections that appear "grayish" or weak and find the PSU diagram

  --
  Scott Frye

  Audio-fixation.net

  Vermont