Roland Jet Phase incoming!

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
Post Reply
User avatar
chicago_mike
Tube Twister
Posts: 1759
Joined: 03 Jul 2008, 05:38
Has thanked: 20 times
Been thanked: 288 times

Post by chicago_mike »

I have a Roland JetPhase AP-7 coming in the mail today. Does anybody need any measurements or anything from it?
Skyline FX 2013

aionios
Breadboard Brother
Posts: 111
Joined: 22 Mar 2012, 01:12
Location: Des Moines, IA
Has thanked: 4 times
Been thanked: 152 times
Contact:

Post by aionios »

I would love to get the specs of the matched JFETs! Vgs(10k), Vgs(off) and Idss if you’re able. I’m curious to see how the voltages match up with something more common
    like the Phase 90. I saw some taken from a unit awhile ago that were in the 0.7-0.8v range, which seemed really low to me - so I’m wondering if that was an anomaly or pretty standard.
    Aion Electronics - DIY PCB projects for classic and obscure circuits

    User avatar
    modman
    a d m i n
    Posts: 4545
    Joined: 19 Jun 2007, 17:57
    Has thanked: 3181 times
    Been thanked: 659 times

    Post by modman »

    We have a thread on the Roland Jet Phaser here: viewtopic.php?f=1&t=589
    Links to service notes etc...most of the links to guts are dead though...
    Please, support freestompboxes.org on Patreon for just 1 pcb per year! Or donate directly through PayPal

    User avatar
    chicago_mike
    Tube Twister
    Posts: 1759
    Joined: 03 Jul 2008, 05:38
    Has thanked: 20 times
    Been thanked: 288 times

    Post by chicago_mike »

    aionios wrote:I would love to get the specs of the matched JFETs! Vgs(10k), Vgs(off) and Idss if you’re able. I’m curious to see how the voltages match up with something more common
      like the Phase 90. I saw some taken from a unit awhile ago that were in the 0.7-0.8v range, which seemed really low to me - so I’m wondering if that was an anomaly or pretty standard.
      Im cool with helping out!! Whats the easiest way to measure the fets ?
      Skyline FX 2013

      aionios
      Breadboard Brother
      Posts: 111
      Joined: 22 Mar 2012, 01:12
      Location: Des Moines, IA
      Has thanked: 4 times
      Been thanked: 152 times
      Contact:

      Post by aionios »

      The Vgs(10k) measurement is the most important one for phasers - there's a super simple circuit here that could be breadboarded:
      http://www.geofex.com/article_folders/f ... tmatch.htm

      Vgs(off) (which is basically the same as Vp) and Idss can be taken with another circuit:
      http://tagboardeffects.blogspot.com/201 ... tcher.html
      (The 2nd one on this page is much simpler and should work the same)
      Aion Electronics - DIY PCB projects for classic and obscure circuits

      User avatar
      chicago_mike
      Tube Twister
      Posts: 1759
      Joined: 03 Jul 2008, 05:38
      Has thanked: 20 times
      Been thanked: 288 times

      Post by chicago_mike »

      Cool.

      I should test ALL fets in the phase section yes? Not just like 2 - 4 ?
      Skyline FX 2013

      aionios
      Breadboard Brother
      Posts: 111
      Joined: 22 Mar 2012, 01:12
      Location: Des Moines, IA
      Has thanked: 4 times
      Been thanked: 152 times
      Contact:

      Post by aionios »

      chicago_mike wrote:I should test ALL fets in the phase section yes? Not just like 2 - 4 ?
      Yep. An average Vgs is helpful, but also knowing the spread of lowest to highest, to know what Roland considered to be matched well enough for the circuit.

      MXR was satisfied with up to 0.1V for the Phase 90, which is pretty wide, but matching 8 JFETs instead of 4 is even trickier so I’m curious if it’s tighter or broader than that.
      Aion Electronics - DIY PCB projects for classic and obscure circuits

      User avatar
      chicago_mike
      Tube Twister
      Posts: 1759
      Joined: 03 Jul 2008, 05:38
      Has thanked: 20 times
      Been thanked: 288 times

      Post by chicago_mike »

      breadboarding an Arduino fet tester for this. Should have the jets testedasap!
      Skyline FX 2013

      aionios
      Breadboard Brother
      Posts: 111
      Joined: 22 Mar 2012, 01:12
      Location: Des Moines, IA
      Has thanked: 4 times
      Been thanked: 152 times
      Contact:

      Post by aionios »

      chicago_mike wrote:breadboarding an Arduino fet tester for this. Should have the jets testedasap!
      Oh awesome! Which one is it?
      Aion Electronics - DIY PCB projects for classic and obscure circuits

      User avatar
      chicago_mike
      Tube Twister
      Posts: 1759
      Joined: 03 Jul 2008, 05:38
      Has thanked: 20 times
      Been thanked: 288 times

      Post by chicago_mike »

      this one:

      https://create.arduino.cc/projecthub/pl ... ter-dbafb4


      I didnt really know there were others :hmmm:
      Skyline FX 2013

      User avatar
      chicago_mike
      Tube Twister
      Posts: 1759
      Joined: 03 Jul 2008, 05:38
      Has thanked: 20 times
      Been thanked: 288 times

      Post by chicago_mike »

      Okay I posted my initial FET measurements. Only for the 8 phasing FETS right now.

      When I get more time, I take measurements of the other fets
      Skyline FX 2013

      Post Reply