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SCI Prophet 5 restoration
Old 1st January 2010
  #1
Moderator
 
Don Solaris's Avatar
 
4 Reviews written
🎧 10 years
SCI Prophet 5 restoration

SCI Prophet 5 restoration - This is how typical synth restoration looks like.



Boards out. Shown above: mainboard (left), voice board (right). As you can see the wood was in a pretty bad shape. I've managed to fix that as well (more on that later).





Main panel out. Approaching bare bones.





Shower time. The only a proper way to remove all the dirt accumulated over the past 30 years.





Keys out. Time to install bushings where needed (luckily just one was in bad shape)





Cleaning keyboard contacts with alcohol.





Keys put in a hot bath. Some liquid soap was added.





Use a sponge and rub each key. Then wash away everything with hot water.





Putting back black keys first. That's the way you want to do it, else, they won't go in.





Time to replace CMOS chips on the control board. These tend to fail and you might end up in unit throwing random values each time you tweak a knob. While there, replace tantalum with electrolytic. There's something like 25 caps or so, not much.





Old chips removed, sockets soldered in, new CMOS chips installed (use sockets, it will save you a lot of time in the future if some chip needs to be replaced). Potentiometers prepared for air compressor cleaning + contact spray "wash".
Old 1st January 2010
  #2
Moderator
 
Don Solaris's Avatar
 
4 Reviews written
🎧 10 years
...continued from previous post


PSU board. My advice, replace all capacitors, including the tantalum ones. These tend to fail after 30 years. The last thing you want is a failure on a PSU board. Also replace those three electrolytic capacitors. Apologize for the blurry photo. But you can notice those small "blue pills". These are tantalum caps, to be replaced with electrolytic of the same value.





New 6800 uF caps are smaller, they won't fit the metal holders. But don't worry, as soon as you screw in those three regulators, the board will become fixed in.





A wet cloth was used to clean the surface of the wood. A lot of dirt accumulated over the years. Notice the condition of the keys now after they have been washed.





Putting boards back in. Bottom cover is little bit wet (cleaned it as well).




Left side = untreated, right side = treated.

Starting a treatment with wood wax. You can see the change for yourself. Explanation: original wood was totally dry, washed out and damaged on many places (scars). Then i remember what they use for restorations - a wood wax for furniture (these are available in every store). Use some cloth and apply one layer carefully. You can see it applied on the right side. Not only it brought back original color and shine of the wood but it magically removed all the scars and traces by filling and coloring them. I couldn't believe the results i got. This is the best discovery i've had for a long time (and it started with, hmmm let's try this...).




Finished baby. Total work time: 8 days.





With its younger brother. Wood side panels on Pro One courtesy of Chris K. aka The Wasp.

Text / images copyright Don Solaris 12.27.2009.
Old 24th July 2013
  #3
Gear Maniac
 
starfield's Avatar
 
🎧 10 years
amazing post/restoration Don! great info also
Old 24th July 2013
  #4
Deleted 8456dd3
Guest
Don you mentioned, Potentiometers prepared for air compressor cleaning + contact spray "wash".
This is something that would be handy to know how to do properly, because pots are sealed i never knew where to apply some contact cleaner, any more info on that?
Ive always got something with a dirty pot, in fact my Technics SL-1800 has 2 dirty pitch pots that i could do with cleaning out.
Cheers
Old 24th July 2013 | Show parent
  #5
Moderator
 
Don Solaris's Avatar
 
4 Reviews written
🎧 10 years
Quote:
Originally Posted by Deleted 8456dd3 ➡️
This is something that would be handy to know how to do properly, because pots are sealed i never knew where to apply some contact cleaner, any more info on that?
Don't have sealed pots here, so can't help on that.
Old 25th July 2013
  #6
Gear Head
 
🎧 5 years
Thanks for this awesome thread, Don! It is a beautiful synth!

Quote:
Originally Posted by Don Solaris ➡️
SCI Prophet 5 restoration - T
Time to replace CMOS chips on the control board. These tend to fail and you might end up in unit throwing random values each time you tweak a knob. While there, replace tantalum with electrolytic. There's something like 25 caps or so, not much.

Old chips removed, sockets soldered in, new CMOS chips installed (use sockets, it will save you a lot of time in the future if some chip needs to be replaced).
This is especially great info, because I think I have this problem on one of my filter knobs. It's weird, occasionally when I turn the cutoff, I get a random reset of several values, including the noise level (which is right next door). Sounds like a CMOS chip replacement is in order!

Last edited by Quadrupole; 25th July 2013 at 02:22 AM.. Reason: corrected grammar
Old 25th July 2013
  #7
Lives for gear
 
Teknobeam's Avatar
 
🎧 10 years
WOW ! a labor of love. Such a worthwhile use of time also. great photos.
Old 25th July 2013
  #8
Deleted #8726
Guest
Awesome!
Old 25th July 2013
  #9
Lives for gear
 
🎧 10 years
Great post Don tho where's this been hiding?
Three years for a response is a little unusual!
Old 25th July 2013
  #10
Moderator
 
Don Solaris's Avatar
 
4 Reviews written
🎧 10 years


Special thanks to SuitAndTieGuy without who I would never had this synth!
Old 25th July 2013
  #11
Here for the gear
 
🎧 5 years
Technics SL-1800 has 2 dirty pitch pots that i could do with cleaning out.
Old 25th July 2013 | Show parent
  #12
Deleted 8456dd3
Guest
My mistake, i didnt mean sealed pots. Wrong term.
I have normal pots on my Prophet but because when you look at them they *look" sealed thats why i used that term, so in fact my question was more about how does one go about injecting some sort of cleaning fluid into pots like these and whats the best substance to use?
Cheers
Old 25th July 2013
  #13
Moderator
 
Don Solaris's Avatar
 
4 Reviews written
🎧 10 years
First you take high pressure air (compressor) and apply it to the horizontal hole where the legs are located to remove all the dust from inside potentiometer. Then you apply this into same place:

Teslanol® T6-OSZILLIN Kontakt- und Tunerspray 400ml: Amazon.de: Elektronik
Old 25th July 2013 | Show parent
  #14
Deleted 8456dd3
Guest
Ah ha, good man. Good tips, this will come in handy.
Cheers

Quote:
Originally Posted by Don Solaris ➡️
First you take high pressure air (compressor) and apply it to the horizontal hole where the legs are located to remove all the dust from inside potentiometer. Then you apply this into same place:

Teslanol® T6-OSZILLIN Kontakt- und Tunerspray 400ml: Amazon.de: Elektronik
Old 24th March 2014
  #15
RDP
Gear Addict
 
🎧 10 years
Ok, now it's my turn. I just got a 3.3 w/MIDI

Here is the list of things I have decided to do:

1. Figure out the voltage/hz issue. My P5 is switched to 115 operation on the back. However I am using it in Japan on 100/50hz (Tokyo). Currently I am running it on a transformer that provides it with 115v but at 60hz. From what I know (which admittedly is not much...) you should always try to respect the ratio of voltage to hz. In this case I would respect that ratio by simply plugging the P5 into the wall as the ratio is:

115 : 60 = 100 : 52.17

Am I thinking this through right or should I be trying to refticy BOTH voltage and Hz. My goal is to have the P5 run at optimum levels. Right now with the unit being fed 115v @ 50hz it does get hot on the heatsink, but as this is my first P5 do not know how hot it should normally be. I certinally do not want to break it.

2. Replace all the bushings. Is this the one and only place I should be looking for the parts? index

3. Figure out why some Pot's turn smoothly and have a consistent resistance while others have:

a) Differing resistance through the turn. On the one pot that exhibits this behaivour I can see when looking at the clearance between pot and the nut that it has more clearance than the other pots in relation to the nut. So, in laymans terms the pot is sitting higher up on the stem than the other pots.

b) Having almost no resistance at all. I have a few pots that basically have no resistance to turning at all, and it feels 'wrong'. There is absolutely no resistance.

4. Wood Wax! I went to the store yesterday and they had about 10 different options of Wax. There was Clear, Mahogany, Teak, Dark, Antique, etc. etc. Don, what did you use? Do I risk something going wrong if I get the wrong one?

5. Transformer hum and cap replacement. I really want to do all the upgrades that people talk about, but I think I want to get through tasks 1 ~ 4 first before sending the synth out for this, but it does need to be done. I see there is much to do, though some of this is Rev 2 related: https://gearspace.com/board/electron...storation.html

6. A good tech: If anyone knows of someone in Japan that is reasonable with rates and reliable then I would love to know.


Thanks all,
RDP
Old 25th March 2014
  #16
Lives for gear
 
Xero's Avatar
 
🎧 10 years
The heatsinks on a rev3.3 generally get pretty hot regardless. Recapping will help, but the only way to really reduce the heat dramatically is to get a new transformer with a dedicated tap for the +5v line. You probably won't even need the heatsink after that, although I would just leave it since otherwise there'd be a big ugly spot on the back, haha. I have some instructions on the transformer swap here, it's written for the rev2 but it should work on a rev3.3 as well, just ignore the first half of that document, and start from "second improvement"
http://www.xero.cc/p5cass/powersupply.txt

as for the pots, you might be able to resolve that with some fader lube...its called lube but its more like grease and it can add a little bit of friction, but I don't know, if there's nothing wrong with the pots other than that, I wouldn't touch them or put fader lube in em, just cause they are getting hard to find those original pots and the last thing you wanna do is ruin them by applying some cheap fader grease or something...

as for good tech in japan - only one I really know is Ko Okatake - I'm more used to buying stuff from him though, not sure if he actually does repairs individually, but I think he does. Worth a try either way though, he definitely works on prophets! Modeless Factory.
Old 25th March 2014
  #17
Gear Addict
 
Blackdog128's Avatar
 
🎧 5 years
Don, thanks for doing this great work! Now you've got a beautiful classic synth, and the population of remaining P5's has been improved by that much.

I had a rev 1 back in the day (s/n #33); it was updated once (to rev 2 i'm guessing). I sold it in the 90's during a career change, still have seller's remorse!

Thanks again for the hard work and sharing the beautiful pics!
Old 25th March 2014
  #18
Lives for gear
 
dlmorley's Avatar
 
2 Reviews written
🎧 15 years
Great stuff. Crazy how the first affordable polysynth is still the best imho.
Old 25th March 2014 | Show parent
  #19
Gear Maniac
 
🎧 5 years
Quote:
Originally Posted by dlmorley ➡️
Great stuff. Crazy how the first affordable polysynth is still the best imho.
play one daily here and have to agree , just a thing of beauty with a tangible sonic soul to it.
Old 6th February 2015
  #20
Gear Guru
 
fiddlestickz's Avatar
 
🎧 5 years
Now that is super slutty...

Outstanding...
Old 25th April 2016
  #21
Lives for gear
 
ELI-173's Avatar
 
🎧 15 years
Has anybody found a suitable replacement for a Rev 3.3 P5's power transformer? I've got the dreaded hum over here, and it's driving me batty.

I found this photo online, but not sure what part, exactly, the transformer is. I read the above piece from Xero, but wondering about this round tranny.



Also, did anybody find out exactly which wood wax to use? Thank you!
Attached Thumbnails
SCI Prophet 5 restoration-prophet-5.jpg  
Old 28th April 2016
  #22
Gear Nut
 
🎧 5 years
The photo is of a toroidal transformer replacement.

I am just about to recap my Rev3.3 and replace the power supply. I am still researching the replacement ps but am thinking something along these lines:

Signal Transformer MT-8-15 http://www.signaltransformer.com/sit...pdf/MT-DMT.pdf

As for the wood, I have had great success with Howard Feed-and-Wax Feed-N-Wax Wood Polish & Conditioner | Howard Products which is available on Amazon.
Old 28th April 2016 | Show parent
  #23
Lives for gear
 
ELI-173's Avatar
 
🎧 15 years
Quote:
Originally Posted by jdk998 ➡️
The photo is of a toroidal transformer replacement.

I am just about to recap my Rev3.3 and replace the power supply. I am still researching the replacement ps but am thinking something along these lines:

Signal Transformer MT-8-15 http://www.signaltransformer.com/sit...pdf/MT-DMT.pdf

As for the wood, I have had great success with Howard Feed-and-Wax Feed-N-Wax Wood Polish & Conditioner | Howard Products which is available on Amazon.
Thanks for the info, JDK!
Old 28th April 2016
  #24
Lives for gear
 
🎧 10 years
nice work, thanks for sharing. you should post the time required to do such a restoration job. also, socketing IC chips does make them way easier to replace, but it can also sometimes result in bad connections which wouldnt occur if the ICs were soldered directly to the PCB.
mini
Old 28th March 2018
  #25
Lives for gear
 
🎧 10 years
this guy posted a full restoration process of a prophet 5 on youtube. also other synths are available on his channel. its really amazing, enjoyed watching it so much and instantly realized where some of my P5s problems are coming from.

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