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PROPHET 5 REV 2 Q's
Old 15th October 2013
  #1
Gear Head
 

PROPHET 5 REV 2 Q's

Hello,

I own a P5 REV 2 and I was wondering what my options would be to have MIDI retrofitted to it. Do you guys have any suggestions?
I dont know if I should worry about shipping it anywhere or how safe that procedure would be... It's in pretty mint condition.

Also, I have a feeling that the tuning drifts a bit, especially with osc2...
For example, if I created a 2 osc patch and adjust the osc2 FINE knob for say C3 to sound good, maybe C5 would need retuning of the FINE knob.
Another thing I noticed is that after the synth has been on for a while, I find myself adjusting the master tune knob to keep the synth in tune with my other gear.
Of course I expect some degree of drifting as this is a 30 year old synth but I wonder how much is normal.

Cheers
Old 15th October 2013
  #2
RE: midi, yes you can fit midi to a rev2 no problem, a couple of kits to choose from i think.
i have an older (90s) kenton kit on mine, works a treat. email kenton and ask them for advice. any tech would be able to fit it.

RE: tuning drift, all oscs should drift roughly the same amount. sounds like you have a calibration error on your osc 2. i have actually just tuned mine yesterday, read this if you want to go through the procedure yourself. you can always pm me questions about that

https://www.gearslutz.com/board/elect...5-rev-2-a.html

but in short, no your osc2 should not go out of tune relative to osc1.

RE: general drift over time. yes this is normal always save your patch and hit auto tune and then re-adjust the main tuning knob before recording the synth. it does drift constantly but after about a couple of hours the drifting slows. also its not just the tuning that drifts, the envelopes drift too, they get shorter and shorter over time (a little)

there is a guy that's done a major upgrade to his Pro5 rev2 here on GS. I'm sure he'll make an appearance in this thread soon. his rev2 seems to have none of these problems due to a re-designed powersupply. that's the REAL way of doing it - future-proofing your synth.

i just tinker with a screwdriver until the thing works well enough to use, day to day
Old 10th December 2013
  #3
Gear Head
 

Thanks golden beers.
I took your advice and got Kenton MIDI installed. It's great.

Another question I had was, I have a few Spare SSM's in case i need to replace any of them, but what would the common symptoms be for;
-Dead VCA
-Dead VCO
-Dead VCF
-Dead EG

Once a problem with either of them is identified, is it easy to swap given that they are socketed IC's? I have no experience as a tech at all...
Old 11th December 2013
  #4
Lives for gear
 

Quote:
Originally Posted by sawtooth View Post
Once a problem with either of them is identified, is it easy to swap given that they are socketed IC's? I have no experience as a tech at all...
Bold emphasis mine...

If you have no experience at all, the last place you want to poke around or swap ICs is a rev 2 P5. These are complex machines and parts for these things are getting very scarce. Swapping ICs often does not solve the problem, and the real problem could be elsewhere which is waiting to fry your precious SSM spares.
Old 11th December 2013
  #5
Lives for gear
 

Quote:
Originally Posted by sawtooth View Post
what would the common symptoms be for;
-Dead VCA
-Dead VCO
-Dead VCF
-Dead EG
There are no common symptoms. The SSMs are not always the problem. Too many other potential suspects - CMOS, TTL latches/decoders, S&H buffers, OTAs, bad/aging caps and/or trimpots. My OB-X had many many faults, all due to the listed suspects and zero CEM ICs were defective.
Old 11th December 2013
  #6
Lives for gear
 
Xero's Avatar
Quote:
Originally Posted by sawtooth View Post
Thanks golden beers.
I took your advice and got Kenton MIDI installed. It's great.

Another question I had was, I have a few Spare SSM's in case i need to replace any of them, but what would the common symptoms be for;
-Dead VCA
-Dead VCO
-Dead VCF
-Dead EG

Once a problem with either of them is identified, is it easy to swap given that they are socketed IC's? I have no experience as a tech at all...

Cheers,
P
If your power supply is good and putting out nice clean power, and there's nothing seriously wrong with the synth, SSM's shouldn't just be dying randomly. More often than not it'll be old CMOS logic IC's, all the various 4000 series logic. They are notorious for going bad, much more so than SSMs. And also bad solder joints on the various boards more than likely caused by a faulty soldering process used on these. It could also be due to the crappy mounting of the boards that the boards are put under extra stress and causing the broken/bad solder joints as well.

I definitely agree with others, I wouldn't go blindly swapping around SSMs unless you have some idea of what the problem is to begin with, you don't want to start frying your other SSMs by inserting them into a socket which is blowing them up...and pretty much all of those SSMs have surrounding components that will cause them not to function if those components are also not functioning. I guess if you have spare SSMs then it might not be as big of a deal. I got a few spares myself around the same time I got kenton installed into mine, just in case, but fortunately, none of them were necessary. My tech ended up re-flowing the solder on most of the CPU board and it's been solid ever since. However, the prophet 5 rev2 is one of my synths I rarely ever attempt to work on myself, and I've worked on my jupiter 8 no problems. The prophet 5's are just too damn fragile, and the way you work on them with the board hanging out is just insane.
Old 11th December 2013
  #7
Lives for gear
 
pulsar modular's Avatar
 

I would check with Greg Montalbano who specializes in P5s. He's not too far from you (Oakland).

Analog synth service
Old 11th December 2013
  #8
Gear Head
 

Thanks for the replies. I'll be sure not to open it no matter what
Also, curious what your thoughts are :

Here and there when I power the synth up after not having used it for while it'll do something a little strange, although it's always for a fraction of a moment.

For example, after turning it on, the tuning might be off, but as soon as I reset the synth, itll be back to normal.
Or another example, I 'll power it up and play a chord and maybe one of the notes might cut out for like a millisecond, or have a very quick drift in pitch ( almost like a pitch bend ) and then go back to normal.

After like 5 minutes of playing it, nothing
else would come up during that day.

I am aware that it's over 30 years old and that little quirks here and their might be acceptable...
Old 11th December 2013
  #9
Lives for gear
 
Xero's Avatar
Quote:
Originally Posted by sawtooth View Post
For example, after turning it on, the tuning might be off, but as soon as I reset the synth, itll be back to normal.
Or another example, I 'll power it up and play a chord and maybe one of the notes might cut out for like a millisecond, or have a very quick drift in pitch ( almost like a pitch bend ) and then go back to normal.

After like 5 minutes of playing it, nothing
else would come up during that day.
the voices dropping out thing sounds much like what mine was doing until my tech reflowed all the solder on the cpu board. I mostly noticed it crashing every few hours. I didn' notice the voice drop as much, but it was doing that too.
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