Analog synthesizer repair, parts, sales, and innovation. I buy broken synthesizers!
OMG! The long awaited 6th installment of my my Prophet 5 restoration video series has finally arrived!
Last spring we mostly restored a broken Prophet 5, but I got busy with customer repairs and never finished it up. Today we’ll track down and repair one final problem with the P5… Seemingly random out of tune notes.
Billed as a preset-only OB-X but sporting nearly identical voice cards to the OB-Xa, the Oberheim OB-SX is a pretty underrated synth. Here I give some love to a long neglected OB-SX by rebuilding the power supply, voice cards, and keybed, and repairing a few other problems I encounter along the way.
Repairing another customer’s ARP Pro Soloist. This one had very few patches working when it came in due to bad switches and a faulty VCA. Also engaging the Wow touch sensor effect would short circuit the keyboard and cause there to be no output at all.
No, not repairing 4 ARP 2600s, making 4 repairs to the same ARP 2600…
In this video we bring life back to an ARP 2600 with 2 dead oscillators, dead sample and hold, and dead left speaker.
A customer sent in his Pro Soloist for repair because the touch sensor effects weren’t working and some presets sustained indefinitely after releasing the key. I also noticed several of the presets were dead. So we dive in and get this all fixed so he can get back to making awesome music with it.
Wrapping up the restoration of yet another dead ARP Omni 2, I hook everything up for testing & calibration, but there’s no output. Together we use some simple logic to figure out what’s wrong and fix the synthesizer!
The Prophet 600 Panasonic keybeds often have problems with dead or intermittent key contacts. In this video I show you how to access the key contacts, and how to repair them for reliable long-term operation.
I was working on an ARP Omni 2 and came across a really bad soldering job. Someone had replaced the gating capacitors, but all of their solder joints were “cold solder joints”. What’s a cold solder joint? Well, first let me explain what a good solder joint is. With a good solder joint, both the pad on the circuit board and the leg of the component you’re soldering are sufficiently clean (both clean before soldering and from the flux in your solder) and hot for the solder to form a solid bond between the two parts you’re soldering. A good solder joint looks nice and shiny, like my work on this ARP Omni 2 below:
Now that we understand what a good solder joint is and how it’s made, we can understand that a “cold” solder joint is made when the two metals are not sufficiently heated or clean enough for the solder to truly bond between both metals. In a cold solder joint, the two parts may be stuck together, but may not have good electrical contact, and since the solder is really just a blob sitting on the surface of the pad or component, it’s very prone to crack or break off. You can typically spot a cold solder joint by its dull appearance, like I saw in the ARP Omni 2 below:
On the closeup photo you can really see the dull solder blobs just caked onto the pads and leads of the capacitors. And to no surprise, several of them just cracked off when I was going through removing and replacing all these capacitors.
Hopefully this explains what a cold solder joint is and how to spot one. To avoid making them yourself follow the following Synthchaser tips:
If you find yourself melting the solder on the tip of the soldering iron, or “painting” solder onto the component from a blob on the tip of your iron, you’ll probably wind up with a cold solder joint.
Hopefully this helps, please comment if you have any other tips to avoid cold solder joints that I missed!
First, we restore a dead ARP Odyssey. Not the new Korg one, a real vintage, 1973 Mk 1 Model 2800 Whiteface ARP Odyssey. We change the ICs, capacitors, sliders, repair a dead oscillator and a damaged power supply. This Odyssey gets the full Synthchaser spa treatment!
Then, we use that ARP Odyssey as a test bed to fix a customer’s Odyssey oscillator board. Customer was reporting his Oscillator 2 couldn’t be calibrated and was drifting. The trimmer should be adjusted to make a 20Hz square wave, but the lowest it would go was 40Hz. What I saw was cool enough that I had to edit it into a Synthchaser video!
Most OB-8’s use a different style of keybed than found on other OB’s. These keybeds often have problems with dead or intermittent key contacts. In this video I show you how to access the key contacts, and how to repair them for reliable long-term operation.
This OB-8 is for sale:
Oberheim OB-8 Analog Synthesizer Keyboard w/MIDI & Page 2 Serviced – Excellent!
