Tuesday, May 13, 2014

TTSH

After sitting for about a month with several issues, I finally finished the Mini-Meanie (sort of)! I finished the build quite a while ago, but I was waiting on the "rare" parts to become available at Thonk. Impatiently I ordered everything from UTSource. After I installed the key parts, I found that 1 of the 4027 oscillator boards was DOA and VCO 2 was not outputting the Tri/Sine waves. I scoured that damned PCB looking for either a solder bridge or the wrong part. I checked every component 3 times each looking for something misplaced, but it all looked ok. Figuring it was a bad part from UTSource, I shelved the TTSH until the Thonk stuff arrived. While I waited I worked on the clock bleed by removing the LED blinky transistor for the S&H rate and did the jumper fix. This got most of the bleed, but it is still there unfortunately. For now, setting the rate to max keeps it unnoticeable, but I want to figure this out eventually. I did try several different power supplies as well as my bench top supply and none of it fixed it.

Last week the Thonk kit came and I finally had some time over the weekend to start looking at it. First thing was the 4027 board. I pulled out the fancy trannies and put in the Thonk ones. The 4027 was still dead. About this time I started really freaking out. How could something with barely any parts not work! It couldn't be a resistor or cap.... oh wait, maybe the 3906/3904 is bad! I pulled them out and dropped in 2 new ones. There it was! Bummed that I sacrificed some of the rare parts, but, good to know the UT stuff wasn't bad. Keeping this in mind, I pulled out the 3904's in the VCO 2 circuit that's part of the Tri/Sine wave. Again, problem solved!

One last thing was the filter cutoff would raise the pitch of the VCO's as I would raise the cutoff. Another headpounder which ended up being that a keyboard CV needed to be applied. I know that it's mentioned to add a jumper to short the CV to ground, but that didn't change the issue.

To Do is add the reverb tank (which is on order) and add the 2 speakers, which I'll do eventually but it's not a priority for sure. Lastely I'd like to add a MIDI 2 CV internally. Right now I'm using my Kenton Pro Solo, which works great because it can send the gate and trigger needed for the envelopes to fire. I have a midimplant I could add, but I'd need to make a gate to trigger converter. Not hard, just not wanting to do that at the moment.

Below is a quick video of the first patch. It's annoying and ear piercing and sounds like a Tron junkyard bike race, but, it was fun to patch and mess with nonetheless. Soon I'll put together a proper demo.

As for building these: I'll do it, but the availability of future batches is really up in the air. There were some serious issues with the logistics company. They damaged a large amount of the cases and panels (mine being one of them). I know the issue has since been addressed and corrected, but there has not been any word of a new batch being processed. We shall wait and see.

2 comments:

  1. did you manage to fix the left over clock bleed after the mod? mine is the same as yours in that I can still hear the bleed after the mod, less than before but still there making it unusable.

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    1. Since I posted this, this was developed: http://www.muffwiggler.com/forum/viewtopic.php?t=116172&postdays=0&postorder=asc&start=0

      They are OOS right now but it looks like he'll be making another batch. I did this to mine and it completely got rid of the clock bleed and I was able to put the blinky LED back with no issues!

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