Some additional documentation for TTSH

A friend recently asked me to "clean up" a TTSH V2 that he had purchased.  I was surprised to not find any component placement diagrams for the pcb, (which has no reference designators printed on it).   Component values are indicated on the silkscreen, but for servicing or troubleshooting,  some way to match up components to the schematics would also be useful.   So I have created a few of these diagrams myself, and offer them here.   I did not label every component, as it's pretty tedious work.  Note that these diagrams may contain errors.  Use them at your own risk.  Someone else may have created similar documents, but so far I have not found them.

Here is an archive containing five diagrams showing different sections of the pcb with many of the components labeled.  I used MW user sduck's great pcb pictures, and reversed the image colors to make them more printer-friendly.   These show the V2 pcb, although it seems that most of the reference designators are the same for V1 and V2.

There is a lot of information available about the TTSH spread over the hundreds of Muff Wiggler posts.  Also, there is a list of known issues with the V1 pcb's here:

https://www.dsl-man.de/display/DSO/TTSH+known+issues

One thing that is not listed here is changing the lag buffer op amp (A39) from LM301 to TL071 to reduce the voltage error when using long lag times.   The V2 pcb has a note concerning this substitution in the silkscreen next to this op amp. 

Another thing not listed is that the V1 and V2 pcbs both already have locations for four coupling capacitors in series with the inputs to the filter.   There are four sets of eyelets, indicated on the pcb, but the traces between them need to be cut before installing the (non-polarized, ~1 uF) capacitors.

Here is a list of some TTSH V2 issues and mods that builders/techs might want to look into.

In case anyone is trying to troubleshoot a slider LED problem, this schematic shows the LED wiring order.  (On my friend's unit, the builder had removed all of the LED's to paint them, and then re-installed them with seemingly random polarity.  I discovered that although the longer lead is usually the anode on these, it isn't always.)

TTSH ADSR Information

Some people have implemented a way to select different ADSR timing capacitors to get different envelope speed ranges.  The factory value was 2uF.   If this is reduced to 0.1uF, the ADSR maximum output voltage can increase from the normal 10V to 15V.  This is because once the output level has reached the 10V threshold at the end of the attack period, it takes the circuit a little time to switch into the decay mode.   During this time, the timing capacitor will keep charging.   With the normal value of 2 uF, the capacitor only charges a few tenths of a volt during the switching time, and it's not noticeable.   With a much smaller timing capacitor, it charges much faster, and can go all the way up to 15V in the same amount of time.   I don't think the higher voltage would cause any damage, but having the ADSR output level change depending on the timing capacitor selected doesn't seem like a good thing.   It seems that reducing the timing cap from 2 to 1 uF does not cause any overshoot, and still makes the envelopes faster, so this might be a good choice.

The sustain voltage circuit was changed (improved) in the Odyssey from what was used in the 2600/TTSH.   Here is a drawing showing the two circuits and explaining why they made the change.  The TTSH can be modified to use the Odyssey circuit pretty easily.

A few free TTSH Oscillator Sync PC Boards Available

I ended up with four extra oscillator sync pc boards.   These are blank boards from OSH Park.  If you need one or two, just cover the postage and they are yours.   I seem to have two different revs of the board.  One says Rev A.   The other does not indicate a revision level.  They are very similar.  I have two of each, so could send one of each type to the first two people that want them.  You can check OSH Park to see which one is the latest.

     

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