BOSS TR2 Tremolo - second version with That2181 vca

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BOSS TR2 Tremolo - second version with That2181 vca

Postby bajaman » 10 Sep 2019, 09:30

Boss TR2 second edition with THAT VCA preliminary.gif
Hi folks
Throwing this one out there to see if anyone can help supply the missing component values - cannot believe that this schematic is nowhere to be found on the internet - I have modified the first edition schematic but need some help to finish the schematic.
If you can help it would be good. :thumbsup
Thanks
bajaman
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Re: BOSS TR2 Tremolo - second version with That2181 vca

Postby bajaman » 10 Sep 2019, 09:35

I need component values for R46, R47, R54 (and the parallel capacitor number and value), C22, and D9
cheers
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Re: BOSS TR2 Tremolo - second version with That2181 vca

Postby george giblet » 11 Sep 2019, 09:25

Here's a few fixes. Still missing a few things. If I get time I have another look.

BTW, I'm not sure that's V2. There might be two versions prior to the THAT version.
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Re: BOSS TR2 Tremolo - second version with That2181 vca

Postby bajaman » 11 Sep 2019, 10:33

Thank you George :thumbsup
Here is the updated preliminary schematic with your amendments added.
Still not sure about that D9 diode :? The best board picture I have seen it is clear glass with a blue band.
cheers
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Boss TR2 second edition with THAT VCA preliminary 2.gif
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Re: BOSS TR2 Tremolo - second version with That2181 vca

Postby aionios » 11 Sep 2019, 16:04

bajaman wrote:Still not sure about that D9 diode :? The best board picture I have seen it is clear glass with a blue band.


Clear glass with a blue band are usually the Japanese 1N914/4148 equivalents, right? 1S1588 or similar? I see them on Maxon and Ibanez boards too.
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Re: BOSS TR2 Tremolo - second version with That2181 vca

Postby karul » 11 Sep 2019, 16:39

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Re: BOSS TR2 Tremolo - second version with That2181 vca

Postby bajaman » 11 Sep 2019, 22:14

Thanks for that aionios and karul :thumbsup
It is great news getting all this help to finalize the schematic
here is the latest schematic update
cheers :D
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Boss TR2 second edition with THAT VCA preliminary 3.gif
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Re: BOSS TR2 Tremolo - second version with That2181 vca

Postby george giblet » 12 Sep 2019, 05:48

FWIW, the diodes I saw had a smaller package DO-34 (MHD), like these,

Image

The part numbers for blue diodes were,
1SS119, 1SS120, 1SS270

The 1SS120 has a marking "1",
https://w.atwiki.jp/mcmaster/pages/356.html

The pic I saw of the TR-2 had a marking "2" but I can't find any diodes with marking.

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Re: BOSS TR2 Tremolo - second version with That2181 vca

Postby bajaman » 12 Sep 2019, 06:12

Yes George - the pictures I have seen do show a diode like that - short and stubby - could it be a zener perhaps ?
I checked the datasheets and the only diode with a mark on it was the 1SS120 (1)
Thanks for the info - we are not there yet :wink:
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Re: BOSS TR2 Tremolo - second version with That2181 vca

Postby bajaman » 12 Sep 2019, 06:21

here is the best picture I have found showing the D9 diode - the board marking does not suggest a zener - perhaps the 1S120 will work
D9.gif
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Re: BOSS TR2 Tremolo - second version with That2181 vca

Postby george giblet » 12 Sep 2019, 06:21

Thanks for the info - we are not there yet

In one pic I saw a black diode with a number on it. The package looked a bit more like the 1N4148 etc.

I can at least confirm C27 *is* 47n.
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Re: BOSS TR2 Tremolo - second version with That2181 vca

Postby bajaman » 12 Sep 2019, 07:09

updated schematic with confirmed C47 :wink:
Thanks George
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Boss TR2 second edition with THAT VCA preliminary 4.gif
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Re: BOSS TR2 Tremolo - second version with That2181 vca

Postby karul » 12 Sep 2019, 10:50

this may help a little bit, navy vs light blue

1ss119 - Cathode band: Light Blue
1ss120 - Cathode band: Light Blue
1ss270 - Cathode band: Navy Blue
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Re: BOSS TR2 Tremolo - second version with That2181 vca

Postby karul » 12 Sep 2019, 11:03

Correction:
1ss270 - light blue
1ss270a - navy blue


* data is from hitachi datasheets
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Re: BOSS TR2 Tremolo - second version with That2181 vca

Postby aionios » 12 Sep 2019, 14:49

I've got one of these incoming, so next week I can confirm anything else you need and take any necessary measurements (diode forward voltage, for instance). We'll get this one conquered!
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Re: BOSS TR2 Tremolo - second version with That2181 vca

Postby george giblet » 12 Sep 2019, 22:19

I've got one of these incoming, so next week

Be cool if you could check the value of C29 too.

I haven't been able to narrow the diode down. The only diode I saw with a "2" marking was a green one.
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Re: BOSS TR2 Tremolo - second version with That2181 vca

Postby Manfred » 12 Sep 2019, 22:30

IMO D9 could be any small signal diode, because IC3b works as an inverting amplifier where its amplification gain is depending on the signal polarty,
switched by the diode.
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Re: BOSS TR2 Tremolo - second version with That2181 vca

Postby george giblet » 12 Sep 2019, 22:51

IMO D9 could be any small signal diode, because IC3b works as an inverting amplifier where its amplification gain is depending on the signal polarty,
switched by the diode.

You would think so. What I find odd, which also make me a little suspicious, is they are already using the yellow band 1SS133 diodes so why use a different diode in that one position?
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Re: BOSS TR2 Tremolo - second version with That2181 vca

Postby Manfred » 13 Sep 2019, 07:24

The only difference between the both diodes is the maximum reverse voltage, the other data are the same.
The maximum reverse voltage of the 1SS270 is 35 Volts, of the 1SS270A is 70 Volts,
but without relevance for a 9 Volts power supply application.
My guess is that BOSS used both one for the same applications depends on its availability.
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Re: BOSS TR2 Tremolo - second version with That2181 vca

Postby Manfred » 13 Sep 2019, 08:04

you would think so. What I find odd, which also make me a little suspicious, is they are already using the yellow band 1SS133 diodes so why use a different diode in that one position?


Sorry, you talked about the 1SS133 diode.
The the junction capacitaces and the reverse recovery times differ a very ittle from the 1SS270x diodes.
These values in the Pikofard and Nanosecondes range are without relevance for this application too.
The threshold voltage is 0.1 Volts higher than the those of the 1SS270x diodes.

As mentioned above, any small signal diode should work for this application.
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