Tech21 Character Series [schematic]
- JiM
- Diode Debunker
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That's because the first models to be traced (Blonde, British, Liverpool) do indeed have the same values there.Mbas974 wrote:I've noticed that the EQ section use different caps from type to type. ( C23 to C28 )
Why these are not mapped into the comparison matrix some posts above
Feel free to expand the table.
Those resistors are open-circuit inside the gooped module. The feedback loops are not open though, look closer at the schematic.Mbas974 wrote:R100, R103, R104 labeled NOT USED.... means that the Op-Amp are buffer or have the feedback loop has to be leaved open ?
I only give negative feedback.
- x-tn
- Breadboard Brother
bajaman wrote:...
Anyway - back to the CH34-4 module
This module uses the LINCMos TLC2262 dual op amp - internally entirely constructed with mosfets - it gain swing the signal full rail before it clips and Tech 21 have used this same device in all of their pedals from the original Sans Amp onward. It has a very soft clipping characteristic and can sound a bit "mushy' in the bass region in my opinion. However it's implementation in the character series pedal is a little different With reference to the schematics earlier in this thread you may notice two back to back 3.3v silicon zener diodes in the feedback loop of the second stage of the CH34-4 module.
It is THESE zener diodes that clip FIRST in this module according to my simulations NOT the op amp as in the original Sans Amp pedals. These zeners also roll off the high frequency response of this stage - the signal is -3dB down at 5khz and drops to over -22db at 100khz. Without the zeners, the response is flat to 100khz and beyond
I must emphasize that the signal is attenuated at high frequencies by these zeners EVEN when the signal is NOT being clipped by them
The TLC2262 NEVER has the chance to influence the clipping behaviour in these pedals - all the clipping and high frequency rolloff is performed by the two back to back zener diodes - food for thought
Cheers
bajaman
If "The TLC2262 NEVER has the chance to influence the clipping behaviour in these pedals" what would be the reason to change the TL062 with a TLC2262?bajaman wrote:I just bought a JOYO California sound pedal
...
I changed the dual op amp (TL062) - put a TLC2262 in it's place - i left the other two quad op amps (TL064).
...
bajaman
- bajaman
- Old Solderhand
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good point
be kind to all animals - especially human beings
How close are you guys to getting this finalized? I'm really anxious to build a tech21 blonde clone
- Nocentelli
- Tube Twister
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Hi all.
My bro-in-law has given me his Blonde to try and repair the intermittent footswitch. I knew it would be electronic switching from the schem, but I'm struggling to get it a part to check the actual board-mounted switch.
Do I actually have to de-solder the in and out jacks to get access to the board?
My bro-in-law has given me his Blonde to try and repair the intermittent footswitch. I knew it would be electronic switching from the schem, but I'm struggling to get it a part to check the actual board-mounted switch.
Do I actually have to de-solder the in and out jacks to get access to the board?
modman wrote: ↑ Let's hope it's not a hit, because soldering up the same pedal everyday, is a sad life. It's that same ole devilish double bind again...
I have mesured value of the California Joyo:
Code: Select all
+------------------------------------------------------+-------------------------------------------+
| T e c h 2 1 | J O Y O |
+---------+---------+------------+-----------+---------+----------+---------+------------+---------+
| Blonde | British | California | Liverpool | VTBass | American | British | California | AC Tone |
--------+---------+---------+------------+-----------+---------+----------+---------+------------+---------+
R4 | *3.3k | 10k | | 3.3k | 3.3k | *10k | 10k(R4) | 10k (R4) | 10k |
E1 | open | 18n | | 22n | 10nF | open | 18n(C3) | open (C3) | 22n | Input &
Cin | 22n | 22n | | 22n | 22n | 22n ? | 22n(C1) | 22n (C1) | 22n | filtering
C2 | 47n | 47n | | 47n | open | 47n ? | 47n(C2) | 47n (C2) | 47n |
--------+---------+---------+------------+-----------+---------+----------+---------+------------+---------+
C5 | 22n | 10n | | 22n | 10n | 22n | 3n (C8) | 10n (C8) | 22n |
C6 | 22n | 10n | | 22n | 10n | 15n | 82p(C7) | open (C7) | 22n |
R6 | 1k | 1k | | 1k | 1k | 1k ? | 1k (R6) | 1k (R6) | 1k | Character
R7 | 100k | 100k | | open | 100k | 100k | 100k(R7)| 100k (R7) | 100k | pre-EQ
R9 | 1k | 3.3k | | 3.3k | 3.3k | 3.3k |3.3k(R10)| 3.3k(R10) | 3.3k |
--------+---------+---------+------------+-----------+---------+----------+---------+------------+---------+
R14 | 47k | 33k | | 47k | 33k | 33k | 33k(R24)| 33k (R24) | 33k |
C14 | 470p | 470p | | 180p | 470p | ? |470p(C17)| 560p (C17) | ? | HP sim
C15 | 2.2n | 2.2n | | 2.7n | 2.2n | 2.2n |2.2n(C18)| 2.8n (C18) | 4.7n ? |
--------+---------+---------+------------+-----------+---------+----------+---------+------------+---------+
C20 | 10n | 22n | | 18n | 10n | 15n |15n(C25) | 22n (C25) | 18n | MID
C21 | 10n | 22n | | 22n | 10n | 15n |22n(C24) | 22n (C24) | 22n | EQ
--------+---------+---------+------------+-----------+---------+----------+---------+------------+---------+
*Not used
About speakersim on-off switch.
It's strange to have 22k-10n chain after high pass filter C11-R13, because we have bass drop on speaker-sim off. It's important for VT Bass variation. So i think low pass filter 22k-10n can be moved before C11-R13 without any issues.
It's strange to have 22k-10n chain after high pass filter C11-R13, because we have bass drop on speaker-sim off. It's important for VT Bass variation. So i think low pass filter 22k-10n can be moved before C11-R13 without any issues.
I was wrong, the problem is in C13-R16 filter, that reduce bass response as bajaman noted above. But the solution is the same - move HP filter before C11-R13
CloneME, it's opamp noise, so use them with low noise value(e.x.e TLC2272)
- azrael
- Cap Cooler
Which universal schematic does this refer to? Some of the links in the thread are to incomplete or dead images.Stephanovitch wrote:I have mesured value of the California Joyo:Code: Select all
+------------------------------------------------------+-------------------------------------------+ | T e c h 2 1 | J O Y O | +---------+---------+------------+-----------+---------+----------+---------+------------+---------+ | Blonde | British | California | Liverpool | VTBass | American | British | California | AC Tone | --------+---------+---------+------------+-----------+---------+----------+---------+------------+---------+ R4 | *3.3k | 10k | | 3.3k | 3.3k | *10k | 10k(R4) | 10k (R4) | 10k | E1 | open | 18n | | 22n | 10nF | open | 18n(C3) | open (C3) | 22n | Input & Cin | 22n | 22n | | 22n | 22n | 22n ? | 22n(C1) | 22n (C1) | 22n | filtering C2 | 47n | 47n | | 47n | open | 47n ? | 47n(C2) | 47n (C2) | 47n | --------+---------+---------+------------+-----------+---------+----------+---------+------------+---------+ C5 | 22n | 10n | | 22n | 10n | 22n | 3n (C8) | 10n (C8) | 22n | C6 | 22n | 10n | | 22n | 10n | 15n | 82p(C7) | open (C7) | 22n | R6 | 1k | 1k | | 1k | 1k | 1k ? | 1k (R6) | 1k (R6) | 1k | Character R7 | 100k | 100k | | open | 100k | 100k | 100k(R7)| 100k (R7) | 100k | pre-EQ R9 | 1k | 3.3k | | 3.3k | 3.3k | 3.3k |3.3k(R10)| 3.3k(R10) | 3.3k | --------+---------+---------+------------+-----------+---------+----------+---------+------------+---------+ R14 | 47k | 33k | | 47k | 33k | 33k | 33k(R24)| 33k (R24) | 33k | C14 | 470p | 470p | | 180p | 470p | ? |470p(C17)| 560p (C17) | ? | HP sim C15 | 2.2n | 2.2n | | 2.7n | 2.2n | 2.2n |2.2n(C18)| 2.8n (C18) | 4.7n ? | --------+---------+---------+------------+-----------+---------+----------+---------+------------+---------+ C20 | 10n | 22n | | 18n | 10n | 15n |15n(C25) | 22n (C25) | 18n | MID C21 | 10n | 22n | | 22n | 10n | 15n |22n(C24) | 22n (C24) | 22n | EQ --------+---------+---------+------------+-----------+---------+----------+---------+------------+---------+ *Not used
Hi, don't know if you saw, I just posted PSA-1 traces and schematics: https://www.freestompboxes.org/viewtopic.php?f=7&t=25708mxrmxr wrote:
BTW, just got hold of a Sansamp PSA-1 rack preamp. Maybe that can be the next project after this one
Ok, I realize this is an old post, but after breadboarding this schematic and hearing other's DIY build recordings, I have to ask, are we certain that the open circuit resistors are indeed resistors? With the amount of noise generated at the gain stage, and the obvious lack of capacitors compared to other tech 21 circuits, this leads me to believe these are in fact capacitors. Does anyone still happen to have this deconstructed and able to check the capacitance of: R100, R103, and R104?mxrmxr wrote:o.k here's the resistor values for the 'Goop Hybrid Module'.
This little baby still had a few surprises left.
R104 measured open circuit. My initial reaction was 'shit I've damaged it during the de-goop'. But no, closer inspection with a magnifying glass revealed that the laser trimming has cut completely through and across the resistive element, making it an open circuit. Phew, I can breath again. So, this resistor is not used.
R102 measured 218K laser trimmed. You can clearly see a couple of short laser cuts in the resistive element with a magnifying glass. So, this resistor will be 220K.
R106 measured 218K laser trimmed. You can clearly see a couple of short laser cuts in the resistive element with a magnifying glass. So, this resistor will be 220K.
R101 Measured 221K laser trimmed. You can clearly see a couple of short laser cuts in the resistive element with a magnifying glass. So, this resistor will be 220K.
R103 measured open circuit. Again, closer inspection with a magnifying glass revealed that the laser trimming has cut completely through and across the resistive element, making it an open circuit. So, this resistor is not used.
R105 measured 100K laser trimmed. You can clearly see a couple of short laser cuts in the resistive element with a magnifying glass. So, this resistor will be 100K.
R100 measured open circuit. Again, closer inspection with a magnifying glass revealed that the laser trimming has cut completely through and across the resistive element, making it an open circuit. So, this resistor is not used.