Böhm- Trickverzerrer

sinner · Post by **sinner** » 11 Apr 2012, 10:27

Promised picts, looks the same?

D-Day · Post by **D-Day** » 11 Apr 2012, 17:21

NEATO! Thanks you guys, I can't wait to fool around with this one.

Post by **digi2t** » 12 Apr 2012, 13:00

Nice sinner... excellent pics. Thanks!!

Updated, and verified, vero...

Nothing major. Changes;
- Had the wrong value on one of the trimmers,
- added an optional 150pF cap to help tame some high end fizz,
- moved some stuff around to make more room for playing with the clipping diodes (if one is so inclined),
- and to facilitate grounding of shielded cables to the board,
- changed tuning instructions for adjusting Q3C voltage.

It's not bad with guitar, real synthy sounding buzz/fuzz all over, but sounds much better with bass IMHO. Going into the lower registers, I thought the kid's amp was going to puke up it's one and only speaker!

Video to come, once it's boxed up.

Cheers,
Dino

mäk · Post by **mäk** » 12 Apr 2012, 21:50

i also got one of these trickverzerrer. if someone wants, i can make some gutshots.

mäk · Post by **mäk** » 12 Apr 2012, 21:52

sometime it better to go to the end of the thread

Seiche · Post by **Seiche** » 22 May 2012, 18:26

sinner wrote:Veb Musikelektronik and the model simply says Verzerrer

Verzerrer = Distorter/Overdriver
VEB Musikelektronik = Volkseigener Betrieb music electronics

TWSpedals · Post by **TWSpedals** » 31 Dec 2020, 00:01

I recently bought one of these and traced it out and mine has a number of differences from the factory schematic.
Nearly every resistor value is different, and there's is a difference in the the tone stack too. Instead of the 100n cap going between 'Diskant' lug 1 and ground, it goes between said pot lug and Q3 collector. This makes the full counterclockwise postion of the Diskant pot pretty much a tone stack bypass rather than a low pass filter.
I haven't seen this documented online before so i thought I'd post it here.
Below is a link to my schematic trace and a few gut shots as well. My unit is red in colour which again seems to be at odds with the other units documented online.
https://drive.google.com/drive/folders/ ... sp=sharing

Manfred · Post by **Manfred** » 31 Dec 2020, 23:29

I bought a Trickverzerrer years ago, forgot about it and never touched it.
I remembered it again through this thread.
I took a few snapshots of it, will open it the next few days and trace.

DiscoFreq · Post by **DiscoFreq** » 01 Jan 2021, 16:54

Manfred wrote: ↑31 Dec 2020, 23:29 I bought a Trickverzerrer years ago, forgot about it and never touched it.
I remembered it again through this thread.
I took a few snapshots of it, will open it the next few days and trace.

That's nice, all the ones I saw so far (have/had around 5 myself) had embossed text and logo, I don't think I saw any with painted text before.

Manfred · Post by **Manfred** » 02 Jan 2021, 23:23

Now I have opened the case, the previous owner had exchanged the transistors T1 and T2 against BC109C, T3 has the imprint F18 C-1.
At the right lower corner of the board, the conductor track and soldering eye are corroded obviously once the battery had leaked.
I have a PCB clone in work soon follows more.

TWSpedals · Post by **TWSpedals** » 03 Jan 2021, 15:34

That large 100n cap between the pots is the capacitor in the tone stack that departs from the factory schematic. It looks like yours has the same board layout as mine. There is no doubt yours too will have resistor value variations.

I'm kind of envious that yours looks that nice with the white text on it.

ppluis0 · Post by **ppluis0** » 03 Jan 2021, 23:27

I really like those hand drawn artwork of copper layer on older PCB's !!!

Manfred · Post by **Manfred** » 05 Jan 2021, 01:48

Here is the PCB layout, the schematic will follow soon.
I found some differences, R3 = 2k2, P1 = 25k,
R6 = 15k and D1 = GA101 in my version of the device.
In addition, the shown circuit of the treble control in the schematic is wrong.

Manfred · Post by **Manfred** » 05 Jan 2021, 17:03

In addition, the shown circuit of the treble control in the schematic is wrong.

I meant the "diskant" control, this is shown correctly in the hand drawn circuit diagram of TWSpedals.

Manfred · Post by **Manfred** » 05 Jan 2021, 23:55

Here is the schematic of my device.
It does not work, after the repair I will make some measurements.

TWSpedals · Post by **TWSpedals** » 06 Jan 2021, 22:45

Manfred wrote: ↑05 Jan 2021, 23:55 Here is the schematic of my device.
It does not work, after the repair I will make some measurements.
BoehmTrickverzerrerSchematic.JPG
GA101 If_VF.jpg

I think you need the power filter cap after the 270ohm resistor not before, other than that it looks the same as mine in terms of components in the right places. If it's a componet value issues that is making it not work maybe raise the value of the resistor going been Q1 base and Q2 emitter. The value in my unit is over double the one in the unit you traced.

Regardless I'm glad someone else was able to confirm my schematic and it wasn't just me finding that cap being different in the tone section. I emailed Fredric Effects (who make a clone of the Trickverzzer) and they were dismissive of my findings and pointed me to the factory schematic.

Manfred · Post by **Manfred** » 07 Jan 2021, 14:01

I think you need the power filter cap after the 270ohm resistor not before, other than that it looks the same as mine in terms of components in the right places. If it's a componet value issues that is making it not work maybe raise the value of the resistor going been Q1 base and Q2 emitter. The value in my unit is over double the one in the unit you traced.

Regardless I'm glad someone else was able to confirm my schematic and it wasn't just me finding that cap being different in the tone section. I emailed Fredric Effects (who make a clone of the Trickverzzer) and they were dismissive of my findings and pointed me to the factory schematic.

Thanks for the hint, you are right the 20u capacitor is correct in the layout but I drew it in the wrong postion in the schematic. I will replace the schematic in the post above.
I first need to fix the oxidized solder joint and trace.

Manfred · Post by **Manfred** » 08 Jan 2021, 00:26

I found a bunch of SC207 transistors in the box of the Trickverzerrer, I obviously bought them back then after I bought the unit, I didn't remember since that was a long time ago.
But anyway I am glad about it.
The SC207 has the same data as the SC206 with the difference that this one is selected for low noise.
I measured them all, the hFE@Ic=5mA values are in a range from 75 to 113, the average value is 82.
Here are the diagrams for a SC207 with this average value:

Original datasheet:

SC206.pdf: (130.11 KiB) Downloaded 159 times

silverdog · Post by **silverdog** » 09 Jan 2021, 16:13

ppluis0 · Post by **ppluis0** » 09 Jan 2021, 18:27

ppluis0 wrote: ↑03 Jan 2021, 23:27 I really like those hand drawn artwork of copper layer on older PCB's !!!

Sorry for quote myself, but I also like those old hand drawn schematics according to DIN drawing standards

BTW, Manfred: perhaps you must check the connection of DISKANT potentiometer in your board, according to this new diagram ?

Cheers,
Jose

Böhm- Trickverzerrer [schematic]