Hi all,
I got a red one. This module is very functional and beautiful. I really like it.
And anoto32 is a gentle man and a nice guy.
Thank you.

I added 741 oscillator and LFO to 208 Toolbox with reference to this circuit diagram. But it did not work. https://www.muffwiggler.com/forum/userpix2/34537_741osc_1.jpg I searched the circuit diagram of the 741 oscillator on the web and learned. I noticed a small thing. The cross in the red circle m...

This is a little idea.
I can switch between Long and Short at any time.




Happy Holidays!

papz wrote:Any NPN should work, I generally use 2N3904.
The left trimpot should be adjusted carefully, the "sweet spot" is very small, above and below there's no noise.
The right one sets the output level.

Thanks

This one, but there are many noise circuits available on the net. https://www.muffwiggler.com/forum/files/101_0132_290.jpg Hello papz, Could you tell me about the transistor in this circuit diagram.. What is the transistor model number? I would like to install a noise generator in BOB expander. Tha...

I think I have heard that people with fake uA726s found that their oscillators produced extremely high frequencies (relatively speaking). Perhaps there is a build error with the pA726 on the MO card or a faulty CA3046? You can try replacing the sub module temporarily with two 2N3904 (or any generic...

This movie is the MO sounds like a mosquito.


The channel A level is 2.5 but the channel B level is 10.
The channel B is very small sound.

Do you have any advice?
Thanks.

I checked card 6 three times. But the sound of MO is like a mosquito sound.
I didn't swap only Q1 (2N4341) of card 6. I will swap as soon as parts arrive from mouser.

They are the images of card 6.





pa726.





Also the images of card 11.





Do you have any advice?
Thanks.

Sorry, my English is not good.
Wait a while for the results.

Although the shapes and amplitude are approximately correct, the frequency is well outside the range of what the MO should be producing. Where were the frequency slider and fine tune pot set when these images were taken? I think you need to remove card 6 and double and triple check all solder joint...

Thanks Guys. I swaped IC 1 of card 11 five times. Is it still necessary to swap? Do you know how to check whether the IC is OK or error? These are waveshape images of card 6 pin 4. I have not calibrated yet. sorry. It's saw. It's rectangle.(I understand not square, haha ) It's triangle. Please let m...

I'm sorry for the late reply. Any value from 10k to 100k is ok but a faulty channel B pot could also be a cause. When I checked with the scope, channel B pot is working. Because, when channel B pot is CCW, the waveform becomes horizontal. And CW, the height of the waveform becomes maximum. With a si...

Any value from 10k to 100k is ok but a faulty channel B pot could also be a cause. With a signal routed to LPG2 fully open, you can check for signal with the scope from card 11 pin 3 and trace it untill card 12 pin 11 via the pot and R71 33k resistor on the MB. I checked, but the above case is no p...

I'm asking about 5 pots of 208 mother board. I am using the following pots. CHANNEL B (A100K) CHANNEL A (A100K) REVERB LEVEL (B100K) MONITOR LEVEL (A100K) OUTPUT LEVEL (A100K) However, I noticed it when I saw the DAVE's site. https://modularsynthesis.com/roman/buchla208v2/208%20Motherboard%20front.p...

The vactrols matching is not related to this issue. Vactrols faults are rare and since the panel LED lights up I wouldn't suspect a dead one at first. Their resistance should be infinite or very high (several Mohms) with the slider to 0 and between around 1K and 1.5K with the slider to 10, measured...

The MO seems working. If you increase the MO frequency, does the CO pitch and amplitude modulation well get faster ? The issue is probably related to LPG2. Does the LED light up if you push the LPG2 right slider up ? You don't seem very familiar with how the 208 works or should work. Do you have th...

I meant the mod CV out banana socket in the top right of the panel. Can you patch it to a CV input, such as CO pitch or other, and check if it modulates ? Can you also check if pushing the MO index sliders up modulates the CO pitch (FM) or amplitude (AM) depending on the modulation switch position ...

Does the MO work as a modulation source ? You can check it with the index section and the mod CV out. If it works, the problem is likely not in the MO but in the LPG2, on card 11, or in the modulator, on card 5. You can check the LPG2 with another source : external signal patched to the preamp, wit...

Please someone give me some advice. I have problems with MO. When the routing switch is centered, the sound of CO can be heard from the output, but the sound of MO is very small at output. The MO signal reaches the Molex pin 9 of the card 11 from the Molex pin 4 of the card 6 via R 84 (120 K ohm) of...

MO has many troubles.
You need luck and detailed troubleshooting is to succeed.

Hello everyone. I need help. I removed the flux. And I confirmed soldering with a loupe. I can not hear anything from card 6. Which pin of molex is the MO output of card 6? And there is sound from card 7. However, moving the FINE TUNING knob and the PITCH slide does not change the sound. Where is p...

Hello everyone. I need help. I removed the flux. And I confirmed soldering with a loupe. I can not hear anything from card 6. Which pin of molex is the MO output of card 6? And there is sound from card 7. However, moving the FINE TUNING knob and the PITCH slide does not change the sound. Where is pi...

papz wrote:Hi
I monitor the audio outputs for calibration.

I see. Thanks.

Hello everyone.

It is a question about calibration.
Where are the oscilloscopes connected when calibrating Buchla 208?
The ground is easy to understand. But at which point should each calibration be connected?

Hello everyone. I ask questions here because I can not find the build thread of Buchla 211. I built the POWER SUPPLY UNIT MODEL 211. However, the +15V terminal has only 11.75 voltage. Does anyone know the information on the circuit diagram of Buchla 211 ? I post a photo. Please give me advice. the ...