Search found 21 matches

ok - so got to change the j111, the LM311N and the OPA2137 with fresh new components today as new parts arrived. Sadly it made no difference.

And the recalibration did not change the behaviour.

As I have three boards with the same issue, it think is is unlikely (but not impossible) that I did the same mistake three times.

Perhaps it ...

Why do all the images show 1.00 V/ except the last one which has 2.00 V/? Is that the volts per division or something else?

Yes it is the voltage division. The pictures were not taken in the order ...

Oh, sorry, you need to turn your coupling from AC to DC so we can see what the DC offset is.

Also, U6 pin 7 doesn't look right, the amplitude doubled. You sure that wasn't pin 1?

Ah my mistake, ...

And the same but U6 pin7 against U5 pin3

They are identical

50 Hz
https://preview.ibb.co/ceH2hn/IMG_4150.jpghttps://preview.ibb.co/hJ168S/IMG_4151.jpghttps://preview.ibb.co/mwceTS/IMG_4152.jpg

I'm curious what the actual voltages are at U5 pin 2 and the gate of the JFET (probably need to scope them because of the pulsing) as well as the signal at U5 pin 3 (should look like U6 pin 7 but I' ...

Based on that, off hand I'd say double check C7 (100pF), that both emitters of J4 are connected to R15, R15 is not shorted and that the base of J4 that should be connected to ground actually is.

...

The rail voltages are the approx. +/- 10.6V you see out of the 7xL12, you're near 0V which is in the middle. .

Ah yes, my mistake. I misread you and thought it was not supposed to be close to GND ...

3. U3b pin 7 should be a constant negative voltage (for a given frequency setting) but not too close to the negative rail voltage.

Let me know what you find and we'll go from there.

Changing t ...

I would suggest starting by checking the following:
1. 5V reference : check at U7a pin 1, C8, Q1 drain and R13 to make sure they all have the same constant voltage of approximately 5V.

Defin ...

Thanks the input. I’ll try it out and let you know. I am away for a few days but will take a look as soon as I get home

OK - so last weekend i tried to convert one of the VCO's to running +/- 15 volts, (changed the 78l15 and 79l15, and the three resistors) to see if that would make a difference. But unfortunately every ...

Thanks - I really appreciate it - let me know if you need a closeup photo of anything.

You are absolutely right - I did remove the R12 on my other boards, when I installed the tempo. It will not work with both as you say, but I the odd behaviour pictured above with the scopes was with t ...

https://preview.ibb.co/btESy7/DSCF1050.jpghttps://preview.ibb.co/d6O4BS/DSCF1056.jpg
[url=https://imgbb.com/]url for an image

Yeah - All three boards act the same way, and I have double checked the caps so many times I have lost count Smile

The J112 is also placed correct according to the PCB layout. I have tried replacing ...

OK - so I had a further look, but still not found the solution. Also tried he boards/pots when they were not connected to the panel, but it made no difference. Ive put on the oscilliscope on the sine ...

the value of the trimmer t1 should not be so crucial, but in the schematic the value is 220k --> do u have a 100K?

I have a 200K trimmer for T1. That should be alright according to the build i ...

Just noticed that i only have a 20k port for the T2 10 turn trimmer. I dont have a 22k/or25K so Ill have to get some before i can test, but perhaps that could be explanaiton?

Thanks for our help Gabbagabi.

Yes, I can easlily make it go down below 200 with the pots. The out of tune "drift" happens below 200 Hz regardless of the pot setting, as long as the " ...

I have just finished building 3 yusynth VCO's using circuitboards from soundtronics.

Everything seems to work - different waveshapes etc, but i can not get the VCO to track at below 200 Hz - on al ...

Author	Message
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Sat Mar 17, 2018 1:07 pm Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	ok - so got to change the j111, the LM311N and the OPA2137 with fresh new components today as new parts arrived. Sadly it made no difference.
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Mon Mar 12, 2018 4:01 am Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	And the recalibration did not change the behaviour. As I have three boards with the same issue, it think is is unlikely (but not impossible) that I did the same mistake three times. Perhaps it ...
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Sun Mar 11, 2018 4:12 pm Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	Why do all the images show 1.00 V/ except the last one which has 2.00 V/? Is that the volts per division or something else? Yes it is the voltage division. The pictures were not taken in the order ...
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Sat Mar 10, 2018 3:30 am Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	Oh, sorry, you need to turn your coupling from AC to DC so we can see what the DC offset is. Also, U6 pin 7 doesn't look right, the amplitude doubled. You sure that wasn't pin 1? Ah my mistake, ...
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Fri Mar 09, 2018 1:24 pm Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	And the same but U6 pin7 against U5 pin3 They are identical 50 Hz https://preview.ibb.co/ceH2hn/IMG_4150.jpghttps://preview.ibb.co/hJ168S/IMG_4151.jpghttps://preview.ibb.co/mwceTS/IMG_4152.jpg
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Fri Mar 09, 2018 1:12 pm Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	I'm curious what the actual voltages are at U5 pin 2 and the gate of the JFET (probably need to scope them because of the pulsing) as well as the signal at U5 pin 3 (should look like U6 pin 7 but I' ...
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Fri Mar 09, 2018 10:42 am Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	Based on that, off hand I'd say double check C7 (100pF), that both emitters of J4 are connected to R15, R15 is not shorted and that the base of J4 that should be connected to ground actually is. ...
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Fri Mar 09, 2018 12:31 am Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	The rail voltages are the approx. +/- 10.6V you see out of the 7xL12, you're near 0V which is in the middle. . Ah yes, my mistake. I misread you and thought it was not supposed to be close to GND ...
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Thu Mar 08, 2018 3:35 pm Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	3. U3b pin 7 should be a constant negative voltage (for a given frequency setting) but not too close to the negative rail voltage. Let me know what you find and we'll go from there. Changing t ...
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Thu Mar 08, 2018 3:00 pm Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	I would suggest starting by checking the following: 1. 5V reference : check at U7a pin 1, C8, Q1 drain and R13 to make sure they all have the same constant voltage of approximately 5V. Defin ...
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Sun Mar 04, 2018 1:28 pm Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	Thanks the input. I’ll try it out and let you know. I am away for a few days but will take a look as soon as I get home
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Wed Feb 28, 2018 3:41 pm Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	OK - so last weekend i tried to convert one of the VCO's to running +/- 15 volts, (changed the 78l15 and 79l15, and the three resistors) to see if that would make a difference. But unfortunately every ...
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Fri Feb 16, 2018 5:34 am Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	Thanks - I really appreciate it - let me know if you need a closeup photo of anything.
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Fri Feb 16, 2018 5:22 am Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	You are absolutely right - I did remove the R12 on my other boards, when I installed the tempo. It will not work with both as you say, but I the odd behaviour pictured above with the scopes was with t ...
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Fri Feb 16, 2018 1:24 am Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	https://preview.ibb.co/btESy7/DSCF1050.jpghttps://preview.ibb.co/d6O4BS/DSCF1056.jpg [url=https://imgbb.com/]url for an image
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Mon Feb 05, 2018 1:06 pm Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	Yeah - All three boards act the same way, and I have double checked the caps so many times I have lost count The J112 is also placed correct according to the PCB layout. I have tried replacing ...
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Sun Feb 04, 2018 10:42 am Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	OK - so I had a further look, but still not found the solution. Also tried he boards/pots when they were not connected to the panel, but it made no difference. Ive put on the oscilliscope on the sine ...
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Sat Feb 03, 2018 2:25 am Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	the value of the trimmer t1 should not be so crucial, but in the schematic the value is 220k --> do u have a 100K? I have a 200K trimmer for T1. That should be alright according to the build i ...
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Thu Feb 01, 2018 1:36 pm Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	Just noticed that i only have a 20k port for the T2 10 turn trimmer. I dont have a 22k/or25K so Ill have to get some before i can test, but perhaps that could be explanaiton?
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Thu Feb 01, 2018 11:49 am Subject: Yusynth VCO problem tracking at low frequencies Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	Thanks for our help Gabbagabi. Yes, I can easlily make it go down below 200 with the pots. The out of tune "drift" happens below 200 Hz regardless of the pot setting, as long as the " ...
Topic: Yusynth VCO problem tracking at low frequencies
hoby Replies: 34 Views: 19374	Posted: Tue Jan 30, 2018 2:51 pm Subject: Yusynth VCO problem tracking at low frequencies Subject description: VCO tracking problem Forum: DIY Hardware and Software » YuSynth
hoby Replies: 34 Views: 19374	I have just finished building 3 yusynth VCO's using circuitboards from soundtronics. Everything seems to work - different waveshapes etc, but i can not get the VCO to track at below 200 Hz - on al ...