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TM3030 problem with trigger and sound
MUFF WIGGLER Forum Index -> Oakley Sound Systems Goto page 1, 2  Next [all]
Author TM3030 problem with trigger and sound
morelius21
Hi

i have a tm3030, and i have a problem.

when I press a key , I can hear in the first moment, only the trigger or gate (just a kick sound) after i can hear the sound perfect. In the osciloscope i can see the waveform before de PCB switchwave, when i press de key, this waveform disappear and after arrive the wave again.

any idea ? my english is very bad sorry.

Thanks
Synthbuilder
My first thoughts are that the power supply is not doing its job. I'd check that R60 is definitely a 10R resistor and not something like 100R.

Tony
studyman
Hello,
i just finished my TM3030 issue 1, i know i'm late..wink but i've got a problem, all the leds are ok . When i play a midi sequence via my DAW i just ear a sound like a bass drum very short. I can ear that the note respond to the accent but just this sound at the same ton...i measured the power thru the U13 and i only have 14,8V. I use a 15V AC power supply (500mA-7,5 VA). I tried with an other power supply 15V 2,4A 36VA but i've got a very big sound of "masse" !!! i already checked the R40-R50 and R60....
Can you help me ....???
Thanks
Stuyman
Synthbuilder
studyman wrote:
i measured the power thru the U13 and i only have 14,8V. I use a 15V AC power supply (500mA-7,5 VA). I tried with an other power supply 15V 2,4A 36VA but i've got a very big sound of "masse" !!!


Pin 7 of U13 should be roughly 12V. Pin 1 of U13 should be around 5.33V. You should be able to adjust pin 1's voltage to exactly 5.33V by adjusting the trimmer PSU. If you can't get 5.33V then you probably have a fault with the components around U10. If you have 14.8V at pin 1 of U13, switch off and thoroughly check the components around U10 - maybe even replace U10.

Make sure your power supply is providing 15V AC and not DC. A 500mA power supply is plenty good enough but it does need to be an AC output. The bigger 36VA supply should work just fine but only if the output voltage is AC and not DC.

If you only have an DC output power supply then you need one with an 18V or 24V output.

Tony
studyman
ok i'll try with another supply...thanks
studyman
it's not easy to find in France a 15V AC transformer...wink
studyman
i've got a 19v DC 4,74A from an old computer is that would be ok ?
Synthbuilder
studyman wrote:
i've got a 19v DC 4,74A from an old computer is that would be ok ?


Possibly. The 19V is fine. But the 4.74A is huge and the TM3030 will be using only a fraction of that. This might mean your power supply won't work properly. Being a computer power supply it is almost certainly a switch mode design and these types of power supply have minimum loads. That means you have to take out a quite a bit of current for them to work properly and the TM3030 may not provide a big enough load to do that. Plus switch mode power supplies designed for computers are normally electrically noisy. Personally, I would not use it.

Look for a 18V or 24V DC output power pack.

Unfortunately, good quality AC output ones are rare in the UK too now - although Ebay is usually a good source of cheaper Chinese made ones.

Tony
studyman
hello,
i just received the right ac power, i changed Q5 Q4 and Q3...but i have the same problem...just a kick sound...i've got volume, accent, midi in.
I've got the 5,33v ...
what can i do more please....?
Pierre
Synthbuilder
Unfortunately, there are quite a number of things that can lead to you just getting clicks at the output.

What is the voltage at pin 7 of U13? It should be around 12V.

What is the voltage at pin 7 of U7? This should change depending on the note you play and will be from 1V to around 5V. High notes being higher voltages. If this is OK then the midi-CV section is working.

What are the voltages on pin 2, pin 12, pin 13 and pin 14 of U6? 13 and 14 should be 5.33V and 12 should be 4.6V or so. Pin 2 will be around 5.33V but will vary with the note played.

Tony
studyman
hello,
i'm sorry but maybe i didn't precise that i've a issue 1 board, the U6 is SSM2210 so there are only 8 pin... wink
Pierre
Synthbuilder
Sorry, didn't see that bit.

What are the voltages on pin 2, pin 6, pin 7 and pin 8 of U6? 7 and 8 should be 5.33V and 6 should be 4.6V or so. Pin 2 will be around 5.33V but will vary with the note played.

Are pins 7 on U13 and U7 correct though?

Tony
studyman
so i checked the voltage, here they are :
U6: pin2:5,33V/pin 6: 4,83V/pin 7: 5,34V/pin 8:5,34V with a variation between an octave 5,29-5,31
U7: pin 7 variation between 3 and 4 V
U13: pin7 11,83V
Synthbuilder
These voltages look good enough. So the problem is probably not with the circuitry around the pitch control voltage or nor the exponential convertor U6.

The oscillator may not be oscillating though. The next thing to check is the FET. It is imperative that you have the right FET in the right holes. The J201 should be in Q2 or the 2SK30 in Q1. Which one have you used?

Tony
studyman
Synthbuilder wrote:
These voltages look good enough. So the problem is probably not with the circuitry around the pitch control voltage or nor the exponential convertor U6.

The oscillator may not be oscillating though. The next thing to check is the FET. It is imperative that you have the right FET in the right holes. The J201 should be in Q2 or the 2SK30 in Q1. Which one have you used?

Tony


Hello,
i used a J201 in Q2, is there a possibility to test it ?
Synthbuilder
studyman wrote:
i used a J201 in Q2, is there a possibility to test it ?


Not without taking it out of the board. Do you have access to an oscilloscope? If not what is the DC voltage across R5? Measure between both ends of R5. What is the AC voltage across R5? This time use the AC volts setting on your meter.

If you do have a spare J201 it may be worthwhile swapping it with the one you have.

Tony
studyman
AC 16,5V
DC -8,19V
for R5 mesures

just a question....J201 FET and J201 JFET is the same thing ?
thanks
Synthbuilder
studyman wrote:
AC 16,5V


Are you sure about that one? A dead VCO would give around zero. A working one would be around 4V. 16.5V sounds too big.

Quote:
J201 FET and J201 JFET is the same thing ?


Yes. The J stands for junction and a JFET is normally just shortened to FET.

Tony
studyman
ok i'll check those values again, i think my voltmeter is a little bit tired...wink
studyman
maybe a stupid question but for the value i must put the power supply "ON" ? because that's what i did....
Synthbuilder
studyman wrote:
for the value i must put the power supply "ON" ?


Yes, when measuring voltages, both AC and DC, the unit should be switched on. When measuring any resistances then the unit should be switched off.

The problem with measuring AC voltages is that some meters do not do it very well. The AC range is often only there to measure voltages that come out of power supplies. They don't do audio frequencies very well. Even so, you should be able to tell whether something has an AC signal on it, if it comes up with something other than 0.00V.

Tony
studyman
ok but you asked me to measure at R5, so switched off...
studyman
so, i did the mesures with a new voltmeter,
switched power on thru R5: DC= + or - 8,20V and AC: 17V or 0v if i inverse the pointers...
studyman
i've just checked all my U and i saw a 6N139 instead of 6N137...is that bad ?
Synthbuilder
studyman wrote:
i've just checked all my U and i saw a 6N139 instead of 6N137...is that bad ?


If your midi is working then the 6N139 is working fine. I used 6N139 instead of 6N137 on the earlier builds.

Tony
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