Author Topic: Harbinger (univibe) LFO locking  (Read 2054 times)

idy

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Harbinger (univibe) LFO locking
« on: April 14, 2015, 05:45:21 PM »
I built a Harbinger One last year, actually two. I had an intrmittent issue with the LFO locking up now and then, where I could get it going again by turning the rate knob. Now it won't get going ever. I used the LED, it lights up, the trimmers have no effect. Any ideas?

brejna

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Re: Harbinger (univibe) LFO locking
« Reply #1 on: April 14, 2015, 05:55:55 PM »
I built a Harbinger One last year, actually two. I had an intrmittent issue with the LFO locking up now and then, where I could get it going again by turning the rate knob. Now it won't get going ever. I used the LED, it lights up, the trimmers have no effect. Any ideas?
It shouldn't be hard to find the answer.. Check these..
What charge pump do you use?
Have you check wrong values around lfo, resistors and caps?
It could be burned Q11, Q12 or Q13?

madbean

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Re: Harbinger (univibe) LFO locking
« Reply #2 on: April 14, 2015, 06:30:02 PM »
I've seen lockup happen when the rate gets too fast on the bulb and it cannot keep up. So, you can prevent that by increasing the value of the two stopper resistors on the speed pot. The default is 4k7, so if you have used a lower value increase them. You really should not have lock up if they are 4k7, so if that is the case you are going to have start looking at voltages and other debugging.

Possibly the other issue is not related to the resistors. It could be a burnt bulb.

idy

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Re: Harbinger (univibe) LFO locking
« Reply #3 on: April 14, 2015, 07:12:51 PM »
The bulb is lighting, I have a light shield that comes off.
I am powering it with an 18v adaptor, no charge pump.
Remember it worked for the first year, not likely a mistaken part value...
I used the default value for the speed limit. It won't start anymore, hasn't for weeks.  Its not a matter of the speed being too high, knob has no effect.
Maybe Q 11, 12 or 13... I thought of trying a darlington before because I thought the bulb could have been brighter, never tried. I was hoping for greater dark/light contrast....
Cripes, I plugged it into check voltages on the transistors and .... it is working again. Thanks guys.

pt67

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Re: Harbinger (univibe) LFO locking
« Reply #4 on: August 28, 2023, 07:17:10 AM »
I am having a similar lock up issue with the harbinger two. Any suggestions?