[sdiy] troubleshooting a LFO

[luna]

anyone know a sub for IR9022? will NJM022D work 
(http://www.njr.co.jp/pdf/ae/ae04007.pdf)? so far i'm thinking that the op 
amp in 3b is fried...



At 02:36 AM 11/7/2004, luna wrote:
>hello everyone, i've just subscribed, and it looks like the sh-101 is a 
>current topic so...
>
>i just recently bought a roland sh-101 with a non-working LFO, thinking 
>that the slider was dead. but it looks like the slider is operational, so 
>something else is wrong with the LFO. so here's how it looks:
>
>LFO light on the sh-101 is always on; all modulations work to VCF and VCO, 
>but the impact is static. the LFO isn't 'moving'. i know that the EXT 
>Clock in still works with the sequencer and arpeggiator and changing the 
>sample and hold, so it is hopefully not a CPU issue. it just looks like 
>the LFO is dead. although i'm not new to a soldering iron and construction 
>(have made a fatman and a number of effects), troubleshooting and 
>LFO/oscillator design theory is a bit new to me. my question is, what 
>should i look for to identify what is the problem in the circuit, if 
>indeed it is not a CPU issue?
>
>any help is appreciated, as i would love to use the sequencer as 
>standalone, not to mention having a LFO for modulation ;)
>
>also, schematics are located here: http://tinyurl.com/6ktq9
>
>thanks in advance.