Reasons why an LFO might "freeze"

[LaceSensor]

HI

Can someone run me down a few reasons why an LFO might not "work"?
Im talking about a Op amp based LFO. assuming the power, bias, and GND are all connected, what might cause it to not work?

For detail, I am building another Lovetone Flange and the LFO isnt spinning
ive tested all traces for continuity, checked parts values, changed the Op amp chip, tried different op amp types etc.

Ian

[Govmnt_Lacky]

Couple of suggestions:

1) Check the proper wiring on ALL of your jacks. Especially the Trig/Gate jack
2) Check to ensure that you have the correct semis in Q14 and Q15 (BC307B and J113 respectiively)
3) Check proper continuoty for SW1.

Good Luck! 

[LaceSensor]

Couple of suggestions:

1) Check the proper wiring on ALL of your jacks. Especially the Trig/Gate jack
2) Check to ensure that you have the correct semis in Q14 and Q15 (BC307B and J113 respectiively)
3) Check proper continuoty for SW1.

Good Luck! 

cheers Gov

i havent wired the jacks yet but ive grounded the trigger wires, so that does 1)
2) I dont. I have switched the JFET for 2n5457, and the BC307B i only have a BC560 which should be compatible. Any thoughts on that?
https://www.fairchildsemi.com/datasheets/BC/BC556.pdf
3) switches wired properly. 

pretty sure I used the same transistor subs previously with no issue, definitely the Jfet

with that said I have ordered the proper part replacemetns which will arrive soon

[alanp]

2N5457 and J113 respond differently at low freq... my 3046vco's won't go LF with 2n5457, they are meant for 113's. Suspect that is your problem.

[LaceSensor]

2N5457 and J113 respond differently at low freq... my 3046vco's won't go LF with 2n5457, they are meant for 113's. Suspect that is your problem.

ok i will replace all those. I could have sworn I used the 5457's last time...

[LaceSensor]

2N5457 and J113 respond differently at low freq... my 3046vco's won't go LF with 2n5457, they are meant for 113's. Suspect that is your problem.

however, still, I used 2n5457 in place of the j113 in the wobulator too, as its used in that part of the circuit to enact the trig/gate same as the flanger, and it was fine then...

The LFO here is generated from the op amp unless I can be eduicated, so I dont see why the JFET are involved....

can you confirm?thanks

edit - i may be talking shit, just checking my email for "j113" reveals I did order some !

[LaceSensor]

hurrah

just subbed Q15 for a MPF102 and the oscillator is now working

thanks hive mind
no thanks to my alzheimer mind

[Govmnt_Lacky]

I love it when a plan comes together!