andresound wrote:The return pot of the FX loop is acting like a master volume. The send pot makes no difference.
The return pot will act like a master, that's normal if you have the output from the return pot going to the amp's MV. With nothing in the loop, you should be able to control the volume with the send too.
andresound wrote:Will try bypassing the FX loop. So just to be clear, clip lead from wiper (centre lug?) of send pot, to wiper of i meg level pot (OD master?).
No, by the "input" to the pot I mean the clockwise lug, or the non-grounded end of the element. The wiper is typically the "output" of the pot.
Last edited by martin manning on Sat Jan 09, 2016 1:39 pm, edited 1 time in total.
That would be a way to begin to isolate the problem. What happens if you plug into the return jack? If you get sound that way then the recover stage and the power amp are working, and that portion is disconnected from the preamp and the send stage. You could then use a probe made from a cap and a piece of cable plugged in there to find out where you lose the signal.
A phone is fine, send that into the input and trace the signal wit the scope. You could run the phone signal into the return jack to see if the recover stage and power amp are working too.
getting 1k tone through the output. not very loud. If I turn the overdrive pot up will i am going though the return jack, that wired sound comes in. Could be something wrong nwith the relay board?
There should be enough gain in the recover stage to get a pretty big signal going into the PI input from a line level input at the return jack.
Not to say that this is the cause of the loss of signal you are seeing, because I don't know exactly how you have the loop wired in, but I suggest doing it as shown below, where the FX "Drive" and "Recover In" pots are on the back panel, and the master volume Level remains on the front panel. This is like an outboard three-knob D'lator set-up, except the redundancy of the "Recover Output" pot and the amp's MV pot is eliminated.
Edit: See later diagram below.
Last edited by martin manning on Mon Jan 11, 2016 10:13 am, edited 2 times in total.
That seems to narrow it down to the recovery stage or output stage? plugged the send jack into another amp, sound with level!! Tone stack sound a bit wierd compared to sat my express. This tone stack has much more control exept for the mids (not such a big difference).
That's good, so the relay switching works too, i.e. you have good signal at the send on both clean and OD? If so then you could jump from the send to the PI input and see if it's the recover stage or the power amp. Check your send and return jacks to see that they are wired correctly, and that the shorting contacts are passing the signal from send to return.
Martin,
No the I think I might have wired the relay incorrectly Would you be so kind as to please check previous post of the wiring for relay, sent to me from Dave (colossal). Is that the same as your suggestion?
This is when I put my hand up in class, and say "im confussed" sir
Would you be so kind as to please check previous post of the wiring for relay, sent to me from Dave (colossal). Is that the same as your suggestion?