Hi all,
I have a Peavey Transformer 212 with an odd issue. After power up, I hear this "whooshing" noise (sounds like a steam train). See video here for details. The only things that seems to affect the sound are the delay switch and pots.
I pulled out the control boards (very interesting PCB layout!) and noticed that the delay level pot (I guess it's an encoder) was wobbly. See video here for details. Other than that, there were no visible issues that I could see; the boards look brand new.
Checking the schematic (see attached), it looks like the encoder in question is an ENC2425V 16mm 24 pulse vertical encoder w/o detents. I haven't been able to find this part via a websearch, so I emailed Peavey about it.
Anything else I should try to troubleshoot? I'd like to confirm this encoder is bad before replacing, but probing the pins with a DMM didn't really tell me anything (readings were jumpy, but so were the other encoders I probed).
I have a Peavey Transformer 212 with an odd issue. After power up, I hear this "whooshing" noise (sounds like a steam train). See video here for details. The only things that seems to affect the sound are the delay switch and pots.
I pulled out the control boards (very interesting PCB layout!) and noticed that the delay level pot (I guess it's an encoder) was wobbly. See video here for details. Other than that, there were no visible issues that I could see; the boards look brand new.
Checking the schematic (see attached), it looks like the encoder in question is an ENC2425V 16mm 24 pulse vertical encoder w/o detents. I haven't been able to find this part via a websearch, so I emailed Peavey about it.
Anything else I should try to troubleshoot? I'd like to confirm this encoder is bad before replacing, but probing the pins with a DMM didn't really tell me anything (readings were jumpy, but so were the other encoders I probed).
I was able to bend the tabs on the delay encoder back into place to fix the wobbling issue, but I still have the odd "steam train" sound. It appears to begin when I adjust the reverb or delay knobs, so the issue must be in that circuit. The LEDs on the reverb and delay knobs seem to track to the rotation, so I think the encoders are ok?
Encoders don't hiss.
Reverb can hiss, but excess hiss is probably an analog fault, and that schematic is too blurry for me. Ask Peavey about the *hiss*, not the encoder.
Reverb can hiss, but excess hiss is probably an analog fault, and that schematic is too blurry for me. Ask Peavey about the *hiss*, not the encoder.
Messed around with it a bit more; nothing conclusive. Sometimes it will work fine for a bit, but the issue comes back whenever I adjust the reverb knob. However, sometimes the issue will come back even when the reverb knob isn't touched. I tried plugging directly into the FX return jacks: the issue doesn't immediately appear, but sometimes comes back (seemingly at random). I thought that playing through the FX return would bypass the preamp, so does this mean I have an issue in the power amp as well? A little stumped here...
So I found that if I hit the delay button immediately after powerup, the issue does not appear unless I change the preset or turn on the reverb. I can use the amp (apart from the reverb) and it works fine (even the delay). This suggests the issue is in the reverb encoder/circuit. Unfortunately, my schematic comprehension leaves something to be desired, so I'm not sure what to try next. Could one of the ICs be bad?