Revibe- Verb but no Vibe?

[theundeadelvis]

Took a couple days, but I got my revibe wired up. My problem at the moment is, I have reverb but no tremolo. Pretty sure it's oscillating, but I'm not getting any effect on my guitar signal. The reverb also, seems a little week. Not bad sounding, just not enough reverb for a stand-alone unit. couple things I noticed while measuring my voltages: 1. When I touch my multimeter probe to pin 1 of V5 I could hear a faint sizzling or arcing noise (barely), but didn't see anything with the lights out. 2. When I touched my DMM probe to pin 3 of V3 my DMM would go crazy for a half second or so before showing the measurement. Any suggestions of where I should look? Thanks in advance!

Here are my voltages
V1
1 - 269
2 - .2mV
3 - 3.72
4 - 2.93
5 - "
6 - 181
7 - 2.9
8 - 1.35
9 - 2.87

V2
1 - 125
2 - 2.9
3 - 2
4 - 2.87
5 - "
6 - 137
7 - .7
8 - 2
9 - 2.91

V3
1 - 23
2 -
3 - 304
4 - 309
5 - 22.5

V4
1 - 270
2 - 1
3 - 2.7
4 - 2.93
5 - "
6 - 278
7 - .7
8 - 2.75
9 - 2.88

V5
1 - 120 - 215 (122 when vibe is bypassed)
2 - -130 to -140
3 - 1.28
4 - 2.93
5 - 170
6 - 1
7 - 1.7 170
8 - 1.15
9 - 2.88

[sluckey]

I would divide and conquer. Fix the verb then fix the trem.

You have several tube voltages that look wrong...

V1-7 should be zero.
V2-2 should be zero.
V3-5 should be zero.
V4-2 should probably be zero.
V5-2 should be zero. (I don't see any way to measure -130 to -140)
V5-7 should be zero.

A pattern I see is that most of your control grid voltages are reading wrong. Maybe your meter. Maybe your procedure. Maybe a common ground is bad.

[DummyLoad]

voltages on V5 seem amiss...

check wiring on V5  - pins 4 & 5 should be ~3VAC. pin 6 is a plate - i would expect to see more than 1V there. perhaps the 170V you show on pin 5 is a typo?

--ISO

[EL34]

Revibe jack info for those who don't know
You don't need to short out the vibe jack to make it work.

You need to short out the jack to make it stop.
Oposite of th way a Fender opto trem works.

[theundeadelvis]

I did read pin 6 of V5 wrong. It's 170V. I'll check my grids as soon as I get chance. Thanks for all the tips!

[theundeadelvis]

Took another look at it, and here's what I've found. The grids of V1 and V2 are zero, but pin 5 of of the 6v6 hovers around 25mV, and pin 2 of V4 and pins 2 and 7 of V5 all fluctuate in the very low negative mV's (around -1mV to -1.8mV).

Another thing, if I turn the intensity to 10, I can hear loud noisy oscillation. The guitar signal is not oscillating just background noise, and as I decrease the speed pot the speed of this oscillation actually increases?

[tubeswell]

Something is likely wired wrong. Thoroughly check everything again

[theundeadelvis]

I made a little progress. I now have some tremolo (repalced a bad cap). It sounds great, but isn't not noticeable until I turn the intensity to about 7. If I turn the intensity all the way up I get horrible distorted, blatty tremolo. 

Also the reverb is still pretty weak. If i replace V2 with a 12AX7 instead of the AT7, it gets better, but still not a strong as my standard reverb unit.

I'm also still getting some DC voltage on pin 5 of V3, pin 2 of V4, and pins 2 and 7 of V5. What could be causing this?

Thanks again for everyone's input!

[sluckey]

I'm also still getting some DC voltage on pin 5 of V3, pin 2 of V4, and pins 2 and 7 of V5.

How much? I would not worry about a few millivolts.

[theundeadelvis]

V3 has about 60mV on pin 5. V5 pin 2 actually jumps around in negative mVs?

[theundeadelvis]

I've been checking my components, and I think I may have found another bad cap. It's the .002uF coming off of pin 5 of V3. Unfortunately I don't have another to replace it with at the moment.

I'm wondering, if this cap is bad, could this explain the voltages on my grids, and what other ill affects might it have?

Thanks!

[sluckey]

Quit worrying about 25mv on V3-5. 25mv is 0.025 volts. That's zero as far as that grid can tell. Look for wiring errors and incorrect component values. Those are the #1 culprits in a new build. And this is a really complicated circuit that's compounded even more if you crammed it into that 6G15 style chassis. Get your looking glass out. Print the schematic and layout. Use a highlighter and ponder everything until your chassis, schematic, and layout are all in agreement. I'm betting you will find something that's not quite right,,, yet.

[theundeadelvis]

OK, forgetting about the grids. I've triple checked everything and haven't found any obvious mistakes. BUT, I think I may have found the problem area. I've linked a video of what I'm experiencing. I can change the noise by moving the wire connected to pin 7 of V5, but I can't make it go away. Tried a different tube, same thing.

Here's the vid:

[sluckey]

I can't see youtube while at work. V5 is part of the trem oscillator circuit. Just totally remove V5 for now. Turn the reverb mix pot all the way down (max CCW). Do you get a good clean guitar sound thru the unit? Signal flow would be input jack to V1B to V4(A,B) to output jack.

[theundeadelvis]

Yes, after pulling V5 and turning down the mix, I still get good guitar signal out. Thanks!

[sluckey]

OK, that's good. Leave the mix pot down while troubleshooting the tremolo. Put V5 back in. V5A is the LFO and V5B is just an inverter. V5A modulates V4B and V5B modulates V4A. Look for problems with V5 circuit.

[theundeadelvis]

Thanks sluckey! I'll see if I can find anything.

[sluckey]

I just listened to your youtube clip. You have tons of tremolo. Too much. It's way overdriving V4 when turned up. Look for things like wrong value resistors around the intensity pot. Make sure all the circled resistors are the correct value.

[theundeadelvis]

sluckey - Thanks again for your help. I'll be back to troubleshooting tomorrow, and I'll take a close look at the components you've highlighted.

[theundeadelvis]

Well, I was able to get rid of that horrible noise, when the Intensity is at 10, by changing how the wire going to pin 7 was routed. Now it's dead clean all the way to 10 on both the speed and intensity.

BUT, I still feel like there's not enough reverb. With it maxed out, it's probably not as much reverb as a Deluxe Reverb. I have a weber 5g15, but the tank in it is bad, so I can't compare the two at the moment. But if I remember correctly, it has reverb to spare. So now I need to figure out where my reverb has gone? There's no loss in signal, just seems like there's not enough dwell. It would be enough to make me happy, but I'm building this for a friend who's in a band that is verb crazy! I'm getting closer though!

[theundeadelvis]

Spoke too soon. Noise is not gone in vibrato. Moving the wires (mainly on pins 1, 6, 7, and 8) on V5 can make the noise mostly go away, and changes where the noise is audible in the range of the speed pot. So, back to checking components.

I also, can't determine if I need more dwell or if it's that there isn't enough reverb in the mix? 

[sluckey]

Divide and conquer. It will be nearly impossible to troubleshoot two very different symptoms simultaneously thru the internet. Although, it may be a common problem, but that's not obvious at this point. So, which do you want to work on first? Reverb? Or tremolo?

And what about those resistors?

[theundeadelvis]

Checked all the resistors you circled. I even went as far as to replace all but one (the 4.7M) with new metal film resistors just to be certain they were correct. But, now I'm not even sure if there's anything wrong with the trem or not. I can get the noise to go away by adjusting the lead dress of V5, but I'm afraid I'm not fixing the problem, just covering it up somehow?  I can get it dead quiet, but moving any one of 3 or 4 wires can make it come back.

I'll stay on track with the trem until I know it's as it should be, then I'll dive into the reverb.

Thanks again for taking the time to help me out. I do appreciate it greatly.

[theundeadelvis]

Well, I think I have it about where it should be. I had a 12AX7 in V1 and I swapped it with an AT7, and the reverb seems much better.

The tremolo seems to be completely related to lead dress. Not sure if it's picking up some parasitic oscillation or what, but when I moved one of the leads closer to the heater wires, it's dead quiet for now. Here's a video of how drastically it would change, just by slightly moving one of the wires on V5:

[sluckey]

I'd replace that socket just to eliminate it from the suspect list.

[theundeadelvis]

I am considering replacing it, but, it's dead quiet now, and since I moved that one wire, I can move the others around without any noise.

Thanks again sluckey. I really appreciate you taking the time to give me a hand.

[theundeadelvis]

Well crud, it's back. Guess I will replace that socket and see what happens. I've noticed if I cover the chassis with metal it get's better. Actually, I can just bring my hand close to it, and it quiets.

Oh well, here's what it's looking like:

[sluckey]

What I saw on that video is not an indication of bad lead dress. It looks more like you found a bad connection on that socket. May be your solder connection or may be a bad connection between the socket and the actual tube pin.

[theundeadelvis]

Replaced the socket last night, and in the process I've lost my reverb now. It also didn't seem to cure the issue. Now adjusting the tone can affect the noise, and I'm getting noise when I move the shielded cables on V1. I've missed something somewhere. Back to the drawing board after work.

P.s. is it necessary to isolate the send/return jacks to the reverb pan? I did on my 6G15, but in the photos Doug has of his revibe, it looks like they are not.

[theundeadelvis]

Reverb is fine. In my tired rush last night, I forgot to put the 6v6 back in. Wouldn't have the though the trem would work without the power tube.

Still having the other problem though.

[theundeadelvis]

I think (knock on wood) it's working now. I messed with the lead dress a bit, and added some shielded cable going from the intensity pot to the junction of .1 and .057 caps. All is pretty quiet. I have a barely audible distortion on the decay of the reverb, but I think that may be a characteristic of the tank (I have another to test it with).