DRRI's reverb won't turn off

Make it loud here.
Post Reply
User avatar
funkyeah!
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 892
Joined: Mon Feb 07, 2011 11:02 am
Location: Virginia

DRRI's reverb won't turn off

Post by funkyeah! » Sat Jul 25, 2020 6:40 pm

I have a second-hand '65 DRRI with lots of little quirks but one has developed recently and I'm not sure where the cause is.

When I turn on my amp and switch it out of Standby, there is a small hiss that creeps up fast and drops off just as quickly. I also can't entirely dial out the reverb. When all they way rolled down I can still hear a considerable amount and using a footswitch to try to switch it off does nothing.

I'm pretty sure it wasn't moved around or banged about before this happened. The amp has had an issue with the tremolo not turning on with the footswitch. The amp light is green and flickers, often with boomier or louder notes I play. I have 6L6 power tubes instead of 6V6. It came with an Eminence Sidewinder speaker. And it was rigged so that the tremolo can work on both amp sides.

So, I have no clue what else may be messed up or misconnected here. Any clues how to disengage the reverb?
Some days you just can't get rid of a bomb.

User avatar
MuscleDad420
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 257
Joined: Sat Jul 07, 2012 5:19 am
Location: Los Angeles, CA
Contact:

Re: DRRI's reverb won't turn off

Post by MuscleDad420 » Mon Jul 27, 2020 1:05 am

I would take a look inside the footswitch egg and see if you have a loose ground. Check the plug end as well -- it's two screws. Possible the footswitches might have also worn out. A multi-meter with continuity mode helps here.

Start up noise may be a tube going South. The "clunk" of the metal standby switch and B+ being applied can promote issues in weak or microphonic tubes. Assuming it's a consistent noise, try subbing a known-good 12ax7 and 12at7 in each position until the noise disappears. From there it might be tech time.

As for the pilot light, may be a dirty contact in the bayonet housing or worn-down bulb. Try substituting a new bulb and see if the issue remains.

User avatar
funkyeah!
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 892
Joined: Mon Feb 07, 2011 11:02 am
Location: Virginia

Re: DRRI's reverb won't turn off

Post by funkyeah! » Mon Jul 27, 2020 11:01 am

The bulb: I have removed it before to check but haven't replaced it. It seems to do this for a while and then when I look back after I've been playing a while, the light is off

The sound only happens on start up and I don't believe it's switch related because I tried turning the amp on with Standby off immediately. When the amp had enough on to make sound it still did the ramp up in reverb like when I normally switch it out.

I'll check the footswitch. I don't actually have a Fender one but have used a Marshall one from my old MG100HDFX. That footswitch almost never got used though so any faulty wiring wouldn't be from wear and tear. It's worked with the amp a long while ago too so it shouldn't be incompatibility.
Some days you just can't get rid of a bomb.

User avatar
MuscleDad420
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 257
Joined: Sat Jul 07, 2012 5:19 am
Location: Los Angeles, CA
Contact:

Re: DRRI's reverb won't turn off

Post by MuscleDad420 » Mon Jul 27, 2020 11:19 pm

funkyeah! wrote:
Mon Jul 27, 2020 11:01 am
The bulb: I have removed it before to check but haven't replaced it. It seems to do this for a while and then when I look back after I've been playing a while, the light is off

The sound only happens on start up and I don't believe it's switch related because I tried turning the amp on with Standby off immediately. When the amp had enough on to make sound it still did the ramp up in reverb like when I normally switch it out.

I'll check the footswitch. I don't actually have a Fender one but have used a Marshall one from my old MG100HDFX. That footswitch almost never got used though so any faulty wiring wouldn't be from wear and tear. It's worked with the amp a long while ago too so it shouldn't be incompatibility.
Bulb definitely sounds like it's on its way out. Replace it and I'd bet that'd fix the intermittent blinking.

I actually have an MG-series footswitch in my parts stock. Just popped it open to look and sure enough the case isn't grounded. Fender's reverb and trem circuit gets shunted to ground and that's what effectively silences the effect when you cycle the footswitches on and off. The Fender amp footswitches (the "egg") have a ground that goes through both switches and gets soldered to the inside of the metal housing, completing the circuit. I would encourage you to pick one up or use some means to borrow one to test.

As an aside, I would be careful with 6L6's in a Deluxe Reverb. I have seen my share of blown power transformers in both vintage and new DR's and that's with 6v6's. They're robust but not indestructible.

User avatar
funkyeah!
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 892
Joined: Mon Feb 07, 2011 11:02 am
Location: Virginia

Re: DRRI's reverb won't turn off

Post by funkyeah! » Wed Jul 29, 2020 7:01 am

MuscleDad420 wrote:
Mon Jul 27, 2020 11:19 pm
As an aside, I would be careful with 6L6's in a Deluxe Reverb. I have seen my share of blown power transformers in both vintage and new DR's and that's with 6v6's. They're robust but not indestructible.
It is pretty hot behind my amp when it's been on for a while. Not dangerous hot but hotter than it should be. I love the way it sounds though; the oomph that it can get. I can only turn it up to like 2 1/2 though so maybe that will help reduce a little bit of headroom.
Some days you just can't get rid of a bomb.

User avatar
øøøøøøø
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 5984
Joined: Sun Jan 06, 2008 8:26 pm
Location: Los Angeles
Contact:

Re: DRRI's reverb won't turn off

Post by øøøøøøø » Wed Jul 29, 2020 9:21 am

Strange issue.

I suspect an issue wherein one end of the reverb pot has imperfect continuity to ground.

Try this: Remove the knob and check the tightness of the nut holding the pot to the faceplate. If it's not completely tight, give it a good crank and try again.

If that doesn't fix the issue, reflow the solder joints for that pot on the PCB daughter board to which the pots are soldered. While you're in there, check and re-seat the ribbon cables in their connectors, and/or reflow the joints on the headers.

If that doesn't give you at least some information, I'm not sure what to tell you next.

User avatar
funkyeah!
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 892
Joined: Mon Feb 07, 2011 11:02 am
Location: Virginia

Re: DRRI's reverb won't turn off

Post by funkyeah! » Wed Jul 29, 2020 7:10 pm

^^^^^^^^^
my dude
Some days you just can't get rid of a bomb.

Post Reply