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Post subject: DRRI Reverb Problem
Posted: Wed Apr 08, 2015 6:54 am
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I recently bought a new DRRI Fudge Brownie but it has developed an intermittent problem with the reverb in that it will suddenly stop working. I have replaced the tubes in V3 and V5 but the problem still persists. The problem can be solved by switching the amp off and on again and I have now discovered that if I bang the top of the amp with my fist that also makes it work again.

Any suggestions as to what the problem could be?


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Post subject: Re: DRRI Reverb Problem
Posted: Wed Apr 08, 2015 7:26 am
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Sounds like solder issues. What prolly needs to be done, is drawing up the solder points on the input jacks and wiring to the reverb tubes' sockets. And reapplying good quality 60/40.

Or returning the amp. Unfortunately, this solder problem is associated with RoHS compliant solder. Which is used on most circuits these days. It take more heat to do a proper soldering job. However, more heat = more chance of damaging the marginal circuit boards which are often used. So, manufacturers are stuck in a difficult position. Very few use heavy duty mil spec circuit boards --- due to cost.

In other words... you'd prolly end up with another amp that needs re-soldering. If you really like this amp, you may want to re-solder ALL solder points. PITA. But, it would most likely end the transient poor connection problems.

Sorry about that. :(


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Post subject: Re: DRRI Reverb Problem
Posted: Wed Apr 08, 2015 10:40 am
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There's a good chance Beemer is right. But before you tear it down, Pull and reinsert the reverb tank connnectors. They are the RCAs under the chassis.
Resoldering any modern ROHS amp is a good idea.


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Post subject: Re: DRRI Reverb Problem
Posted: Wed Apr 08, 2015 2:43 pm
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Thanks for the comments and suggestions.

I forgot to add in my original post that the problem only occurs when the amp is "cold" i.e. been on for up to 5 minutes or so. If it stops working and I give it a thump it stays working so perhaps the cause of the problem is heat sensitive.

I have re-seated the reverb plugs but not tried it yet. However, I will be running the amp for about 5 hours in the rehearsal studio tomorrow so it will get a good workout and I will see what happens.


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Post subject: Re: DRRI Reverb Problem
Posted: Thu Apr 09, 2015 2:20 pm
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Update: Had the amp running for about 5 hours today. It was on standby for about 10 minutes while I was setting up. Switched standby to 'on' and reverb didn't work. Switched power off, let is stand for a minute then switched on again. Reverb was ok for the rest of the session.

As long as the fault is easily fixed I think I'll take no immediate action but if it starts to fail mid-session then I'll have to get it looked at under warranty.

Incidentally, it is an amazing amp. This is my first Fender amp and I think the DRRI Fudge Brownie and my American Standard Stratocaster is a match made in heaven! It is stock apart from V6 which I have replaced with a Mullard CV4024.


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Post subject: Re: DRRI Reverb Problem
Posted: Thu Apr 09, 2015 6:32 pm
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You can also try contact cleaner on the tubes and sockets. Interconnect lines between tank and amp. Etc. Not too much , just enough to cleaner the contact surfaces. Wipe up excess.

Good luck!


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Post subject: Re: DRRI Reverb Problem
Posted: Fri Apr 10, 2015 1:05 am
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My money's on one or more marginal solder joints.

Arjay

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Post subject: Re: DRRI Reverb Problem
Posted: Fri Apr 10, 2015 4:10 am
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Thanks for the latest comments.

Just when I was beginning to think the random problem was becoming predictable there has been what might be an interesting development.

I switched the amp on this morning but the stock Fender 2 button switch was still packed away from yesterday so instead I used a Boss FS-6 and TRS lead and so far no problem. I'll need to try it a few more times but I'm beginning to wonder if it could be the switch that is the cause of the problem. When I was getting the problem I stamped on the switch a few times because I wasn't sure if the reverb was on or not. Still doesn't explain why the problem only occurred once each session but if it solves the problem I'll not complain!


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Post subject: Re: DRRI Reverb Problem
Posted: Fri Apr 10, 2015 8:36 am
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Your amp is designed in such a way that the reverb is always "on". The footswitch is required only to turn it off. If you disconnect the footswitch, is the reverb still intermittent?

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: DRRI Reverb Problem
Posted: Sat Apr 11, 2015 2:37 am
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I've tried it without the footswitch connected and had no problems so far. It's probably too early to be sure but it is beginning to look like the footswitch might be the cause of the problem.

Perhaps I should be more scientific in my approach to problem solving in future. Switching the amp off and on and/or banging it on the top seems not to have been solving the problem but rather my stamping on the footswitch repeatedly was both the cause and the solution. I'll spray some switch cleaner around the buttons and see if that fixes it.


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Post subject: Re: DRRI Reverb Problem
Posted: Sat Apr 11, 2015 9:36 am
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Some time back, Fender received a supply of bad footswitches from a sub-contractor which caused a myriad of problems for purchasers of re-issue blackface amps. Most were purged via warranty replacement but it's possible that a few escaped. You may have one of these. Try a different footswitch and see if the symptom still manifests.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: DRRI Reverb Problem
Posted: Sun Apr 12, 2015 6:59 am
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I'd be a little suspicious of the reverb tank coil wires if the footswitch is'nt the culprit.


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Post subject: Re: DRRI Reverb Problem
Posted: Sun Apr 12, 2015 2:11 pm
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I think the intermittent problem is now resolved. I have used the amp several times over the last 2 days with no footswitch attached and with a Boss FS-6 and TRS lead and have had no problem. I also sprayed around the Fender footswitch buttons with a switch cleaner and spent a couple of minutes repeatedly pushing the button on and off. I have plugged the Fender footswitch back into the amp and so far it has worked without incident so I am hoping that the problem has been resolved.

One other thing I have noticed is that there is a "hum" that get louder as the Reverb is turned up. Is this normal and if so can it be reduced by replacing the stock Chinese Groove Tubes 12AT7 in V3 with something different (such as a EHX 12AT7WC)?


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Post subject: Re: DRRI Reverb Problem
Posted: Sun Apr 12, 2015 2:15 pm
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A better-quality tube in your V3 position (and V4 for that matter) may reduce or eliminate the audible hum in the reverb circuit.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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