DRRI dead, do I put it in trash and buy a Tone Master?

BorderRadio

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Seriously though, I switched it on the other day and nothing. Checked the fuse, seems ok. The lamp doesn't come on, and yes the bulb is ok. I know that's hardly enough info, but busy week, but I can get it on 'the bench' this weekend. Any ideas where to start troubleshooting next?

It's a 2013, I didn't mod it, planned to ride it hard in the warranty phase but of course, I'm out of warranty now.
 

Preacher

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I did not have the same amp, but a similiar issue. Apparently the plug in the back of the amp almost had pulled out (it was one of those computer type plug units) and it was not making contact.
I checked the wall, the fuse, the signal path, the fuse again, the wall again, and even opened it up and put a voltmeter on it and found no voltage. Then I bumped the cord and saw a spark... Ah it was not plugged all the way in, it was just barely in the housing.
 

teletail

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Yes, throw it out. Solid State amps NEVER break.

dog looking.gif
 

jondanger

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Seems like you’ve got to start by taking voltage measurements from before and after the PT. Once you have verified that voltage is getting through the PT right, then you might want to start by checking the heater circuit. Is the pilot bulb in line with the heaters like it is on the BF/SF models?

Just checked the schematic - pilot is in line with the heaters.
 

Drew617

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I don't know your comfort level working on these but I'd say if you know you can do it safely, certainly worth safely discharging caps and at least checking continuity from the cord to fuse/switch and PT, and output from the PT.

Maybe "put it in trash" is hyperbole but if your patience or budget for dealing with it ends there, I'd think the cab-chassis-transformers should be valuable to someone else either as a repair or rebuild project. :)
 

unixfish

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If it were mine, I would first check the plug (does the DRRI have a PC style cord?) and the outlet. Often the most obvious gets me. I've had outlets get "crusty" behind the entertainment center - un-plug and re-plug them about 5 times and voila.

Beyond that would take a circuit tester or a tech.
 

BorderRadio

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Thanks guys, bad joke to a real problem, though I do want to try a Tone Master :) I'm fairly comfortable but very much a newb to working on tube amps. The most I've done is re-cap a few amps (on PCBs). I have a DMM, that's about it.
 

jondanger

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Make sure you’re getting 120 VAC from black to ground and between the PT primaries. If not, you have a problem between the PT and the wall voltage. Fuse and any other wired or socketed connections should be checked.

If you’re getting 120 in those spots and still having a problem, make sure you’re getting 6.3 VAC on the heaters. Since the light is out, I’m guessing your issue is before the PT or in the heater circuit.
 

corliss1

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No power is always a quick check - it's easy something cheap and easy, or something expensive an easy.

If you're comfortable doing so, watch the AC component come in. Right at the plug, across the fuse, into the PT. Make sure all that is present. Then, check the AC on the secondary of the PT - you can check the heater lines and the high voltage lines for AC, although you'll need to pull the rectifier to check the AC.

Go from there. One of those points will be missing some AC, and that will tell you where the problem is.
 

corliss1

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@stantheman - the rectifier would not be involved in the pilot light or tube heater circuit, so it should still give the appearance of "turning on" even if it produces no sound.
 




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