Roadster Reverb Issue

[kyldh]

For some reason I have a hard time keeping the reverb functional in my Roadster head. I love that over-saturated-with-reverb blues sound, so I'd love to get it working again.

In the past when it died, it was just a tube. I'd swap some tubes and everything was good. This time, I only had 1 good spare tube, so I swapped that into the rotation but it didn't help. I also used my old Knight tube tester to check all the tubes and they all tested good. I understand that tube testers like that only really do a basic test and don't mean the tubes are 100% flawless, but I figured it was a good starting point.

So, in summary, I ordered some replacement tubes but they're on back-order and I'm wondering if there's anything else I should be looking at while I wait for them?

All the connections look fine to the naked eye in my reverb tank, but is there any way to be sure my tank is fine without spending $45 to order another one from Mesa? The amp has been taken to a few gigs, so I suppose it probably got bumped around a little in the car and everything. I'm as careful as I can be with it though and it's always in a road case.

 

[afu]

I wondering if the road case allows the top vent to let the heat out? Heat can make tubes fail early. That it's a regular thing seems odd to me.

I would wait for the tubes, unless you are confident about cracking it open to look for a cold solder joint. I sometimes use the opportunity of having the tubes out to clean the contacts by spraying an old tube and inserting it a few times or so. Since replacements usually fix it, I'd wait.... or use a different brand just for testing and replace them when your preferred tubes arrive.

 

[kyldh]

I wondering if the road case allows the top vent to let the heat out? Heat can make tubes fail early. That it's a regular thing seems odd to me.

Heat shouldn't be a problem because my road case is the style that only leaves a "platform" underneath the head while it's in use. So the top and sides of the head are completely uncovered.

Thanks for the reply

 

[Authorized Boogie]

I wondering if the road case allows the top vent to let the heat out? Heat can make tubes fail early. That it's a regular thing seems odd to me.

Heat shouldn't be a problem because my road case is the style that only leaves a "platform" underneath the head while it's in use. So the top and sides of the head are completely uncovered.

Thanks for the reply

If you're handy with a meter you can test for continuity of the tank...

Shielded wire measured at tip and sleeve should read about 200 ohms

Input wire tip and Shielded wire sleeve should read about 1 ohm

Thanks!

 

[kyldh]

Hello, Thanks for the tip Authorized Boogie. Maybe you're the same Mesa Boogie tech that emailed me with similar information.

I apologize for my late response. I just got around to grabbing my multimeter and testing this out.

I’m a bit of a novice with amp repairs and the use of a multimeter. First let me start by saying, I have my multimeter set to “200” in the Ohm section (it has selections from 200 to 2000K). Whether I’m checking input or output with your provided instructions, I get readings anywhere from 130 to 190. It jumps all over the place; 135, then 162, then 190, the back down to 140. Does this make it seem like I have a bad tank or that I’m using my multimeter incorrectly?

Just for fun, I tested a random 8ohm speaker using the same settings on my multimeter and it jumped around a little too, but only between about 6.7 and 7 ohms.

Also, I do have a brand new battery in the multimeter.

Sorry for being such a novice!!!

Thanks

 

[kyldh]

Additionally, I did recently buy 4 new 12AX7s. Even though the current tubes tested "good", I tried swapping them out with various positions in the head and it made no difference. I made a point to replace V1 (input stage) and V4 (reverb).

 

[kyldh]

UPDATE: I just remembered I owned another cheapo multimeter so I gave it a shot too and it's doing the exact same thing. When testing the output cable, readings are jumping around like 1... 140... 1.... 185... 1.... 190.... 1.... 155.

I wish I had another "known good" reverb tank to try testing.

Thanks in advance.