Tube Troubleshooting Question

[Addictedtokaos]

Last night my Rectoverb started acting up with volume drops and some hiss and crackles. I just put new tubes in v1,2, and 5. So im suspecting either V3 or 4.

When the issue starts happening can I simply plug directly into the FX Return to see if the problem exists in my Power Tubes, V4 or V5? Do I need to do anything with Preamp or FX send jack when doing this?

Also, when looking at the tube chart do the stages relate to the different modes at all? Does 2nd stage Rhythm = CH1 Clean and 3 Stage Rhythm = CH1 Pushed?

Description of Tube Functions
V1A= Input Stage
V1B= 2nd Stage (Rhythm & Lead)
V2A=3rd Stage Rhythm
V2B= 3rd Stage Lead
V3A= 4th Stage Lead
V3B= 5th Stage Lead
V4A= FX Send
V4B=FX Return
V5A/B = Phase Inverter

 

[MrMarkIII]

If the problem started *AFTER* you put new tubes in V1, V2, and V5, the new tubes in V1, V2, and V5 are suspect, not V3 or V4, although it's best not to rule anything out yet.

The first rule of tube troubleshooting is:
ONE-AT-A-TIME.

So, start with V1. Remove V1, and replace it with a tube known to be good,
Then do a sound check.
If the problem remains, put the original V1 back in the socket.
Remove V2. Replace it with the known good tube.
If there is no change, put V2 back. Move on to V3.
Rinse and repeat.

If you use Mesa power tubes, you should be able to remove and test ONE-AT-A-TIME as above, but it's usually best to replace both power tubes if one goes south, as they work in matched pairs. Mesa tubes are generally *all* matched to each other, but you should at least use a pair from the same color group (yellow, red, green, grey, blue). The power tubes are marked with the color with a sticker on the base of the tube.

It's tempting to just blanket replace all the tubes at once, but if one of the new tubes is bad, then you are actually worse off. Now you have *two* sets of tubes, any of which could be causing problems, and you still have no idea which tube it is.

Mesa has a tube troubleshooting video on You Tube:
http://www.youtube.com/watch?v=wSl-l9aWDHw

 

[Addictedtokaos]

Yes, good idea not to assume anything. Could I not save some time and determine if its preamp or power amp by plugging in directly to the power amp section as I asked in my original post?

Edit: Found this in the manual.

We suggest that when using the RECT-O 50’s power section only, that you have the amp switched to Channel 1’s CLEAN mode or Channel 2’s MODERN mode. This assures a more neutral power sensitivity thus making the RECT-O 50 more friendly to use as a power amp. See PRESENCE Control section of this manual for more information.

 

[MrMarkIII]

What are you going to plug into the Effects Return? The manual is referring to using the Recto power section as a slave power amp. IOW, you would use your guitar plugged into *another pre-amp*, then plugged into the power section of the Recto. A guitar plugged directly into the power section via the Effects Return will not be very loud, if you can hear it at all. That's pretty much the job of the pre-amp, to amplify the guitar signal enough for the power section to take over.
You could start with the power tubes, as there are only two, as opposed to the five pre-amp tubes.

 

[elvis]

When testing power amps, I find it helpful to plug an iPod into the input (or FX return for a guitar amp). It's enough signal so that you don't need a preamp. You just need a mini to 1/4" adapter cable.

 

[Addictedtokaos]

When trying to troubleshoot my problem I remembered that it started when I took my noise gate OUT of the loop.

After much testing, it seems my issue is not tube related but with the FX loop jack switches. If I had the loop jumped my amp was fine, as soon as I would remove my cable from the jacks the Hiss, pops, volume drops came back. If I jumped the loop it would be fine and the problem kept returning as soon as I disconnected.

At least I know where my issue is - I tried some switch cleaner in the jacks last night hoping its just the switch contacts.

 

[cyber104]

Try a new tube in V4.

 

[Addictedtokaos]

The problem seems to be gone now. Im guessing it was all the pluggin/unplugging the fx jacks cleaned them up.

But if it does come back that is where I will start (v4).

Thanks!

 

[thunda1216]

The problem seems to be gone now. Im guessing it was all the pluggin/unplugging the fx jacks cleaned them up.

But if it does come back that is where I will start (v4).

Thanks!

dirt/dust/ corrosion can build up on the effects loop jacks, causing loss of signal. It is a good idea to occasionally spray some contact cleaner on a plug and work it in and out of the send and return jacks a few times to clean them up, even if you never use the effects loop.