DRRI HUM when Rev is on

[hawkeye2u]

Hi all long time no me being here, searched the forum re my 3 tear old DRRI having a loud hum when rev is switched on, checked all the connections from the main unit and also on the rev tank itself, in doing so I noticed that the output from the tanks was working as I got loud output when disturbing the tank, so I think its the input to the tank not working, all valves are lit, even replaced the driver tube for the tank.
Reverb ,when played with a guitar, is really faint even turned up to 10, rev pot turned to 0, no hum.
Hope to get some useful input from U guys
Thanks

[Kap'n]

Try rotating the tank 180%. IIRC, the drive side should be under the power transformer. If it's the other way around the PT will induce hum into the reverb tank output transducer.

I'm surprised accutronics never made a humbucker transducer for the tank.

[Offshore Angler]

And on the DR and DRRI, the marking on the amp for input and output for the tank is backwards from what you would think.

[phantomman]

And on the DR and DRRI, the marking on the amp for input and output for the tank is backwards from what you would think.

The reverb tank jacks and cable plugs for the DRRI are color-coded in red and white......just like on a piece of hi-fi or video gear. There are no "markings" per se on the chassis. All blackface re-issues share this feature.

[Kap'n]

The reverb tank jacks and cable plugs for the DRRI are color-coded in red and white......just like on a piece of hi-fi or video gear. There are no "markings" per se on the chassis. All blackface re-issues share this feature.

Red goes to the outside, like on the silverface amps, right?

[Bill Moore]

I A-B-C tested some tanks a few weeks ago, (Accutronics and Belton 9 series, and a Mod 4 series), and had to swap leads twice on most every test!

[phantomman]

Red goes to the outside, like on the silverface amps, right?

[Kap'n]

Guess my lack of modern technology knowledge is showing.

[phantomman]

Guess my lack of modern technology knowledge is showing.

No harm - no foul, Kap'n.

FMIC made a wise decision on the BF re-issues IMO -- the jacks on the new repro tanks are color-coded as well to eliminate the ambiguity of the originals when servicing is needed, plus the footswitch jacks were changed from dual RCA's to a single ¼-inch stereo phone jack (which remains located on the rear panel as per the vintage amps).

[yankeerob]

Well I hate to be a fart-arse... but it must be the only wise decision they've made lately... not picking a bone with you Rog... but we see this stuff coming in and out for repair all the time now... workshop joke is - a guy phones up and says 'I have a Fender amp for repair' and the punch-line is 'yeah?... which one?'...

Same goes for Marshall stuff... Jim (Healey) and I have great respect for both LF and JM but the majority of the stuff sold under those brands... and for some considerable time now... is mostly crap... in terms of if it's gonna be around in 20 yrs... you don't realise it until you see it day after day and we cherry-pick our repair work for this reason...

Any road - good luck to you hawkeye... and no offence to you owner's of a FMIC mftr'd amps... good luck to you all... it just continues to grieve me to see the look on guys faces when they peer into the back of their cherished Fender amp after they've seen our stuff lying around waiting to go into cabinetry... they try to keep smiling but you can see the pain in their eyes :@)

[Kap'n]

Construction on Marshalls has been pretty much crap since they introduced the 900 series. Never really peered into a FMIC amp firsthand, but those HRDx pix that show up here look pretty scary.

[Gravity Jim]

Speaking of the guts of Fender amps: this months' MIX magazine has an article from Eddie Ciletti (who once helped me debug a noise problem in my studio when we were both writing for EQ) about everything that's wrong with the Hot Rod amps (from a studio perspective... too much gain, big, flabby low end, etc) and how to modify them so them suck less. He doesn't address reliability, just the way they sound.

[Kap'n]

HRDx modification tool.