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Problems with the vibrato/tremolo on my DRRI...

gypsyseven

Member
Joined
Nov 17, 2009
Messages
767
A few days back i noticed that the tremolo/vibrato doesn't work anymore on my DRRI...
Any suggestions to check what's wrong?

Changing the tube?

Should it work also without the footswitch?

Unfortunately i have no amp tech near me....
 

MikeSlub

Administrator
Joined
Jul 15, 2001
Messages
15,166
I believe blackface amps need a foot switch for the vibrato to work.

If that doesn't help, I could be the tube that drives the vibrato.
 

gypsyseven

Member
Joined
Nov 17, 2009
Messages
767
I believe blackface amps need a foot switch for the vibrato to work.

If that doesn't help, I could be the tube that drives the vibrato.

Yeah, thank's.I already found out that it needs the footswitch....check the tube tonight...thanks, Mike.:dude:
 

cryptozoo

New member
Joined
Jun 25, 2008
Messages
2,738
Only a handful of components in that circuit, most of which you can't mess with unless you drop the chassis.

But you can:

- change the V5 and V4 tubes, see if you get Vib.

- make youself a shorting jack with the end of an rca male or 1/4" connector (can't remember which the DRRI uses, but ground the tip and sleeve), plug that in to the footswitch jack, see if you get Vib.
 

gypsyseven

Member
Joined
Nov 17, 2009
Messages
767
Only a handful of components in that circuit, most of which you can't mess with unless you drop the chassis.

But you can:

- change the V5 and V4 tubes, see if you get Vib.

- make youself a shorting jack with the end of an rca male or 1/4" connector (can't remember which the DRRI uses, but ground the tip and sleeve), plug that in to the footswitch jack, see if you get Vib.

Thanks mate,

but i changed all tubes and even tried another footswitch but nothing....:dang :dang :dang
 

Wally

Well-known member
Joined
Feb 27, 2003
Messages
3,535
V5 is the vibrato function tube. A grounded RCA plug as suggested is a definite tool for this application...it will make the ground that the circuit has to see in order to work. There is such a thing as two bad footswitches...unless they work with another amp.
Sometimes, you can take a peek through the Ext Spkr jack with the Vib function engaged and see whether or not the opto-isolator bulb is working...sometimes the shrink wrap is closed off on that end and one cannot ascertain anything by peering through that 1/4" hole. IF the gruonded plug and/or a new V5 doesn't cure the problem, one is going to have some tech time inside the circuit....bad resistor, bad cap, bad connection, or a bad opto-isolator.
 

cryptozoo

New member
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Jun 25, 2008
Messages
2,738
And not to assume, but you are plugged into the reverb / vibrato side of the amp, right?
 

gibson-r8

Active member
Joined
Jul 15, 2004
Messages
574
Did you try a scientifically placed whack on the side of the cabinet?
 

gibson-r8

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Jul 15, 2004
Messages
574
Sorry, but i don´t get it:hmm

Sorry, tried and true technique I learned from my father to get the television to tune into the station. When in doubt, give the beast a whack on the side with the flat of your hand!
 

Wally

Well-known member
Joined
Feb 27, 2003
Messages
3,535
gibsonr-8's 'whack on the side of the cabinet' is almost always a temporary fix when looking for a solution, but it can be a very good diagnostic clue when looking for a problem.
 

gibson-r8

Active member
Joined
Jul 15, 2004
Messages
574
yea, poor connection, bad solder joint, tube socket, lots a potential connection issues. The discrete whack can point you in a direction. Plus, it is cathartic.
 

gypsyseven

Member
Joined
Nov 17, 2009
Messages
767
Sorry, tried and true technique I learned from my father to get the television to tune into the station. When in doubt, give the beast a whack on the side with the flat of your hand!

Now i got it....sorry, my English´s not the best.....
 
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