Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: mresistor on January 12, 2019, 01:01:14 pm

Title: Orange Rockerverb 50 Mki question
Post by: mresistor on January 12, 2019, 01:01:14 pm

I have an Orange Rockerverb 50 Mki head on the bench with very weak output in both channels.  Using my listening amp I followed the signal all the way through to the plates of the PI. The signal is also good to me at the grids of the power tubes. At the PI Plate the signal is very strong, I had to turn down the pot on my listening amp to almost off, and the Amplifier I was using way down too, of course it is hv.  (sf Champ) The sound from my listening amp sounded way better than the weak output of this Orange.  I pulled the 4 6V6 tubes and the OT primary wires and measure the two primary windings, one is 31.2 ohms and the other is 16.1 ohms. There is no continuity from any primary wire to the secondary. What is your opinion of these OT readings? Doesn't seem very balanced to me.  Here are the schematics.  Also they are not in the library.  The plates have around 375vdc and the screens about the same..  The filaments are fine.


http://www.orangefieldguide.com/OFG_SCHEM/RV50C_sheet1.jpg (http://www.orangefieldguide.com/OFG_SCHEM/RV50C_sheet1.jpg)


http://www.orangefieldguide.com/OFG_SCHEM/RV50C_sheet2.jpg (http://www.orangefieldguide.com/OFG_SCHEM/RV50C_sheet2.jpg)


http://www.orangefieldguide.com/OFG_SCHEM/RV50C_sheet3.jpg (http://www.orangefieldguide.com/OFG_SCHEM/RV50C_sheet3.jpg)

Title: Re: Orange Rockerverb 50 Mki question
Post by: sluckey on January 12, 2019, 01:18:53 pm

I would expect the two readings to be closer than that. What reading do you get between the two plate leads?

Title: Re: Orange Rockerverb 50 Mki question
Post by: mresistor on January 12, 2019, 01:27:57 pm

Between the plate leads    23.9 ohms. With two different meters. Between yellow and black.

Title: Re: Orange Rockerverb 50 Mki question
Post by: sluckey on January 12, 2019, 01:41:20 pm

Are you sure you're measuring correctly? Plate to plate resistance should have been the sum of your first two readings, 31 + 16 = 47

Title: Re: Orange Rockerverb 50 Mki question
Post by: mresistor on January 12, 2019, 01:47:30 pm

Yes. that's what's throwing me for a loop..  I measure


White/black   31.2 ohms
White/yellow  16.1 ohms
Yellow/Black   24 ohms 


I first measured with a near new Extech with a brand new copper top in it
Then this time with my Fluke


there is no way to confuse the wires as they are all the exact length to go to their respective terminals    and their colors


Something very fishy with this OT

Title: Re: Orange Rockerverb 50 Mki question
Post by: mresistor on January 12, 2019, 01:54:18 pm

I don't have a 50w OT hanging around with 4K primary..  I do have an OT that was running two 6V6 PP  in a Hammond organ.  I suppose I could use that and just use two 6V6 in the amp to test it.


Sluckey -  aren't those primary winding readings a little on the low side..  I would think they'd be in the 100's of ohms.. 

Title: Re: Orange Rockerverb 50 Mki question
Post by: mresistor on January 12, 2019, 02:20:09 pm

Subbed in my little Hammond OT  sounds great !   Verdict     Orange OT bad.. 


I think this OT would work pretty good in a quad 6V6 Rockerverb    http://www.classictone.net/40-18025.html

Title: Re: Orange Rockerverb 50 Mki question
Post by: Willabe on January 12, 2019, 04:32:17 pm

Quote from: mresistor on January 12, 2019, 01:01:14 pm

Here are the schematics. Also they are not in the library.

Their in their, now anyway.

Maybe Sluckey put them in there?