Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: plexi50 on October 13, 2010, 09:47:23 am

Title: No Vibrato 1977 Twin Reverb / UPDATE:
Post by: plexi50 on October 13, 2010, 09:47:23 am
I have no vibrato in this Twin Reverb

http://s356.photobucket.com/albums/oo5/plexijtm45/?action=view&current=TRVibrato.mp4
Title: Re: No Vibrato 1977 Twin Reverb
Post by: sluckey on October 13, 2010, 11:18:21 am
Take a look...

http://www.el34world.com/Forum/index.php?topic=10162.0
Title: Re: No Vibrato 1977 Twin Reverb
Post by: plexi50 on October 13, 2010, 11:43:54 am
Excellent. I tested the roach as instructed in the thread. The analog shows no wobbling or movement. I had ordered one last week and it should be here by friday. Thanks Steve*
Title: Re: No Vibrato 1977 Twin Reverb / UPDATE:
Post by: plexi50 on October 14, 2010, 09:52:54 pm
I got the new roach today and put it in the amp. Vibrato is working now

When removing the old roach the LDR fell out of the plastic tube so it appears that the old roach was bad after 33 years

I
Title: Re: No Vibrato 1977 Twin Reverb / UPDATE:
Post by: mresistor on October 15, 2010, 01:19:39 pm
Before you throw the old roach away, it could be that the adhesive glueing the neon lamp to the ldr just got old and failed. One could glue them back together and see if it still works. Webers site has some info on this. It sure appeared that your neon bulb was still working.

some roach info (https://taweber.powweb.com/store/opto_kit.htm)

Title: Re: No Vibrato 1977 Twin Reverb / UPDATE:
Post by: plexi50 on October 15, 2010, 07:36:30 pm
Thats an interesting link mresistor. Thanks for the info! :grin:
Title: Re: No Vibrato 1977 Twin Reverb / UPDATE:
Post by: duke of earl on October 17, 2010, 09:13:20 pm
This is the amp that motivated me to build my first. I have one of these and got sick of playing it because it was incapable of producing good tone. Built my own 50 watt Hoffman version and wow was I amazed. Sorry about hijacking your thread.