Roland Bolt-60 Retube

[Blue Fin]

Greetings,

I've decided to retube my old Roland Bolt-60 amp and had several questions regarding the procedure. This amp has a fixed bias and I was trying to decide if I should attempt to convert it to a variable bias. Also, does it actually need to be rebiased when I replace the 6L6GC's? I think I still have the original tubes in it from when I bought the amp around 1980 but it wasn't used very much over the years.

I would appreciate any information.

Thanks,

[oc disorder]

Hi Blue Fin just wondering if you have seen http://bolt60.no.sapo.pt/
There is a lot of useful info there including changing the amp to adjustable bias.
I would recomend you check out the standby switch modification.
ie (paste from site)
"Design mistake in standby switch: If you switch the amplifier to "standby", only the plate voltage is switched off, but the screen voltage stays on. This increases the screen current outside the limits allowed by tube manufacturers.

Modification: the wiring of the standby switch must be modified so, that all high voltages are cut off "

I saw one once where the a valve was well and truly cooked......

If its still working ok the 1980 valves may be more rugged (note no b or r)
than some of the new ones.....but make sure the right fuse(s?) are fitted.