spamtrap1888 wrote in message
...
On Apr 12, 8:20 am, "N_Cook" wrote:
All the steelwork is corroded a bright sulphur-coloured lemon-yellow. I
don't remember seeing that before, actual sulphur?

Not a zinc dichromate or cadmium plating?

I'll try scraping off and
burning some
I've recorded all the R values sequenced through the amp
A previous repairer had marked V1? and V2 ? positions as ECC83, the op
bottles are CV2975 so EL84, RR is marked EZ80 leaving just the valve
posistioned as ,and wired cusory-looking as , a splitter driver V3? it
looks
like a double triode and I will test as ECC82, has 4OD etched on the
envelope , when I dig out those crib sheets for that.

Looks like guitar amp repair keeps you folks in business. Do you do
your own reconing, or do you have favorite people to do that? Can they
match the cone and fundamental resonance fairly close, or does
reconing inevitably change the sound?

+++

Unlikely a plating as all different makers/sources of steel, valve base
skirts,
retainer springs, pot casings and large capacitor clip all bright powdery
yerllow. Against that - the mains Tx someone has replaced and the steel
frame of that is normal colour , so perhaps some tropicalizing or spraying
by
the maker that has deteriorated . The op Tx is stove-enamelled so grey
colour.
Another thought , as stored under the stairs, if the household gas
supply/meter is there and whether long-term so undetectable by human nose,
North Sea gas leakage, gives off sulphur component that reacts with steel ?


The only reconing I've done is where I can remove a couple of turns of VC or
a repairable braeak at a bend of the VC tails , but I do have an 18 inch
speaker and cone that I will sometime? try rewinding the broken VC as the
former is not burnt beyond a 2mm x 1mm spot

The prices of new cones I've seen means the usaul response "well I may as
well buy a complete new speaker for that cost"