Fender Roc Pro 700
Phil Allison
** Hi,
just been looking at the insides of a Fender Roc Pro 700 SS combo.
It had a nasty problem that caused intermittent low volume - traced to
overheating 16 volt zener diodes and scorched tracks in the low voltage PSU.
Sorted that out by mounting the zeners on a tag strip supported off the PCB
and wiring them back to the appropriate spots.
When first testing the amp afterwards, it seemed the "Tube Drive" channel
was dead - then it suddenly came good for no reason. This process was
repeated each time I switched the amp off for a minute or two and back on.
Then the penny dropped, there was a *time delay* built into the amp that
mutes THAT channel for about 25 to 30 seconds after switch on. I can see
it on the schem built around U3A.
Not a word about it in the owner's manual.
The deliberate time delay has to do with the 12AX7 tube's operating
characteristics - plus the fact it is used in diode mode rather than
triode.
Very cunning of Fender.
.... Phil
WB
>
> Very cunning of Fender.
>
>
>
Big Fucking deal.
You never say a nice thing about anyone here
then you post this useless turd of information.
Phil Allison
>
>> Very cunning of Fender.
>>
>>
> Big Fucking deal.
** Shame you deleted the whole context -
must all be waaaaayyy over your thick, pointy fuckwit head.
> You never say a nice thing about anyone here ...
** Fraid that is not any kinda obligation on posters.
Cos this NG is utterly fucked with brain dead trolls.
Like you.
> then you post this useless turd of information.
** Not one tiny bit useless if you are a practising service tech OR you
have even the slightest interest in the subtler points of design relating to
commercial guitar amps OR you have a fucking clue of any kind.
Leaves brain dead retards like you right out.
And all guitar players.
Wot a boring cunt you are - WB
.... Phil
WB
>
>
*plonk*
Hook, line, and sinker.
I was right on. That was an easy point to prove.
Phil Allison
Like you.
And all guitar players.
Piss off.
.... Phil