Ashton GA80 guitar amp (Australia)

[N_Cook]

RoHS date of introduction for Australia ?
Anyway 1/4 inch i/p socket too weak even for domestic use , breaking up in a
few years ( within RoHS regime), no obvious datecodes except main electros
seem to be 2000, otherwise maybe 2004 or 2005 IC dates. No-name flimsey junk
, the type with 2 insulated change over contacts. On trying to work out the
functions, apart from the tip contact/grounding setup there is a line to one
of the isolated switches that grounds at plug inserted and o/c when removed
, it goes DC connected to the base of a pnp transitor - function ?

 

[N_Cook]

RoHS date of introduction for Australia ?
Anyway 1/4 inch i/p socket too weak even for domestic use , breaking up in a
few years ( within RoHS regime), no obvious datecodes except main electros
seem to be 2000, otherwise maybe 2004 or 2005 IC dates. No-name flimsey junk
, the type with 2 insulated change over contacts. On trying to work out the
functions, apart from the tip contact/grounding setup there is a line to one
of the isolated switches that grounds at plug inserted and o/c when removed
, it goes DC connected to the base of a pnp transitor - function ?

If it kills the gain for bang-less plug insertion then it would only work
for insertion , not removal, as that switch makes before tip makes/breaks
ground

 

[N_Cook]

Maybe it mutes the reverb?



Gareth.

Luckily the owner wanted a reliable input socket and was unconcerned about
the loss of the plug-in de-thump cct. To replace the domestic headphone
socket (has isolated switching) would have been a work up as 0 or 15V on
that control line so could not use an effects pedal type ring switch action.
And the ring switch for a normal stereo 1/4 inch jack is the wrong action
for here anyway, requiring an inverter somewhere or one of those awkward and
rare offset 1/4 inch switch actions. cct proper, holds off full gain for 0.5
seconds or so after plug insertion, all the while removed 30dB or more gain
drop via 15/-15V control into the first amp. Although no obvious PbF solder
problems the original input socket had thin+wide blade pins going into holes
of that wide diameter and loads of filler solder, asking for problems with
ordinary solder let alone new-fangled

 

[N_Cook]

More as a reminder to myself, for the next time this problem appears. A work
around without having to cut into the existing cct to put in an inverter.
Use a small SPDT relay (+emf diode) with power adapted from whatever
convenient rail.
Permanent ground on the flexing ring contact in a 1/4 inch TRS socket and
the fixed ring- contact to the low side of the relay.

 

[N_Cook]

More as a reminder to myself, for the next time this problem appears. A work
around without having to cut into the existing cct to put in an inverter.
Use a small SPDT relay (+emf diode) with power adapted from whatever
convenient rail.
Permanent ground on the flexing ring contact in a 1/4 inch TRS socket and
the fixed ring- contact to the low side of the relay.

The added delay, due to relay action, only adding to the desired effect of
delaying the removal of the gain suppression until after tip contact is made
( unless someone is very slow at plug-in)

 

[N_Cook]

RoHS date of introduction for Australia ?

....snip...
the answer I got was,
"Not on the radar."


RoHS printed on pcb overlay, and definitely grotty PbF-looking solder (but
not any actual observable or twizzleable bad joints). No RoHS stickers on
the outside, so presumably standard asian product internally, badged as Oz
externally