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 ?
Ashton GA80 guitar amp (Australia)
Nov 11, 2009
7 Replies
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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
Maybe it mutes the reverb?
Gareth.
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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
-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on
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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.
-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on
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work
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)
-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on
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...snip... the answer I got was, "Not on the radar."
...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
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