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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Ashton GA80 guitar amp (Australia)
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 ? |
#2
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Ashton GA80 guitar amp (Australia)
N_Cook wrote in message
... 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 |
#3
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Ashton GA80 guitar amp (Australia)
"N_Cook" wrote in message ... N_Cook wrote in message ... 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 Maybe it mutes the reverb? Gareth. |
#4
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Ashton GA80 guitar amp (Australia)
Gareth Magennis wrote in message ... "N_Cook" wrote in message ... N_Cook wrote in message ... 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 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 -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
#5
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Ashton GA80 guitar amp (Australia)
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 http://home.graffiti.net/diverse:graffiti.net/ |
#6
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Ashton GA80 guitar amp (Australia)
N_Cook wrote in message
... 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 http://home.graffiti.net/diverse:graffiti.net/ 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 http://home.graffiti.net/diverse:graffiti.net/ |
#7
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Ashton GA80 guitar amp (Australia)
On Nov 11, 9:10*am, "N_Cook" wrote:
RoHS date of introduction for Australia ? ....snip... the answer I got was, "Not on the radar." |
#8
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Ashton GA80 guitar amp (Australia)
Robert Macy wrote in message
... On Nov 11, 9:10 am, "N_Cook" wrote: 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 |
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