sci.electronics.repair@googlegroups.com

Google Groups

boomer#6877250@none.com: Dec 08 06:20AM -0600 On Sun, 4 Dec 2016 18:25:58 -0800 (PST), "Ron D." <Ron.Dozier@gmail.com> wrote:   >You might just bag it and replace the entire adapter.   Why? The adapter works fine, it's the female plug on the speaker thats bad.

N_Cook <diverse@tcp.co.uk>: Dec 08 11:30AM Not owning the proper long nose , parallel soft jaw , pliers for this job. I've always reinforced the plastic strip with some fabric mesh upholstery tape, wrapped around plastic strip and extending over the ribbon a bit, as so easy to fracture a foil at any bend there. This time very restriced space to reinsert inch wide CD ribbon. So cut/melted away some of the intruding underframe so more like 1/2 inch of gap rather than 1/4 inch gap. Then ordinary carpenters size long nose pliers, added a Hammas bead to each tip as soft jaw for clamping across the ribbon strip, especially at the distant end , to reinsert, bit at a time each side, to keep the ribbon straight on. Hammas makes plastic ring/beads for kids to make mosaic pictures from, by pushing over peg matrix board.

N_Cook <diverse@tcp.co.uk>: Dec 08 10:16AM Another Mark Bass amp - symptom fluttery rustling noise . Just a wooden cocktail stick was enough to lever the "solder" joint from the central pin of the rear elbow jack on the speaker lead. Must have been,in effect, just the resin/flux holding the wire on there, ball of solder resting in the cup of the pin with no sign of solder on the pin.

Phil Allison <pallison49@gmail.com>: Dec 07 09:47PM -0800 > > ** I wonder how you know that?   > Because bypassing them at the primary junction board allowed full > and normal operation.   ** Which is as expected, given that the fuse is DESIGNED to open before any harm occurs to the insulation. It is never OK for one to open afterwards.   You are completely missing the point.     >> If the fuses were rated to open that close to the normal operating >> temp of the XFRs,   ** What does it say on typical thermal fuses ?   120C or the like ?   That is way above the normal operating temp of most transformers.     > the fuse to open, I certainly couldn't say, nor did I. I only know > that none of the ones I encountered were nothing more than nuisance > failures.   ** You cannot know that, unless you were able to check the transformer's internal temp at the time of the fuse going open.     > Strangely, the transformers that I have seen overheat and burn in older 60s and 70s vintage electronics (both TV and audio) were *not* equipped with thermal fuses. They just sat there and puked tar.   ** Not strange at all, those items used a safety ground conductor and so did not need a thermal fuse for safety.   The AC transformers fitted to "double insulated" items are designed to be very safe unless they overheat - the thermal fuse prevents that one remaining scenario.   Replacing thermal fuses is a dodgy practice and bridging them out is highly dangerous.       .... Phil

Phil Allison <pallison49@gmail.com>: Dec 07 09:55PM -0800 frank wrote:   > It's unlikely that a secondary dead short would take out the thermal fuse > before the main AC fuse, so I just bridged the thermal fuse and the amplifier > works perfectly.   ** Don't leave it like that - you have removed the most important safety feature in the whole amplifier.     > Can someone suggest a failure mode where the thermal fuse would blow before > the main AC fuse?   ** A sustained overload, high ambient temp or both will cause that.     > This amplifier has a double insulation AC input, so no > earth wire. Its chassis has a ground post anyway, so it could be connected > to some external equipment that is earthed.   ** One way to make the amp safe is to fit a 3 core AC lead to it and remove the double square symbol.     .... Phil

You received this digest because you're subscribed to updates for this group. You can change your settings on the group membership page. To unsubscribe from this group and stop receiving emails from it send an email to sci.electronics.repair+unsubscribe@googlegroups.com.