- Thermal Faults - 2 Updates
- IcePower module - 1 Update
- please refresh my memory: what a PFC capacitor does and a real life example of what it means?? - 2 Updates
| tabbypurr@gmail.com: Sep 25 03:13PM -0700 > As already noted, many things *can* get hot. What is in question is how heat will affect various components. In no particular order: > a) Carbon comp/film resistors will change value over time, and much more-so of heated. Some types are so awful that they will change in value simply from the heat required to install them. Given the alternatives, the only reason to use them today would be based on audiophoolery. We use carbon film aplenty. The reasons are low cost & good availability. Carbon comp is used on occasion for its pulse power tolerance. NT |
| "pfjw@aol.com" <peterwieck33@gmail.com>: Sep 26 03:56AM -0700 > We use carbon film aplenty. The reasons are low cost & good availability. > Carbon comp is used on occasion for its pulse power tolerance. In other words, kick the can down the road.... Peter Wieck Melrose Park, PA |
| Phil Allison <pallison49@gmail.com>: Sep 25 05:52PM -0700 John-Del wrote: -------------- Phil Allison wrote: > I can promise you that if you saw several of these a month, > you would have by now acquired both the equipment (cheap enough) > and the skill to do this in your sleep. ** The bigger issue with SMD boards is that makers do not expect them to be repaired so discourage service techs from even attempting. To this end, they make NO service info available, provide NO schematics and sell NO spare parts that go on such boards. Invariably, the PCBs are double sided with vias, making visual circuit tracing a nightmare and hence fault diagnosis too. By sheer dint of effort I have fixed a number of items that used SMD, sometimes using regular parts to relace SMD versions. One ( famous Italian make ) powered speaker PCB was possessed with heat sensitive intermittents that another good tech could not fix. I found a faulty via and fixed that - then found about 20 others after applying heat to them individually using a soldering iron tip. Some of the vias were solder filled, so not so easy to run a wire through. BTW: My eyesight is Ok and I have a magnifying glass - I still fix broken, hair fine wires on Accutronics reverb unit coils ( ones with plugs and sockets) rather then replace the whole tank. Investing in SMS gear and a stock of parts would NOT be sensible or economic. ..... Phil |
| Ralph Mowery <rmowery28146@earthlink.net>: Sep 25 12:47PM -0400 In article <16a879a4-381c-4f70-a7c6-12b2ef95c5cd@googlegroups.com>, pallison49@gmail.com says... > It has everything to do with the current wave be made up of pulses ( at double the supply frequency ) and so not being a sine wave. > The "true rms" value of a pulsed current is higher than a comparable steady sine current. Ok I can see that , The meters are not really showing what is going on. I do understand the part about a 'true rms' not being the same as what most simple meters show when calibrated for a sine wave and not all kinds of non sine waves. Just faulty thinking about the inductance of a transformer. |
| Phil Allison <pallison49@gmail.com>: Sep 25 04:51PM -0700 Ralph Mowery wrote: ------------------- > most simple meters show when calibrated for a sine wave and not all > kinds of non sine waves. > Just faulty thinking about the inductance of a transformer. ** The simple mistake that most folk make is not knowing the definition of VA and hence the meaning of Power Factor. FYI: VA = rms Voltage times rms Current. and PF = true power / VA For example, a true rms clamp mater allows a sparkie to measure the VA of a load but he would need a "watt-meter" to find the true power. Plug-in meters that do both cost very little nowadays. .... Phil |
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