speaker@ttidcb.UUCP (Kenneth Speaker) (10/25/85)
I have a problem with a pair of Carver 400t amplifiers. The power supply injects noise back into the A/C power line which interfers with the operation of my BSR X-10 control system. I took one amplifier to the local repair shop who, after 6 weeks and several calls to Carver, reports that "this is normal and not a defect". Ok, fine (BEWARE POTENTIAL BUYERS), but what do I do now? How can I filter this mess before it gets to the A/C? Would a "computer protector" style power line filter do the trick? Or an isolation trans- former? What would one of these jobs cost for about 1kwatt of output? Any 39 cent solutions? HELP! The amplifiers SOUND excellent and I don't want to have to junk them and replace with something else. --Kne
rfg@hound.UUCP (R.GRANTGES) (10/30/85)
[] Radio Shack seems to have just what you need. '86 catalog, page 130, AC line filter - $7.95. From the looks of the picture, you may have to buy a small metal box to install it in. Go chat with your RS store. Perhaps they will agree to take it back if it doesn't solve your problem - but I think it will. -- "It's the thought, if any, that counts!" Dick Grantges hound!rfg
seifert@hammer.UUCP (Snoopy) (10/30/85)
[adding net.analog to newsgroups] In article <501@ttidcb.UUCP> speaker@ttidcb.UUCP (Kenneth Speaker) writes: >I have a problem with a pair of Carver 400t amplifiers. The power supply >injects noise back into the A/C power line which interfers with the >operation of my BSR X-10 control system. I took one amplifier to the local >repair shop who, after 6 weeks and several calls to Carver, reports that >"this is normal and not a defect". Ok, fine (BEWARE POTENTIAL BUYERS), but >what do I do now? Actually not so fine. The Carver amp may do wonderous things, but if it dumps trash into the AC line, it is DEFECTIVE. Unfortunately, I don't know of anyone who tests for this. UL is only concerned about safety, and the FCC presumably only cares about *radiated* noise, not conducted. (anyone know for sure?) The days of not having to worry about the garbage you dump into the AC line are long gone. Carver should put a filter (or whatever) in his amps to prevent this. Of course if the BSR X-10 is one of those units that puts control signals on the AC line, and expects it to be reliable, it's even more bogus... Snoopy tektronix!tekecs!doghouse.TEK!snoopy Mail sent to hammer which arrived last thursday (10/24/85) may have been lost due to <expletives deleted>. Mail is now being forwarded to doghouse (a nice, *reliable* 6130 workstation) to prevent a reoccurance. -sigh-
szepesi@fluke.UUCP (Les Szepesi) (11/13/85)
> Actually not so fine. The Carver amp may do wonderous things, but if it > dumps trash into the AC line, it is DEFECTIVE. Unfortunately, I don't > know of anyone who tests for this. UL is only concerned about safety, > and the FCC presumably only cares about *radiated* noise, not > conducted. (anyone know for sure?) The FCC *does* care about conducted noise, but at a lower frequency (tens of megahertz rather than hundreds). The idea is that the power grid can look like a pretty good antenna at these frequencies, since power transmission lines are long enough relative to the wavelength. I don't remember all the details, but conducted emissions are handled in the same docket as radiated emissions for Class B computing devices. The "Computing devices" definition may exempt an audio amplifier - I believe it is defined as anything that uses switching speed in excess of ~10kHz. Les Szepesi -- Les Szepesi decvax\ John Fluke Mfg Co. ihnp4 >!uw-beaver\ PO Box C9090 MS 274G allegra >!fluke!szepesi Everett, WA 98206 USA ucbvax >!lbl-csam / (206) 356-6362 hplabs/