sci.electronics.repair@googlegroups.com

Google Groups

Paul Drahn <pdrahn@jodeco.com>: Dec 05 10:09AM -0800 > I have a McIntosh MX110Z with a bad transformer. Any recommendations for rewinding? I've never done one and have no interest in trying. Thanks.   You can do better that that post. How is it bad? Shorted turn, open turn, short to core? Which winding? Primary or secondary? What told you the transformer is bad? Likely there is a transformer available with similar ratings that will replace the transformer.   Paul

"ohg...@gmail.com" <ohger1s@gmail.com>: Dec 05 11:01AM -0800 On Saturday, December 5, 2020 at 1:09:39 PM UTC-5, Paul Drahn wrote: > Likely there is a transformer available with similar ratings that will > replace the transformer.   > Paul   It *looks* bad...

Phil Allison <pallison49@gmail.com>: Dec 05 12:04PM -0800 Paul Drahn wrote: ============== > What told you the transformer is bad? > Likely there is a transformer available with similar ratings that will > replace the transformer.   ** For sure - sitting inside another MX110Z that is non working.     .... Phil l

"Peter W." <peterwieck33@gmail.com>: Dec 06 04:49AM -0800 A few things: a) McIntosh winds their own transformers. b) McIntosh has been in business for many years, and through many ups and downs. c) Meaning that their management at least has some basic business intelligence. d) Suggesting that the transformers they make/made are not unique to each individual component. e) Suggesting that it is quite likely that they may have that transformer available.   Peter Wieck Melrose Park, PA

"ohg...@gmail.com" <ohger1s@gmail.com>: Dec 06 06:39AM -0800 On Sunday, December 6, 2020 at 7:49:16 AM UTC-5, Peter W. wrote: > c) Meaning that their management at least has some basic business intelligence. > d) Suggesting that the transformers they make/made are not unique to each individual component. > e) Suggesting that it is quite likely that they may have that transformer available.     It's not. I emailed McIntosh asking about a replacement, or a suggested "universal" replacement that might physically fit the tight chassis that could be installed with some circuit modification, or perhaps a suggestion of a rewinder they were familiar with or might even have used. I received a very quick and terse (if not polite) email from McIntosh Friday that answered all three of my questions with a simple "I'm sorry there are no options for this transformer." Boom.   The MX110Z is very very tight. There's literally no room for a transformer that would allow the case to fit if the replacement was any bigger even by a small percentage. This particular piece is known to have a power transformer that runs *very* hot even when everything is otherwise normal. The transformer has a B+ winding and three filament windings and is also supposed to be more heavily shielded than the average bear.   I could probably find a way of cobbling a different power transformer and another smaller filament transformer somewhere else on the chassis (or just build a remote XFR box with an umbilical) but I don't want to reinvent the wheel at this point, plus I feel most of the *value* of this piece is in the originality of it, not to mention Mc's careful design of the filament circuit and wire routing for hum mitigation. Add to that the fact that two of the four selenium rectifiers under the deck relieved themselves of tiny solder balls (which happens when the 1A slow blow is replaced with a 20A fuse), and all cans are original and probably need to be restuffed, and it just seems like a project not worth the time at this point.   I returned the tuner/pre to the owner yesterday with the suggestion of either putting it on ebay, where this model in non working condition will bring $400 at least, or keep checking ebay and finding one in poor cosmetic condition with a good XFR in it.

"Peter W." <peterwieck33@gmail.com>: Dec 06 08:33AM -0800 > I returned the tuner/pre to the owner yesterday with the suggestion of either putting it on ebay, where this model in non working condition will bring $400 at least, or keep checking ebay and finding one in poor cosmetic condition with a good XFR in it.   Or send it out to be rewound.

Ralph Mowery <rmowery28146@earthlink.net>: Dec 04 11:00AM -0500 While not really a repair,but more of a question.   Why is it that I have one of the portable receivers with a whip antenna that is about 2 feet long and can receive very well the short wave stations, but my ham receiver with a couple of feet of wire on the back receives almost nothing. When I hook the normal antenna to it, it receives vey well. The signal generator shows the sensitivity is very good. It is not just one ham receiver,but several.   My theory is that the portable receiver is matched for a high impedance short antenna, where the ham receiver is matched for a 50 ohm antenna.

Phil Allison <pallison49@gmail.com>: Dec 05 12:12PM -0800 bilou wrote: =========== > In car radios there was an adjustable capacitor to compensate for the > short length of the cable and front end tuning was good only on the > station selected.   ** But ( older) car radios had high impedance inputs on the AM band. A short run of coax is a pure capacitor at AM frequencies. The trim cap set the antenna coil to resonance while moving ferrite slugs did the actual tuning.   ..... Phil

Ralph Mowery <rmowery28146@earthlink.net>: Dec 05 03:24PM -0500 In article <e40e544b-0dec-41a6-952e-d86983f8efa8n@googlegroups.com>, pallison49@gmail.com says... > A short run of coax is a pure capacitor at AM frequencies. > The trim cap set the antenna coil to resonance while moving ferrite slugs did the actual tuning.   > ....   I don't recall the impedance of the car antenna coax, but it was special low capacitance/high impedance . Most common coax for radios and TVs are usually either close to 50 or 70 ohms and have about 2 to 3 times the capacitance per foot as the car coax.

David Farber <farberbear.unspam@aol.com>: Dec 05 10:49AM -0800 On 11/11/2020 1:43 PM, Phil Allison wrote:   > ** Be sure not to confuse the topic with "alphabet people".   > ..... Phil   I finally reassembled, tested, and returned the amp to the customer. It works just fine now. I've watched several video explanations of the class D and H amps. I don't want to take this thread too off topic but those new classes really seem to help the efficiency of an amp. This Carvin amp weighs in at 14 lbs (5.2kg). That would be unheard of 50 years ago.   Thanks for your support (and RL too) throughout this adventure! -- David Farber Los Osos CA

Phil Allison <pallison49@gmail.com>: Dec 05 12:06PM -0800 On Sunday, December 6, 2020 at 5:49:15 AM UTC+11, David Farber wrote: > Carvin amp weighs in at 14 lbs (5.2kg). That would be unheard of 50 > years ago.   > Thanks for your support (and RL too) throughout this adventure!   ** Wow - a happy customer.   " Should have him stuffed... "     ..... Phil

KenW <ken1943@invalid.net>: Dec 04 09:09AM -0700 On Fri, 4 Dec 2020 11:00:07 -0500, Ralph Mowery >good. It is not just one ham receiver,but several.   >My theory is that the portable receiver is matched for a high impedance >short antenna, where the ham receiver is matched for a 50 ohm antenna.   Amateur Radio equipment is built to favor ham frequencies and not broad banded like your general equipment.     KenW

OJ Oxford <bestnet@none.com>: Dec 04 08:36AM -0500 My former post was on the unwanted heating up of a cigarette lighter and it was determined that there was too much resistance in such a connector, so switched out to the XT60 based mainly on Jeff Liebermann's recommendation. I initially had great difficulties with my various soldering irons on hand heating up both the connector and the 12 ga copper wires enough to get an acceptable connection, so proceeded to order a brand new 60 watt temp controlled iron and some flux. Well, I'm happy to report that all is well. I have been pleasantly surprised by how well the combination of the iron and flux are working and all connections, while still delayed a bit, are being satisfactorily made and I no longer have lack of connection, melting, or cold solder concerns. Oh, and I have been working with silver solder too as the standard had not yet arrived.   Apparently, my other irons on hand either didn't have the correct tips, were too old to heat up correctly and/or lacking the additional flux all worked to disadvantage. I must say that this 60 watt iron heats up faster than any of my other irons. It is a pencil type and ready to go in about 15 seconds, where my other pencil units always took several min.   Thanks again to the group for setting me straight.

Fox's Mercantile <jdangus@att.net>: Dec 04 09:16AM -0600 On 12/4/20 7:36 AM, OJ Oxford wrote: > Thanks again to the group for setting me straight.   Not all of us give bad advice just to see our name in print.     -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com

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.