- Hella LED switches - 1 Update
- A lucky find - 8 Updates
- Using a Variac for starting an old tube set - 3 Updates
- Bloody customers - 2 Updates
tabbypurr@gmail.com: May 18 09:39AM -0700 On Wednesday, 17 May 2017 14:52:27 UTC+1, rickman wrote: > I give up. The pages you point to show dozens of switches. I'm not > going to try to read your mind. If you can't tell me what switch you > are using, I'm not going to try to guess how to wire it. the whole thread is him stringing folk along. NT |
oldschool@tubes.com: May 18 08:12AM -0400 I went to a rummage sale and the guy had a box of cables for 10 cents each. Some computer power cords, and some RCA cables, and a couple phone cords. 16 cords total. I offered $1 for the whole box, and he agreed. He asked me why I needed all of them. I told him I work on electronics. Thats when he said he has something I might want. He went in the house and came out with a Kenwood Basic C2, Stereo Control Amplifier. Made in (1984-90). The guy said it's dead, and he was going to throw it away, so I can have it. He said he connected speakers to it and it dont do anything. I got home and was getting out a RCA plug to connect to the output terminals, to hook up a speaker, when I began to look closer at it, and thought "this is a preamp, not a power amp". To make sure what I had, I looked on the web, and found this: https://www.hifiengine.com/manual_library/kenwood/basic-c2.shtml I have to admit, this is called an "amplifier" so I did sort of think it needed speakers, even though RCA plugs are not usually used for speakers except some of the real old cheap stuff. It turned out this was my lucky day. This preamp sounds great. (And I didn't even connect it to my main power amp yet, I just connected it to a small mono guitar amp that I use for testing stuff in the shop. It needed a little contact cleaner on the selector switches, but works great. I am a little confused though about the phone switch. It has the following selections: MM (Moving Magnet) 47K 100K MC (Moving Coil) 10 ohm 30 ohm 100 ohm Ok, I understand what they are saying, but how do I know if my cartridge is MM or MC, and what the resistance rating is? This appears to be a real useful thing, but I never even knew there were different kinds of cartridges. In the past, I just installed a cartridge and plugged it into "Phono". |
"Dave M" <dgminala@mediacombb.net>: May 18 08:32AM -0500 > This appears to be a real useful thing, but I never even knew there > were different kinds of cartridges. In the past, I just installed a > cartridge and plugged it into "Phono". Take a look at the description at http://www.needledoctor.com/core/media/media.nl?id=2701&c=ACCT106601&h=192e59a68f2e49fdd1f8&_xt=.html. That should get you going on the differences and why you would choose one over the other. Basically, it's a choice based on your listening habits and the type of sound you want from your system. Dave M |
Ralph Mowery <rmowery28146@earthlink.net>: May 18 09:59AM -0400 In article <ge0rhc1u4ivka1711na2ap84mjn8ratkbd@4ax.com>, oldschool@tubes.com says... > This appears to be a real useful thing, but I never even knew there were > different kinds of cartridges. In the past, I just installed a cartridge > and plugged it into "Phono". It would seem to me you could just use an ohm meter on the cartridge and see what the resistance is. If very low it would be the mc and if say 10K or greater it would be the MM. |
"pfjw@aol.com" <pfjw@aol.com>: May 18 07:33AM -0700 On Thursday, May 18, 2017 at 9:59:31 AM UTC-4, Ralph Mowery wrote: > It would seem to me you could just use an ohm meter on the cartridge and > see what the resistance is. If very low it would be the mc and if say > 10K or greater it would be the MM. Ummmmm.......... Be EXCEEDINGLY careful in putting a VOM across any phono cartridge, most especially an MC cartridge. Some (cheap) VOMS will put as much as 9V through the coils - not a good thing. And batteries will deliver current to their chemical limits - thinner-than-human-hair wire does not like heat. Peter Wieck Melrose Park, PA |
"pfjw@aol.com" <pfjw@aol.com>: May 18 07:35AM -0700 > This appears to be a real useful thing, but I never even knew there were > different kinds of cartridges. In the past, I just installed a cartridge > and plugged it into "Phono". You have an MM cartridge unless it has an outboard head-amp and/or transformer. Start at 100K. If it sound anemic, move to 47K. Peter Wieck Melrose Park, PA |
Michael Black <et472@ncf.ca>: May 18 10:56AM -0400 |
Ralph Mowery <rmowery28146@earthlink.net>: May 18 11:30AM -0400 In article <9dc02317-2ec5-4558-b585-02b29cb51a14@googlegroups.com>, pfjw@aol.com says... > > 10K or greater it would be the MM. > Ummmmm.......... > Be EXCEEDINGLY careful in putting a VOM across any phono cartridge, most especially an MC cartridge. Some (cheap) VOMS will put as much as 9V through the coils - not a good thing. And batteries will deliver current to their chemical limits - thinner-than-human-hair wire does not like heat. Maybe with the older anlaog meters. I so seldom drage out the analog meter for ohms I was not thinking about that one. The newer digital meters only let a very small ammount of current flow in the ohms position. I mesured a cheep HF $ 5 (free with coupon) meter at less than 2 ma, and a Fluke 87 with less than .5 ma on the low ohm scales. My good old Sompson 260 will put out just under 100 ma on the low ohms scale. |
tabbypurr@gmail.com: May 18 09:33AM -0700 > This appears to be a real useful thing, but I never even knew there were > different kinds of cartridges. In the past, I just installed a cartridge > and plugged it into "Phono". 99.99% of hifi phono carts are MM 47k. You can try the 100k setting without harm, but that may not be true of the MC setting, which expects far lower input. NT |
ohger1s@gmail.com: May 18 05:43AM -0700 > b) Please explain to me how a Variac delivering 84 VAC on a transformer-type device, and that being the minimum trigger voltage on say... a 5Y3, will deliver any less current than that rectifier is able to pass at that voltage? Because the filament voltage of the 5Y3 (for example) will be reduced a similar amount. Low filament voltage makes a weak tube. With low filament, the current capability of the rectifier will sag with a load causing a corresponding voltage drop. Whether the reduced current capability of the sagging rectifier is enough to keep a leaky cap from trashing some other component is something I don't know or really care about - I replace all old paper caps if I should happen to be working on vintage stuff. I use my variac mostly for isolation but also for troubleshooting. |
tabbypurr@gmail.com: May 18 09:25AM -0700 > If one happens to have a metered Variac, one can observe the onset of B+. It does NOT hover when the rectifier starts to pass DC. > Peter Wieck > Melrose Park, PA If you show at attempt to follow what I explained I'll gladly explain further. NT |
tabbypurr@gmail.com: May 18 09:30AM -0700 > On Wednesday, May 17, 2017 at 10:49:22 PM UTC-4, pf...@aol.com wrote: > > b) Please explain to me how a Variac delivering 84 VAC on a transformer-type device, and that being the minimum trigger voltage on say... a 5Y3, will deliver any less current than that rectifier is able to pass at that voltage? > Because the filament voltage of the 5Y3 (for example) will be reduced a similar amount. Low filament voltage makes a weak tube. With low filament, the current capability of the rectifier will sag with a load causing a corresponding voltage drop. it will of course drop to the voltage where the cap no longer leaks too badly, if circuit resistances are satisfied with current. > Whether the reduced current capability of the sagging rectifier is enough to keep a leaky cap from trashing some other component is something I don't know or really care about Nothing is getting trashed when the rectifier only delivers 10mA. You can only reform lytics, not paper caps. Normally lytics go across the supply, often via a dropper, and paper caps go from anode to grid. > - I replace all old paper caps if I should happen to be working on vintage stuff. I use my variac mostly for isolation but also for troubleshooting. Memory a bit vague but I think rectifier conduction started somewhere just over 60v for a 1937 240v set. NT |
Chuck <chuck@mydeja.net>: May 18 08:19AM -0500 On Wed, 17 May 2017 14:44:45 -0700 (PDT), dansabrservices@yahoo.com wrote: >I too have held onto items for way too long. In one case, I had the unit for almost 2 years. While moving others around, I realized this and ended up selling a few weeks later. Customer showed up the week after the sale looking for it... Threatened legal action. I told him, go ahead and see where that gets you. Never heard from him after that. >Dam In the late 70s a guy bought in a very nice reel to reel to be repaired. It was completed within two weeks. None of our calls or letters were answered. Three years later we were moving the business so we sold it. Two weeks later he showed up to pick up the unit. He had moved to Alaska and expected us to hold on to it in perpetuity and was very upset. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
Michael Black <et472@ncf.ca>: May 18 10:51AM -0400 |
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. |
No Response to "Digest for sci.electronics.repair@googlegroups.com - 14 updates in 4 topics"
Post a Comment