#46
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The oscillator coil consists of the whole L2 assembly, the two windings together.
Adjusting the trimmer is explained in the instructions with the schematic, but it all boils down to a simple thing: making sure the stations are at the correct frequencies on the dial. By the way, it might be time to give the amplifier a try, feeding it with the line output of a CD player or mp3 player. Adapters with RCA plugs that fit the phono input are quite easily found. Bye for now. Last edited by electroking; 05-25-2010 at 12:35 PM. Reason: corrected spelling |
#47
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Not to worry, I have plenty of RCA-outputting hardware at my disposal, not to mention some R2Rs
I've been holding off on ordering the caps etc. because I'm going to be very busy for the next three weeks- no time for projects such as this. (Hence I started with something simple like the turntable). After that, I should have plenty of free time to get in to my own projects, and then this will take off Thus, the original caps are still in place, and it's not quite ready for a bench-test yet... The epoxy should be cured (>24h) by tonight, so I'm going to grab a test (read: not particularly important) 78 and take it out for a spin. |
#48
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As electroking noted, both the coils shown as L2 are on that assembly, and the two lower ("cold") ends of the coils are connected together and to system ground. If substituting a different coil, determine the common terminal and connect the same as before. If the set won't oscillate (as determined by the set tuning broadly, maybe one station all over the dial), reverse the connections of one of the coils.
Main tuning cap alignment: tune in a station of known frequency near 1400 Khz. The trimmer on the smaller section of the tuning cap will move the station up or down the dial until it reads correctly on the dial scale. Then tune to a weak station around 1400 and peak reception with the trimmer on the larger section of the tuning cap.
__________________
Reece Perfection is hard to reach with a screwdriver. |
#49
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Hello again,
The reason I suggested trying out the amplifier was to help you find something stimulating to pursue the project: the amplifier will work even if the radio section is not fixed. As long as the function switch is set to phono or stereo, the radio section is not powered (except for the tube heaters). If you have to set this project aside for sometime, I would suggest that you do some reading on the principles of superheterodyne receivers (that just means a receiver with a local oscillator and demodulation at a fixed carrier frequency called the Intermediate Frequency). Examples of useful books include any old edition of the ARRL handbook, good old textbooks such as the one by Terman (Electronic and Radio Engineering), etc. Bye for now. P.S.: testing with the turntable and an old 78 is fine too! Last edited by electroking; 05-25-2010 at 06:12 PM. Reason: added note |
#50
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Well... game over for now The TC8S is indeed quite dead... there was crystal dust everywhere.
Looks like I'm on the hunt for a new cartridge. Any recommendations for a drop-in ceramic replacement (TC12H?) or how much I can expect to spend? (and possibly a good supplier in NL?) Thanks! |
Audiokarma |
#51
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Canadian Astatic. Send them your set model number, and all the numbers on your cartridge. They will have one that will work.
http://www.canadianastatic.com/
__________________
Reece Perfection is hard to reach with a screwdriver. |
#52
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I've sent them an email and am waiting for a reply.
While googling, I came across this: http://www.angelfire.com/electronic2...ge-rebuild.htm Anyone tried it before? Or will that hack only work well in a mono cartridge? I have several piezo buzzers I've salvaged... and it's not as though they are expensive. Perhaps I'll give it a shot. |
#53
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Quote:
be that hard to find, and it will come with brand new styli. By the way I looked at your site (thanks for the credit to me regarding the schematic!) and I wonder why you concluded that the oscillator coil was shot. Maybe it's obvious to you, but did you trace the connections to the rest of the circuit to confirm that something was wrong? Good luck. |
#54
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Quote:
I figured as much... I'll have a look around to see what I can find locally in addition to AES; chances are a specialty electronics shop may have something. Re Coil: There are several broken wires coming off the side (click the picture for a larger version, easier to see) and there is no continuity if I test the lower coil with a DMM. I'm going to give Reece's suggestion a try as soon as I can get back to the project- I think it may be fixable with some care... it looks worse than it is. |
#55
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Okay... Just in time
I dropped by a specialty electronics store and I managed to get his last ceramic pick-up for a good price. I never heard back from Canadian Astatic, and the cost was less than they asked anyway. So now I have a Philips GP-815, and I just have to figure out a way to mount it (which shouldn't be difficult- it comes with a small metal plate to clamp it securely; If I drill and tap the plate then I should be able to use the original mounting screw in the BSR tone arm. Does anyone have detailed specs? All I can find is this page, which offers little help (except confirming that it is ceramic): http://www.topkaufmunich.de/plaintex...temphilips.php I would assume the standard tracking weight of around 6g would apply. (Though I've heard it's better to be on the higher end of the range- which would be ~8g. I know too light will damage the record as the stylus skates around, but what sort of problems would you get with too much tracking weight?) |
Audiokarma |
#56
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Quote:
ok i can't imagine where you scored a ceramic cartridge in our city...i don't do vinyl,but i'm thinking it might be useful to know what business around here even sorta carries stuff like that...best guess's? Hamblins?maybe Peak? |
#57
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Sorry, it's not in Canada, actually
This is in Europe- I've found the newer American Philips (Magnavox?) products to be nothing but crap, whereas here it's still decent quality and a respected brand. As an FYI, the store is Technica B.V. in Nijmegen, NL. They would probably still have some tubes on a back shelf or know where to get them, but I didn't think to ask (and trying to transport them by plane is asking for it!)- This guy is basically your local electronics shop for the hobbyist, all kinds of components and supplies. Edit: I'd wager a store like that would do really well for the tinkerer in Halifax.. but you might try RAE electronics in Burnside. I usually order all my other stuff from Digi-Key, but if you'd like, I can ask around as I know a few people who support older electronics and might know where to get the stuff locally. |
#58
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Quote:
i haven't been into RAE in several years,it was usually a wasted stop unfortunately.they always seemed to put more emphasis on commercial/industrial concerns..alltho welcome,they're not really there for the individual in need of a few bucks in parts was always my impression...Jentronics also in Burnside is my store of choice these days...never had a bad experience,friendly,happy to offer advice and usually have what i need,or will order it in if not...found out on my last trip in that the guy on the counter also had experience in restoring radios...very helpful |
#59
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Quote:
II've heard of Jentronics, and I'll have to give them a look sometime. Another decent place is Princess Auto; while they have mostly tools and car parts, they have miscellaneous electronics in the surplus section... great place for AC adapters and cheap cables, fans, etc- While I doubt they carry pickups, it couldn't hurt to give them a call. I wonder if Halifax is just too small to support such a store- the major problem being supply. It seems to me that this "old" technology is just much more alive in Europe than in the Americas. (e.g. the video about the man making his own triodes- he's in France) |
#60
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*Hisssss* *crackle* bada-BUMP! :D
Okay, I'm back at it .
Just for kicks, I asked the guy if he also had any dial cord or tubes... Negative on both counts, but I did win that bet Anyway, I was able to mount the new cartridge, wire it up and set the tracking weight using a jury-rigged balance and a loonie (which is exactly 6g!). However, doing a dry run, (nothing connected to the turntable), I can actually hear the sound on the record. It's not loud, and somewhat tinny (kind of like someone standing next to you with their earbuds cranked.) The needle isn't skating, it is well seated in the groove. I don't want to damage anything, so I stopped right away... More newbie questions: - Is that normal, or too much/little tracking force? -If not, could it be the stylus angle (and should it be 90 bang on, or more/less)? Finally, I still have the TC8G and TC8S styli... Both look in good shape. Anyone want to buy them to fund my restoration? "Super macro" pics on request. |
Audiokarma |
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