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Phono preamp in old receiver problem
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Phono preamp in old receiver problem
"Brian Gaff" wrote in
: Thanks for replying. Well, it is most unlikely that both the channels woold go down together now I'd imagine. Right. Firstly, if you do not get a buzz when you touch the live of these connections, then something is not as expected. Sharp did tend to do stuff in funny ways though, and as has been said elsewhere you need to find out what the turntable actually did. Was there, for example, as I found on an old Teleton unit of similar vintage, a little extra cable from the turntable to the circuit board? No, there are two (grey and brown, thankfully labeled L and R) RCA cables which plugged into the bottom of the BSR turntable where the 4 wires from the cartridge were soldered to the other side of the 2 RCA connector. I cut them and extended them. And something went wrong, see below. This little line appeared to mute the pick up input in some way, presumably via a switch on the pick up bearing or similar. I got the impression it used an optical switch, but as the unit blew a power amp module shortly afterwards, I never investigated further.. No, someone else suggested the muting device, but I do not think this unit had that... It is an amazing piece of vintage quality TODAY but it was a cheapish thing in its day... As for 8 track carts, most have seized up by now I'd imagine as the tape was lubricated. Akai used to make an 8 track recorder which sounded quite good, but the recording time per track was rubbish and the mechanics were designed to wear out by the looks of it. I am curious to see what the deal is here, IF I can find an 8- track cart. (About 15 yrs ago I knew a guy who had an 8-track of Lou Reed's "Metal Machine Music" !!!!) Quite how you cleaned things is hard to see. I am good at cleaning stuff, and I have a pro circuit board cleaner. I did not use WD-40 - although I /have/ done so in the past, with perfect results. -- Update (very long, I apologize!) -- First of all, many thanks to all who replied. It is very much appreciated. Now for the /bad/ part. Something one person mentioned in his reply made me remember a rather *crucial* detail which I had forgotten (I am not completely senile yet, but I have been /incredibly/ busy for the last few weeks, and my brain is running out of RAM). It is this: BEFORE I removed the BSR turntable, I DID check to see whether there was AUDIO SIGNAL coming from it. There was, loud and clear - when I touched the stylus, it sounded like an earthquake. Very little "system noise", too. The turntable itself was "seized" - after I have (with some violence) managed to take it apart, I saw that the 2 main cog wheels of the belt-less motor were practically frozen together at a bizarre angle and would NOT budge. I have NO idea how that happened - and the 4" screwdriver shaft, 2 children's plastic letters with magnets, and assorted bits of 30+ year old food I found inside the receiver could NOT have had anything to do with it, either, since the BSR motor was fairly well enclosed within the /incredibly/ complicated mechanical design (a changer). Now that I have remembered this, it is obvious I screwed something up. I have never seen a ceramic cartridge, but I am 99.99% positive that BOTH the BSR and the Sony (ca. 1990) turntable carts are magnetic. So, since I have no signal but weird pink noise, I must have screwed up the cables. Or do you think I may have destroyed the preamp? (This may be a good moment to mention that I am using the term "phono preamp" in a generic sense. I always thought a phono preamp might be/would be a small enclosed piece of electronics, but in this receiver, it appears to be a part of the main circuit board - the two original (and now extended) cables from the BSR turntable stylus/arm are soldered right onto the circuit board, and go who-knows-where - presumably, into components which make up this receiver's "phone preamp" section.) (THIS may /also/ be a good moment to mention that while I have had some disastrous luck with simple things and astoundingly good luck with complicated things, I am NOT a technician, and do not own an oscilloscope - I check connections with two gator clips connected to a 1.5V battery with a flashlight bulb, and after over 30 years of "considering it", I finally bought a five dollar "voltmeter" which /appears/ to work - I found out a cheap 110V/22V AC/DC adapter outputs 25VDC when set to 12V output [when the input voltage is set to 110V] and 12.5VDC from its 9V setting [when the input voltage is set to 110V (it is 110V here)]. The Sony turntable (originally a component of a system, with a tiny power connector which plugs into the back of the main system unit and where I found out 12VDC is output) is running on a supposedly "regulated" fancy Radio Shack AC/DC adapter which puts out 11.8V DC. (When I reverse the polarity, the turntable spins backwards.) If anyone has read this far, please accept my deep thanks for your patience. I can't write more concisely - I realize it's an illness. Anyway - the question now is WHAT did I do to mess things up? Since I consider the receiver largely indestructible, I do not think I have *destroyed* anything, not to mention the voltages involved are totally minuscule and it being a solid state unit - as the front panel proudly states ;-) - there is little danger of blowing it up. Plus everything else works. My plan is as follows: 1. Cut the original "BSR cartridge/turntable to the main circuit board" cables, strip ends. 2. Attach gator clips to them and connect to the Sony turntable output cable. 3. Hopefully, hear sound. Extend cables again, making SURE I don't screw up this time. If I hear no sound, I will connect the 4 very thin cables from the original BSR cartridge (I saved the cart assembly and cables before I saw the turntable was connected to the circuit board with 2 standard cables with RCA plugs) to the cut cables leading to the circuit board and see if I hear anything. If I do, I will post for more advice. But for now, my question is: If after doing all this, I still get the /same/ pink noise (NOT hum - strange, huh?) and get NO audio, WHAT do I do? Thank you /very much/ for your patience, and my apologies for having forgotten a crucial part of the puzzle. Further help will be greatly appreciated. If anyone wants to see pix of the 2 cartridges or the circuit board where the phono audio cables are soldered into it, I can post them to photobucket or something, OR a binary group if you have binaries access. The replies are different in every one of the 5 groups, so I will post this followup to each group separately. I don't really understand how crossposting works, since I never do it, and eternal september /may/ be "funny" about crossposting to boot. -- Any mental activity is easy if it need not be subjected to reality. |
Phono preamp in old receiver problem
"Mark Zacharias" wrote in
: Thanks for the reply. snip Perhaps the stylus on the replacement turntable is not quite seated properly. It works perfectly with its original system (see below). This would produce your symptom. No sound when plugged into the (ceramic) phono input, hear a pop w/ unplug, hear low sound on another input. Hmm. The two cartridges, while different, both appear to be magnetic. I can post photos (see below). I'm presuming your original turntable had a ceramic cartridge, but it would help to know if this is true; also what kind of cartridge is in your replacement table. I am 99.99% sure both are magnetic, but I can post photos. Please take the time to read the following. -- Update (very long, I apologize!) -- First of all, many thanks to all who replied. It is very much appreciated. Now for the /bad/ part. Something one person mentioned in his reply made me remember a rather *crucial* detail which I had forgotten (I am not completely senile yet, but I have been /incredibly/ busy for the last few weeks, and my brain is running out of RAM). It is this: BEFORE I removed the BSR turntable, I DID check to see whether there was AUDIO SIGNAL coming from it. There was, loud and clear - when I touched the stylus, it sounded like an earthquake. Very little "system noise", too. The turntable itself was "seized" - after I have (with some violence) managed to take it apart, I saw that the 2 main cog wheels of the belt-less motor were practically frozen together at a bizarre angle and would NOT budge. I have NO idea how that happened - and the 4" screwdriver shaft, 2 children's plastic letters with magnets, and assorted bits of 30+ year old food I found inside the receiver could NOT have had anything to do with it, either, since the BSR motor was fairly well enclosed within the /incredibly/ complicated mechanical design (a changer). Now that I have remembered this, it is obvious I screwed something up. I have never seen a ceramic cartridge, but I am 99.99% positive that BOTH the BSR and the Sony (ca. 1990) turntable carts are magnetic. So, since I have no signal but weird pink noise, I must have screwed up the cables. Or do you think I may have destroyed the preamp? (This may be a good moment to mention that I am using the term "phono preamp" in a generic sense. I always thought a phono preamp might be/would be a small enclosed piece of electronics, but in this receiver, it appears to be a part of the main circuit board - the two original (and now extended) cables from the BSR turntable stylus/arm are soldered right onto the circuit board, and go who-knows-where - presumably, into components which make up this receiver's "phone preamp" section.) (THIS may /also/ be a good moment to mention that while I have had some disastrous luck with simple things and astoundingly good luck with complicated things, I am NOT a technician, and do not own an oscilloscope - I check connections with two gator clips connected to a 1.5V battery with a flashlight bulb, and after over 30 years of "considering it", I finally bought a five dollar "voltmeter" which /appears/ to work - I found out a cheap 110V/22V AC/DC adapter outputs 25VDC when set to 12V output [when the input voltage is set to 110V] and 12.5VDC from its 9V setting [when the input voltage is set to 110V (it is 110V here)]. The Sony turntable (originally a component of a system, with a tiny power connector which plugs into the back of the main system unit and where I found out 12VDC is output) is running on a supposedly "regulated" fancy Radio Shack AC/DC adapter which puts out 11.8V DC. (When I reverse the polarity, the turntable spins backwards.) If anyone has read this far, please accept my deep thanks for your patience. I can't write more concisely - I realize it's an illness. Anyway - the question now is WHAT did I do to mess things up? Since I consider the receiver largely indestructible, I do not think I have *destroyed* anything, not to mention the voltages involved are totally minuscule and it being a solid state unit - as the front panel proudly states ;-) - there is little danger of blowing it up. Plus everything else works. My plan is as follows: 1. Cut the original "BSR cartridge/turntable to the main circuit board" cables, strip ends. 2. Attach gator clips to them and connect to the Sony turntable output cable. 3. Hopefully, hear sound. Extend cables again, making SURE I don't screw up this time. If I hear no sound, I will connect the 4 very thin cables from the original BSR cartridge (I saved the cart assembly and cables before I saw the turntable was connected to the circuit board with 2 standard cables with RCA plugs) to the cut cables leading to the circuit board and see if I hear anything. If I do, I will post for more advice. But for now, my question is: If after doing all this, I still get the /same/ pink noise (NOT hum - strange, huh?) and get NO audio, WHAT do I do? Thank you /very much/ for your patience, and my apologies for having forgotten a crucial part of the puzzle. Further help will be greatly appreciated. If anyone wants to see pix of the 2 cartridges or the circuit board where the phono audio cables are soldered into it, I can post them to photobucket or something, OR a binary group if you have binaries access. The replies are different in every one of the 5 groups, so I will post this followup to each group separately. I don't really understand how crossposting works, since I never do it, and eternal september /may/ be "funny" about crossposting to boot. -- Any mental activity is easy if it need not be subjected to reality. |
Phono preamp in old receiver problem
Tim Schwartz wrote in
: Thanks for your reply. while I don't know your specific Sharp receiver (you did not specify the model number) many 'compact systems' with BSR changers used ceramic cartridges that give a line level output, so this receiver may not have a phono preamp at all. AHA! This WOULD explain /everything/! (Including WHY there does NOT appear to be an identifiable "phone preamp", just the 2 cables going into the circuitry.) The model number is SG-164U. Can you confirm the ceramic cart thing? And is there ANYTHING I can do to make a magnetic cartridge work with this unit? (Buying a phono preamp is OOTQ, it would cost more than a new DVD player, but perhaps I could make one? Would you happen to have a schematic/link to one?) For /all/ the gory details: -- Update (very long, I apologize!) -- First of all, many thanks to all who replied. It is very much appreciated. Now for the /bad/ part. Something one person mentioned in his reply made me remember a rather *crucial* detail which I had forgotten (I am not completely senile yet, but I have been /incredibly/ busy for the last few weeks, and my brain is running out of RAM). It is this: BEFORE I removed the BSR turntable, I DID check to see whether there was AUDIO SIGNAL coming from it. There was, loud and clear - when I touched the stylus, it sounded like an earthquake. Very little "system noise", too. The turntable itself was "seized" - after I have (with some violence) managed to take it apart, I saw that the 2 main cog wheels of the belt-less motor were practically frozen together at a bizarre angle and would NOT budge. I have NO idea how that happened - and the 4" screwdriver shaft, 2 children's plastic letters with magnets, and assorted bits of 30+ year old food I found inside the receiver could NOT have had anything to do with it, either, since the BSR motor was fairly well enclosed within the /incredibly/ complicated mechanical design (a changer). Now that I have remembered this, it is obvious I screwed something up. I have never seen a ceramic cartridge, but I am 99.99% positive that BOTH the BSR and the Sony (ca. 1990) turntable carts are magnetic. So, since I have no signal but weird pink noise, I must have screwed up the cables. Or do you think I may have destroyed the preamp? (This may be a good moment to mention that I am using the term "phono preamp" in a generic sense. I always thought a phono preamp might be/would be a small enclosed piece of electronics, but in this receiver, it appears to be a part of the main circuit board - the two original (and now extended) cables from the BSR turntable stylus/arm are soldered right onto the circuit board, and go who-knows-where - presumably, into components which make up this receiver's "phone preamp" section.) (THIS may /also/ be a good moment to mention that while I have had some disastrous luck with simple things and astoundingly good luck with complicated things, I am NOT a technician, and do not own an oscilloscope - I check connections with two gator clips connected to a 1.5V battery with a flashlight bulb, and after over 30 years of "considering it", I finally bought a five dollar "voltmeter" which /appears/ to work - I found out a cheap 110V/22V AC/DC adapter outputs 25VDC when set to 12V output [when the input voltage is set to 110V] and 12.5VDC from its 9V setting [when the input voltage is set to 110V (it is 110V here)]. The Sony turntable (originally a component of a system, with a tiny power connector which plugs into the back of the main system unit and where I found out 12VDC is output) is running on a supposedly "regulated" fancy Radio Shack AC/DC adapter which puts out 11.8V DC. (When I reverse the polarity, the turntable spins backwards.) If anyone has read this far, please accept my deep thanks for your patience. I can't write more concisely - I realize it's an illness. Anyway - the question now is WHAT did I do to mess things up? Since I consider the receiver largely indestructible, I do not think I have *destroyed* anything, not to mention the voltages involved are totally minuscule and it being a solid state unit - as the front panel proudly states ;-) - there is little danger of blowing it up. Plus everything else works. My plan is as follows: 1. Cut the original "BSR cartridge/turntable to the main circuit board" cables, strip ends. 2. Attach gator clips to them and connect to the Sony turntable output cable. 3. Hopefully, hear sound. Extend cables again, making SURE I don't screw up this time. If I hear no sound, I will connect the 4 very thin cables from the original BSR cartridge (I saved the cart assembly and cables before I saw the turntable was connected to the circuit board with 2 standard cables with RCA plugs) to the cut cables leading to the circuit board and see if I hear anything. If I do, I will post for more advice. But for now, my question is: If after doing all this, I still get the /same/ pink noise (NOT hum - strange, huh?) and get NO audio, WHAT do I do? Thank you /very much/ for your patience, and my apologies for having forgotten a crucial part of the puzzle. Further help will be greatly appreciated. If anyone wants to see pix of the 2 cartridges or the circuit board where the phono audio cables are soldered into it, I can post them to photobucket or something, OR a binary group if you have binaries access. The replies are different in every one of the 5 groups, so I will post this followup to each group separately. I don't really understand how crossposting works, since I never do it, and eternal september /may/ be "funny" about crossposting to boot. -- Any mental activity is easy if it need not be subjected to reality. |
Phono preamp in old receiver problem
"thanatoid" wrote
And is there ANYTHING I can do to make a magnetic cartridge work with this unit? (Buying a phono preamp is OOTQ, it would cost more than a new DVD player, but perhaps I could make one? Would you happen to have a schematic/link to one?) Low-cost phono pre-amps are readily available. As you appear to live in the US could I suggest looking at what Radio Shack has to offer? You should be able to get a simple phono pre-amp on a small PCB (no case, connectors or power supply) for a *lot* less than the cost of a DVD player and for little more than the retail cost of the components. David. |
Phono preamp in old receiver problem
"David Looser" wrote in
: snip Low-cost phono pre-amps are readily available. As you appear to live in the US could I suggest looking at what Radio Shack has to offer? You should be able to get a simple phono pre-amp on a small PCB (no case, connectors or power supply) for a *lot* less than the cost of a DVD player and for little more than the retail cost of the components. I use eternal september but I live in a god forsaken horrible 3rd world country (without a SINGLE Usenet server, paid or otherwise) where everything is either unavailable, does not work (returns or exchanges are not a known concept here) or costs 2-5 times what it does in civilization. Are you saying the unit DOES use a ceramic cartridge? Is it possible to put a ceramic cartridge in the Sony turntable? (I can probably find a car. cart. /somewhere/...) -- Any mental activity is easy if it need not be subjected to reality. |
Phono preamp in old receiver problem
"Peter Larsen" wrote in
k: snip Are you sure the original turntable had a magnetic cartridge? - and if so, did it contain a preamp for it? Thanks for replying. I'm /not at all/ sure now. Someone in another group just said he is almost certain the Sharp units of that vintage used ceramic cartridges, which would explain /everything/. Also, please see below (heavily edited for you ;-) : (...) Something one person mentioned in his reply made me remember a rather *crucial* detail which I had forgotten (I am not completely senile yet, but I have been /incredibly/ busy for the last few weeks, and my brain is running out of RAM). It is this: BEFORE I removed the BSR turntable, I DID check to see whether there was AUDIO SIGNAL coming from it. There was, loud and clear - when I touched the stylus, it sounded like an earthquake. Very little "system noise", too. Now that I have remembered this, it is obvious I screwed something up. I have never seen a ceramic cartridge, but I am 99.99% positive that BOTH the BSR and the Sony (ca. 1990) turntable carts are magnetic. So, since I have no signal but weird pink noise, I must have screwed up the cables. Or do you think I may have destroyed the preamp? (This may be a good moment to mention that I am using the term "phono preamp" in a generic sense. I always thought a phono preamp might be/would be a small enclosed piece of electronics, but in this receiver, it appears to be a part of the main circuit board - the two original (and now extended) cables from the BSR turntable stylus/arm are soldered right onto the circuit board, and go who-knows-where - presumably, into components which make up this receiver's "phone preamp" section.) (...) -- Any mental activity is easy if it need not be subjected to reality. |
Phono preamp in old receiver problem
"thanatoid" wrote in message
Now that I have remembered this, it is obvious I screwed something up. I have never seen a ceramic cartridge, but I am 99.99% positive that BOTH the BSR and the Sony (ca. 1990) turntable carts are magnetic. So, since I have no signal but weird pink noise, I must have screwed up the cables. Or do you think I may have destroyed the preamp? How old is the BSR? Most of the BSR turntables I am familiar with from the 60s and 70s were cheaper than cheap and had ceramic cartridges. |
Phono preamp in old receiver problem
|
Phono preamp in old receiver problem
On 9/9/2010 10:08 AM thanatoid spake thus:
"David Looser" wrote in : snip Low-cost phono pre-amps are readily available. As you appear to live in the US could I suggest looking at what Radio Shack has to offer? You should be able to get a simple phono pre-amp on a small PCB (no case, connectors or power supply) for a *lot* less than the cost of a DVD player and for little more than the retail cost of the components. I use eternal september but I live in a god forsaken horrible 3rd world country (without a SINGLE Usenet server, paid or otherwise) where everything is either unavailable, does not work (returns or exchanges are not a known concept here) or costs 2-5 times what it does in civilization. Are you saying the unit DOES use a ceramic cartridge? Is it possible to put a ceramic cartridge in the Sony turntable? (I can probably find a car. cart. /somewhere/...) Couple points to try to allay further confusion: 1. Even a ceramic cartridge requires a preamp, but one that has different equalization from one for a magnetic cartridge. A ceramic cartridge does *not* output a line-level signal. 2. As someone else said, you can get small, standalone phono preamps (for mag. carts) for not very much. No need for a fancy-schmancy full-featured preamp. You could permanently wire it into the unit and would be on your way. 3. Ceramic cartridges aren't as good (fidelity-wise) as magnetics, and aren't as kind to your records either (less compliance). So try to use a decent magnetic cartridge. -- The fashion in killing has an insouciant, flirty style this spring, with the flaunting of well-defined muscle, wrapped in flags. - Comment from an article on Antiwar.com (http://antiwar.com) |
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