johnyholiday Posted March 19, 2008 Share Posted March 19, 2008 This has boards by Shannon Parks......to be unveiled at a later date Quote Link to comment Share on other sites More sharing options...
WopOnTour Posted March 19, 2008 Share Posted March 19, 2008 original form on right Cool Johnny Thanks! Those look IDENTICAL! So can you tell me what year, make, model of console this amp was sucked out of? Is it a Magnavox I presume? Would you happen to have a schematic?? WOT Quote Link to comment Share on other sites More sharing options...
Clipped and Shorn Posted March 19, 2008 Share Posted March 19, 2008 http://radioatticarchives.com/archive.php?page=a7 Our Atwater Kent is closest to the model 60C from the post '28/'29 period seen in this museum page (far right with high legs). The cabinet was beautiful, and why fini snagged it without hesitation out at the county dump, but inside it needed some tube replacements, tube shields, top shield, cap clips, speaker restoration, and a repair to an interstage transformer (which I got help on). The most dramatic bit of restoration was gluing the totally smashed speaker cone back together using tissue paper and "Service Cement" from Antique Radio Supply. Also replaced the tattered grille cloth. The tuning mechanism relies on a rubber bushing which I had to improvise. The radio works fine with good ground and long wire antenna. I was amazed to find how nice the speaker sounds after repair. The tubes used are 80, 24A, 27, and 45. c&s Mike, I checked the tube box , turns out there were no 71A. Quote Link to comment Share on other sites More sharing options...
mike stehr Posted March 19, 2008 Share Posted March 19, 2008 http://radioatticarchives.com/archive.php?page=a7 Our Atwater Kent is closest to the model 60C from the post '28/'29 period seen in this museum page (far right with high legs). The cabinet was beautiful, and why fini snagged it without hesitation out at the county dump, but inside it needed some tube replacements, tube shields, top shield, cap clips, speaker restoration, and a repair to an interstage transformer (which I got help on). The most dramatic bit of restoration was gluing the totally smashed speaker cone back together using tissue paper and "Service Cement" from Antique Radio Supply. Also replaced the tattered grille cloth. The tuning mechanism relies on a rubber bushing which I had to improvise. The radio works fine with good ground and long wire antenna. I was amazed to find how nice the speaker sounds after repair. The tubes used are 80, 24A, 27, and 45. c&s Mike, I checked the tube box , turns out there were no 71A. Well, thanks for looking anyway.....I appreciate that. My audio buddy Dan has a '29 Edison that's fully restored, it was quite the piece. It used 45's for outputs. Another triode I could try that's lying about is the RCA 801A. About the same wattage as a 2A3 with a 7.5 volt thoriated tungsten filament. I could try the 35 volt 10 amp regulated supply to heat the filaments, I think I could get away with that. The high voltage DC regulated supplies I have probably won't supply enough B+ for the plates. I think I'll need a good 400-600 volts DC. I think the 801A needs a bit of drive voltage as well. Quote Link to comment Share on other sites More sharing options...
fini Posted March 19, 2008 Share Posted March 19, 2008 Hey Mike, Since I sort of stalk you, I've kept all our correspondence. Turns out you've already sent "under the hood" shots! I'm practicing soldering this afternoon, putting together that step-up transformer. I think I need to switch to a larger tip... Geeze, getting close to 10K posts. I gotta get a life... Quote Link to comment Share on other sites More sharing options...
mike stehr Posted March 19, 2008 Share Posted March 19, 2008 Uh......ok..... I got 4000 posts.....and you ain't alone, brother. Just practice, get used to the heat/temp and time involved. Keep the tip clean, blah, blah, blah..... Quote Link to comment Share on other sites More sharing options...
fini Posted March 19, 2008 Share Posted March 19, 2008 Don't worry. It's like a celery stalk. (?) I saved your emails for when I'm smart enough to follow your directions! ;^) Anyway, the step-up is done (except for any fancy wood or other material I might use to fir-, ash-, or spruce-up the outside. The larger tip helped. I was using Vampire RCA jacks, and one must solder wires to a notch in the body of the jack, which is quite a heat sink. No worries: Teflon insulation and dielectric. Quote Link to comment Share on other sites More sharing options...
johnyholiday Posted March 19, 2008 Share Posted March 19, 2008 original form on right Cool Johnny Thanks! Those look IDENTICAL! So can you tell me what year, make, model of console this amp was sucked out of? Is it a Magnavox I presume? Would you happen to have a schematic?? WOT only know it's a Motorola.......still searching........sounds good, idling might have a 120 HZ hum {no choke?},with ear next to Cornwall grill Quote Link to comment Share on other sites More sharing options...
Clipped and Shorn Posted March 19, 2008 Share Posted March 19, 2008 fini, "done", by all rights, means it woiks? how does it sound? good going....in any case.... c&s Quote Link to comment Share on other sites More sharing options...
fini Posted March 19, 2008 Share Posted March 19, 2008 No, I haven't tried it out. Don't have the Deneen 103 installed on the SME. I had to back-track a bit, but got 'er buttoned up (and the mess cleaned up) before Cathy got home! Dig the purple crushed velvet!! EDIt: Dang, sorry about the size...I will try to edit. Quote Link to comment Share on other sites More sharing options...
Marvel Posted March 19, 2008 Author Share Posted March 19, 2008 Cool fini, what did you wire up? Quote Link to comment Share on other sites More sharing options...
mike stehr Posted March 20, 2008 Share Posted March 20, 2008 "only know it's a Motorola.......still searching........sounds good, idling might have a 120 HZ hum {no choke?},with ear next to Cornwall grill" I would guess the hum is coming from the woofer. It could be the multi-capacitor can....dunno... Something you could try is to see if the 6.3 volt heater winding has a center tap. But I really doubt it does, and you are probably hearing a little heater growl from the floated 6.3 heater winding....maybe... Take a couple 100 ohm resistors, (1/2 watt is fine) and run a resistor from each heater winding leg to ground. It might help.... Quote Link to comment Share on other sites More sharing options...
Clipped and Shorn Posted March 20, 2008 Share Posted March 20, 2008 fini, nice work on the MC cartridge step-up box. You were lucky to get those beautiful Altec 4722 transformers when you did. They sound fantastic and is why they have been collected so agressively by Japanese audiophiles among others . c&s Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted March 21, 2008 Share Posted March 21, 2008 Fini: If there is leakage caused by an AC filament supply, it wouldn't be 120 cycle hum. If this is a preamp, it might be a good idea to use DC filaments. What Mike said about the center tapped filament transformer can help, as can the 100ohm resistors on each leg of the heater supply with the other ends grounded. That still may not be enough, though. In a preamp, because of the lower signal levels, you might like to try DC, which, if you were able to do this, wouldn't be hard for you. Those step up transformers look really nice b the way. For DC filaments, Radio Shack will have the full-wave bridge rectifier that would be needed. The ripple filter capacitor across the neg/pos DC output can be in the range of 10,000uf, but you may need a dropping resistor to bring the voltage back to what you want. Adding the capacitor will likely bump the voltage up a little bit. You can install the resistor after the first filter cap in series with the pos. end of the next electrolytic and from there run the leads to the heater pins on the tube sockets. You can also make the rectifier with 4 individual diodes, which might be a little cheaper. If you want some asistance, let me know. A power resistor would be needed in the above description. If the hum is in fact 120 cycles, you might try adding extra capacitance in the power supply. Good luck; that looks like a nice little project. Oh, I wanted to mention, too, that for RCA jacks and speaker posts, you might find the larger Weller soldering gun helpful. Erik Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted March 21, 2008 Share Posted March 21, 2008 Fini: Check your grounding scheme, as well, making sure that you don't have power supply grounds and preamp/amp circuitry grounds combined together. Depending on how you;re grounding this circuit, the preamp section and power supply section should have their own ground nodes, which are then each connected to a single star ground on the chassis, usually near the input. Also, if you have a center tapped power transformer, it's helpful for the center tap ground position to be the same as that used for the first input to filter capacitor -- which may be film-foil type or an electrolytic. Erik Quote Link to comment Share on other sites More sharing options...
mike stehr Posted March 21, 2008 Share Posted March 21, 2008 original form on right Cool Johnny Thanks! Those look IDENTICAL! So can you tell me what year, make, model of console this amp was sucked out of? Is it a Magnavox I presume? Would you happen to have a schematic?? WOT only know it's a Motorola.......still searching........sounds good, idling might have a 120 HZ hum {no choke?},with ear next to Cornwall grill Pay attention,Erik....... Quote Link to comment Share on other sites More sharing options...
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