strange console phonograph- pictures

[init4fun]

Hi Rob ,

6SJ7-GT most certainly is a tube identification number , and designates that tube as the "pre amp" or "1st audio" , depending on whose terminology you choose to use . The other two numbers are not tube identification numbers and are likely either manufacturer code or date of manufacture code . Those two tubes will likely have numbers 5Y3-GT , which is the rectifier that supplies DC plate voltage for the two audio tubes , and 6V6-GT which will be the "audio output" or "final audio" tube . It's likely that the final could also be one of the cousins of the 6V6 , and there are a few , with such numbers as 6F6 , 6K6 , 6L6 , and the "GT" designation refers to it being a "Glass tube of tubular construction" as opposed to being glass of a bell type shape or all metal .

As to a schematic , you may not find one exactly for the equipment , but just about any 3 tube amp with the same tubes will likely have the same wiring . The schematic will be needed really only if a recap fails to produce a running amplifier . The caps you will replace are all labeled with their ratings , and you simply replace them with new caps of equal ratings . The two ratings are "working voltage" , which is as it sounds , the amount of voltage the cap can be safely asked to endure , and "capacitance" which refers to how much electricity the cap can store till it's needed to be released back into the circuit . Yes , to the casual glance , a capacitor acts similar to a small battery in that it builds up an electrical charge to be used later , the difference being that the cap can charge and discharge many thousands of times each second , instead of the much slower charge/discharge cycle of a common battery . Ripple filtering and AC blocking are two prime uses , as well as interstage coupling . Your likely to find the B+ filtering to be a couple of "40 MFD 450 Volt" electrolytic type capacitors , and these are to be found in a round can made of either metal or cardboard . These caps ARE polarity sensitive , having a defined positive and negative connection that must be observed during instalation . The other caps , the ones taking sound from circuit to circuit will have fractional MFD numbers like ".05 MFD at 450 Volts" and are not polarized , it will work no matter which connection is + or - . The general practice here with the replacements is to come as close as possible to the MFD rating (.047 being a perfect modern day replacement for a .05) and to AT LEAST meet (or better , to slightly go over) the voltage rating (a 600 Volt cap is a perfectly acceptable replacement for a 450 volt one , and a 400 volt one WILL fail in short order) .

I'm happy to hear your willing to give recapping the amp a try , and if you could post pictures of the underside of the amp I'll be more than happy to let you know what's what under there to get you going in the right direction .

[rob Cashin]

alright its all still confusing but at least i have some intelligent people to help . i just finished sanding down the cabinet too, it looks incredible. its going to be a blonde with the original mahogany color on the inside and around the speaker. here is what the underside looks like, some of the caps dont have any writing on them, but im sure between the pictures and you knowledge we can figure it out! also, i took a picture of the volume control, as that will need attention too

[electroking]

6SJ7GT is a legitimate number, but the other two are just production codes. Look
for numbers like 6V6GT, 5Y3GT, 6X5GT, etc. This is your basic, single-ended
phono amplifier, but it does have a power transformer unlike some cheaper
so-called AC-DC designs. Definitely restorable and should make decent sound.
Looking at picture number 4, this could definitely have been built from salvaged
components. A clear picture of the bottom side of the chassis would make it
possible for us to guide you with the restoration. Good luck!

P.S.: sorry, I understand this basically duplicates post number 16 above, but I
can assure you I did not read it before writing this. We must be on the right path!

[rob Cashin]

i did post 3 pictures up above in my last post. 2 are of the underside of the chassis and the 3rd one is of the volume and tone control. i have a solder iron and im ready to recap, i just need some more advice on where to begin! lol

[init4fun]

OOps , We got problems !!!!

Looking at the bottom of that chassis , my first impression is that the rectifier tube socket has had most of it's wiring removed , and that's really bad as it indicates that some hack has been at it before ya got it . This will not be a simple recap , as the wiring will need to be put back right . The green "dogbone" resistor likely was connected to the rectifier socket and is part of the missing wiring I see . There are only 4 capacitors there , and the two more in the round can so as long as no others of them are missing (and it does look like there are the right number of caps in there , at least ) then it's only a grand total of 7 caps with the one at the volume control added in . But now , the missing wiring is concerning , was there prior troubleshooting attempted there and something removed ? Possibly a filter choke like one that may have resided at the back of the speaker ? Or maybe it's the output transformer that's missing ? A couple of good closeups of each of the three tube sockets (from below , of course) and a good look at whatever iron (the two transformers) is on the top of the chassis would be most helpful right now .

PS , are there any wires coming from the bigger transformer that are not hooked up to anything ?

[rob Cashin]

i dont know what to make of it. there is nothing hacked up on the bottom and no loose wires. i think the empty spot was just a dud and someone took out the filler. where you see wiring that isnt there, it looks like nothing was ever there to begin with. there isnt any solder or anything on the pins sticking out. ill include more pictures, maybe that'll help! i hope the pictures help!

[init4fun]

Ok , very good , I can now see the red wires going to the rectifier socket , so all is good . In your first shots , it looked like only the yellow wires were hooked up , but the red ones were just hidden by the angle of the shot . Now then , back to the recapping The first thing you will need to do is to read the values of the caps so ya can get replacements . In the silver can are the two that first should be done . On the can it will list the capacities and voltages of each of the can's sections , and those will end up replaced with much smaller units than the original can . The next one I'd do is that cardboard electrolytic under the chassis that connects to the cathode (Pin #8) of your output tube . That cap and the two in the can are the only electrolytic caps in the amp , and don't forget the polarity . Next would be the wax paper caps , yes those DO have values printed on them too , they're just somewhat obscured in the grungy wax . A great solution here is to use a hairdryer or heat gun (Carefully !) to heat and somewhat melt the wax , this will make the wax much easier to see through to read the readings . You may need to slightly twist the caps to read all the ratings since caps are seldom installed with regard to positioning of the labels for easy reading . Now , once you've got your list , and have watched a few You Tube videos on recapping , your ready to go buy your caps . Since I know where Sturbridge Mass is , and know that your not horribly far from Needham , I'd send ya to ''You Do It Electronics" which is the only electronics store I know of that you can drive to and get caps of the needed voltage ratings . Radio Shack sucks , don't even bother , as they carry NOT ONE 450 volt rated cap and only stock the most common low voltage transistor circuit based stuff .

Also , just to make certain , the 5Y3 rectifier tube does go into the socket that has the yellow and red wires going to it , with no other components . The 6SJ7 pre amp goes to the socket that has the braided shielded wire that plugs in from the side of the chassis . And the 6V6 output tube goes in the remaining socket , the one in the middle with the positive side of the electrolytic to pin #8 on the socket . This is correct placement just in case any were mistakenly switched before ya got it .

So your homework now is to get that list of caps going ......

[rob Cashin]

ok, you are an awesome help. i do have a few questions. the little things that are brown with the red blue and yellow stripes dont have any electrical value stamped on them. how do i know what to get? and the silver can, how do i remove it and open it up? or is that non openable? (i know thats not a word, but it works). and should i replace any of the wires on or coming out of the chassis? and when i test the unit while i replace the caps, should i use a ground fault adapter so i dont get a nice zap just in case i screw something up? i think thats about it for now.. im sure im going to have 1000 more questions when i start. first thing first though, im going to find a better speaker (maybe a bose) and finish the cabinet.

[init4fun]

Hi Rob ,

The things with the stripes are resistors , and we will check those with an Ohm meter to verify that they are good . Although they can be known to age fail just like caps , It's far less likely . Once all the caps are replaced it's usual practice to bring the amp up to power slowly using a variable transformer usually called a "Variac" , and with a small rated fuse (like 5 Amp max) in series in case of any inadvertent short circuits . The only caps likely to be holding any kind of residual charge would be the electrolytics , but since the ones in the amp are so old they aren't holding anything but a future place in the wastebasket . The new caps , after instalation and first power up , COULD hold enough residual charge for a little zap if ya get across it , that's why we will always discharge the new caps before working under there . All ya do is with the power off and unplugged , take any old piece of jumper wire and put one end solidly on ground (yes , the metal chassis IS circuit ground on your amp . Not on all , but on yours for sure) and then touch the other end of the jumper to the + side of each electrolytic . This will bleed off any residual charge to ground ensuring ya don't get bit .

So , get going on the list of caps and we'll discuss this further then . Also , DON"T go out and buy an expensive , high power handling Bose or some such speaker !!! Realize that this system puts out precious few watts , and will sound plenty loud and clear enough when properly matched to an appropriatly rated speaker . The speaker for this amp should have a working range of approx 20 watts and no greater , since the amp aint gonna be driving any 100 watt speaker . Remember , this was built in a time of "Quality of sound over quantity" and no small phonograph had the BOOM BOOM BOOM attitude of today's killer megawatt systems . It'll sound good . And clear . Just don't expect your hair blowin in the wind from it , cause that ain't happening ...