GENERAL ELECTRIC

RC 6731BWD-A

RESTORATION & INFORMATION










This is the same unit with the speaker "doors" closed. They are also removable and can be extended from the cabinet by cords (originals included).
These grills are suppose to be brown. It's difficult to see but the stain on the right has actually eaten up some of the fabric.
I continue to look for replacement speaker acoustic fabric that is similar.
If you have some original, or similar, contact me.


RC 6731 BWD A




This is how it was found. The power button is broken off, the power switch inoperative.
A line cord switch was installed. The cabinet veneer has some issues as well.
All 4 grills are heavily cigarette smoke damaged, and faded. One grill has been damaged by something that
spilled on it. It has eaten through the grill cloth in places. The turntable would not rotate at a constant speed.
The right speaker sound would cut off completely, or sound low and distorted.
The stylus installed was the original GE stylus as well. Note: the tuning dial is darker on the right side, because a lamp is out.
Given all the above, it's still in pretty good shape for a 50 year old stereo.

I have been looking for one of these for a while.
We had a similar one when I was growing up mounted to the dining room wall, and it's what I played 45's and LP's on.



One of the biggest pluses buying this particular unit was that all the original paperwork was with it!

                                                                            1. The original template to mount the stereo on the wall  (I have the original mounting brackets also!)
                                                                            2. The positive select record size label.     (see photo)                        
                                                                            3. The cabinet composition label               (see photo)                                                             
                                                                            4. Unpacking Instructions                                
                                                                            5. Owners manual
                                                                            6. Tuner schematic
                                                                            7. Amplifier schematic
                                                                            8. Original bill of sale

                                                  
                                 



Note: the stylus box in the photo, it turns out the original owner purchased a stylus in 1972 ( I have receipt for it), but it is the wrong one!
It's totally wrong for the cartridge in this tone arm, it would however fit into the older (tube) version of this stereo.





Cabinet Labels


Below is an ad explaining some of the features.

RC6731BWD AD
This ad appeared in a 1965 newspaper, it's surprising that is doesn't mention the provision for the optional Porta-Fi transmitter.
Once a Porta-fi transmitter is installed, a external "receiver" speaker could be plugged into any one of the homes ac outlets and it would pick up
the transmitted music from the stereo.



Technical Specs and Info.

15- Transistor Am-Fm-Fm Stereo Receiver / Tuner      Model TU-500-7            Sams Set 888 folder 6
14- Transistor  Stereo Amplifier                                    Model T20A                   Sams Set 888 folder 6
  4- Speed Auto-Record Changer                                 Model RD-225-6            Sams Set 828 folder 8

Dial lamps- #51
Turntable Cartridge GE C650
Turntable Stylus N74SD / 2744DS / 510-DS77
Idler Wheel  EA80X61, RS6065, WALSCO 1499-35, PRB W07
Motor  EA80X153, RS6297
Automatic Spindle  EA80X22, RS6027
Audio Outputs (Q20,Q22,Q27,Q29)  EA15X26, DS-520, GE-3, SK3009, NTE 104 (TRANSISTOR PNP GERMANIUM 50V 10A TO-3 AUDIO POWER AMP)


Here is the wiring diagram






RESTORATION

One of the first things I had to get a handle on was the inoperative power switch. Once I pulled the amplifier chassis to get a look at it, I found there were 2 issues.
First, the plastic button was snapped off at the point it was connected to the switch and the second was the switch itself was jammed in the ON state.
My guess is the button was broken in a attempt to get it to turn off. When that failed and the button broke the previous owner installed a line cord switch.
Originally, I thought I could just find a plastic button and attach it to what was left of the original button.
That turned out to not be an option. The spring clip around the button was all that was holding what was left of it together.
So ....I had to make a replacement button. The button is unusual. It connects to the power switch off center.

Here is a sketch.

POWER SWITCH BUTTON


I made it by turning a piece of hardwood, and using the original spring clip. I painted it chrome, once done.
Now if I had a metal lathe, it would have been better out of aluminum for example.




AMP & TUNER

The mode selection rocker switches were in need of attention. Sometimes, placing the rocker in the tuner position  resulted in NO sound from the right channel. Along with the right channel  /speaker cutting out , sometimes it was low and distorted, sounding like a blown speaker.
Cleaning the switches helped but there was still an issue. That turned out to be the connection at the hinge. The hinges top and bottom provide the speaker connections. The hinges had oxidized after 50 years and non use. I assume if the speaker (doors) had been opened regularly the connections would have been better. 0000 steel wool polished the hinge pins up and between the clean switches and the hinges the sound was now stable.
Time to move onto the missing light on the dial right side.
Getting at that one is a little tough on that chassis. It it behind the tuning shaft weight and dial cord pulleys. The sockets had clips that slid over mounting areas on the chassis. Once I had the bulb in my hand I was able to ID it as #51. which is a 7.5v bulb. Of course I didn't have any.  Yes, I could have used something else but because they used these it gives the dial a certain intensity on the 6v line plus they would last longer than 6v bulbs as well.
Once I had the bulbs, I changed both of them.

To help in cleaning the unit and to gain better access I removed the front panel from the cabinet, though it doesn't need to be removed.
It's held on by 4 screws and washers on each end of the panel accessible from the back.
All the knobs must be removed, along with the nut on the tuning shaft.

The chassis screws are 1/4" , I think there were 6 of them holding both chassis units to the front along with the tuning shaft nut I mentioned.
The power switch issue, which probably caused the demise of the knob was caused by the external case of the switch oxidizing.
This caused the locking / release arm on the switch case to "hang-up" in one direction not allowing it to release. This effectively kept the unit locked in the on state.
Cleaning and polishing the switch case along with a lite lubricant allowed the locking arm to work correctly again.

Once the cabinet interior was clean in the area where the chassis units mount they were returned and secured in place. Installing the "new" knob for the amp before hand.

Fortunately  the amp and tuner work so nothing was really done to them, other than trimming some component leads on the amp to help in gaining access to the mounting screws for that chassis.

TURNTABLE



T
he turntable is a Ge 225-6. The previous owner had played it for me, though not long enough to recognize that the speed was changing.
I suspected the idler wheel. I also noticed that the stylus appeared to be the original, clearly marked GE.
I decided to dismount the turntable from the cabinet. First to gain access to the area under it for cleaning but also to check the condition of the mechanism.
It's a little tricky to get it out.
It has what are pretty standard clips on the lock down screws. Those clips can pivot to a straight up or horizontal position. In the straight up vertical position they can be pulled out of the pre drilled cabinet holes. When snapped into the horizontal position the screw can not pass through the hole it's in.
It also has large wooden washers with a flat edge held above the clips.
The front washer needs to be rotated in a direction to clear the cabinet on that hole. The front one (right-front) is slotted , The rear left is not and it's position does not matter. That other washer will have to be removed when the screw post clip is snapped into the upright position.
There is also a holding clip on the front left turntable spring. that spring must be free of it to remove the table.
Finally, once the turntable is lifted up, the wires need to be disconnected to avoid damaging them. The audio cables are toward the back and the power connector is toward the front.
They are short so care must be taken to not damage them. Also the turntable once dismounted will be close to the back compartment area and can damage the wood there.

To gain access to the idler, remove the spring clip ("C" clip) on the spindle.  It turned out the idler looked to be in good shape on mine. Smoke and age had given it's surface a smooth glaze like appearance. Alcohol and a Q tip and some scrubbing restored the surface and gave it some "grab".
Once reassembled into he case and tested it proved all that was needed.
I ordered a replacement stylus. It came and I went to change it. It turns out this cartridge C650 has a clip to hold the needle in place.
So...you can't just pull it down and forward to get it out as is normally the case on this type of cartridge.
The plastic U shaped clip on the cartridge must be moved out of the way to install a new stylus and remove the old one and then put back.

These drawings below are from the original owners booklet


I suggest just tilting the clip forward after gently releasing the clip ends.  This plastic is tiny (see actual cartridge photo) and 50+ years old. In the photo it has been pulled down and tilted forward. Note: Someone said their cartridge was missing the "bump" near the model#, that is rubber glued in place to help protect the stylus, it's missing on some C650's. It will not effect it's operation if missing, not sure how effective it was. As you see in the original drawings it's not shown.

A little lubriplate on some of the moving linkages, record hold down arm etc. and that's it.
The above restored the table along with cleaning to remove 50 years of smoke damage.

Extra Tech Tip

Once the turntable was in use (unit hung on the wall) I noticed some excessive noise from the motor , this noise picked up by the cartridge while playing.
I dismounted the turntable to investigate. I removed the motor bearing cap (2 screws), and the armature. I found there was some rust on the armature. I removed the rust with 400 paper and 0000 steel wool. I put a coating of oil on the armature surface and  bearings and re-assembled the motor. All noise gone!
There are 2 nuts on the bearing cap screws, used to lock them in place, they will come loose, be sure to put them back.

SPEAKERS & CABINET

The finish on the cabinet was "perked up" with some new stain and oil rubbed finish.

The speaker grill has proven to be a challenge. Trying to find replacement grill material that mimics the original has so far not happened.
I'm hoping, in posting this on my projects page, someone will step forward with a source for a similar material.

Here is what it's suppose to look like, with a dime on it for reference for the weave size.

The area near the edge, where the dime is represents the most accurate original color.
Looking at the photo at the page start shows how much the fabric faded and was damaged by cigarette smoke.

To temporarily finish it I chose to use cloth I had laying around, (black)- to be used  on the outside , until I can find the right material... I left the original material on what is the front of the speakers which face the cabinet when closed. I think it looks pretty good in black. But I am still looking for a match for the original speaker fabric.

Here is what it looks like now, until I find that fabric.






Not only does it look good, but it sounds good too.
I read on one of the forum sites someone claim these have the same sound quality as the portable plastic GE's of that time. They do not.
The amp uses TO3 style outputs for example.
Though the turntable uses a ceramic cartridge, it still sounds pretty impressive. The stylus pressure is adjustable 2.5-5 grams.


More info will follow:
Some  info. detailed below

Besides the grill cloth, I'm looking for a original power button, this from Nos or a parts unit.
If your reading this and have a TU20A parts unit , with a power button, contact me.

Here is some additional: NEW INFO.

These are the original  wall brackets to hang the stereo. They are made from aluminum.       These are the original rca style patch cords to extend the speakers.
Dimensions are shown. They are approx. 1/16" thick. Except at the bend.                           Sockets to use them are on the bottom surface of each speaker.



Below are recently found Porta-Fi components. These would not have been the units offered with the above stereo. They came later but are functionally equivalent.
These were offered with or incorporated in newer models. Other than an ac adapter I will construct to use the prewired cheater cord  installed in my
RC6731BWD cabinet, the solid state transmitter (SP66) should mount directly in the area meant for the tube transmitter SP30.


NEW!

Though there is no model label on this, I believe it is SP15, it is a tube based receiver version

It uses an unusual lamp. (#15?)
This is the inside of the SP15, interesting how the componets were combined as a set (sp66,sp15) , one solid state and the other tube based.
These were factory supplied with a later console unit.



This is the solid state Sp66g .  Though as you see there are both left & right inputs, it's mono.  The last photo shows the audio level adjustment.

There turned out to be a few issues with this, first the 1/2 amp pigtail fuse was blown. The repair, years before was to install a clip lead across it.
I found out why the tech. made this repair, still no excuse. The audio input jacks and the ac socket are riveted to the case. There is one screw holding the board,  on one side, the other side is held by bends in the side cabinet. In order to get to the board bottom side, the screw needs to be removed, the wires unsoldered from the rca sockets and the socket posts moved out of the way. Bottom line, it's tough to get it apart.
It is possible after doing these things to open the case sides far enough by bending them to allow the board to slide free and be flipped over.
Once this was done I removed the blown fuse, and found it was loose anyway, the leads having worked the solder loose holding them.
I also found the filter cap installed next to it was also not soldered any longer.
I took the opportunity to inspect the 50 + year old board for other issues. I found the the tunable coil connections were a bit questionable, so they were resoldered as well.
It was re-assembled and tested.  A slight re-tuning was needed as well.
Next job, was to create a adapter plug/socket  to allow the standard AC plug on the SP66 to mate with the cheater cord in the stereo.
This was done to maintain the original wiring in the stereo.

Here a cheater style socket was soldered to a standard 3 prong ac adapter.
Doing it this way will allow the the SP66 to just plug right in.
Though not shown here, the mounting "wings" at each side were removed since the cabinet mounted cheater cord is vertical.

Here it is installed in the  RC6731bwd


It's tilted because the older tube version of the transmitter is longer and would reach the second pre-installed mounting post.
Note: the adapter installed to allow the standard attached ac cord of the Sp66 to be used without any alterations of either unit.


PORTA-FI OPERATION
This system seems to work well when it's on the same branch of the homes AC. When on another branch, it picks up noise.
Not sure if  a filter of some sort would work without eliminating the signal imposed on the line. (300kc Fm?)
If anyone knows?,  was anything  effective in reducing noise picked up on this system, email me.

TIPS  FOR BETTER OPERATION
When it's on the same AC circuit there is absolutely no noise at all and it sounds great.
Additional Information- Besides being on the same branch of the AC in the home or the same circuit, there should be NO switching power supplies present.
Switching power supplies did not exist in 1965. These supplies are used in many if not most ac adapters, to eliminate the need for a power transformer.
If  such a supply is used on the same ac circuit as the Porta-Fi,  the noise generated from it will drown out the music transmitted.
From what I've been told this is similar to what happens to signals transmitted on the X10 remote operation system.
The fix, remove those supplies, or unplug them when using the Porta-Fi. A transformer based adapter could replace the offending adapters as well.
Switching power supplies are also incorporated in products as well, these may also interfere.





WANTED  TO COMPLETE THIS PROJECT

Speaker Grill Cloth - original or a close match- see photo on page above.
Original Power Button- Does not have to be from this exact model. Should have been used in a number of different units around 1965 (from a parts unit or nos)
FOUND -A Porta-Fi transmitter-Model SP66  (the transmitter available at the time this was sold was SP30) Would be interested in finding a SP30 also.
FOUND -A Porta-Fi Speaker-   Model SP15 There are a number of different models of this as well, again I would like to find a solid state version. These show up regularly on ebay, so I should be able to find one.  The SP15 is a tube version. (SEE ABOVE)




INFO WANTED

There is a model of this stereo almost identical in configuration with large chrome rocker switches and smaller black rockers to select functions, that may have had
Porta-Fi incorporated. Instead of using an external speaker, one of the removable speakers was equipped with a porta-fi receiver.
Looking for info on it. If you have one, or know of this model, please share the info. Thanks.



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