GE Classic Radio Player 7-4135 schematic and amp question.

[Jason Watkins]

Hey guys. I've got one of those antique radio replicas that I would like to do some modifications to since it appears to be a fairly nicely finished little unit. It's from the '80s most likely and is a GE Classic Radio Player 7-4135. Does anybody know where I might find schematics for such a device? I'd like to bypass the internal (2?) watt amp, replace the speaker and add an input. Assuming I am unable to determine where to cut in to get a line level signal, is there any way to hook up this things power output to the input of another amp? It's probably only putting out 2-5 watts max. Maybe not even that much. A power resistor maybe? I would like the flexibility of a more powerful amp board for better speaker selection. Any help would be greatly appreciated.

 

[73's de Edd]

Sir Jason Watkins . . . . .

Sooooooo . . . . if you want room SHATTERING volume, it will be dependent upon a remoting out of this units audio via a shielded line to a mo' powerful amp and a like enhanced speaker utilization.

Can youse spels volume control . . . .? . . .sure you CAN ! . . . .just watch my lips . . . .

Since I am seeing ONLY one speaker . . . . . this is being SOLELY a MO-naural unit . . . no stee-row FM.

Viewing inside from the back , looking towards the small right PCB, see the basic reddish brown phenolic disc of the volume control. (You KNOW where it's frontal knob is. )

We now need to see if this is utilizing 21st century DC control of a transconductance amplifier for audio level control, or using old school control of audio via a variable logarithmic potentiometer.
AKA . . . . . volume control.
At the top of that volume control, you will see being . . . . .oops . . . my ole' dyslexia kicking in . . . .be seeing . . .3 silver terminals with their connected wires..
Now if there are wires going to all 3, we may be in luck. But, if only two wires connect, we will have to revert to tactical invasion plan TWO.

I await your feedback . . . . .

73's de Edd
.....

 

[Jason Watkins]

Most excellent. Thank you for the quick reply. Indeed, all three wires are connected to the volume control.

 

[AnalogKid]

Why is there a motor at the top of the unit?

ak

 

[73's de Edd]

Sir Jason Watkins . . . . .

It's a miracle . . . IT'S A MIRACLE . . . I can now see better . . . How you do dat ?

Now you need to go into a deep benign state of sonambulance and fully use your minds eye to visualize that the WHITE wire terminal is connected to a rotary wiper within the pot that swings a 270 degree arc of a circle between the RED wires terminal. Its other extreme rotation would have it at the YELLOW wires terminal
If the control is at max CCW position the WHITE wires rotor connection is being at the RED connection which is being grounded and there is being no audio signal into the WHITE wire.
As you start moving the volume controls WHITE wire rotor CW it becomes progressively less grounded and is starting to pick up the FULL audio level which is being /and originating / over at the YELLOW wire and its associative terminal.

Now lets electronically confirm that.

You turn on the unit and place it in AM radio function and confirm a radio signal and volume control action.
THEN . . . we don't want that stations audio, so you tune off from the station until you find a silent spot on the dial where there is NO audio with the volume control set at max volume . . . .silence... . .silence . . . .silence
Then you take a nail, small screwdriver, etc which would be a metallic conductor. Wet your fingers with spittle to enhance your connectivity to the metal.
Touch the metal to either YELLOW or WHITE wire terminals and wave your free hand in the air back and forth while shouting Wooooooo . . . . . Woooooo . . . .Wooooo . . . at those periods between Wooooos you should hear a hum coming from the speaker. ( You might also attract an audience)
Should you then move that free hand up close to and onto the safely INSULATD wiring on the units power transformer *** the HUMMM level should increase.
( ***** Located In the left front quadrant, just inside of the back of the unit . . . finger-thumb gripping the ORANGE wires will give you the greatest HUMMMMM pickup.

If all of this tallies . . . . .HOUSTON . . . . we have liftoff !

Your connection of a shielded line, with its ground shield, gets connected to RED wire connection / terminal and its internal wire that carries the signal , gets connected to the :

YELLOW wire and its terminal if you want max audio output from the unit and THEN your controlling of that volume with the remote amps volume control

WHITE wire and its terminal if you want to adjust the volume at THIS unit and have further control at at the remote amp.

Time for your findings.

73's de Edd
.....

 

[73's de Edd]

Why is there a motor at the top of the unit?

How about a cassette player and recorder at the left, with its drop down electronics board under it and spare tape storage on the right half . . .access is obtained by lifting up the top lid.

NOW if this was a CROSLEY retro unit, you would have access slots in the sides for cassette tape player, CD player and a phono turntable when you lifted up the lid.

 

[Jason Watkins]

Up until the last part everything checks out. I haven't gotten to practical experimentation yet. Just theory, It'll probably be a few weeks, but I'll be sure to post an update at that time. You're also correct about there being a tape deck with storage under the lid. Also, if you're not already a teacher of some kind, you'd be a good fit.

 

[73's de Edd]

Sir Jason Watkins . . . . .

Where did I lose you . . . . then ?.
If you heard the HUMM thru the speaker, you verified that all is good for being able to / for connnecting to an external amp.
I may have lost you on just the very end, in the manner of connecting up a shielded line to the ext amp.
A 24-36 in audio patch cord with its end RCA connectors make for good and cheeeep interconnecting wiring, where you just chop off one RCA end and interconnect that shielded wire to the two volume control terminals.

73's de Edd
.....

 

[Jason Watkins]

No no. You didn't lose me. I just haven't got the unit on my workbench yet. I'm not ready to start clipping leads and whatnot. You were very clear and everything I could do worked great. Just gonna be a few weeks before I can go further. Kinda researching right now. Planning and whatnot.

 

[kellys_eye]

Most modifications of this type involve installing a Bluetooth receiver......

 

[Jason Watkins]

I'm planning on putting one in this unit as well. I wasn't sure how to patch in to a line level source to begin with though so I went ahead and got on the forum here. I'm planning on putting in a monoblock amp board and it's power supply. I'm thinking 30-60 watts or so. If I can't find one with an integrated Bluetooth receiver, I'll have to install a discreet one alongside the new amp. The cabinet itself is almost empty as it is so there's plenty of room for modifications.

 

[kellys_eye]

so an upgraded power supply and new more powerful speaker too?

 

[Jason Watkins]

Ideally. My issue with it is that at about 50% volume and up there is some serious distortion. It like to be able to hear it from the other room without it sounding terrible. Other than that I just like modding stuff.

 

[Audioguru]

Since the original radio has a cheap little speaker and the enclosure is not even designed for a speaker then I think the radio's electronics is also cheap and will produce no bass and maybe also no sizzling highs with a good external amplifier and speaker.

BUT, I purchased a cheap but Name Brand clock radio at a surplus electronics store for less than two bucks. Its cheap tiny 2" speaker (squeaker) sounded pretty bad so I tried my good 2-way speaker system that has a 6.5" woofer and 1" dome tweeter. No bass.
I replace a couple of coupling capacitors on the pcb with much higher and normal values and now it sounds very good with plenty of deep bass and highs that go as high as I can hear. The output power is plenty for a clock radio.

For more volume in another room without distortion then you need an amplifier with maybe 10 times more power and a speaker system designed properly. Do the coupling capacitors trick that I did for better bass.