Heya guys. I have a fun new problem/project. I bought a Panasonic RE-8244 to play with for $25 at a thrift store today. After replacing the 8-track belt which haad melted, I discovered there is no sound from the rear channels. No sound reom either rear channel speaker connection, nor the rear channel headphone connection. Not just in 8-track mode, but all modes including 4-channel aux. No bulging or leaking caps and the thing is pretty clean inside and out. It is no audio, no buzz no hum no static no nothing. The front channels work fine. Where do I start?
Help! Bought A Receiver Today, No Sound Rear Channel, Panasonic RE-8244
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Doug G.
2K Club - QQ Super Nova
Listen real closely to the back channels with the volume fairly high and no signal. Do you hear any hiss at all? If you do, the back channel amplifiers are OK and the problem is farther upstream. If you don't hear any hiss, it indicates the two back channel amplifiers are blown (output transistors) or there is something open between the back amplifiers and the speakers/headphones.
Is there a switch on the back to change from 2 channel to 4 channel?
Doug
Is there a switch on the back to change from 2 channel to 4 channel?
Doug
The unit uses 4 seperate volume sliders which I've cleaned, not even the slightest static when I move the two rear ones.. From the little research I've done, I saw that it may be the output transistors causing that sort of problem. I've went through the thing doing my amateur wire wiggling and componant wiggling to try and find loose connections and everything seems pretty good. I've also visually inspected the bottom of the main board trying to find solder issues. How does one identify and properly test the output transistors? I own both a digital and analog multimeter.
Doug G.
2K Club - QQ Super Nova
In most solid state designs for audio output, there are two transistors per channel since most amps are push-pull, class AB circuits. So, there should be 8 output transistors in your unit unless they just used some type of Hafler (Dynaquad) circuit for the back speakers.
Doug
Doug
I'm guessing that the rear speakers should be the same amount of power as the front as it as a built in Quad 8-track deck. I think the unit does have some sort of weak sound feild generator though. I keep looking around and don't see anything that looks like some of the pictures of output transistors I've seen online. There are no less than 6 IC chips on the board. They are labled like IC1, IC2, Etc. I hope one of those aren't causing the issue cause aren't those fairly impossible to find replacements for? Also it looks like the transformer may have leaked a little bit of something at some point that hardened like some sort of resin. I'm still scouting around for another local repair person, but I would like to learn this stuff myself if possible.
A unit with an 8 track built in isn't a receiver, it is a compact system. Conversely, a unit with controls, but no amplifier or tuner is a preamplifier. I couldn't help myself. Color me Bitch.
The official Panasonic title is AM-FM 4-Chanel Amplifier with 8-Track Tape Player
Yes, it's technically a compact system. You aren't a b... Just a tad nitpicky. And thats okay by me.
I would like to save it, cause I could use a compact quad system as an office or bedroom quad system. Plus it looks very pretty. I wish there were some real pictures of it online. It has a kind of Harmon Kardon look to it. A lot better looker than most crumpacks. Also the 8-track player is built quite well. They didn't skimp too much on materials (except for the belt which had melted). Now that the flywheel and pully are all cleaned up and have a new belt, the 8-track player works like new (the alignment was even magically correct. The only problem it seems to have are the rear channels being completely dead wit no sound whatsoever (and believe me, I've tried coax some sort of sound from it, even a buzz or a hum, i was off yesterday so I poked around some more in it, still no action). I followed the connections around in it and everything seems to be solid.
I wonder why it's both rear channels. Maybe somebody tried to hook speakers up that they shouldn't have.
Or, ran it with no speakers connected to the rears.
Will that blow it on a low power unit with RCA speaker connections and 4 seperate volume sliders? In my testing, I've ran it a little with no front connected and haven't blown that out lol.
You made me think of something though. This is going to sound really stupid. But, I have not tested the thing with 4 speakers connected at the same time except if you consider quad headphones. Could there be any protection/grounding circutry that would require both front and rear speakers to be attached for the rear channels to activate (although I don't know why this would allow the fronts to run through headphones with no speakers attached)?
You made me think of something though. This is going to sound really stupid. But, I have not tested the thing with 4 speakers connected at the same time except if you consider quad headphones. Could there be any protection/grounding circutry that would require both front and rear speakers to be attached for the rear channels to activate (although I don't know why this would allow the fronts to run through headphones with no speakers attached)?
Depending on the design, no load could cause the circuitry to blow, probably the output transistors. Some units could run for a long time with no load, others would blow.
I should test with 4 speakers attached, but I only have 2 (that I could feesably get to) cheap old speakers with RCA connections.
I'm guessing in a pinch, I could just strip one end of an RCA cable and as long as I get the +/- right, I could connect the exposed wires to the screw type terminals of the other compact speakers I have. That will work won't it?
I'm guessing in a pinch, I could just strip one end of an RCA cable and as long as I get the +/- right, I could connect the exposed wires to the screw type terminals of the other compact speakers I have. That will work won't it?
quadsearcher
1K Club - QQ Shooting Star
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Tube amps need a load or the output transformer will blow. Transistor amps can run all day with no load. 
Tube amps need a load or the output transformer will blow. Transistor amps can run all day with no load.
So I'm guessing that if the rears were going to work, they would work the way I'm testing?
Okay, I dug out some old compact speakers and tested this thing properly. There is buzz from the rear channels. The buzz is low in volume, constant, no other soun, just the buzz. It does not change in volume when I adjust the volume of the rear speakers. Any ideas?
Doug G.
2K Club - QQ Super Nova
Yes, solid state amplifier designs don't care whether there are speakers connected or not. Without speakers connected, there is no current flow and no heat built up.
And it also wouldn't care if you had all speakers connected or not. If you have one connected, it will play. If you have all connected, they will all (normally) play.
You said there doesn't appear to be any output transistors or what would look like them. Are there any devices which look like kind of large rectangular flattish pieces mounted on heat sinks? Those would be what are called output modules which contain all the output circuitry in one unit. If none of those are present, it may be that the power outputs are low enough that the output transistors are just normal-looking transistors stuck into the boards.
In any event, both back channels not working would point to something in common with those channels which would normally be a power supply issue. However, being that the front channels work, it is hard to imagine them using separate power supplies for the front and back channels in a unit such as that. Hence me asking about power output modules of which one may contain both back channels.
Doug
And it also wouldn't care if you had all speakers connected or not. If you have one connected, it will play. If you have all connected, they will all (normally) play.
You said there doesn't appear to be any output transistors or what would look like them. Are there any devices which look like kind of large rectangular flattish pieces mounted on heat sinks? Those would be what are called output modules which contain all the output circuitry in one unit. If none of those are present, it may be that the power outputs are low enough that the output transistors are just normal-looking transistors stuck into the boards.
In any event, both back channels not working would point to something in common with those channels which would normally be a power supply issue. However, being that the front channels work, it is hard to imagine them using separate power supplies for the front and back channels in a unit such as that. Hence me asking about power output modules of which one may contain both back channels.
Doug
I'm not sure I know what I'm looking for anymore. lol. Could one or more of the ICs do the power output to the rear channels?
Also, I've went Crumpack crazy. Last weekend I bought a Bradford Quad 8-track AM/FM Amplifier for $5. It was one of the ones made by Panasonic. All channels (thankfully) work on this one. This one has been sitting in a garage forever and is dirty, had a bunch of bulbs out and some of the metal on the faceplate peeling. I had to replace the 8-track belt of course. I have replaced the stereo light bulb. I still need to replace two of the three radio dial backlight bulbs and the bulb for the tuner needle. All the bulbs I need are at radio shack so this will be restored soon. Then glue the trim back down and it should be ready for a night out on the town.
I also bought another compact Q8/AM/FM box (although calling this one compact is a stretch). It is an electrophonic. I paid $25. It powered on in the store and all the lights worked. It is the kind with the round radio dial and round display for the balance joystick position. I plugged an 8-track in it and it seemed to go in the store (didn't have speakers hooked up though). I couldnt resist this one cause it looked so cool.
Why do I keep buying quad compacts? Whats wrong with me?
Also, I've went Crumpack crazy. Last weekend I bought a Bradford Quad 8-track AM/FM Amplifier for $5. It was one of the ones made by Panasonic. All channels (thankfully) work on this one. This one has been sitting in a garage forever and is dirty, had a bunch of bulbs out and some of the metal on the faceplate peeling. I had to replace the 8-track belt of course. I have replaced the stereo light bulb. I still need to replace two of the three radio dial backlight bulbs and the bulb for the tuner needle. All the bulbs I need are at radio shack so this will be restored soon. Then glue the trim back down and it should be ready for a night out on the town.
I also bought another compact Q8/AM/FM box (although calling this one compact is a stretch). It is an electrophonic. I paid $25. It powered on in the store and all the lights worked. It is the kind with the round radio dial and round display for the balance joystick position. I plugged an 8-track in it and it seemed to go in the store (didn't have speakers hooked up though). I couldnt resist this one cause it looked so cool.
Why do I keep buying quad compacts? Whats wrong with me?
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