Finally...it is out

[hermitcrab]

Been scratching my head as to how these chassis come out for about a week.. after lying on my back inside the console , I found these spring metal clips that I guess help hold it tight in the cabinet by friction... one of them was bent and somehow below the mounting board was keeping it from coming out... I hope I took enough picture to figure out where everything goes, because it is a rat's nest of wires everywhere... I gotta say, I give Motorola a zero on service ability... horrible .. and no wiring diagram anywhere to assist in wiring it back in... it outta be fun...

20210814_113831_copy_800x800.jpg (132.05 KiB) Viewed 9593 times

[William]

Congrats Elton, I knew you could do it.

Bill

[hermitcrab]

I took pictures as I pulled it out , and of course my phone ran out of memory ... so I got nothing...looking at the little individual charts on each chassis shows the inputs and outputs but not the wiring from each chassis ... and to top it off the color codes for the wires don't match... you would think they would paste a wiring diagram inside somewhere like magnavox does or inprint by the jacks ...but nooooooooo!.... my opinion on serviceability still stands... and where does the tape function come into play?... I see no inputs for a tape anywhere... unless you give that up with the MPX option ?

[electra225]

Magnavox may provide a wiring diagram, but the rat's nest of wiring on them is horrendous. The wires lay on top of output tubes. They find the hottest part of the cabinet to mount the Multiplex adapter. I'm glad you found the secret to dismounting the tuner on your Motorola. I'd wager that if you sit and study the rat's nest in front of you, you'll figure out how it all goes together. Plus, you have all of us here to help if we can.....

[William]

I may be in trouble reading what Elton has gone through. When I brought my Motorola home several years ago I immediately pulled everything out of it so I could really give it a good scrubbing. It was filthy beyond description, and was filled with drywall dust. Since I knew I would not be starting the restoration for some time, which I still have not done because the cabinet needs complete restoration as well, I just left everything out of the cabinet. I may be in trouble trying to remember how things mount and where all the wires go. But, at the rate I'm getting around to that project I may be to old to even do it.

Bill

[Hi-Fi-Mogul]

I may be in trouble reading what Elton has gone through. When I brought my Motorola home several years ago I immediately pulled everything out of it so I could really give it a good scrubbing. It was filthy beyond description, and was filled with drywall dust. Since I knew I would not be starting the restoration for some time, which I still have not done because the cabinet needs complete restoration as well, I just left everything out of the cabinet. I may be in trouble trying to remember how things mount and where all the wires go. But, at the rate I'm getting around to that project I may be to old to even do it. Bill

It seems in my case, that I don't always keep EVERY part
removed in the same cabinet or zip lok bags, et cetera.

Currently the Ambassador tube stereo suitcase is
missing its control escutcheon plate.
I have everything else, but what the heck ?

Self-organizing is my Achilles heel.

[hermitcrab]

Agree with electra on the wires in a magnavox... the small tube imperial I have , I was dumbfounded to see the speaker wires just hanging inches from the tops of the tubes baking them... instead of running them around the chassis , just drape them over the hot tubes... smh

[William]

My guess, the bean counters said cut backs, save money, so they shorted the wires. At least, at that point in time, they had not started making cabinets cheaper or the components that went into them. That all came later.

Bill

[hermitcrab]

Hey all , went through the amp and tuner chassis.... not many electrolytics in side at all, mostly all ceramic caps . it took me a couple times to remember where all the wires went , but it is all together and running fine except the FM tuner was way off... found out the FM tuner string collet came loose and caused the dial to veer off badly ... I got it close but it is still not correct, looking at the sam's data , it seems the tuner needs to come out and remove the covers to align just the 108mc to the dial ... while somehow keeping it all connected to everything else ... no thanks.. I can deal with 104 coming in at 98 ... I think my expectations were way too high on this especially with its push pull 6V6's for the bass... I expected way more than what it is ...even with the bass turned all the way up it is so-so , but it is only a 5 watt per channel , the radio is OK but the phono has barely any bass ...I guess I want 100 watt sound for everything...

[Moto_TJ]

The bass on all of the Motorolas that I have worked on has always been too much and could never run them with the bass at 10. Did you check your tubes? The amp in your is a mid-level amp, so they may not be pushing it as hard as the upper level PP 6V6 amp.

[TC Chris]

Agree with electra on the wires in a magnavox... the small tube imperial I have , I was dumbfounded to see the speaker wires just hanging inches from the tops of the tubes baking them... instead of running them around the chassis , just drape them over the hot tubes... smh

We may be blaming the wrong people. Most consumer electronics came with some sort of wire sorting and wire routing methods, whether that gray-black paper looped and stapled, or plastic retainers etc. But here comes a service guy, and he needs to pull the chassis, and it's too much bother to re-route the wires and make sure they're in their retainers. Seen it... and, true confession time, done it.

Chris Campbell

[electra225]

That may be true with some manufacturers, but Magnavox had sloppy wiring.

[hermitcrab]

The bass on all of the Motorolas that I have worked on has always been too much and could never run them with the bass at 10. Did you check your tubes? The amp in your is a mid-level amp, so they may not be pushing it as hard as the upper level PP 6V6 amp.

That is what I have heard about these.. but this one is mediocre at best ...I have solid state silvertone that will rattle the windows ... went through the amp checked resistors for values a few were up but nothing out of the ordinary... the tubes are all branded motorola and test strong on my Jackson 648, only odd ball tubes are a couple of the 12AV7 tubes have been replaced with RCA's... I ordered another 6BQ7 for the FM RF , as it tests as it has a cathode short , so I had another one in my tube stash , and it also checked the same .. don't know if it is a thing with these tubes or the way the Jackson tests them....

[Moto_TJ]

Agree with electra on the wires in a magnavox... the small tube imperial I have , I was dumbfounded to see the speaker wires just hanging inches from the tops of the tubes baking them... instead of running them around the chassis , just drape them over the hot tubes... smh

We may be blaming the wrong people. Most consumer electronics came with some sort of wire sorting and wire routing methods, whether that gray-black paper looped and stapled, or plastic retainers etc. But here comes a service guy, and he needs to pull the chassis, and it's too much bother to re-route the wires and make sure they're in their retainers. Seen it... and, true confession time, done it.

Chris Campbell

All of the Motorolas that I worked on had wire ties routing all of the wires and to keep them orderly. I will agree that it is a shame that Motorola didn't post a wiring diagram, but the wiring is pretty simple to follow on them, there are no crossovers to connect to, black is the common wire color for the speakers, each channel has it's own colored wire, and the terminals are labeled on the amp, and there was a tube layout diagram on the amp that also said which wires connected to which terminal on the amp. If that is missing, it sounds like someone has been in there before.

[Moto_TJ]

The bass on all of the Motorolas that I have worked on has always been too much and could never run them with the bass at 10. Did you check your tubes? The amp in your is a mid-level amp, so they may not be pushing it as hard as the upper level PP 6V6 amp.

That is what I have heard about these.. but this one is mediocre at best ...I have solid state silvertone that will rattle the windows ... went through the amp checked resistors for values a few were up but nothing out of the ordinary... the tubes are all branded motorola and test strong on my Jackson 648, only odd ball tubes are a couple of the 12AV7 tubes have been replaced with RCA's... I ordered another 6BQ7 for the FM RF , as it tests as it has a cathode short , so I had another one in my tube stash , and it also checked the same .. don't know if it is a thing with these tubes or the way the Jackson tests them....

Does the tube diagram on the amp call for 12av7 tubes? Motorola usually used 12AX7 tubes on the amp and preamp, and that could be part of your issue, I think the 12AZ7 is like a 12AT7 for output specs but was designed for different purpose than a 12AT7, but workes in its place.

[hermitcrab]

nope my bad I mistyped the number , they are 12AX7's

[electra225]

Are the cathode bypass components on the output tubes known to be good? If it has poor bass response, perhaps somebody put a Magnavox bi-amp in it....

[hermitcrab]

Not sure ... I guess you would mean the PP 6V6 outputs for the bass?

[electra225]

I was trying to be funny with the Magnavox bi-amps comment. Magnavox bi-amps are infamous for their puny bass response. I guess I shouldn't try to outdo Leno. He retired.

The cathode bypass components I referred to would be the cathode bypass capacitor and the cathode bias resistor. If the bypass cap is partially shorted, not only can that affect bass response, but it is also hard on output tubes and audio output transformers. If the bias resistor has drifted, that can affect bass response, as well as the life of the output tubes. The bias resistor should be almost dead on as to value. If it has drifted any, it should be replaced. Sorry for the confusion. I hope this helps.

[Moto_TJ]

I was trying to be funny with the Magnavox bi-amps comment. Magnavox bi-amps are infamous for their puny bass response. I guess I shouldn't try to outdo Leno. He retired.

I would agree to this comment and limit it to the stereo bi-amp amps. The mono bi-amps, have tons of bass, but they have 4 or 6 tubes on the bass channel with a much larger output transformer.

I to agree with checking the electrolytic caps on the amp, a bad cathode bypass could be your issue!