Here I was tonight gathering up the loose odds and ends of a nice old Emerson ED354 that I basically had completed last fall. It was awaiting cabinet work so it sat all winter.
One of my customers who tells me he does furniture refinishing offered to help do a couple cabinets for me at $25 each... so I gave him two to do.

Well he brought them back today ( not my level of quality... but hey for $25 I couldn't make him feel bad) and anyway...that's what prompted the need now for me to get this Emerson reassembled.

I saw that it still needed a new power cord though but everything else had been done. So I hooked up a temp power cord and fired it up as a test while my iron warmed up to solder on that new cord.

Well it came to life quickly and sounded beautiful... so I shut it off and put on the new AC cord.
But when I turned it back on.... There was no signal anymore.

What?

So I quickly checked that everything is in order.. antenna connection... B+ ...yes, yes yes..
Plenty of static.. but no signal.

Fire up my scope to see the oscillator... sure enough that's fine!
Still... no stations coming in!

Fire up the signal generator to 455khz modulated... connect it to the ext. antenna terminal lug on the loop antenna ... and boom!.. plenty strong tone!

Okay I've got IFs aligned and signal getting ALL the way through right from the antenna.
BUT no stations are coming in off the air like it was before I put the power cord on!???

What the heck kind of a problem is this I thought?

So I now changed the signal generator to 1-Mhz with modulation and connected it right to the antenna... and sure enough as I turn the tuning dial.. the signal is there right where it should be on the center of the dial....

Ok.. so that means that EVERYTHING is in fact working.... yet I still can not get a signal off the air!

What gives here?

So I clipped another antenna lead to the grid of the 6sa7 RF stage... but I still got no signal... except a slight weak one with volume all the way up.. and that is a nearby 50kw station... how can this be??

So fiddling around measuring voltages on the RF stage .... and each time I touch pins, the leads make static sounds that are real loud... but the signal is still down in the mud!

just shot-gun fiddling...I clipped the external antenna right onto the oscillator coil and now I can get some stations... but way off frequency of course as I'm killing the oscillator.. but there is at least medium strength signals coming in now.

So I stopped and said... wait a minute I should be able to just use my brain and think this through... but just like Curly from the 3 stooges says.. " I'm trying to think... but nothing's happening"!!

This was now the craziest thing I ever had to deal with.

So while trying to think I started replacing a few wires here and there just to make sure I didn't have any internal breaks or cold joints... and nothing is making any difference.

I was drawing blanks. I had no clue what to do.
So for no good reason I tweaked the RF trimmer cap on the tuner a tad... and the signal came in loud and clear. But I just lightly touched it.
Then I turned it in and out and as it went in.. the signal died and backing out the signal returned.

Why?

Then I look at the other trimmer for the oscillator right next to it and I notice that the screw head looks a little different.
Sure enough... someone had replaced this trimmer screw... and it was just a few threads longer than the other one!
So as it got turned downward the tip would ground out or short the tuner cap!
So all the time before as the radio had played the screw must have been one tiny hair's width away from shorting... and it chose this moment to touch and drive me nuts!

I cut it shorter and the radio plays like a dream.
Who'd a thunk it?

Every once in a while one of these F.E.P. symptoms pop up to test our intelligence and resolve. Murphy's Law at it's finest.

(F.E.P. = Freaky Electronic Phenomenon)

Peter,
Reminds me of an old digital camera I tried to fix a couple years ago. Never worked after I heaved it against a wall during a wild temper tantrum. Recently my newer cam had failed for no reason or tantrums, so first order was to open/repair it. My only choice was to unsolder/removed a tiny backup batt, which would reset the microprocessor to all factory defaults. Didn't help, still won't take pix. Got nuthin to lose, so back to the older cam, a larger body, old technology with components I could probably see, but still need a magnifier. The symptoms were still the same. All functions worked, but every stored picture was black. Hmmm, that would indicate the CCD is not functioning, so removed all those tiny screws, layed them on double sticky tape stuck to my bench, so I can find them again. Opened it up, removed more tiny screws (that double sticky tape is great) There were 5 different printed circuit boards inside and a 2 piece plastic case splayed out all over my bench. Put on my super-duper triple power head band magnifier and inspected every board for missing/broken components, but only found one suspicious area on the board containing the CCD and lens mechanism. Looked at it in different lighting conditons and several different angles, but still wasn't sure. Gotta get serious here. So in addition to my triple power head band, started using a small spotting magnifier. OK, now I can see a faint outline (about 1/16 inch) of where a component had been, but so what, without a schematic, parts list, no idea what had been there. Scratching my head thinkin about my next move or the purchase of a new camera, glanced down into the opened case and noted a small rectangular object stuck to piece of, Yes double sticky tape again. Using my tweezers, plucked it from the tape and did a size comparison with the solder pads where I suspected a missing component. Yes, yes, it fits. A measurement with my DMM indicated it was probably a SMT jumper or possibly a ferrite bead, but soldered it on anyway. Unsplayed all those boards, reinstalled those tiny screws plucked from my double sticky tape savior. All back together now, installed fresh batts, pushed the power button, and WOW, it came to life just like the good old days. Took a few shots, and they looked great. The beauty of this old Olympus was its macro mode with an advertised min. range of 4 inches, but regularly get good focused close-ups of small radio related items at 2 inches. Moral of the story thank God for double sticky tape an "DON"T HEAVE YOUR CAMERA AGAINST A WALL", if you want it to work again.

marv

:Here I was tonight gathering up the loose odds and ends of a nice old Emerson ED354 that I basically had completed last fall. It was awaiting cabinet work so it sat all winter.
:One of my customers who tells me he does furniture refinishing offered to help do a couple cabinets for me at $25 each... so I gave him two to do.
:
:Well he brought them back today ( not my level of quality... but hey for $25 I couldn't make him feel bad) and anyway...that's what prompted the need now for me to get this Emerson reassembled.
:
:I saw that it still needed a new power cord though but everything else had been done. So I hooked up a temp power cord and fired it up as a test while my iron warmed up to solder on that new cord.
:
:Well it came to life quickly and sounded beautiful... so I shut it off and put on the new AC cord.
:But when I turned it back on.... There was no signal anymore.
:
:What?
:
:So I quickly checked that everything is in order.. antenna connection... B+ ...yes, yes yes..
:Plenty of static.. but no signal.
:
:Fire up my scope to see the oscillator... sure enough that's fine!
:Still... no stations coming in!
:
:Fire up the signal generator to 455khz modulated... connect it to the ext. antenna terminal lug on the loop antenna ... and boom!.. plenty strong tone!
:
:Okay I've got IFs aligned and signal getting ALL the way through right from the antenna.
:BUT no stations are coming in off the air like it was before I put the power cord on!???
:
:What the heck kind of a problem is this I thought?
:
:So I now changed the signal generator to 1-Mhz with modulation and connected it right to the antenna... and sure enough as I turn the tuning dial.. the signal is there right where it should be on the center of the dial....
:
:Ok.. so that means that EVERYTHING is in fact working.... yet I still can not get a signal off the air!
:
: What gives here?
:
:So I clipped another antenna lead to the grid of the 6sa7 RF stage... but I still got no signal... except a slight weak one with volume all the way up.. and that is a nearby 50kw station... how can this be??
:
:So fiddling around measuring voltages on the RF stage .... and each time I touch pins, the leads make static sounds that are real loud... but the signal is still down in the mud!
:
:just shot-gun fiddling...I clipped the external antenna right onto the oscillator coil and now I can get some stations... but way off frequency of course as I'm killing the oscillator.. but there is at least medium strength signals coming in now.
:
:So I stopped and said... wait a minute I should be able to just use my brain and think this through... but just like Curly from the 3 stooges says.. " I'm trying to think... but nothing's happening"!!
:
:This was now the craziest thing I ever had to deal with.
:
:So while trying to think I started replacing a few wires here and there just to make sure I didn't have any internal breaks or cold joints... and nothing is making any difference.
:
:I was drawing blanks. I had no clue what to do.
:So for no good reason I tweaked the RF trimmer cap on the tuner a tad... and the signal came in loud and clear. But I just lightly touched it.
:Then I turned it in and out and as it went in.. the signal died and backing out the signal returned.
:
:Why?
:
:Then I look at the other trimmer for the oscillator right next to it and I notice that the screw head looks a little different.
:Sure enough... someone had replaced this trimmer screw... and it was just a few threads longer than the other one!
:So as it got turned downward the tip would ground out or short the tuner cap!
:So all the time before as the radio had played the screw must have been one tiny hair's width away from shorting... and it chose this moment to touch and drive me nuts!
:
:I cut it shorter and the radio plays like a dream.
:Who'd a thunk it?