New project, Emerson 637 10"

[Eric H]

Now that the Philco is pretty much done I thought I'd start on something else.
I always liked the looks of this Emerson so I figured I'd start on it tonight.

This set is small but substantial, it weighs in at 66 lbs, and a lot of it is the transformer!
The CRT is in fair shape, it makes it to the lower end of the good range which is plenty for a 10BP4.

Someone had been in here before, probably in the 1950's or early 60's because there were some Sprague Black Beauties that had been installed and a rather sloppy job was done of it. (3rd pic) Don't bother trimming the leads and installing them properly, just tack them on anywhere , (note the one old cap still in place with one end cut!)

[Celt]

Yep...I see a lot of that sort of thing in old tube guitar amps. Sometimes can't help but wonder how they managed to keep working without a major meltdown.

[Dan Starnes]

Wow!
Dan

[Sandy G]

Well, uhh, that's ONE way of doin' it...

[Patnukem]

looks like a neat set!

[Eric H]

Man, what a mess.

Does anyone have a Sam's 97-4 they would sell to or scan for me?

[David Roper]

I have Rider 6 with 637 in it!

[Eric H]

David, thank you so much for your offer but I've been given a Sams.


Eric

[David Roper]

Alright, maybe next time. Remember that I've got a bunch of Riders skizzies and a big ol' honkin' copy machine.

[Eric H]

This set is not cooperating much

I've replaced every cap in the sweep circuits except a few .1's (because I forgot to order them) still I only have a little tiny bit of H.V.
Horiz osc is running, I can hear it but I only get a tiny little arc at the top of the 1B3.

I plugged in the speaker and I don't have any sound to speak of either, just hum so maybe I still have a power supply problem.
There is one more 4 section can that I need to redo then maybe it'll work.

It doesn't help much that someone had done a lot of "repairs" in the past, I don't know if it ever worked after those attempts or not.
I do know that in one case they just clipped one lead on the old cap and soldered a new one in, the old one was a .047 but the new one was .01 it doesn't give me a lot of confidence.

[Eric H]

Got all the Electrolytics replaced and still no HV, 6BG6 plate glowing red, finally figured out it was an open 470k resistor (drifted to 9 meg) to the grid of the 6BG6, fixed that and got a raster!

Still no video but one of the 12AU7's is running scorching hot so I suspect the problem is there, another bad resistor or maybe one of the few caps I haven't changed yet.

[Eric H]

Whew, finally getting somewhere with this thing.

After getting a schematic I found a miswired cap causing the blank raster.
After that I spent a couple hours trying to get it to work with a DVD player with no luck, finally I figured out I could get a picture with a pair of rabbit ears but I had no sync at all.

After a few more hours poking around I figured out that the
12AU7 sync sep tube was losing it's heater connection, it would work sometimes but not others and because it was the heater connection there was a delay between wiggling the tube and the set resuming operation so it was difficult to figure out exactly what was happening.

I wonder if all the half fast repairs that were done to this set were done to try and fix this same problem? or perhaps I damaged the socket when I was recapping it?


Last of all I figured out why the DVD player wouldn't work, I'd plugged the RF modulator into the optical sound output of the DVD player instead of the video connector,

So here it is, 2:40 a.m. and the set is playing pretty well!
I still have to change the tube socket, for the time being I've found the sweet spot where it'll work but it's not very solid.

[John Folsom]

Good job, Eric! I had a lot of trouble with the front end of my set. The IF transformers in that set have a tendency to go bad, as they have built-in capacitors.

[Phil Nelson]

Originally Posted by Eric H

Last of all I figured out why the DVD player wouldn't work, I'd plugged the RF modulator into the optical sound output of the DVD player instead of the video connector,

Sounds like the kind of thing I'd do at 2:40 AM. I can't tell you how many times I have pulled out a tube for one reason or another, then forgotten to reinsert it by the next time I powered up the set.

Freakout: "Dang, the TV worked fine 10 minutes ago and now it's dead!!"

Followed by the big forehead slap.

My worst Bad Repairman experience was the radio in which a previous owner had pulled the tubes, put several into the wrong sockets, and carefully written those wrong numbers onto the chassis next to each socket. I was working without a schematic, and naturally assumed the numbers were correct. Drove me nuts until I left the project alone for a while, then came back and played "What's wrong with this picture?"

Phil Nelson

[Eric H]

I finally finished this set up and got it back in the cabinet!

Wound up replacing 2 tube sockets for the 12AU7 tubes, I have to wonder if all the tacked on caps I found when I started this project were someones (failed) vintage attempt to fix this same problem? They were most all in the same general area.

Other than that I found one bad i.f. tube that would short when warming up and kill the pic and sound intermittently.

Even though the 10BP4 checks good I was having a real hard time getting the picture set up right what with having to mess with an ion trap and the focus coil and trying to get it centered and no neck shadow.
I wound up putting in a 10FP4 tube that doesn't use an ion trap and was much easier to deal with.

The difference in brightness between the BP4 and the Aluminized FP4 is astounding!