View Full Version : Starting work on a GE 800 Locomotive.


Eric H
05-29-2017, 04:35 AM
I wanted a project that didn't need a massive amount of cabinet work for a change so I dug out this Locomotive that I've had for quite a while.

I'm not sure what the difference is between the 800 and the 805, Brass vs Aluminum grille perhaps?
Mine is Aluminum but there are no tags on this set to identify it for sure.

It has a 10BP4 that test's like new, probably a replacement because I believe these came with a 10FP4 as original equipment.

Anyhow, I brought it up semi slowly on the Variac while watching the current draw, at about 75 volts I heard the Oscillator kick in, at 90 I could draw an arc from the cap of the 1B3 but no light on the screen, at 100v I could see a faint line on the screen and tweaking the Ion Trap brought it up to a short, bright raster.

It's always a good sign when a set shows this much life right out of the gate, bumping the line voltage to 110 fills out the width completely, a recap ought to bring it back to full life.
Many of these sets are missing the top to the high voltage cage, this one is missing the side, luckily i have a spare chassis with that part on it.

decojoe67
05-29-2017, 11:41 AM
I have one of these and it's one of the best playing '40's TV's I've ever owned. No issue with it in any way and no fiddling with the controls. It started-out with troubles after it's first resto, and then my repairman went over it again and worked his magic on it! It plays like a period Admiral.

jr_tech
05-29-2017, 02:52 PM
Mine is labeled "800 D"... it has a 3:4 mask and aluminum front panel. I think that I will get it out and play along. I think E/M has just restored one as well, cute little sets!

Here is mine, from old thread:

http://www.videokarma.org/attachment.php?attachmentid=170160&d=1302897431

Good players, the wood model on the right played well into the 90s with mostly original parts, now needs filter caps, however.

jr

Eric H
05-29-2017, 05:15 PM
I found 800 and a large C stamped on the rear of the chassis so I guess it's a model 800, run C.

I have another chassis that I recapped about 20 years ago and then gave up on because all the controls were shot (and the cabinet was a mess), it still has all the nearly unused Sprague Atom Electrolytics in it so I will pull them out of that and put them into this, the film caps I will just replace with new, not worth the trouble of removing them.

Bill Cahill
05-29-2017, 07:05 PM
I think mine is an 805. Mine has a brass front.
I started rebuilding mine last year. Took it off the bench when I got an antique Edison Triumph phonograph in bad shape. Hope to get back to my GE tv soon, again.:yes:

Radiotronman
05-29-2017, 09:52 PM
I just finished restoring mine a few months ago. Mine was missing the model sticker on the bottom, but was stamped model 805 W on the chassis in black ink. It was a fun restoration, with only a few hard to get to caps. Mine has the brass plate on the front. Advice someone gave me, put some cardboard over the speaker, because they're easy to put your hand through.

Electronic M
05-30-2017, 10:47 AM
I found 800 and a large C stamped on the rear of the chassis so I guess it's a model 800, run C.

I have another chassis that I recapped about 20 years ago and then gave up on because all the controls were shot (and the cabinet was a mess), it still has all the nearly unused Sprague Atom Electrolytics in it so I will pull them out of that and put them into this, the film caps I will just replace with new, not worth the trouble of removing them.

Perhaps it would be easier to just swap controls and use the recapped chassis.

jr_tech
05-30-2017, 06:27 PM
Brought mine slowly up on a variac... no light in any of the tubes... cleaned and deoxit the pins... half the tubes are lighting... found open heater resistor... got them all going.

Now getting about 7 kV on anode and most voltages are low, but it makes sound and somewhat of a short and VERY unstable pix. The cat is alive!

Most solder joints on the set have never been touched (still painted red), it seems a shame to disturb these but re-cap job is definitely called for.

great fun,
jr

Eric H
05-30-2017, 08:15 PM
Perhaps it would be easier to just swap controls and use the recapped chassis.

I think I'd rather start fresh with this one, the other chassis was a bit of a dog as I recall, I may have borrowed parts from it also.

Eric H
05-30-2017, 08:17 PM
Brought mine slowly up on a variac... no light in any of the tubes... cleaned and deoxit the pins... half the tubes are lighting... found open heater resistor... got them all going.

Now getting about 7 kV on anode and most voltages are low, but it makes sound and somewhat of a short and VERY unstable pix. The cat is alive!

Most solder joints on the set have never been touched (still painted red), it seems a shame to disturb these but re-cap job is definitely called for.

great fun,
jr

Cool, looks like we're both in about the same boat.

I was wondering about the red marks, assembly line marks to show a step completed?, or maybe anti tamper marks to prevent warranty fraud?

Bill Cahill
06-01-2017, 01:19 AM
As a matter of fact, I believe that is why the company painted those connections.
That chassis definitely needs a complete re capping.
Those filament have me stumped. Sams only says 75 ohms. But hose resistors change resistors change resistance as they warm up. So, I'm mixed up as to what values of resistors to put in there.
Bill Cahill

Electronic M
06-01-2017, 09:34 AM
As a matter of fact, I believe that is why the company painted those connections.
That chassis definitely needs a complete re capping.
Those filament have me stumped. Sams only says 75 ohms. But hose resistors change resistors change resistance as they warm up. So, I'm mixed up as to what values of resistors to put in there.
Bill Cahill
To get the correct 'hot resistance' (which is what you want to use) use the schematic to determine the tubes in the string, add the heater voltages of those tubes (you will get a more accurate sum if you go by the datasheet heater voltages), subtract the sum of the heater voltages from your AC outlet voltage (or a reasonable reckoning of it) to get the voltage the resistor needs to drop. take that voltage and the heater current of any tube in the string and use Ohm's Law (R= E/I) to find the resistance.
You can find the power by P=EI, P=(I^2)R, or P=R/(V^2)...Probably good to double that value as many power resistors get hot enough to unsolder themselves when they reach rated power.

If you are worried about achieving a soft start, you could round that resistance up a bit, and or add a CL-90 inrush current limiter to the set.

jr_tech
06-01-2017, 01:41 PM
A few comments and questions:

1. Possibly the red paint indicates a QC inspection... I have seen it on many high quality instruments from the WWII era.

2. 75 ohms in each heater string is about correct for average line voltage...I may add an additional resistance if necessary, depending mostly on what I read for CRT heater voltage, or protect the CRT heater with a TVS diode, see:
http://www.videokarma.org/showthread.php?t=268968

3. I got full height by replacing the .04 cap (actually 2 caps in parallel) in the vert osc/amp. (the 4.3 meg resistor was ok). Nice to start the re cap job with a unit that makes a halfway decent, although unstable pix!

4. Finding some surprises where the circuit seems to match later models, The Riders schematic cannot be assumed to be 100% accurate. For example, that big cap shown in my underchassis pix in my second post between the tuner and the vertical output transformer (0.5 uf) is not shown... it bypasses the contrast control and is similar to the way the later 10T4 is configured.

5. Tom, did you get the .0022 cap mounted on the flyback?

jr

Electronic M
06-01-2017, 01:46 PM
5. Tom, did you get the .0022 cap mounted on the flyback?

jr

I did not see one during the recap work...Guess I should go back and check.

Eric H
06-02-2017, 11:28 PM
I replaced nearly a dozen paper caps tonight.

I lost a little vertical sweep but gained some video signal, the horizontal frequency is way off, there are multiple images across the screen, but the vertical seems to lock.

Regaining the video probably had more to do with cleaning the tuner than replacing capacitors, I didn't change any in the i.f. section as far as I know.

Eric H
06-03-2017, 02:56 AM
And a few more caps, a little more progress. None of the Electrolytics have been replaced at this point.
The vertical was cutting in and out when I tapped on the 12SN7 tube so I replaced it, it seems solid now, I'll see what happens when it cools back down.

kvflyer
06-03-2017, 06:23 AM
And a few more caps...
The vertical was cutting in and out when I tapped on the 12SN7 tube so I replaced it, it seems solid now, ...

Could that cutting out and tapping be a dirty tube socket, or possibly the tube that you took out having dirty pins?

I recently brought back to life a factory wired Dynaco PAS pre-amp. One channel was fine; the other was dead. I had not cleaned the sockets yet and wiggling one of the 12AX7 tubes brought it back temporarily.

Long story short, DeOxIt on a toothpick into each socket and all is well now.

Just a thought, could be still a good tube!

Eric H
06-03-2017, 04:30 PM
It could be a dirty socket, the tube tested good so I'll try it again, but for now its solid and the vertical is taller.

kvflyer
06-03-2017, 09:47 PM
It could be a dirty socket, the tube tested good so I'll try it again, but for now its solid and the vertical is taller.

"I hear ya..."

Eric H
06-04-2017, 05:45 AM
I tried the tube again and no vertical, until I whacked it with a screwdriver.

Tested the tube again, very good on both sections and it's a fairly new looking Sylvania.

I tried it in the Horizontal Oscillator circuit and it works fine, in fact I was able to adjust the horizontal down to a single image.

It's an odd looking 12SN7, taller than most and the plates are different than the usual thin, flat ones usually seen, it actually looks more like a 12SL7.

The chassis still has a lot of old caps in it, none of the Electrolytics have been changed yet so it could be the circuit is just being fussy at this point.

jr_tech
06-06-2017, 02:04 PM
Update/Comments on my set:

1. Received the 75 ohm 10 watt ceramic resistors for the heater circuits... they seem to be about the right value. At 125 volts line input, I get about 6.5 volts on the CRT heater, and pretty close to 6.3 volts at 117 volts line. Turn on surge at CRT heater is slightly greater than 8 volts, so I may add a TVS diode later, when set is no longer used with the variac. The resistors run quite warm, so I positioned them against the back of the HV cage and used a bit of heat sink grease between them and the aluminum surface. They now run under 200F.

2. Pulled off the front (indeed, I protected the speaker, as recommended) repaired the speaker (previously damaged by careless fingers) and replaced the rectifiers and power resistor (corroded wire fell off).

3. Finished up the caps (29 in my set) and replaced the electrolytics. (see pix). Picture has improved only slightly from previous photo, but is now stable.

4. Getting about 10.3 kV HV, other voltages are now at spec or slightly higher.

5. Bright spot on center of CRT lingers for nearly a minute after turn off... anybody have a mod to eliminate it ?

6. Next, check the tubes, upgrade if necessary, fine adjust horiz and vert size linearity, polish cabinet.

fun project!
jr

Eric H
06-06-2017, 09:09 PM
I hooked this thing directly to the DVD player instead of using over the air with the Agile Modulator, after a bit of fiddling I got a really decent picture, the sound was weak and had static like a control was arcing, I started tapping around on the controls and the field coil of the speaker and it started getting better and better, now it has reasonably good sound, not sure if something was shorted or what but it cleared it up.

This is the slowest warming set I've ever seen, it takes at least a full minute before I hear the oscillator kick in, did I read somewhere it has some voltage dependent resistors in the heater string? Possibly those black round things in the HV cage?

The pictures a little cockeyed and I had to remove the focus magnet so it would center on the 5AXP4 test CRT but it's bright, has great contrast and no retrace lines.

jr_tech
06-06-2017, 09:38 PM
This is the slowest warming set I've ever seen, it takes at least a full minute before I hear the oscillator kick in, did I read somewhere it has some voltage dependent resistors in the heater string? Possibly those black round things in the HV cage?


Yep! I think that those glowbar (sp?) resistors exhibit an increase cold resistance as they age. With the 75 ohm resistors installed, my set produces a full, stable picture in about 20 seconds after turn on. The 6Al5s light up pretty bright at initial turn on, but seem to be holding up ok.

jr

Eric H
06-08-2017, 12:57 AM
My parts chassis had some 75 ohm resistors installed instead of the Globars so I swapped them into this chassis, it warms up quickly now, some of the small tubes come on a bit brightly but the CRT warms up normally so I can live with that, I might experiment with a Thermistor in the future but I wonder if it can handle the load.

Theses resistors look pretty hefty, maybe 10 watt and they get really hot.

Bill Cahill
06-08-2017, 01:21 AM
The best of luck on it. Information much appreciated.
Bill Cahill

DavGoodlin
06-09-2017, 04:58 PM
I don't have one of these but this thread makes me want one. They respond so well to your attention.

Between the RCA 630, Motorola VT-71, Admiral and GE 800/805 sets all so different yet rugged post-war designs.

jr_tech
06-09-2017, 08:39 PM
Update on mine:

1. The other night during prolonged operation, I experienced a failure... oddly it was a tall Sylvania 12SN7 with unusual looking plates (vert osc/amp), strange coincidence, for sure. Vertical went flat line, and I quickly reduced brightness, to avoid phosphor damage. Replaced the tube quickly, and caught the end of BBT, just in time for the cameo appearance of "the great and powerful Woz".

2. After prolonged operation, the 75 ohm/10 watt resistors are actually closer to 275 degrees F. Much of the heat is transferred to the HV cage through heat sink grease (the back side of the cage reaches about 150 degrees directly behind the resistors). I am working on a "cooler" solution involvind diodes and higher value 200-250 ohm resistors shunting them.

3. For grins, I pulled the chassis out of the wood cased 10T4 and repaired a few problems. It still performs fairly well with *mostly* original parts.

jr