View Full Version : Odd item found


Findm-Keepm
08-13-2015, 10:07 AM
Here's a new one, for me. This is an Eby BG-1 Bar Generator that is apparently placed between the CRT socket and the CRT. I don't have a BW set to try it out on, but by the description, no other equipment is needed.

Anyone every use one, or know the full story?

Smoky Pond
08-13-2015, 06:46 PM
That is pretty neat! I too would like to know how and how well it actually worked.

Electronic M
08-13-2015, 07:10 PM
IIRC I read about them in some period magazine (an AD I think), I wondered how they worked, and doubted that any actually still existed....Guess I was wrong.

Don Lindsly
08-13-2015, 07:24 PM
It appears to be a socket adaptor to enable using a 110 degree test CRT on an older style 50-70-90 TV for bench service.

Findm-Keepm
08-13-2015, 07:41 PM
It appears to be a socket adaptor to enable using a 110 degree test CRT on an older style 50-70-90 TV for bench service.

The plug and socket are the same, and the catalog shows it in a different section than the adapters and extenders. It's definitely a tester (bar generator) of some sort, not an adapter. I came into TV servicing in the late 70s, so the old tube black and white (big neck) sets weren't among items we serviced.

StellarTV
08-13-2015, 07:43 PM
Fascinating. Crack it open! :)

ChrisW6ATV
08-14-2015, 01:31 AM
It only mentions vertical adjustments, not horizontal, so I am guessing that it does some fun shenanigans with the (AC) filament "signal" to put horizontal bars into the cathode or grid of the CRT. These oddball items are fascinating to see now, like the gadget that went under damper tubes to increase the picture width.

Eric H
08-14-2015, 02:35 AM
It appears to be a socket adaptor to enable using a 110 degree test CRT on an older style 50-70-90 TV for bench service.

That was my first thought, it looks just like the sockets that come with the 8YP4 test tube, except this one is 12 pins on both sides so it can't be for that.

Kevin Kuehn
08-14-2015, 10:21 AM
Better find a black and white set and try it. :)

Findm-Keepm
08-14-2015, 11:05 AM
These oddball items are fascinating to see now, like the gadget that went under damper tubes to increase the picture width.

Yeah, I got one of those too. ;)

My username is not a fluke....

jr_tech
08-14-2015, 01:35 PM
It only mentions vertical adjustments, not horizontal, so I am guessing that it does some fun shenanigans with the (AC) filament "signal" to put horizontal bars into the cathode or grid of the CRT.

I'm guessing that it contains a simple 2 transistor multivibrator circuit, producing a 300-400 Hz square wave that is injected into the grid/cathode circuit of the CRT, to produce evenly spaced black bars on the screen... Any other guesses?

jr

Findm-Keepm
08-14-2015, 03:15 PM
It contains a cap and a resistor - I'm reverse engineering, but that is all that is visible - some kind of an integrator, I guess. The resistor is 2 Megs, 1/2W carbon comp.

Someone mentioned coupling of the filament voltage to the cathode or grids - that probably is what is happening. More later!

old_coot88
08-14-2015, 05:45 PM
In order to produce multiple bars, it'd hafta run at some multiple of the line frequency. Seems like that would require an active device of some kind. Tunnel diode maybe?:saywhat:

Don Lindsly
08-14-2015, 11:02 PM
The plug and socket are the same, and the catalog shows it in a different section than the adapters and extenders. It's definitely a tester (bar generator) of some sort, not an adapter. I came into TV servicing in the late 70s, so the old tube black and white (big neck) sets weren't among items we serviced.

Missed that.

Tom Albrecht
08-15-2015, 01:07 AM
Fascinating! How does it manage to sync anything with the sweep?

jr_tech
08-15-2015, 11:11 AM
In order to produce multiple bars, it'd hafta run at some multiple of the line frequency. Seems like that would require an active device of some kind. Tunnel diode maybe?:saywhat:

Perhaps a neon bulb??? :scratch2:

This is a fun puzzle!

jr

wa2ise
08-15-2015, 01:46 PM
How does it manage to sync anything with the sweep?

If the TV is tuned to a station, the vertical would be synced to 59.94Hz vertical sweep. A 60Hz waveform injected into the CRT would slowly crawl up the screen, slow enough so you could adjust the vert height and linearity.