No working oscilloscope but good at poking around.... one of the tubes produces 1,000v so I will make sure it has been unplugged awhile. I am retired so time I have.

You need to discharge the electrolytics before going inside. It MIGHT be okay to just wait, but you'll KNOW it's safe if you discharge the electrolytics. Put a suitably large resistor across the terminals of the electrolytics until they completely drain and then wait a couple of minutes past that (with the resistor still in place). HV electrolytics can recharge a substantial voltage if you quickly disconnect them after draining. Probably not enough to kill you, but you'll feel it!

I don't know how much you know about working with HV, so I offer this info in this spirit. I work with tube amps and in the groups where we discuss that, safety is a big deal. These voltages easily kill. If you don't have experience with tube electronics, I'd highly recommend reading up on high voltage safety... There's a decent treatise on it here.

 

Hi,
If you are saying now that on the starup a dot comes on,this means a vertical and horizontal deflection
was out. look the connector of this cable if it was remove or not connected.

Second,if goes blank maybe due this cable was out(vertical/horizontal connector)it will shutdown the
circuitry in the horizontal causing the high voltage going to the CRT will drop to zero and the heater is OFF.
Try to checked out all your cables if any not connected

 

Hi,
Dot means a missing deflection both of vertical and horizontal drive. checked your cable .

A Blank Screen is missing a high voltage to Crt anode and a missing Heater supply to Crt board drive.
Due to not connected cable of v/h defection cable causing the horizontal ckt to shutdown,
thats why missing a high voltage and the heater.

 

Hi,
Dot means a missing deflection both of vertical and horizontal drive. checked your cable .

A Blank Screen is missing a high voltage to Crt anode and a missing Heater supply to Crt board drive.
Due to not connected cable of v/h defection cable causing the horizontal ckt to shutdown,
thats why missing a high voltage and the heater.

The blank screen took place after I removed the 2 6AU8 tubes V1 V2. I have since swapped these two tubes and there improvements..... the vert position of the trace is in the middle of the Crt and I am wondering if these two tubes should be replace as they are less than $5. I will look at v/h deflection cable for problems. If I have time today I will take some photos of the guts of this thing.

 

I did not expect to see the line disappear and transformed into a dot, or the dot to vanish.

With tubes V1 and V2 swapped, is the line in the center of the screen with the V-POS control at half-way range?

Does the V-POS control adjust the vertical position appropriately?

Connect a jumper cable from SAW TOOTH jack to V-INPUT jack.
Do you get a saw-tooth waveform on the screen?

 

I did not expect to see the line disappear and transformed into a dot, or the dot to vanish.

With tubes V1 and V2 swapped, is the line in the center of the screen with the V-POS control at half-way range?

Does the V-POS control adjust the vertical position appropriately?

Connect a jumper cable from SAW TOOTH jack to V-INPUT jack.
Do you get a saw-tooth waveform on the screen?

The line is at the bottom 1/3 with the V-Pos at halfway range and has been running about an hour without dying. Yes to jumping saw-tooth to V_INPUT but on the second terminal not the top one. I ordered the two tubes as they were cheap.

 

Sounds like you got most, if not all of the scope working.
Next thing to do is get out the DVM and measure voltages at the anodes of all the tubes when the V.POS and H.POS are set to the half-way range.
Are you familiar with reading schematics?

 

Sounds like you got most, if not all of the scope working.
Next thing to do is get out the DVM and measure voltages at the anodes of all the tubes when the V.POS and H.POS are set to the half-way range.
Are you familiar with reading schematics?

I might be able to muddle through this schematic reading is not something I do very often but would be a good learning curve. Thanks for all the help. I am sure I will have more questions.

 

Boat Anchor had/has the manual. You will have to unzip. I think it is postscript so you will need a viewer. I built one of these in the 1960's still have it still works! Had lots of fun with it.

 

Hello,

There are two versions of the 460 manual:
http://bama.edebris.com/manuals/eico/460/

One in PDF format and one in DJVU format.
PDF can be opened in acrobat reader, firefox or fox reader.
DJVU can be opened with a dejavu reader ( http://windjview.sourceforge.net/ ).

Bertus

 

Thanks everyone ...I have the manual and found the build instruction and that was most helpful. I replaced 2 tubes and it made a huge difference so I decided to replace 3 more tubes because they were cheap. When i get those next week i will take some photos and button up the case, I want to put feet on the bottom so that it can breath better. I replaced the power cord and fuse.