Saved a Tek 7503, Tek 455, and BK1420 from storage

[Smokey]

Cool. I'll take a look.

[Smokey]

sooooooooooo....

I looked through a box of data books that I rescued from the same office that the scopes came from, and check out what was in there. 
Two full manuals for the 7503, and manuals for the vertical and horizontal plugins it came with.  I'm not sure what the difference between the two 7503 manuals is. 

I checked the main supply voltages and they all appeared to have ripple within the spec in the manual (5-10mV).  The ripple didn't really change with two or three plugins installed.

One place I did find some issues was on the "z-axis and high voltage oscillator circuit board".  There is a "-1.5V" test point that measured -6.5V.  There was about 125hz 0.5Vp-p ripple on that -6.5V.  I included a crappy cell phone picture of that section of schematic and the layout.  The resistors and caps all seem to be working around that circuit.  Everything looked clean and solid (At least per the schematic) up to Q756.
Some of the other voltages I noted as pretty off are:
TP760=-7.13V (0.6Vpp ripple at 125hz)
TP761=-10.75V (with 2.5Vpp ripple at 77khz)

I don't have time to dig in deeper tonight.  I'll poke around some more later. 
Looks like I might have some scanning to do if a full manual isn't already anywhere on the interwebs.

[MickM]

Hi;
  I have a B&K 1420, if you want to sell yours I would be interested.
I live near Seattle, WA.

  Mick M.

[David Hess]

I looked through a box of data books that I rescued from the same office that the scopes came from, and check out what was in there. 
Two full manuals for the 7503, and manuals for the vertical and horizontal plugins it came with.  I'm not sure what the difference between the two 7503 manuals is.

Good deal.

The 7403 is close but based on the photo, Tektronix added a lot of test points.

I checked the main supply voltages and they all appeared to have ripple within the spec in the manual (5-10mV).  The ripple didn't really change with two or three plugins installed.

Did the DC levels change?

One place I did find some issues was on the "z-axis and high voltage oscillator circuit board".  There is a "-1.5V" test point that measured -6.5V.  There was about 125hz 0.5Vp-p ripple on that -6.5V.  I included a crappy cell phone picture of that section of schematic and the layout.  The resistors and caps all seem to be working around that circuit.  Everything looked clean and solid (At least per the schematic) up to Q756.
Some of the other voltages I noted as pretty off are:
TP760=-7.13V (0.6Vpp ripple at 125hz)
TP761=-10.75V (with 2.5Vpp ripple at 77khz)

The 125 Hz ripple is because the supply for the high voltage regulator is unregulated.

Looks like I might have some scanning to do if a full manual isn't already anywhere on the interwebs.

I am sure Artek Media has it but I have not found a free service manual scan for the 7503.

The basic design is the same down to the component values but from the looks of it, the high voltage oscillator connection to the power supply is different.  On the 7403, that -1.5 volt test point is the ground return to the power supply which should be close to zero volts.  Here it must return to a different point.

[Smokey]

When I was talking about the difference, I was talking about the two different manuals I have for the 7503.  They both appear to be instruction manuals.  I didn't see a revision number, but I probably wasn't looking hard enough.

The DC level didn't change really.  I don't remember seeing a tolerance range for those voltages, but once again I probably wasn't looking hard enough.

http://artekmanuals.com/manuals/tektronix-manuals/
I was shocked at how reasonable the prices for those manuals are.  The service manual for the 7503 is only $7.50 USD.  I guess I'm used to scrolling through the $75 dollar manuals on ebay.

I think I'm going to hold on to the BK Precision 1420 just to enhance my vintage test gear nerd factor.  I know it might have a better home somewhere where it could actually get used, but I can just imagine showing up to a field job and pulling that thing out of the bag.  Hilarity would ensure... especially if it was enough to get the job done.

[David Hess]

When I was talking about the difference, I was talking about the two different manuals I have for the 7503.  They both appear to be instruction manuals.  I didn't see a revision number, but I probably wasn't looking hard enough.

There may be a difference in the back where the change notices would go but I think Tektronix would just include the most recent manual.  More likely there was a second 7503 or an extra manual set was purchased.

The DC level didn't change really.  I don't remember seeing a tolerance range for those voltages, but once again I probably wasn't looking hard enough.

Bummer.  That would explain the problem and be relatively straightforward to diagnose and repair.

Note that when the high CRT voltages drop, the deflection sensitivity goes up and the brightness goes down.  Maybe there is just a loose connection between boards.

http://artekmanuals.com/manuals/tektronix-manuals/
I was shocked at how reasonable the prices for those manuals are.  The service manual for the 7503 is only $7.50 USD.  I guess I'm used to scrolling through the $75 dollar manuals on ebay.

They have excellent prices.  I figured they have the 7503 manual in electronic form but I only buy the ones for equipment I have.  I am unlikely to acquire a 7503 to go with my 7603 that I have had for ages.

I think I'm going to hold on to the BK Precision 1420 just to enhance my vintage test gear nerd factor.  I know it might have a better home somewhere where it could actually get used, but I can just imagine showing up to a field job and pulling that thing out of the bag.  Hilarity would ensure... especially if it was enough to get the job done.

I figured the Tektronix 455 could fulfill that role.