Tektronix 528A Waveform Monitor: Tektronix 1421 PAL Vectorscope

I don't see a burst on the staircase waveform, are the units fed from the same video source?

Well things always come in 3's so I'll be waiting for the next one to turn up.

Yes, same source that was feeding the 521. I will check connections

Chris said
Well like buses there's none then they all come along.

For now some eye candy for the test equipment junkies.
  

 Drool drool over all that stuff.....  fantastic !! 

The burst is there

I also hooked in the 521 as can bee seen below.

Adjusted the input setting on the 1421 I had a very small dot in the screen adjusted the gain and I could see some vector info but still way too small. The 521 was showing a perfect vector trace. I then upped the output Video amplitude on the PM5515, and the chroma, this made the 521 vector trace become huge so had to adjust the gain back. The 1421 vector trace increased a little in size but not nearly enough. Its also looks a little odd. I've no idea at this point if I'm driving it incorrectly or if it need a greater input signal. The 528 is working perfectly so its just down to figuring out how to drive this 1421.

All this kit was designed to work correctly with a 1V pk-pk signal terminated in 75 ohms.  If you have to wind the signal amplitude up, there is something amiss.

From memory, and it's been a while, the 1421 has a variable gain facility.  I suggest you might start by looking to see where this is set.

There seem to be manuals available from a few places on the internet, but at first glance none of them are free.

nuvistor said
I don't see a burst on the staircase waveform, are the units fed from the same video source?

That'll be because the waveform monitor is set to filter the chroma off - leftmost switch.

Cathovisor said

nuvistor said
I don't see a burst on the staircase waveform, are the units fed from the same video source?

That'll be because the waveform monitor is set to filter the chroma off - leftmost switch.  

OK, I can see the switches are in different positions but cannot read the legends. Thanks.

Chris said
The burst is there

I also hooked in the 521 as can bee seen below.

Adjusted the input setting on the 1421 I had a very small dot in the screen adjusted the gain and I could see some vector info but still way too small. The 521 was showing a perfect vector trace. I then upped the output Video amplitude on the PM5515, and the chroma, this made the 521 vector trace become huge so had to adjust the gain back. The 1421 vector trace increased a little in size but not nearly enough. Its also looks a little odd. I've no idea at this point if I'm driving it incorrectly or if it need a greater input signal. The 528 is working perfectly so its just down to figuring out how to drive this 1421.

I'd suggest (a) switching off external subcarrier reference first, and then (b) setting the leftmost switch to match the input you're feeding.

As Occiput said earlier - this stuff is designed to work from 1V into 75Ω video so if the generator is providing that, something is awry. You've not got anything double-terminated or fed from an incorrect output, like the "monitor" output, have you?

occiput said
From memory, and it's been a while, the 1421 has a variable gain facility.  I suggest you might start by looking to see where this is set.

It does and I have tried adjusting it, the best I got was the unlocked to burst vector circular waveform as shown in #1 4th photo.  I cannot see how you get this one to lock, as I mentioned above the older 521 had a toggle switch to set where to get the burst. I was wondering if this needs an external source.

I'll keep at it, I managed to get the 521 sorted so If I keep plugging away at it, hopefully I will suss how to drive this one.

I can see what your problem is now.

You do not, repeat NOT, parallel up video feeds like you have done on the signal generator output!!

Rewire it like the attached: 'T' denotes a termination resistor, 'A' is the input plus loop-through.

Hi Catho,

I had it connected in a number of ways.

Ignoring the 528 totally I had a direct link from the PM5515 to the 1st input on channel B on the 1421 with the 75Ω terminator on the 2nd B chan BNC. Switches set to B and PAL, adjusted gain and all I get was the unlocked vectors

Thanks for the connectivity info I've just tried it which includes the 528 in the loop and same result, unlocked vectors

Have you turned off "external subcarrier" ? The lamp was lit when I looked at your photos. Also, if you're going into the B input the left-most switch needs to be further down.

Yes, the external sub carrier is off.

I've tried all combinations and have had the B chan switch right at the bottom, which states the sub carrier input is on A.So also had the wiring looped thus

All I get all the time is this, ignore where there switch is in this photo I uploaded the wrong one, it looks the same even with the button down in the lower most position.

I'll take a photo tomorrow with the 528, 1421 & 521 all chained in and set up.

A copy of the Operating Instructions is available here:

http://exodus.poly.edu/~kurt/manuals/manuals/Tektronix/TEK%201420%20NTSC%201421%20PAL%201422%20PAL-M%20Instruction.pdf

which you may find useful.

occiput said
A copy of the Operating Instructions [..] which you may find useful.  

Thanks I certainly will

Chris said
The vectorscope looks good too but as yet I cannot get it to lock to the burst. I had this on the 521 below and sorted it when I found the ref toggle switch to set where to get the burst. Not found where to do this on the 1421 yet, only just got in from collecting it so will have a bite to eat then look into it a bit further and see if I can find a manual.

I have to say I much prefer the vintage 521 over these modern ones and it only needs one power socket and one signal input whereas these take two sockets and needs to signal inputs.

Congrats on landing a nice pair of TV signal test instruments!

The half-rack size means two fit the space of the previous 520/521 PAL vectorscope model. I've always thought of the 520/521 PAL as "R&D" or "Laboratory" grade, it is capable of resolving much smaller dG, dP errors. (We'll revisit dG and dP once you have your test equipment sorted) On the other hand the 528 and 1420/1421 PAL instruments were the workhorses of many broadcast plants. So much so that there's still quite a few to be hand for silly prices, or to source as spares.

When I restored the Ampex VRP-2 One inch VTR project it was missing those instruments (and the Tek 650 Colour Monitor) in the 'bridge' above the tape transport. I hunted for quite a while to find replacements, and at one point I had gone through four 1420s - all with low emission CRTs. If yours has a bright trace and no phosphor burning you did very well indeed!!

The Tek 528A had several options, so when you get a manual (highly recommended) take a look at what is really in yours. A Tek 1421 PAL set is quite a bit different to the 1420 NTSC version, so again it would be good to source the Tek manual.

I see you got some solid advice on operating these two. Have fun playing! 

When the covers come off you'll see some of Tektronix' finest work. Of particular note in the Vectorscope is the Goniometer control (Phase knob on front) I don't know of any other application to be found for this phase angle control. I had to do a fair amount of research to understand how it works, and the only other reference to a Goniometer was for vintage WW-II RADAR sets. 

I will download the manual this morning and have a good read, for now this is the state of affairs.

This is how its wired up and how the switches are set. As can be seen the 521 resolves the 1421 does not.

Chris said

This is how its wired up and how the switches are set. As can be seen the 521 resolves the 1421 does not.  

Great! The signal cabling (wiring) looks good.

There should be a "Test Circle" switch or button for CRT adjustment - centre and "roundness" that sets up the internal X and Y Amplifier operation.

Would you make a close up PIX of the left side controls? I can't see the text (on an iPhone, and in an Italia Fecciarossa high speed train to Roma from Firenze) Gracie, Senore!

FordAnglia said

Would you make a close up PIX of the left side controls?

Well I cannot see that I'm doing anything wrong. With the sub carrier set to internal (depressed, not pulled out) it should be detecting the incoming burst on Channel B input, its not, its just free-running all the time. Clearly the burst is there as shown on the 528 monitor and further evidenced by the 521 locking to it.

Possible fault on the 1421 and perhaps why it was decommissioned?