Test Equipment Anonymous

A magnificent result. It makes me feel guilty about my various delayed projects needing cap replacement.

Finally got the opportunity to get the upgraded PSU installed. Powered up with no issues and voltages spot on.




I'm going to order the JAMMA cable as recommended by Paul and modify it for use as an extender so I can calibrate the plug-in's. But for now this project is complete. Moving on to the hp 211A.

That really does look good in the pictures. Did the CRT's display improve once the upgraded rebuilt power supply? If the CRT's worn out, it's got to be something that has to be seen in person because it looks great in the photos.

Surprisingly the CRT display did improve slightly after the re-cap and I'm not quite sure why. The PSU voltages and ripple were well within spec prior to any work being done.

So I got the JAMMA cable for use as an extender. I realize I have to notch the male connector and put a key in the female connector. But there's talk that I have to modify the wiring too? What specifically has to be done?

I haven't used the one I got yet, so I haven't gone through it, but the main thing I'm aware of is that you need to slice the siamesed pads on the end of the male connector where the pairs of black and red wires attach to make the connections separate, and the other thing I'd do is check the connections between like colored wires - they are paired on opposite sides of the connector eg. pink front/pink back, yellow front/yellow back, etc. If they bundle them AFTER they make the connections (likely, I'd think), then they're probably fine, but better safe than sorry - make sure side one pink on the board ties to side one pink on the connector, side 2 to side 2, etc - make sure none of them are crossed front to back.

-Pat

Edit to add - I think you'll likely be ok re front to back crossing - I just took the one I had and checked and the connections match without front-to-back crossover. Probably a good idea to check the red & black power wires once the siamesed pads have been split.

This is the interface in the 5110 (female connector). At first glance it appears that the JAMMA is going to need considerable rework to avoid magic smoke. What I need to determine right away is the interface on the 5110 numbered from the bottom up or top down? And then which is left side vs right side? That should be easy. Just find the +200V on pin 1 and the -38V on pin 1. But if you notice several pins are tied together. Is that on the interface itself or somewhere else. Resistance checks should determine that. And it doesn't use all 64 pins so unused cables will be removed. And of course have to install a key way.

As long as you split the siamesed pads, why do you think the JAMMA cable would need extensive rework? As long as all the connections are 1:1, it should effectively be invisible to the plug in. And why remove the unused cables? If they're no connects, they won't hurt anything, and the TM-500 equipment uses the same connectors so it could potentially be used for that, too (not sure off the top of my head if you have any, but even if not you might eventually...).

-Pat

What are these siamesed pads that you are referring to? I don't see any connected together although I have not verified that with an ohm meter. Or are some cables swapped side to side male to female?



Yes, I do have a TM series. This TM503. I was able to troubleshoot each plug-in in the cabinet but it would be nice to have an extender. So I'll leave the unused cables in place.

Look closely at the ones near the end with the red and black wires - they're solid on the male edge connector - you'll need to slice the fingers/pads lengthwise to separate them. Those pads are siamesed on both sides on mine.



I ohmed out a bunch of the wiring on mine and they appear to correspond 1:1 as a pure extension with no side to side swapping, but I'd suggest running a quick test with an ohmmeter to verify. I can do a more thorough check later tonight and let you know what I find on mine.

-Pat

Pat, you are correct. Just looked at mine and it's the same. Yes, they need to be separated.

Pins 1 and 2 no longer tied together. Same with Pins 3 and 4. A Dremel with a mini rasp bit was the tool to separate the traces. I also verified that the cabling does not swap side to side.



Still to do:

Verify orientation of the 5110 interface. Although I suppose it doesn't really matter because all the cables are now isolated. But I still want to check.
Notch the male end for the key way.
Install a key in the female end.
Smoke test.

Just like the schematic the female connector in the 5110 is arranged with Pin 1 at the bottom with +200V on the left. I just wanted to verify the orientation although it doesn't really matter.




I have to notch out 2 slots as indicated in red on the male connector. Once that's done I'll plug in the extender without a plug-in and just do a quick verification on the female end.

The male end of the cable was notched to clear the keys. A dremel with a rasp bit made quick work of the process. I marked both ends of the cable "TOP" to insure correct orientation end to end. And I did not install keys in the female connector. Not necessary as long as correct orientation is maintained.



A test install of the cable into the 5110 without a plug-in. I wanted to make sure supply voltages were correct. Everything checked out.



It works. Now I can proceed with calibration of the 3 plug-in's.

MED6753 wrote: ↑Mon May 26, 2025 6:32 pm It works. Now I can proceed with calibration of the 3 plug-in's.

Excellent. I'll finish up the necessary mods on my JAMMA cable and go at my 5440, and as soon as I locate the custom Tek IC I bought for

${MUCH}

, there's hopefully going to be chooching horizontals or if not, an expensive fire.

Calibrations. First up, the 5A15N Vertical Amplifier.



Not much to calibrate in this plug-in. Just needed a slight gain adjustment.



Next, the 5A20N Differential Amplifier. This one was a bit fiddly with it's compensation adjustments and had to go for best compromise.




Tomorrow we'll check the 5B13N Time Base.

MED6753 wrote: ↑Tue May 27, 2025 7:28 pm Calibrations. First up, the 5A15N Vertical Amplifier.

That series of CRT are gorgeous to look at! I really like mine too.

mansaxel wrote: ↑Tue May 27, 2025 7:29 pm

MED6753 wrote: ↑Tue May 27, 2025 7:28 pm Calibrations. First up, the 5A15N Vertical Amplifier.

That series of CRT are gorgeous to look at! I really like mine too.

This CRT is not as bright as I think it should be and it exhibits double peaking which indicates lots of hours.

MED6753 wrote: ↑Tue May 27, 2025 7:44 pm This CRT is not as bright as I think it should be and it exhibits double peaking which indicates lots of hours.

I see. Mine is possibly a bit better. And has readouts. Probably peak analog audio scope in some ways that. Low bandwidth, large CRT, lots of inputs (I've 4 on mine, 2 per module) and very nice ergonomics.

I've got the table top form factor on mine, and I'd be really chuffed to find a rebuild kit into 19" form factor. Rack scopes are cool.

MED6753 wrote: ↑Tue May 27, 2025 7:44 pm This CRT is not as bright as I think it should be and it exhibits double peaking which indicates lots of hours.

You're much better at pictures of oscilloscope porn than I am.

mansaxel wrote: ↑Tue May 27, 2025 8:01 pm

MED6753 wrote: ↑Tue May 27, 2025 7:44 pm This CRT is not as bright as I think it should be and it exhibits double peaking which indicates lots of hours.

I see. Mine is possibly a bit better. And has readouts. Probably peak analog audio scope in some ways that. Low bandwidth, large CRT, lots of inputs (I've 4 on mine, 2 per module) and very nice ergonomics.

I've got the table top form factor on mine, and I'd be really chuffed to find a rebuild kit into 19" form factor. Rack scopes are cool.

I would assume those empty stand offs between the plug-in's and CRT would be where the readout board would go.

Calibration of the 5B13N Time Base.

As mentioned before the trigger works fine in both Normal and Auto mode but there is no baseline free run trace in the absence of a trigger in Auto mode. The manual states there should be. There isn't. All the trigger functions are contained in one IC. Here is the block diagram. When the -5V is lifted from pin 15 in Auto Mode the Auto Trigger internal to the chip should free run. I have to assume based upon this that the IC is defective. But as I mentioned before it's listed in like QService but no stock. I'll keep looking and also look for a non working unit that uses this same IC for a reasonable price. What's currently listed on Ebay is freaking robbery.



There's only 3 adjustments in this plug-in. And the calibration was way off. Now is that the result of the defective trigger IC or someone doing twiddly pot? Hard to say. But I was able to bring everything back to spec.



The calibration of all 3 plug-in's is now complete. So for now this project is complete.

If you're gonna work on old Tek iron you need your extenders. The solid one is for 560 series scopes. The smaller one in the center is a home made 500 series extender. And then we have a modified JAMMA cable for 5000 series and TM500 series.

MED6753 wrote: ↑Thu May 29, 2025 6:50 pm Calibration of the 5B13N Time Base.

As mentioned before the trigger works fine in both Normal and Auto mode but there is no baseline free run trace in the absence of a trigger in Auto mode. The manual states there should be. There isn't. All the trigger functions are contained in one IC. Here is the block diagram. When the -5V is lifted from pin 15 in Auto Mode the Auto Trigger internal to the chip should free run. I have to assume based upon this that the IC is defective. But as I mentioned before it's listed in like QService but no stock. I'll keep looking and also look for a non working unit that uses this same IC for a reasonable price. What's currently listed on Ebay is freaking robbery.

Could it be a job for a µcontroller based board? I'm just wondering whether the control/display chip C2506, in Fluke bench DMMs, could be replaced the same way.