TEK RM5110

[MED6753]

Facebook Marketplace score. Tek RM5110 with 5A15N Vertical amp, 5A20N Differential amp, and 5B13N Time Base. It powers up but all the switches on all the plug-in's are extremely dirty. The Volts/Div light is burnt out on the 5A15N. The pull tab on the 5A20N is broken off flush with the plug-in. And the 5A20N and 5B13N are jammed in place and won't pull out. So there's multiple issues to resolve in addition to re-capping the PSU. Should be a fun project.

[Zenith]

Interesting. I've never seen a Tek 5000 series in the flesh. They had a wide range of plugins, including unusual ones such as an audio spectrum analyzer and a curve tracer.

https://w140.com/tekwiki/wiki/Introduct ... illoscopes

[MED6753]

Some updates. I was able to get all the plug-in's removed and cleaned all the sticky and dirty switches. The result is stable operation of all 3 plug-in's. Some noted potential issues. With no signal input and the trigger set to "AUTO" there is no base line trace. Rotating the "LEVEL" control has no effect. That will eventually be investigated. Another potential issue is it seems the CRT should be brighter. And I noticed some "double peaking" which indicates a CRT with a lot of hours. I haven't yet checked the PSU voltages or the HV so it could be an issue in those circuits. I will be re-capping the PSU too.

I found all the manuals online. I forgot to mention yesterday that the scope has a property tag from the University of Rochester, NY.

[tautech]

Has it passed the CAT scan Mike ?

[MED6753]

Has it passed the CAT scan Mike ?

Everything that comes into this residence has to pass by Chief Inspector Harley.

[Cubdriver]

Has it passed the CAT scan Mike ?

Everything that comes into this residence has to pass by Chief Inspector Harley.

As well it should!!!

-Pat

[MED6753]

Started the checkout/repair. First up checked the PSU voltages including the HV. Everything was in spec and healthy. I will eventually do a re-cap but holding off until all issues are fixed.

First repair action is the lack of backlight on the Volts/Div on the 5A15N plug-in. The lighting is actually neon bulbs driven by +200V from the mainframe. See schematic. There's a bulb for the X1 as well as the sense for an X10 probe. Neither lights work.



I was mainly interested in R194 and R190 and check them as shown in the parts location diagram in the manual.



This is what my plug-in looks like. Do you see R194 and R190? I don't either.



The parts location diagram in the upper right shows perhaps 2 resistors and 2 transistors.



My plug-in in the upper right shows many more resistors and at least 3 transistors.



Obviously there was an update on this plug-in. But every manual I found on line reflects the manual I have. I checked Ebay to see if there was a S/N specific manual for sale but no joy. My plug-in is B081382 which is a very high number. So what to do? I'm going to modify the X1 neon bulb so it ties in directly to the +200V thru a 180K resistor. I'll make it reversible so if I find the proper manual I'll delete the mod.

[Zenith]

If the change was made toward the end of the production run, there may have been few units produced with it, and so it was only documented in addendum pages, which are as rare as hen's teeth.

I'd be inclined to try tracing the circuit, which is always a pain, but since it only switches one or other neon, depending on the probe sense switch, I wouldn't have thought it was too involved.

[MED6753]

I was informed by Factory over on the EEVblog that a similar 5A18N plug-in had a production run change that deleted the neon bulbs and installed 5V filament lamps. See here....

https://www.eevblog.com/forum/testgear/ ... msg5827515

So I pulled one of the lamps in my 5A15N and while I accidentally broke the bulb it is indeed a filament lamp. So this plug-in got the same production run change.



Troubleshooting this with power on is going to be damn near impossible with the rack mount scope without an extender (P/N 067-0645-00) There's one on Ebay right now for $170 which is nuts. So my solution is that I'm going to install an LED in the X1 position and call it a day. The change will be reversible. I'm going to experiment with orange, clear, and blue and see what I like best.

[AVGresponding]

Is it not possible to make your own extender boards for a reasonable cost? Anyone asking $170 must be a damn crack-head

[MED6753]

Is it not possible to make your own extender boards for a reasonable cost? Anyone asking $170 must be a damn crack-head

I did some reading on that very subject and the big issue is finding the male connector. If you recall I did make my own for 500 series because the male/female connectors were readily available.

And you think $170 is crack head crazy? I found a TE supplier that wanted $350!

[Zenith]

I was informed by Factory over on the EEVblog that a similar 5A18N plug-in had a production run change that deleted the neon bulbs and installed 5V filament lamps. See here....

I've changed filament bulbs for LEDs sometimes. Filament bulbs can be hard to find and expensive these days.

I've made extenders in the past. They looked rough but did the job. One used ISA connectors from an old PC. $170 seems a lot for a thing to fix a scope that's probably worth nowhere near that. If you bought it for $170, what are your chances of being able to sell it on ebay for that much, or anything like it?

[MED6753]

More work on this scope.

First, I was able to brighten the trace somewhat with the "Brightness" control on the HV supply. It still isn't as bright as I think it should be but it's acceptable. This CRT is worn out.



Next up is the 5B13N Time Base. The unit triggers fine but it always acts as if it is in "Normal" mode. In "Auto" mode there is no baseline trace. Auto mode is engaged by lifting -5V to pin 10 of U30. I was able to verify that this functions as it should but pin 10 only drops to -4.18V. I think it should be lower. I did jumper C18 and there was no change. I'm concluding that U30 is bad. It's Tek P/N 155-0055-00 and there are none to be found anywhere.
QService has it listed but no stock. Nothing on Ebay. So I'll use the plug-in as is for now.




Next up is the 5A20N Differential. It has some issues with the minus input.

[Zenith]

Next up is the 5B13N Time Base. The unit triggers fine but it always acts as if it is in "Normal" mode. In "Auto" mode there is no baseline trace. Auto mode is engaged by lifting -5V to pin 10 of U30. I was able to verify that this functions as it should but pin 10 only drops to -4.18V. I think it should be lower. I did jumper C18 and there was no change. I'm concluding that U30 is bad. It's Tek P/N 155-0055-00 and there are none to be found anywhere.
QService has it listed but no stock. Nothing on Ebay. So I'll use the plug-in as is for now.

On TekWiki the 5B13N page has a link from 155-055-00 to the 155-048-00 page. The 155-048-00 and variants were used in 15 or more scopes and plug-ins. It may give a wider search range and the possibility of picking up a scrap unit of a different sort to supply the chip. I've no idea which units used the 055 and which used the 048.

The 155-0048-00/-01 is packaged in a 16-pin minipac, the 155-0055-00/-01 is the same chip in a 16-pin DIP.

If you came by an 048 it would need an adapter made up.

[MED6753]

Next up is the 5A20N Differential plug-in. The issue with low gain on the minus input was due to dirty attenuator switch contacts under that metal cover. Once deoxit'ed that fixed that issue. The plug-in pretty much works however DC Balance and Atten Step Balance need adjustment as well as a general calibration. Without an extender that's not going to happen. Can't access the adjustments without one. I'm going to continue to search for the male/female connectors and make my own. In the meantime I'm going to order the capacitors for the mainframe.

[mansaxel]

I believe the connectors if not the supply voltages and the pinning (most certainly not!) are the same as for the TM500 series modular instruments. For those, a so-called JAMMA extender cable reportedly can be used, once a bridge in the PCB joining a couple of adjacent pins has been removed. I've got one, bought to run my TM500 gear in extended mode; it's been modified to suit but not tested beyond physical fit, and then of course unpowered.

Tekwiki mentions this and explicitly adds 5000 series scopes to the compatible devices.

[MED6753]

Orange LED tied into +5V and now the X1 position is illuminated on the 5A15N plug-in.

[mnementh]

I believe the connectors if not the supply voltages and the pinning (most certainly not!) are the same as for the TM500 series modular instruments. For those, a so-called JAMMA extender cable reportedly can be used, once a bridge in the PCB joining a couple of adjacent pins has been removed. I've got one, bought to run my TM500 gear in extended mode; it's been modified to suit but not tested beyond physical fit, and then of course unpowered.

Tekwiki mentions this and explicitly adds 5000 series scopes to the compatible devices.

.


https://retroarcade.us has what they call a "Full JAMMA Extender" that is all 56 wired pin-for-pin. It's more expensive than your typical JAMMA extender (~$30 with shipping vs $10-15 OFF Amazon, etc) that only has half the pins connected and often has bridges, but it should save a fair bit of assache.

https://www.amazon.com/RetroArcade-us-r ... 00F1YQMXO/

mnem
*wired*

[Cubdriver]

Yup. You just need to split the paralleled power pin fingers on the male edge card end - two per side.

-Pat

[mnementh]

*looks again*

Yeah, it does appear that even on these those traces might be Siamesed into a single trace... I didn't see that at first. A trap for new players, yo.

mnem
"Itz always somethin'." ~Rosanne Rosannadanna

[MED6753]

Squeezing in some limited lab time among all the daily activities. This is the capacitor set for the 5110 PSU. The new filter caps installed in the 5 pin adapters. I will be removing the PSU from the 5110 to make it easier to work on. While it doesn't look too difficult to remove it's going to be no picnic either. What's going to be the real PITA is removing the original cans. If you've ever done a linear 400 series or 7000 series you'll know exactly what I mean.

[Zenith]

Squeezing in some limited lab time among all the daily activities. This is the capacitor set for the 5110 PSU. The new filter caps installed in the 5 pin adapters. I will be removing the PSU from the 5110 to make it easier to work on. While it doesn't look too difficult to remove it's going to be no picnic either. What's going to be the real PITA is removing the original cans. If you've ever done a linear 400 series or 7000 series you'll know exactly what I mean.

I haven't tried this, but I've heard that the big cans in 400 series scopes, can have the outside lugs and connection pins cut through with a jewellers saw. That way the lugs and pins can be dealt with one at a time, which makes it far easier.

[MED6753]

Squeezing in some limited lab time among all the daily activities. This is the capacitor set for the 5110 PSU. The new filter caps installed in the 5 pin adapters. I will be removing the PSU from the 5110 to make it easier to work on. While it doesn't look too difficult to remove it's going to be no picnic either. What's going to be the real PITA is removing the original cans. If you've ever done a linear 400 series or 7000 series you'll know exactly what I mean.

I haven't tried this, but I've heard that the big cans in 400 series scopes, can have the outside lugs and connection pins cut through with a jewellers saw. That way the lugs and pins can be dealt with one at a time, which makes it far easier.

That works, if you can get to the lugs. Sometimes you can't.

[MED6753]

The 5110 PSU on the bench. Removal wasn't so bad after all. But the fun part has yet to follow. Removal of those cans. Let the games begin.

[MED6753]

It was a royal cussfest but the old filter caps are removed and new installed. Dremel with a cut off wheel was tool of choice. There's a few items yet to complete and then the PSU will be ready to install.