The puzzlement continues

daryl bane · May 28, 2016

After the last installment, the ELSR press to check switch was faulty. Cleared this up and machine ran perfectly. I have not run the machine since this. I fired it up today and machine runs rough, rpm at about 400, but won't adjust slower, can go higher. Looked at C16js while running and LH tube goes dark. Took apart previous faulty switch and cleaned contacts, thinking an odd coincidence with a proven suspect, switch ohms out correctly, no change. Then replaced tube will known tested spare with same result, same with 6N7 just cause. Attached meter to GA2 and S1 to do electronic unit setup. Still reading 75vdc with all pots to zero, which is just not right. Unit runs in forward and reverse, but rough and LH tube goes dark. Not a happy camper right now.

gcude · May 28, 2016

Do your incoming line voltages look correct. Sometimes low voltage or missing leg can keep us chasing our tails when we should be chasing "outside the box".

daryl bane · May 29, 2016

Thanks, but yes line voltage is correct. What gets me is the thought of two nonrelated gremlins deciding to show their faces at the same time. I just can't figure that one, but thats what I get to trying to resurrect ancient electronics.

gcude · May 29, 2016

Problems seem to always come in bunches. It's almost like one problem decides to invite his friends over for some fun.

daryl bane · May 29, 2016

I have a unsubstantiated feeling that is what I call a cascading failure. That is, a component fails or faulty, and in the process of investigation, had caused another component to fail down the line.

Monarchist · May 29, 2016

Climate, Daryl?

Manhattan, New York: I had to replace server and deskside 'Puter mainboards for the accumulation of carbon-dust worn off tires and the asphalt under them by millions of folks hard-driving activity. The carbon dust and critters that came to grow in and on it subtly altered conductivity everywhere on the board.

Difficult to measure. Pervasive and cumulative, but erratic effect.

Hong Kong: Except for servers in well-conditioned Data Centre, gear installed in offices had similar short-lives. Heavier on mold, mildew, other fungoides this time.

Both were LOW VOLTAGE equipments. Very much so. 10EE traffics in around two orders of magnitude higher voltages. Those find leakage paths more aggressively - then add to them.

Could several years now of ordinary Texian seasonal travails have left a different 10EE electrically than your one was when first you finished its restoration?

I suspect so.

A thorough cleaning, end to-end, might well be due. Not just wiring, terminals, mounting blocks. Thermionic valve sockets. Known offenders.

A wash, brush-up, and blow-dry of the electricals could at least remove one more 'suspect' from the mix.

Bill

hitandmiss · May 29, 2016

Lets get to troubleshooting.

I've had several puzzlers over the years where the "working spare" had the identical problem as the one I just replaced.

I know it is a bit more work to swap them, but swapping the C16J's The problem stays with the tube, or with the chassis.
This way you know for sure that the problem is or is not the tube.

"Looked at C16js while running and LH tube goes dark." Is this saying that it is on at some point and goes dark by it's self? Or did you do something and then the tube went dark?
More detail would be helpful.

I like gcude's "Problems seem to always come in bunches. It's almost like one problem decides to invite his friends over for some fun."
It as if the longer you puzzle over it, the more friends get invited over so their fun never ends.

Bill

Monarchist · May 29, 2016

hitandmiss said:
It as if the longer you puzzle over it, the more friends get invited over so their fun never ends.

LOL! Got THAT shot right!

What with the internet expanding the 'door into the shop' to the whole of the Earth, the only GOOD news is they buy their own damned popcorn and beer, scatter-shoot their own terlets, not your one.

That said, I no more work on 'dirty' electricals than on dirty engines or transmissions.

Bill

labeeman · May 29, 2016

daryl bane said:
Still reading 75vdc with all pots to zero, which is just not right. Unit runs in forward and reverse, but rough and LH tube goes dark. Not a happy camper right now.

Sounds like a ground or common lead to the pots is open.

daryl bane · May 29, 2016

Thanks for the replies. The LH big tube goes dark when you move the spindle switch, either forward or reverse. When spindle switch is not engaged, both tubes glow equally. Same result with different known good tube. During the original issue , both tubes would go dark, and spindle would not revolve. Now that I have serviced the switch, only the LH tube goes dark and spindle revolves...roughly. The most important issue that I see is that I am getting 75VDC across S1 and GA2 when all pots are at zero. I have done the electronic procedure many times over the years and reading was always at zero volts when all pots turned down, and spindle does not rotate. Now the spindle will revolve(sorta rough) when you engage the spindle lever either forward or reverse at about 400rpm, with all pots and speed pots turned to zero. Sounds like a major short somewhere to me. You can drag up some pics of my lathe and electronic unit on this forum and the term "sanitary" would not be boastful. It looks the same as when I finished it.

Monarchist · May 29, 2016

daryl bane said:
the term "sanitary" would not be boastful. It looks the same as when I finished it.

"Exemplary", even "Outstanding" if it is still that clean.

That said.. might there be faint carbon(ish) traces across the Thyratron sockets? Steatite are they?

How about in between layers of phenolic on less-hot tube sockets. IF that is how those were built, it was once a common problem.

How 'strong' is that errant 70-odd volts? Dead Short? Or just heavy leakage? Can it be pulled-down with a resistor easily?

And that pesky motor switch.. 'relapse' to (part of) the earlier reported issue. Are they now only HALF corrected?

Bill

daryl bane · May 29, 2016

The big Thyratrons have separate cables not sockets bolted to connection studs. The smaller thyratron(s) which have sockets have been swapped by known good spares, no change. The "press to check" switch which caused grief initially, is a rugged Square D simple affair and can be easily dismantled for cleaning etc, no mystery as to how it works or not. After perusing the factory Monarch construction wiring schematic, my initial gut feeling is the PR(potentiometerw relay) is faulty causing a short circuit between connection of the front speed pot and the rear reverse speed pot. One is connected, the other not and vice versa, and looks like both are connected, but I have't proven this till the morrow. I had to fix the unit as it was faulty years ago with a tiny broken wire. I do believe Russ Kepler had the exact same problem. It s soldered inside a can, which makes repair extra fun. I think these are complete unobtainum, but I will deal with this later if it proves out. And yes, as vistors from this forum will attest, it is still quite clean.

hitandmiss · May 29, 2016

Consulting Wiad schematic #Q-1168-3 that is a revised 20434 that replaces 20199,
here are some basic checks with power off.

From grid to grid on the C16J's should read somewhere around 600K Ohms.

Each grid to ground, then each grid to GA2 should be greater than 1 Meg Ohm.

Measuring from A1 (or A2) to the following, Ground, S1, and GA2 should be greater than 1 Meg Ohm.

Now S1 to ground then GA2 to ground.

Since the minimum voltage with all adjustments at 0 is not 0, a reality check of the minimum voltage pot is in order.
You will need to place paper in the NC contacts of the PR relay. (to remove the shunting of the Fwd speed pot)
Measuring Ohms at the 2 wires going to the min voltage pot at minimum setting it should read a small resistance, in the order of 10-500 Ohms.
At the mid point should be 50K Ohms and 100K at max setting.

These tests are looking for obvious problems that can be found with a common DVM.

If I am not using the proper schematic, what is the correct P/N for the schematic for your machine, or if you have a readable copy on line, I can get more in detail.

Bill

I see we was composing at the same time.

"looks like both are connected" Just unhook wires 18 and 19 at the terminal strip near the relay and measure across the relay, it should be the wires going to the bottom of the terminals. The short you suspect would be a reading less than 1 Meg Ohm.

Since it is in a can, measure to the can from 18 and 19. You can try running it with the wires off too.

Monarchist · May 29, 2016

daryl bane said:
gut feeling is the PR(potentiometerw relay) is faulty causing a short circuit between connection of the front speed pot and the rear reverse speed pot. One is connected, the other not and vice versa,

Sounds like a smoking gun to me. Disconnecting/pulling it should make the stray voltage vanish even if the system cannot be run that way.

Presuming space is even an issue at all, running leads to remote a latter-day replacement stock unit with same actuating parameters and contact form should solve the 'unobtanium' issue.

I DO keep sayin' we are still collectively better-off with even fossilized electricals than those as need custom gears, clutches, or hydraulic shifters. The electrons (or valence 'holes') mostly don't care.

Bill

hitandmiss · May 29, 2016

If the relay is bad, I would use a modern one like a Digikey PB616-ND and a suitable socket. The maximum voltages encountered may be over the rating of this relay. Current is very small for a 10Amp relay. It is less than $20.00 and probably will outlast you.

Monarchist · May 29, 2016

hitandmiss said:
If the relay is bad, I would use a modern one like a Digikey PB616-ND and a suitable socket. The maximum voltages encountered may be over the rating of this relay. Current is very small for a 10Amp relay. It is less than $20.00 and probably will outlast you.

'Outlast' should be easy enough. Digi list at least 4 others in Potter & Brumfield label alone with 400 VAC rated max switching voltages @ 8A per-each on DPDT contacts that could be doubled-up for long-enough DC service.

National/Panasonic and Omron list more yet.

Whatever is chosen, mind you have a DC or AC/DC rated coil and that pull-in and drop-out voltage spec column values won't leave it confused.

Bill

daryl bane · May 29, 2016

Thanks for all the good leads. I will dive into it tomorrow and give an update. Too far into a malbec to give a shit at this time. Thanks again.

Monarchist · May 29, 2016

daryl bane said:
Thanks for all the good leads. I will dive into it tomorrow and give an update. Too far into a malbec to give a shit at this time. Thanks again.

*sigh* I'd rather be.. no shortage of it 'ere. More better I go scrape paint and dirt off a large-frame 3 HP now that the shop is "extra" cool. Glyptal I have put by may otherwise expire whether I do or not. Bought enough of as went solid it in bottles to not want to let a whole quart go the same route.

Bill

daryl bane · Jun 4, 2016

Still stumped. Relay checked ok. I have not a clue, where to procede. Could a bad brush on the motor be a suspect.? This motor was fully restored at great expense at the time, fully certified. Just a thought.

Monarchist · Jun 4, 2016

daryl bane said:
Still stumped. Relay checked ok. I have not a clue, where to procede. Could a bad brush on the motor be a suspect.? This motor was fully restored at great expense at the time, fully certified. Just a thought.

I did have that happening, but seriously doubt you are.

The "tamper" springs are powerful and long of travel. You'd have to be around the whole use out of the 'nominal' 2,000 Power-On-Hour brush life, and have worn the brush so short the tampers were out of remaining reach. As my one was, and on-arrival.

Bill

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