1956 WiaD drive problems

I figured I would start a new post on my current issues. I have a post on here about my voltage conversion using Peter's setup with the transformer to boost the filament transformers and contact coil voltage. I worked through that and now seem to have the proper voltages to run the machine.

I cannot seem to get the drive to run stable at all. For now I am going to take the motor out of the equation as it looks like it was rebuilt shortly before I purchased the machine. The commutator looks very nice, the brushes look new and the inside of the motor was repainted with that red insulating paint that they use. In operation there is never any arcing or noise coming from the motor.

After getting the voltage conversion done I took some voltage readings. As of now, this is running on a single phase line.

L1 to L2 = 246VAC
Output of new transformer = 460VAC
Filament voltages on C16J = 2.45VDC
A29 to A30 checked at bottom of fuses = 621VAC
A24 to A25 = 308VAC
Output of EL1C measured at F2 to 73 = 119VDC
F1 to F2 with spindle running varies with spindle pot at crossover point = 111VDC to 43VDC

The machine pulsates badly and you can see it in the tubes as well. After I reach the cross over point and the field takes over, it seems to smooth out a lot better. The right C16J seems to be acting normally but the left tube only fires intermittantly. Swithing the tubes does not change the problem, left side is still intermittant. None of the relays are chattering or acting up. Contactors pull in very nicely.

http://i1277.photobucket.com/albums/y493/Coyotebill57Bill/IMG_1301_zps442877dc.jpg

Peter had suggested replacing the 8MFD 450V cap. I replaced that tonight with a 10MFD 450V cap, the closest I could get. Still has the same problem. There is an exploded cap that Peter found a match for, it's a 0.1MFD 600V. Problem is, I have no idea where the other end was connected or if it was added. The one end that is left with most of the body is soldered to the case of the 1MFD metal cap behind the front panel at the bottom. I seperated the front and looked carefully for hints of where the other end was. I could find nothing. Tying the cap to the body of the metal cap is basically tying it to chassis ground. I will try and post a picture. I need to know if anyone else has that cap in there system.

http://s1277.photobucket.com/user/Coyotebill57Bill/media/IMG_1310A_zps0675f38a.jpg.html

After replacing the 8MFD cap with the 10MFD cap I tried to do the drive tuning procedure that Monarch sent me. I hooked my meter to GA2 and S1 on the DC scale. I set all the pots to zero, full CCW. I set the speed control pot on the front of the lathe to the mid position and placed the lever into the forward position. At that point I'm supposed to adjust the Minimum Voltage pot to 98VDC. At full adjustment the voltage only comes up to 62VDC, spindle was running about 250 to 300 RPM and pulsating. Right tube was pulsating and left tube was doing nothing. I tried playing with the compensation pot, that brought up the voltage but it was pulsating so badly that I could not get a clear reading.

At this point I think I can say that the field is not the problem, the armature circuit is. I will not be able to get back to the shop till maybe Sunday or Monday but I need some help.

Thank you
Bill

Another thing I noticed last night was when I was tuning the drive and could only get 62VDC, I turned up the compensation pot and that increased the voltage and made the spindle run, pulsating badly. When I turned the speed control pot on the front of the machine to zero, it would give the spindle a short burst of speed followed by 2 or 3 seconds with the spindle off. This happened in a regular timed interval, like a cap charging up and discharging. I'm not sure if this is part of the fault or a symptom of the fault.

What do I need to check next?

Thank you
Bill

I had a problem like that years ago on the one and only WIAD that I ever had and the culprit on mine was one of the little transformers under the cover that is part of the C16J circuit.

I got replacement transformers from a joint out in Las Vegas called Electra-Print Audio ( Jack) and they were about $50 bucks apiece. Years ago a forum member (can't remember who) had him figure out and reproduce these little guys and one made my Wiad all better. He even sent a marked up schematic and noted the one that was the one that failed most often. I'll check my old threads and see who did the legwork on the transformers and update this post with a name in a bit. Good luck, there are a lot of ghosts in that old lathe but when they work right they sure are sweet.

Hi usmachine, I sure hope it's not something that isn't readily available, I have been reading a lot of post on here with WiaD problems and someone mentioned swapping out tubes 6N7 and 6H6. Going to try that tomorrow night. I'll look at the print and see if I can locate that transformer. Maybe I can check it's output while it's running.

Thanks
Bill

I still have one with the little drawing Jack sent me. If that proves to be the problem you can try or buy my spare for what I have in it. If Jack is still around he might be worth getting in touch with. It was easy to swap and it worked like a charm. PS, no more Wiad's for me I am a confirmed MG man from here on out

I sure appreciate the offer, I'll let you know if I need to take you up on it. Tonight I messed around with it some more after reading a bunch more post on here.
Thanks to PaulM, I picked up a boat load of spare tubes, multiples of everything but the pricey C16J tubes. Of course they are untested being pulled out of different WiaD but I would have to guess that most are good.

So I started out by first swapping out both 6H6 and 6N7 tubes, 2 different sets and the machine was still pulsating badly on the armature circuit.

Then I pulled out the 6X5 tube as I read that doing so would disable the compensation circuit. Still behaved the same. Just for the heck of it, I tried 2 other 6X5 tubes. No change.

I read that I should look at the outputs of the current transformers on wire # A20-A26 and A21-A26. Supposed to be 80VAC. With the drive pulsating it looked like they were both outputting about the right voltage. This is were a nice old analog meter would come in handy. Digital's update to fast.

I went back to try and tune the drive again using Monarch's procedure but as before the minimum voltage pot would not increase the voltage beyond 59 to 60 VDC when I was reading on terminals GA2 and S1. What could be holding this voltage down? I'm at a loss at this point and don't know what else to check.

Thank you
Bill

Bill, I was looking for someone to answer who is well versed in WiaD electronics. The wiring on this machine is old and I don't want to disturb anything that I don't have to. If I had the time I would totally rewire the WiaD with modern wire and replace all the components that are available. I don't have that much time. Plus I don't understand the interaction of the components in the circuit like some of the regulars on here. I'm looking for some advice from the experianced people on this board who are far smarter on matters like this than I am.
This is old analog circuitry that was designed well before I was born and few people today understand it well. I have read hundreds of post on here trying to get up to speed all the while taking notes on things that I can check without disturbing the cloth covered wire bundles.
I have included my test results and am looking for expert answers from an expert on this drive. There are several such experts on this board and probably no place else in the world, except possibly Monarch itself.
These circuits are not laid out in a linear progression but rather branch off in a lot of directions with caps and resistors doing whatever they do in the circuit. Just locating a particular component is a nightmare with all the tied bundles of cloth covered wire sans ID numbers. That is why I am looking for direction on this. If I have specific things to look for than I can take those specific test. There is a lot of stuff in a limited space behind the front panel and not a lot of room to work on it.
My game plan is to get this running as soon as possible as it's very much in the way in a very crowded shop so we can replace the POS Jet lathe. After that I want to locate a spare WiaD drive that I can totally rebuild as I like the performance of the DC drive system. I know that the easy way out is to just replace this whole mess with a VFD drive, something that I'm a lot more familiar with. I don't want to go in that direction.

Thank you
Bill

Ok, I had to to think long and hard whether to get involved, but maybe I can help. You will be very hard pressed to find a WIAD "expert" anywhere anymore that can troubleshoot your drive either here or in person quickly. I have fully restored a WIAD from junk, and have no more electrical knowledge than you. My advice (and you don't want to hear it) is to check each component and wire run. Do you have ALL of the WIAD schematics? There is a simplified one that is very common, but then there is a "build" wiring diagram which actually shows where each wire goes. You should have one for your specific machine. The simplified one is worthless to me because I am not an electronics type guy, but I can certainly follow a wire on a old time schematic. Next, you need a analog multimeter, a la Simpson 260. The digital type I find to be more trouble on a analog unit like this. I will pull out my notes at home and see what I have.

I don't have a WIAD. Maybe I can help. My background is that I was raised on repairing radios and TV's from the 1950's forward. What you have is very familiar to me.

To start with, do you have a schematic of the control? If not use this one I got from the forum.



From what you have described, your problem is in the grid circuit of the left C16J. Since the C16J is not firing smoothly, I would suspect that the culprit is the 1.0 mfd cap.

The way that circuit is intended to work is the .001 and 240K resistor are noise suppression. The 51K and the 1.0 cap form the firing circuit. The firing pulse comes from the transformer above the 6H6. The 6H6 is used to discharge the firing circuit between firing pulses, the point of discharge is controlled by the 6N7. It is common in these old circuits for the capacitors to loose their ability to store charge. I would replace both the 51K resistor and the 1.0 capacitor. Do not change their values as this will result in uneven firing of the thyratrons.

Side note. The .1 cap that you noticed was blown and has no place to go except ground? That's where is goes. This is take noise out of the circuit.

Try replacing the .1 first and see what it does, then the firing circuit components.

An oscilloscope really comes in handy for these types of problems.

Tom

P.S. If you still can't fix it, I can take it off your hands for a nominal amount!

I have found a better schematic, but I'll have to send it to you in a email. It doesn't want to upload at Photobucket. Now its is a scan of a blueprint, so it is a tad faint but as a jpg you can enlarge the details.

Daryl, I had come across your pics before of your restored drive. That's why I'd like to find an orphaned WiaD someday. I won't go to the same extent as you but I want to restore one so that it has a new lease on life, for the rest of mine and someone else. Just beautiful. And I never knew it had a cover or one for the field loss relay.
As far as prints go I had Monarch Email me a set after giving them the SN. It's not what you have but it helps. The best set that I have came from Russ, I had it printed out 24 X 36, 2 copies. That at lease let me identify the different components and a whole lot more. Does the manual from Monarch actually show the layout wire by wire?
That would be handy if I ever rebuild one myself.
I'm on the lookout for an older meter. Now that the weather has gotten better, I'm scouring the flea markets for one.
Thanks
Bill

On Edit: Daryl, I think I'm good on schematics now but if it's no problem you can E-mail it to [email protected]

Thanks again
Bill

Tom, I thank you for the specific direction to head to. I agree that old caps can be troublesome and should be replaced. Using the large print that Russ sent me I identified the 1MFD caps as being the metal cans behind the front panel on the right side bottom. Being a metal can I take it that they are oil filled. On the copy of the drive tuning procedure that Monarch sent me was the electrical parts list. Looking at that I see there is a quanity of 2 caps listed with a 1MFD value with a voltage rating of 1000VDCW, with a part number of DYR10100. I'll search for that but I'm sure it's a Monarch number. Can I substitute a different style cap or must it be oil filled? Going to check Antique Electronic Supply and ggogle it right now. If I find them, I think I'll replace them both. As far as the 0.1 caps go, I bought several last week from AES, I'll try that first now that I see where it goes.

Thanks
Bill

For what is needed here, an oscilloscope is your best asset. The biggest problem is that most of the older Tektronix and HP scopes are not designed to handle the kinds of voltages you are looking at without special high voltage probes. The probes are available but pricey.

Regarding the capacitors, What was available in the way of dialectic materials in the 1940's and fifties was paper or oil filled. The paper materials were not that good for industrial conditions, hence the oil filled. Because of the oil, these capacitors were inherently high voltage. Not knowing exactly what voltages are present, I would guess a good quality 400-600 volt cap would be fine.

Tom

Hey Bill, let me know what you find, at least if I buy something off of you I know it will work. Problem with buying at a flea market is you have no idea until you get it home and test it. Didn't a lot of those old meters use non standard batteries? I remember some long cells that had to be special purchased.

Take care
Bill

Tom, I searched Digi-Key and found what I think will work.
1MFD 1000VDC cap Digi-Key PN 338-1155-ND (film caps)
51K 2 watt resister Digi=Key PN 51KW-2-ND

If this looks good I'll order 2 caps and 10 resistors. Parts list says that 7 total in the circuit. Daryl has me looking for a spare WiaD now. LOL Might as well stock up for when I find one.

Thanks again
Bill

On Edit: Quick question, are those caps polarized ?

Before ordering the resistors, try to determine what is there. Most likely it will be a ceramic tube about 3/8" diameter with a screw holding it to the panel. It may have a slider to adjust the actual resistance. If it looks ok, to start with I would not replace it. Whatever you do, don't use a carbon or composition resistor. They can be unstable and have a low voltage rating.

Tom

Tom, if you look at Daryl's pictures you will see a pic of the back side of the front panel. There is 2 sets of terminal strips with resistors mounted to them. My print with the component layout shows them in that location. I think Monarch just used carbon resistors for that application. The resistors I selected are 5% metal oxide film type. Do you think they will be good enough? I'm going to order some solder type terminal strips to mount the capacitors to.

Thanks
Bill

Mr Bridgeport said:

Tom, if you look at Daryl's pictures you will see a pic of the back side of the front panel. There is 2 sets of terminal strips with resistors mounted to them. My print with the component layout shows them in that location. I think Monarch just used carbon resistors for that application. The resistors I selected are 5% metal oxide film type. Do you think they will be good enough? I'm going to order some solder type terminal strips to mount the capacitors to.

Thanks
Bill

Click to expand...

Not sure what photo you are referring to, the only ones that I see are the ones you posted in your first post. There must be another set of photos.

Tom

I found them. Yes, those are two watt composition resistors. The color code is green(5), brown(1) orange(multiplier, 1000) bands. Anything after that is a tolerance, no band, +- 20%, silver band +-10%, gold band +- 5%.

For general information, the color code is, black(0), brown(1), red(2), orange(3), yellow(4), green(5), blue(6), violet(7), gray(8), white(9). Multipliers (zeros added after the color bands) Black(0), brown(1),red(2), orange(3), yellow(4), ...you get the picture.

This is how they taught the color code in the Air Force: Bad Boys Rape Our Young Girls But Violet Gives Willingly.

Cheers

Tom

I gave to color code so that the particular resistors would easy to find, but they need to be verified by tracing the wiring. The reason I gave for not using composition resistors is that they can change value without discoloring. Second problem is that the schematic that I have may not match the actual machine.

Another check to make is disconnect the .001 cap. It may have become leaky. The machine should run just fine without it, it just keeps noise out of the grid circuit. Also check the 240K resistor, it may have gone open. Its function is the limit grid current.

That's about all the components that could be causing one side to be different from the other than the tubes which you say you have changed. I assume that you swapped the 20 amp fuses. You could have corrosion in the fuse holder.

Tom