AVS1408 Drive troubleshooting
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  1. #1
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    Default AVS1408 Drive troubleshooting

    I posted this under the Monarch forum as they bought Lodge & Shipley. I was able to get an electrical diagram from Monarch, but it does not go into detail on the Reliance SCR Drive Power supply. Problem is spindle motor does not run. I have 208V 3 phase at the input terminals to the SCR power supply. When I turn on the spindle I see 5V gate pulses to half of the SCRs. and no voltage out of the SCRs.

    Monarch says parts are obsolete and not available

    My assumption is the Motor is DC. I attached a picture of the nameplate, but reading it I can not confirm it is DC.

    I have been trying to find specs on the SCRs. while google has surplus units, I really want to see a data sheet. I am not fully convinced the SCRs are the problem, which was my first guess. The Assembly Part number is 69371-10A, and the actual SCR is a GE 410403-23AC 839.

    My current thought is if I am only getting gate pulses on one side of the Rectifier I wont get return current thru the return side.

    Brian
    image3.jpgimage1-3-.jpgimg_2052.jpg

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    Motor data plate has a field specification, so DC.

    From what I can see in the schematic the drive looks to be a good one with nice features.

    If your motor spins in reverse and not forward it could be an SCR problem.

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    Motor does not run either direction. In the top right corner of the drawing, where the Driver and Control Rectifiers and power supply block is. I have 208 3 phase on 181,182,183 and nothing between 47 and 45. but now looking at the drawing with trying to under stand how the reversing would work, I don't think i should see voltage between those two terminals. Maybe I should have voltage between X0 and 47 in forward and X0 and 45 in reverse.

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    You do need gate voltages on all 6 SCR's if only half are getting gate voltages then you will not have any DC out to run the motor you need to find the gate driver and check where you are being stopped.

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    if X0 is a center tap on a wye (not sure) then, maybe three would conduct on the positive half and the other three would conduct on the negative half. thuss selecting motor direction. I don't see any other way on the drawing that direction would be achieved.

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    this also would explain the 120V rating on the motor

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    Check each input power phase to X0 should be 120 Volts or so.
    Is the phase rotation correct? You will not get any output power if wrong.
    One bank of SCR's is for Fwd and the other for Rev.

    Bill

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    Quote Originally Posted by kb1cjp View Post
    if X0 is a center tap on a wye (not sure) then, maybe three would conduct on the positive half and the other three would conduct on the negative half. thuss selecting motor direction. I don't see any other way on the drawing that direction would be achieved.
    Seems so, yes.

    Looks to be a typical 3-P-only "2Q" drive. "Contactorless" as to use of the SCR's for determining output polarity for direction of rotation selection (or none / OFF).

    But not with the regenerative braking or over-run management of a "4Q" drive. Even a nominally "2-Pulse" SSD single-phase drive uses 8 trigger circuits into a 12-diode array for that.

    It DOES have Field Regulation, though, so good performance and stability when in the higher-RPM "Field Weakened" zone.

    Are we reading 5,000 RPM as the "Do Not Exceed" on that motor plate?

    The good news is that whilst there are limited OEM choices for the 230 VDC 10EE motors for running off single-phase AC, there are PLENTY of DC Drive choices for 3-Phase feed, 10EE, and easily as many for this motor.

    Most concurrent and newer 3-P DC Drives DO have Field Regulation either on-PCB already, or as a plug-in module option, and OEM integrated, either way.

    No downgrade required. Possible easy upgrade - better braking if you use a 4Q drive, but otherwise much the same as a 2Q. (a 1Q drive would need contactor-reversing)

    Replacing the DC Drive outright with any of several newer ones should be easy, technically.

    Not so good news is the need to find the budget for such a critter. About $700 to $900 and up, even in the used or NOS marketplace, last time I looked. Not sure I'd buy used, though they are lower-risk than a VFD of similar age.

    So....

    Board-level repair of the existing DC Drive is almost certainly do-able as well, if a tad tedious

    First, as to getting a better idea as to how easy/hard to find components, let's see if you have a passle of Burr-brown or Analog Devices op-amps on that board ...or if they did something else to implement the physical world of those schematic logic symbols for sensing and control.

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    My made in 1969 1408 AVS apparently has the same 7.5HP motor. The 120V @ 56.25 amp armature seems a bit odd. Field is 240V. Monarch would not send me anything about the drive, they would just say that it is "Obsolete!"

    Do you know the model of your Reliance drive? My SCRs look very similar to yours, with some differences. The drive is the Cardpak series. I would really like to find a service manual and schematic. While the cabinet is loaded with stuff, it seems very modular and there are no ICs.





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    Quote Originally Posted by Glug View Post
    My made in 1969 1408 AVS apparently has the same 7.5HP motor. The 120V @ 56.25 amp armature seems a bit odd. Field is 240V. Monarch would not send me anything about the drive, they would just say that it is "Obsolete!"

    Do you know the model of your Reliance drive? My SCRs look very similar to yours, with some differences. The drive is the Cardpak series. I would really like to find a service manual and schematic. While the cabinet is loaded with stuff, it seems very modular and there are no ICs.




    An "operational amplifier" is a form of IC - analog, not all that many transistors, but may be in TO round hermetic metal packaging resembling a transistor with "extra" leads.

    The big bump in their adoption was early 1960's to early 1970's before digital took off.

    With not as much exposure to capacitors that age badly, these DC Drives CAN be rebuilt. Service firms charged about as much to do it -not for the parts, but for keeping alive the data and experience plus lots of decent bench tech gear for analysis and testing.

    It became wiser to swap-in a new drive, new warranty, folks did so.

    Meanwhile later AVS used early 3-Phase-only VFD and AC motors, as did later 10EE.

    DC motor is a good 'un, it will be well worth keeping.

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    Glug, your cabinet looks almost identical to this one, and the age is very close. The schematic I put in my OP is the most detailed of the 4 pages I got from Monarch. The other three were more block diagrams, and one with relay logic. I think I made progress on it the other day. I reassembled and re wired the cabinet, and started going thru and writing down voltages on the drawing. Everything seemed right, ececpt the armature output was 5vac, 0vdc. Field voltage looked good. I started moving the current gain control, and watching the armature voltage. It flucutated but not in a manor I would of expected. Then when I rotated the gain control rapidly I heard a hum and the main breaker in the cabinet tripped. That lead me to the conclusion that maybe the problem is on the motor side. I disconnected the wire going to the armature, and ended up with 150vdc. The weekend guys were going to pull the motor and I’ll find out next week. The guy that has been there the longest has not seen any maintenance done to this motor in over 20 years, short of changing the belts. Just talking this one thru with everyone has been a great help, Thanks!

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    Check to see if you have field voltage on the motor and if you can check the current to DC of course

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    Thanks for all the input everyone, Got the Lathe back running today. Pulled the motor out, everything looked good, dropped it off at a local motor shop, who said they could test it, and it came back good. Motor back installed, same symptoms, no voltage on the armature, disconnect it and voltage looks good. Checked Armature current and it looked to be about 0. I disconnected the current feed back on Terminal 219 and the motor started turning and continued to accelerate until I killed the power. On the PCB to the left with the gain controls on it, I found a burned resistor and capacitor. The resistor was in series with the 120V coil on 1S relay. Which looks like 1S grounds the speed control input. I have a feeling the capacitor went bad and took out the resistor. Replaced the components and we are back up and running!

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