Retrofitting a 1986 Maho MH400E

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08 Nov 2019 20:53 #149937 by chris mcm
Yes when I was young I heard about the Dean Smith & Grace being the Rolls Royce of Lathes. They were so expensive only the Government work shops had them. I now have two of these relics of the past.
Frustrating for me but I have to wait for Brad who is very busy.
Thanks Mark

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08 Nov 2019 22:05 #149944 by andypugh

chris mcm wrote: Yes when I was young I heard about the Dean Smith & Grace being the Rolls Royce of Lathes.


Them's fighting words amongst Holbrook owners :-)

(I am caught in the middle, as I was brought up local to DSG, and used one of their headstocks in a cam plastometer once. But now own a Holbrook Minor (converted to CNC). But then the Holbrook folks look a bit askance at the Minor too)

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09 Nov 2019 08:27 #149968 by chris mcm
I should have also have said British Lathes. I am only an amateur machinist so my opinion does not really count. Sure you are right.

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09 Nov 2019 21:52 #150020 by chris mcm
Hello db 1981, Mark and Bob
We are doing the suggested checks tomorrow. I have just gone through the electrical schematics. They relate to the machine electrical number E 967 and I believe I have them all.
For db 1981. You wrote above. -check the 24V between 140/141 Page 8252, better with oszilloscop to see if all Diodes are ok.
Please what is page 8252. Is it a schematic? I don't have that number. My electrical drawings are numbered E 3 . 8260 to E 3 8280. I will post a copy of the list. I regret I can not speak German. Thanks again Cheers Chris

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09 Nov 2019 22:14 #150024 by chris mcm
Mark Bob db 1981
Here is the list of Electrical drawings I have. see documentcloud.adobe.com/link/track?uri=u...16-992a-069c29247a1b

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10 Nov 2019 07:49 - 10 Nov 2019 08:03 #150044 by RotarySMP
"Steuertrafo" = control transformer. This is on your sheet E3.8262. This will be the three phase transformer which outputs 19V AC, which is then rectified to DC by a bridge rectifier (item 6V1 on my mills schematics). It should look something like this...


MAHO numbers all terminals. You will probably find 140 /141 on the terminal strip at the bottom of the control cabinet.


Multimeter across them to ensure 24VDC output, and Brads Osci to check if the bridge rectifier has a dodgy diode.
Mark
Attachments:
Last edit: 10 Nov 2019 08:03 by RotarySMP. Reason: wrong terminal numbers.
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10 Nov 2019 10:37 #150046 by db1981
Hi Chris,

Sorry Your Page 8262, on the left side you can see the 24v Part with 140/141

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11 Nov 2019 06:18 #150084 by BradMck
Hi All,

I have been testing on Chris's Maho today and have found out the following
24 VDC Supply on terminals 140 & 141 is reading 29 volts and is steady.
I could not get the TNC 135 to reset the emergency stop contact (35/7 & 35/8 on the TNC 135) terminals 143 & 144.
I did a system power-up with the terminals in a normal state and bypassed, the TNC only has the LED s on and a point on the top-right display and no information on the screen.
The Hydraulic pump and bed lube pump runs for a Period (approx 20 seconds) I did not time this period
I Removed the enable signal (S21, S22 & S23) from the Indramat and found 9.3V & -9.3V terminal 9 XYZ with 16K1 Energized. I found -3V on terminal 10 XYZ. I reconnected the enable signal and found when trying drive any Axis the drives would only go in one direction. I disconnected terminal 10 XYZ and was able to get manual direction control in both directions on all Axis.
I have replaced the Backup batteries.

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11 Nov 2019 08:46 #150087 by chris mcm
Wow, the Maho is working again but with no D.R.O or TNC. Do we carry on and get the TNC working or do we start the retrofit.I can use the machine as it is today but the D.R.O would be nice.
Thank you Brad and all on this Forum who helped or offered to help. It would not have happened without your encouragement.
Cheers
Chris

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11 Nov 2019 09:06 #150088 by db1981
Hello Chris and Brad,

what we know now:

-hydraulic circuit and sensors are working
-the S5 is working
-the Indramat and the Motors are working
-PSU is ok

-TNC does not start up normal
-there is some strange behaviour in the analog output stages from the tnc

now you have to check if the TNC is internaly broken or is not working because of an extern factor (broken wire / transformator / button etc. )

I will write down the tests for this, as soon as i am back in my office.
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