Allied MultiPrep

Motor

Both motors (drive, osc) were identical

PITTMAN
GM8712-41
19.1 VDC
187:1 RATIO
MFG 05-29-98 S

33 and 17 ohm. Is one of these damaged? Why are their resistances so different?

Tried testing under load

• black goop
  • 12.19 V @ 1.266 A (current limited)
  • 8 ohm after
• other
  • Initially drawing way less current than first
    • 12.12 V @ 0.332 A (voltage limited)
  • then started smoking
    • 11.68 V @ 1.248 A (current limited)
  • 6 ohm after

Aren't these rated 19.1 V? Am I misunderstanding?

Try pinning out the spare bad head

• 1-5: 2.8 k
• 2-6: 147 R
• weird...

what does the secondary machine test? (believe good)

• 1-5: 9.0 R
• 2-6: 10.4 R

What is max voltage allied puts out on motors?

• 1-5
  • 7.6 (fixed)
  • osc

• 2-6
  • 15.0 (max)
  • drive

Head connector

Head plug

• 4x2 (8 pins)
• 3 mm pitch
• Head female, cable male
• Maybe Minitek Pwr™ 3.0 Series
  • https://www.digikey.com/product-detail/en/amphenol-icc-fci/10132445-08LF/609-5283-ND/7590945

8 pin mini-amphenol t o 8 pin mini-DIN "standard connector" https://en.wikipedia.org/wiki/File:Pseudo_miniDIN-8b_Diagram.png

Mini-amphenol	mini-DIN	Signal	Note
1	1
2	2
3	8
4	7
5	3
6	5
7	6
8	N/C

5 pin mini-DIN to 8 pin mini-amphenol Same connector as S-video Needed for old machine https://en.wikipedia.org/wiki/Mini-DIN_connector#/media/File:Close-up_of_S-video_female_connector.jpg

Mini-amphenol	mini-DIN	Signal	Note
1
2
3
4
5
6
7
8

Motor on mini-DIN

• 1: drive motor +
• 3: drive motor -
• 7 V
  

8 pin CPC to 8 pin mini-amphenol Guessing this was a custom cable

Mini-amphenol	cpc	Signal	Note
1	8
2	6
3	1
4	4
5	5
6	3
7	2
8	N/C

Tach board

• Adapts 8 pin to 4 pin
• Includes cap + 4 pin SMD component (489, probably hall effect sensor)
• Must interface to those two red things I was confused about...looks like they have magnets on the end
• Minitek 4x2
  • 1: 4x1.1
  • 2: 4x1.3
  • 3: hall, cap
  • 4: hall
  • 5: 4x1.2
  • 6: 4x1.4
  • 7: hall, cap
  • 8: chassis ground
• 4x1
  • 1: osc
  • 2: osc
  • 3: drive
  • 4: drive
    

Test primary machine motor via 4x1

• drive: 10.2 R
• osc: 5.6 R
  • *** out of spec
  • consistent with a failed motor

failed motors appear to be caused by carbon buildup from brushes. They will fail very quickly if you operate them even close to their rated voltage. I was able to disassemble and blow one out to fix it. Now it runs at about 12.22V @ 350 mA. Current went down over time, maybe was 500 mA initially

Lets try another... initially 12.22V @ 1.25 A. Visible smoke. Rotor very dirty...should have cleaned other rotor. After cleaning dropped to 12.22V @ 1.1A and then rose up. Hmmm. Clean between rotar contacts. Success! Now 12.21 V @ 153 mA! Significant improvement! 9.6 ohm now

Back to original motor. Cleaned, now drawing 12.21 V @ 0.180 mA. Seems pretty concrete: needs to be cleaned, especially between rotar contacts. Try 18.86 V @ 197 mA. 9.6 ohm

McMaster

2020-01-14

• Win cross sectioning kit

2020-02-20

• Order sample holder
• Order replacement tubing
  • Later found I had some spare, but meh can use for other projects

Primary

S/N 568

Hermitage: Allvia Sunnyvale? Not sure if they are still in business

2019-12-19

• Submitted offer. Negotiations failed

2020-02-19

• Seller accepted offer (was firm at old offer). Local pick up

2020-02-232

• Swap DRO from spare to primary machine
• Replace rusted micrometer

2020-02-23

• Observe osc motor is not moving
• Observe osc doesn't have slit like spare to keep in place...how is it supposed to work?
  • Is this a DRM thing of sort where they didn't supply the right adapter if the user didn't purchase osc option?
  • ie the motor was intentionally disabled and also mechanically hindered
    

Spare

???

• Won a few lots of parts TechPrep heads
• Goal: combine into one good head and mount on SBT machine

2019-03-20

• Try to get old TechPrep base. Negotiations failed

2019-12-20

• Won old TechPrep base machine. Change plan from retrofitting SBT machine to actually fitting on this machine
• Without reference machine a little difficult to piece together
• Machine filthy. Significant cleaning

2020-02-23

• Used reference machine to greatly accelerate repairs
• Made cable to hook up head
• E1.43 (error code?) persists, but machine seems to work fine