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
- Initially drawing way less current than first
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
Mini-amphenol | mini-DIN | Signal | Note |
---|---|---|---|
1 | 1 | ||
2 | 2 | ||
3 | 8 | ||
4 | 7 | ||
5 | 3 | ||
6 | 5 | ||
7 | 6 | ||
8 | N/C |
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
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
Try osc motor. Didn't try running initially for fear of damaging. After cleaning (worst of all motors so far) 12.19V @ 175 mA. Current seems to be going down as well. 12.19 V @ 200 mA installed. However system is still not turning it (ie its not applying voltage). Other motor is about the same (even though it wasn't cleaned).
Osc 9V on 8 pin. Osc motor being driven at 1.3V. Maybe power supply is failing? Motor current via benchtop PS seems okay to me. Cross strapped channels and verified drive channel can drive either drive or osc, but osc cannot drive either channel. Probably need to open the unit up
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