SOLVED Van Pelt Drive Problem

[Travis]

I build this Van Pelt Drive and it's doesnt work. I don't know why.

 

[Travis]

Resolder these 3 pads
View attachment 6978

I did, still doesnt works

 

[music6000]

1. Swap BS170 Q1 with Q2 & take reading.
2 Swap Q2 with Q3 & take reading.

 

[Travis]

1.SWAP

D1: 5.49v
S1: 0.48v
G1: 3.06v

D2: 4.57v
S2: 2.14v
G2: 0.14v

D3: 2.39v
S3: 0.86v
G3: 0v

 

[Travis]

2.SWAP

D1: 5.47v
S1: 0.48v
G1: 3.12v

D2: 4.56v
S2: 2.12v
G2: 0.14v

D3: 2.30v
S3: 0.90v
G3: 0v

 

[Travis]

SWAP 1 I changue Q1 with Q2.
SWAP 2 I changue Q2 wih Q3

 

[music6000]

Do a Continuity test with matching Colours, Only test to Component legs, not Pads:

 

[Travis]

Red and blue OK

Green no continuity

 

[music6000]

Updated , Try Continuity Test again ^^^^^^^^^^^^^^^^^^^^^^^

Can you measure RESISTORS R10 -180r & R14 - 330r

 

[Travis]

All correct, i don´t know what happens :/

 

[Travis]

Updated , Try Continuity Test again ^^^^^^^^^^^^^^^^^^^^^^^

Can you measure RESISTORS R10 -180r & R14 - 330r

voltage in resistors?

 

[music6000]

I mean measure Resistance to make sure R10 -180r correct value & R14 - 330r correct value with Multimeter.

 

[Travis]

I mean measure Resistance to make sure R10 -180r correct value & R14 - 330r correct value with Multimeter.

Ok I Will do It

 

[Chuck D. Bones]

WK29 BS170 DSG

D1: 7.75v
S1: 1.54v
G1: 0.62v

D2: 1.31v
S2: 2.46v
G2: 0.26v

D3: 2.49v
S3: 0.86v
G3: 0v


IC TL072
18
27
36
45

1: 4.36v
2: 4.23v
3: 4.29v
4: 0v
5:4.24v
6: 4.29v
7: 4.29v
8: 8.59v

I'm just catching up on this...
Don't bother measuring gate voltages unless you know the meter's input resistance. Even then, it's problematic. The cheap ones are 1Meg and the good ones are 10Meg. They will all affect the measurement. We can infer the gate voltage from the source & drain voltages.

Q1:
D1 voltage is too high, S1 is too low. Measure the voltage at the high (not ground) side of R3.

Q2:
I don't believe the reading because it is not possible for the drain voltage to be less than the source voltage.

Q3:
All 3 readings make no sense.

My best guess is there are shorts or some wrong resistor values.

IC voltages all look good.

Now for the swaps:
Swap 1.
Q1 voltages are not right.
Q2 voltages are not right.
Q3 voltages are not right.

Swap 2:
Same story.

I think some of the measurements are suspect. The board has to be very clean and very dry because the tiniest leakage currents will throw off the bias on the MOSFETs. Make sure only the meter probes are touching the board. Skin resistance is smaller than the gate resistors, so if your fingers touch any of the gate circuitry, the measurement will be wrong. It's very easy to damage MOSFETs with static electricity, so it's possible some of them are bad. Your worktable should be grounded and the humidity must be above 25%. When not installed on a board, MOSFETs should be stored in an anti-static bag or a conductive container. Aluminum foil works well in a pinch.
When everything is working properly, the drain voltages on Q2 & Q3 will be around 4.5V. Q1's drain will be more like 6V.

 

[Travis]

I'm just catching up on this...
Don't bother measuring gate voltages unless you know the meter's input resistance. Even then, it's problematic. The cheap ones are 1Meg and the good ones are 10Meg. They will all affect the measurement. We can infer the gate voltage from the source & drain voltages.

Q1:
D1 voltage is too high, S1 is too low. Measure the voltage at the high (not ground) side of R3.

Q2:
I don't believe the reading because it is not possible for the drain voltage to be less than the source voltage.

Q3:
All 3 readings make no sense.

My best guess is there are shorts or some wrong resistor values.

IC voltages all look good.

Now for the swaps:
Swap 1.
Q1 voltages are not right.
Q2 voltages are not right.
Q3 voltages are not right.

Swap 2:
Same story.

I think some of the measurements are suspect. The board has to be very clean and very dry because the tiniest leakage currents will throw off the bias on the MOSFETs. Make sure only the meter probes are touching the board. Skin resistance is smaller than the gate resistors, so if your fingers touch any of the gate circuitry, the measurement will be wrong. It's very easy to damage MOSFETs with static electricity, so it's possible some of them are bad. Your worktable should be grounded and the humidity must be above 25%. When not installed on a board, MOSFETs should be stored in an anti-static bag or a conductive container. Aluminum foil works well in a pinch.
When everything is working properly, the drain voltages on Q2 & Q3 will be around 4.5V. Q1's drain will be more like 6V.

Thanks Chuck.
I'm learning a lot I Will improve those things

 

[Travis]

I check this and I weld again some pads and now its works. R10 was in bad condition.


Thank you

I mean measure Resistance to make sure R10 -180r correct value & R14 - 330r correct value with Multimeter.