Rework Station Pump - Can They Be Repaired ?

[stj]

Re: Rework Station Pump - Can They Be Repaired ?

start with a re-cap

[mmartell]

Re: Rework Station Pump - Can They Be Repaired ?

I have verified with a magnet that the two magnets on the piston are indeed in the arrangement as posted above.

I need to recheck the coils to rule them out. After that it's a problem on the driver board - will post pics of that board soon.

Is there an easy way to test for the presence of an oscillating magnetic field ?

[mmartell]

Re: Rework Station Pump - Can They Be Repaired ?

Hmm.. will try with a compass though the frequency of oscillation may tear the needle off

[stj]

Re: Rework Station Pump - Can They Be Repaired ?

put a microphone near it - if it's between 50Hz and 15KHz it should detect it.

[mmartell]

Re: Rework Station Pump - Can They Be Repaired ?

Here are some pics of the control board. It has two bt137 triacs and an lm358 on it as well as a/c input from the mains. Can anyone infer from the pics how this works ? And is it safe to put a scope on the two wires driving the magnetic coils ?

[stj]

Re: Rework Station Pump - Can They Be Repaired ?

so which pair of wires goes to the pump?

[mmartell]

Re: Rework Station Pump - Can They Be Repaired ?

The two soldered to the back of the board in pic 4 and pic 5.

[stj]

Re: Rework Station Pump - Can They Be Repaired ?

resolder the power transistor or whatever it is,
the center pin looks strange in the foto's

[mmartell]

Re: Rework Station Pump - Can They Be Repaired ?

Resoldered the two triacs, the lm358 and several dubious joints. Reassembled the pump unit minus the back plate so I could see the movement of the piston.

Fired it up and no change.

The frequency was measured at 60hz. The a/c voltage changes with the air speed knob but the frequency remains at 60hz.

I noticed now that the wand no longer heats up, don't know how long it's been like that or if it's a related problem yet.

Feel like I'm chasing my tail with this one.

[stj]

Re: Rework Station Pump - Can They Be Repaired ?

i have a funny feeling the motor control is a phase-angle controller - like a lamp dimmer.
you will need a scope to see what it does, BUT maybe replacing the pump with a low wattage lamp bulb would be a good test.

[mmartell]

Re: Rework Station Pump - Can They Be Repaired ?

That is a good idea. From what I have read about triacs they can be used for phase angle control.

What should I expect to see with a bulb ? If it's safe to hook up a scope to the motor leads then I can do that, too.

[stj]

Re: Rework Station Pump - Can They Be Repaired ?

if your scope is good for mains - go for it.
if not, hook a small coil or inductor to the scope probe, put the voltage to max sensitivity per div, and put it on the wire!!

you should get a lamp with variable brightness from full to something less - not nothing obviously, but maybe 20% or so.

[mmartell]

Re: Rework Station Pump - Can They Be Repaired ?

But at 60hz I'd doubt I would even see flicker ? Won't hurt to try.

I don't think I'm comfortable hooking up my scope to mains which is why I was wondering if the motor was somehow isolated from mains already.

[stj]

Re: Rework Station Pump - Can They Be Repaired ?

no, unless you see an isolation transformer the pump is live.

is the pump marked with it's voltage or wattage etc?

[vinceroger69]

Re: Rework Station Pump - Can They Be Repaired ?

theres a link in this video at the end that maybe usefull
https://www.youtube.com/watch?v=azmuyKNEyeI

[mmartell]

Re: Rework Station Pump - Can They Be Repaired ?

That is the same unit as mine essentially. My diaphragms are fine though.

The pump has no markings whatsoever.

[mmartell]

Re: Rework Station Pump - Can They Be Repaired ?

Used a short stack of 9v batteries to drive the piston in both directions so the pump itself is fine.

The driver board itself consists of two BT137 triacs, an op amp, a couple of caps and several diodes and resistors including eleven high wattage ones.

Earlier I measured the ac voltage to be variable (60-120v) at 60hz. There is no way this piston can oscillate that fast so there must be a breakdown of the circuit feeding it.

Can anyone explain how they think the ac wave is constructed to drive the pump ? By what means can this circuit change a 120v 60hz voltage to say 120v at 5hz ?

[mmartell]

Re: Rework Station Pump - Can They Be Repaired ?

Need some help here before I back over this thing with my car.

Can anyone shed some light on how the pump is driven based on the pics of the board I posted earlier ?

[stj]

Re: Rework Station Pump - Can They Be Repaired ?

did you try replacing it with a lamp?

[mmartell]

Re: Rework Station Pump - Can They Be Repaired ?

No because I measure 120v @ 60hz at the pump (coil) terminals. I have to believe that 60hz is way too fast for that little piston so I'm relatively certain something in the circuit must have failed.