Used Pasquini Livia 90 with some strange electronics

Need help with equipment usage or want to share your latest discovery?
BenKeith
Posts: 309
Joined: 10 years ago

#1: Post by BenKeith »

I have a Livia 90 Auto I bought not working and missing parts. I installed a new pump and while wired in the machine it won't run, yet there is 120VAC across the two terminals on the motor. I can take a lamp cord with spade terminals on it connected directly to it and plug it into and outlet and it pumps just fine. I both cases, the motor is reading 120VAC across the two terminals.

If it there was a bad connection in the machine, there should be a voltage drop across the terminals when the power is applied to the pump and the machine would not be applying 120VAC across the motor. If it was open terminals I was measuring across, open load voltages will lie to you. When you apply the load, open load voltage can go away, but in this case, the load is applied and has it's 120VAC.

Also understand, I'm not exactly a novice at this stuff, I have a degree in electronics and about 50 years experience, but this one has me scratching my head. Obviously, there is something going on with the machine that I have to locate, but how it can have 120VAC across the motor in both cases, and run in one and not in the other, that's a new one on me.

Advertisement
User avatar
cuppajoe
Posts: 1643
Joined: 11 years ago

#2: Post by cuppajoe »

First off, if you haven't already, disconnect the heating element before further testing.

The Livia 90 has auto fill for the boiler. If the boiler is full. pump won't run. If the fill sensor in the boiler thinks it is full due to a fault, pump will not run. Easy test is to short the fill sensor lead to ground, pump should stop when grounded and stop when not.

If it is the Auto model, that introduces another can of worms as the brain also controls the pump for brewing and auto fill.
David - LMWDP 448

My coffee wasn't strong enough to defend itself - Tom Waits

jonr
Posts: 610
Joined: 11 years ago

#3: Post by jonr »

Try switching the two leads to the pump (which doesn't actually consume AC).

DaveC
Posts: 1743
Joined: 17 years ago

#4: Post by DaveC »

If I understand you correctly...It's an AC pump (so no polarity issues), the pump terminals show power yet it doesn't pump, when you connect those terminals directly to the A/C power supply the pump runs.

if the above is the situation, then you have leakage via some component in the machines with such high resistance that there is insufficient amperage for the pump to run. When you connect it directly, then there is more than enough amps and it runs. The fault could lie in a few places especially if the wiring was ever mucked about with. Normally I would say something like a heating element would be favorite for this sort of high resistance leak, but they usually leak to earth....not neutral.

The other cause could be modifications to the electronics that you have not mentioned, or are not aware of.

BenKeith (original poster)
Posts: 309
Joined: 10 years ago

#5: Post by BenKeith (original poster) »

The heater was disconnected before plugging it in the first time.
I admit, it has to be a faulty component but there's some strange stuff going on
Normally when you have leakage through a bad component giving you a fake voltage, as soon as a load is applied, that voltage is going to drop significantly when the load is applied. No different than throwing a huge resistor in line. I don't know how many times I've seen people check a fuse without a load and assume its good, but as soon as the load is applied that voltage goes away.
No mods have been performed. I have the factory schematics and everything is as it should be.

ira
Team HB
Posts: 5497
Joined: 16 years ago

#6: Post by ira »

Is it possible someone replaced the pump with one with an internal diode and there is also a diode somewhere else? Can you try reversing the leads to the pump and see if that changes things?

Ira

BenKeith (original poster)
Posts: 309
Joined: 10 years ago

#7: Post by BenKeith (original poster) »

It's was missing the pump and this is a new one. I've already tried swapping the leads and it makes no difference.
It will be Sunday before I get a chance to work on it again but I will make up a short jumper and start bypassing components until I find the one causing the problem. Normally, you can just follow the voltage drop back until you find it but for some strange reason, with this one, the is no voltage drop.

Advertisement
jonr
Posts: 610
Joined: 11 years ago

#8: Post by jonr »

An oscilloscope will show what the pump is really seeing. A multi-meter - it completely depends on which model you have.

ira
Team HB
Posts: 5497
Joined: 16 years ago

#9: Post by ira »

Which reminds me, measuring AC on the DC setting of a multimeter is often useful. Why don't you try that on the line and the pump terminals and see what you get.

Ira

BenKeith (original poster)
Posts: 309
Joined: 10 years ago

#10: Post by BenKeith (original poster) »

My meter is a Fluke and it will not read AC when DC is selected.
I don't do enough of this stuff now and really have the room to keep an O-scope setup on my bench. I had to take my reloaders off the bench and put away my reloading equipment to make room to work on it. I have a couple Tektronic scopes I can drag out if needed, but I'm pretty sure when I get a chance to check it, using a jumper cable will identify where the problem is

Post Reply