MEP-804A Gauges

[loosegravel]

I posted a message a few weeks ago about this MEP-804A unit. When I picked it up from the GP auction site in Chehalis Washington it had an A/C volt meter in place of the M9 percent power gauge. I’ve sourced the correct gauge (used on eBay) and installed it today. From the wiring schematic I know that wire #120A is positive and 124A is negative. One thing that isn’t in the schematic is the shunt/spring that was on the back of the A/C volt meter that I removed. Does it belong on the percent power gauge? This shunt/spring is located on the back of the M2 hertz gauge. That gauge is not working at the moment. It stays right where it is in the picture when I run this machine regardless of the frequency adjustment (which works fine) I’ve also shut down the machine and switched to 50 hertz. Still no action. The machine is producing power. Long post, I know. Thanks as always for the help!

 

[nextalcupfan]

Take the spring off its just for transport.
I think its for dissipating static when it's new in the box?

Maybe someone else can chime in here but would that spring damage the frequency transducer? since its dead shorting it?

 

[loosegravel]

Take the spring off its just for transport.
I think its for dissipating static when it's new in the box?

Maybe someone else can chime in here but would that spring damage the frequency transducer? since its dead shorting it?

Thanks. That’s why I posted this. It doesn’t show it in the schematics, but the hertz gauge also has one and it’s also not in the schematics.

 

[nextalcupfan]

Here's the back of the panel on my 803a for some reference.

 

[loosegravel]

Here's the back of the panel on my 803a for some reference.
View attachment 861604

That’s what my MEP-803A looks like also. No shunts/springs on any of the gauges. Interesting huh?

 

[loosegravel]

Here's the back of the panel on my 803a for some reference.
View attachment 861604

Take the spring off its just for transport.
I think its for dissipating static when it's new in the box?

Maybe someone else can chime in here but would that spring damage the frequency transducer? since its dead shorting it?

Thinking about it, the shunt/spring between the two terminals would add a resistance value because it’s a coiled wire. I don’t believe it would be a dead short though. I just wish that I knew if they’re both supposed to be there. I’m only seeing it on the hertz gauge, and it was also on the back of the A/C volt meter that I removed. It was not on the back of the used percent power gauge that I installed.

 

[loosegravel]

Well, I went on GP this morning hoping to find pictures of other MEP-804A units with the gauge panel opened. I came across a couple of them. No shunts/springs/resistors behind any of the gauges on two different units. I'll take them off and run this unit under a load later today and check it out. (If it's not raining of course!)

 

[Guyfang]

No. The shunt spring will not hurt anything. But it will keep your meter from working right. Nextalcupfan has it right. Its for transport and storage. I have seen this ten thousand times. In your case understandable. The right meter was not there. But most times people toss the meter in, and have to take the old meter out. STILL, they put the meter in with the spring. Do not read into the schematic. There is no shunt spring on the schematic, so, there is no shunt spring on the set.

 

[loosegravel]

No. The shunt spring will not hurt anything. But it will keep your meter from working right. Nextalcupfan has it right. Its for transport and storage. I have seen this ten thousand times. In your case understandable. The right meter was not there. But most times people toss the meter in, and have to take the old meter out. STILL, they put the meter in with the spring. Do not read into the schematic. There is no shunt spring on the schematic, so, there is no shunt spring on the set.

Thank you sir!

 

[loosegravel]

With the help from this forum and a little patience all of the gauges on this MEP-804A are now working as designed! I removed the “shipping spring/shunt from the back of the hertz gauge and it dials in just fine. The percent power gauge seems very accurate also. I ran this unit for a good hour this morning using the brine tank method for a load. As the brine heats up the amperage also goes up. So I just have to raise the rods out of the brine tank to reduce the load. Crude, I know. But it works and it’s cheap!

 

[loosegravel]

With the help from this forum and a little patience all of the gauges on this MEP-804A are now working as designed! I removed the “shipping spring/shunt from the back of the hertz gauge and it dials in just fine. The percent power gauge seems very accurate also. I ran this unit for a good hour this morning using the brine tank method for a load. As the brine heats up the amperage also goes up. So I just have to raise the rods out of the brine tank to reduce the load. Crude, I know. But it works and it’s cheap!View attachment 861659View attachment 861660View attachment 861661View attachment 861662View attachment 861663View attachment 861664View attachment 861665View attachment 861659View attachment 861660View attachment 861661View attachment 861662View attachment 861663View attachment 861664View attachment 861665

In case someone is wondering, that’s a MEP-803A behind the brine tank. I have it hard-wired to the main panel on the house with an interlock. I wasn’t working on that machine today. You might also notice that I’m using some grounding rods for the brine tank load. I drilled 1/4” holes in one end and soldered terminal eyes on the cables.

 

[Guyfang]

We did it this way in 1975. Crude, but works. I would not stand within 20 meters of the thing.