MEP 805B CMOS Voltage

[remote power]

Just purchased a MEP805B. Can't get it to produce voltage. I have a CMOS voltage light on backplane and am not sure what that means. Any help is appreciated.

 

[rustystud]

Just purchased a MEP805B. Can't get it to produce voltage. I have a CMOS voltage light on backplane and am not sure what that means. Any help is appreciated.

Check to see what "codes" are showing. They will be numbered 1 to 20 or 22 . Either way there will be codes showing in the message plate. I have not heard of the CMOS voltage code myself.

 

[remote power]

thank you sir! been reading about your rewiring job ..may end up doing this myself ... 805b has a windows based monitoring system the backplane is similar to a mother board with LED status lights..cmos is one of those status lights..read the entire tm and just one paragraph on cmos...really don't know what to check for cmos voltage..AVR has LEDs and is showing to not b receiving field voltage..are they related? followed tm and checked everything related to field circuit and all checked out ok..can manually excite field and generator produces power!!hate to order parts till I figure out cmos LED warning..nice gen but really don't need a computer to create headaches!!

 

[rustystud]

There must be a transistor that feeds the regulator that has failed. This is one reason I truly hate electronic controlled devices !

 

[remote power]

what happened to simplicity?? turn a key,, engage a breaker,, no worries..will end up gutting computer and rewiring.. thanks for the help..will watch forum and figure out how I will convert gen set..

 

[rustystud]

what happened to simplicity?? turn a key,, engage a breaker,, no worries..will end up gutting computer and rewiring.. thanks for the help..will watch forum and figure out how I will convert gen set..

For emergency power I want simplicity not complexity in my generator. That is one reason I have gutted my MEP-002A and MEP-003A generators. I will also never be using any of the newer computer controlled units for my home back-up power. After working on computer controlled diesel engines and transmissions for the last 20 years now I am convinced they have no place in my life !

 

[remote power]

Amen!! Lets eat!

 

[unclebeau]

Just taking a shot in the dark, but on computers, the cmos is the stored data, date time etcetera.

Like a computer it should have a coin type battery to keep the internal clock and information up to date,
When the battery dies and you boot up the computer you get an error, then you use an “F” key to enter
into the cmos to manually enter the data and reboot it. It sounds like the internal battery is / maybe dead…

 

[kloppk]

... I have a CMOS voltage light on backplane and am not sure what that means. Any help is appreciated.

According to TM 9-6115-671-14 page 2-13 the CMOS voltage light indicates....
CMOS voltage.
If indicator is lit, indicates voltage necessary for CMOS device operation is too low.
If not lit, CMOS device voltage source is sufficient.

Lots of good information in the table regarding the diagnostic and status LED's in the TM.

CMOS is a technology type of integrated circuits ( memory & logic)
CMOS memory has been used in computers for many years to hold configuration data for a PC's motherboard and is typically powered with a button battery (as mentioned earlier) so that it doesn't "forget" when the computer is powered off.

 

[The HUlk]

Many circuit boards with digital logic, which is usually what CMOS refers to, use 3 or 5VDC to power the ICs (microchips). The power either comes from an external power supply in the correct voltage, or a higher voltage is reduced and cleaned up in an onboard regulator circuit. As a previous post mentioned, there may be a small battery which is usually on the board to maintain data memory of some sort which is wired directly into the IC power supply circuit. If it's dead it could be pulling down a regulator circuit that is not designed to carry a dead battery. Could be the regulating circuit, or external power supply as well.

 

[The HUlk]

The most common regulator on circuit boards is the 7805 variety. They are a three leaded transistor looking device and should measure 5VDC on the GND(usually center pin) to OUT pin. The reading from GND to the other pin should be 5V or (usually) higher.

http://lmgtfy.com/?q=7805+regulator

 

[mouse123]

Dear sir did you ever come up with a fix for the low cmos voltage I also have mep-805B and having the same problem .

Thanks

Paul

 

[NEIOWA]

pg 74 of TM 9-6115-671-14

LED 5 (red) CMOS voltage. If indicator is lit, indicates voltage necessaryfor CMOS device operation is too low. If not lit, CMOS device
voltage source is sufficient.

 

[Guyfang]

Are your batteries FULLY charged? If the battery voltage is low, you can get this failure.

 

[Billy2642]

Was there ever a solution figured out for this? I'm having the same exact issue

 

[geoheat]

MEP-806B not producing voltage..

Just purchased a MEP805B. Can't get it to produce voltage. I have a CMOS voltage light on backplane and am not sure what that means. Any help is appreciated.

I had the same problem due to me not familiar with the generator I just bought. My maintenance man found out that when you start the engine, hold the selector switch on start for about two more seconds. OR, when the engine is running, hold the start switch on start until the voltage is shown. I hope this helps

 

[brad.boudreaux]

Just purchased a MEP805B. Can't get it to produce voltage. I have a CMOS voltage light on backplane and am not sure what that means. Any help is appreciated.

I see this post is super old but I was unable to find much on the CMOS voltage error so maybe this will help someone in the future. I had the same issue and contacted GAC and was told that this is normal. The design of the board was supposed to include a coin cell battery in the I/O module but that never got put in the final design. I would think all MEP-805B machines will have this 'fault' but it doesn't effect anything.

 

[Guyfang]

I have to differ. If you have no CMOS voltage, the gen set will not run right, or at all.

 

[brad.boudreaux]

I have to differ. If you have no CMOS voltage, the gen set will not run right, or at all.

You are probably right about having no/low CMOS voltage on the board. This fault condition indicated on the TCM102 board is tied to a battery that was omitted in the final design. My unit has this LED lit and runs fine, the manufacturer said its normal on my unit.

 

[Guyfang]

There are several versions of the TCM-102 board. Some have it, some dont.