MEP005A 5volts only

[pf.hal1984]

So I was recently tasked to get this generator working. I only get 5 volts from the 120ac power outlet when I'm holding the start switch and maxing out generator speed. 50hz on the gauge. Once i release the start switch everything goes back to 0. The batteries are not charging as well. It runs perfect. I'm leaning towards the voltage regulator/excitor. If it is this part, what exact part would go out in it to cause neither side to generate power?

 

[Zed254]

All the TM's you need to work on the MEP-005A

Thiy should be all the TM's you need to work on the MEP-005a

www.steelsoldiers.com

Good reference material. TM5-6115-465-34 has a good troubleshooting guide.

 

[pf.hal1984]

So here is what I got. On the A5 circuit board Resistor R3 looks burnt. 5905-00-357-3093 resistor is not available anywhere along with A5 board 6110-00-201-6015 . Would anyone have any information on where to find these parts?

 

[kloppk]

Looks like it's a 1.5 Kohm 10 Watt wire wound resistor.
Length 1.78"
Diameter 0.375"

Digikey has one that match's the specs above.
Resistor

Manufacturer Vishay Dale
Series RS
Packaging Cut Tape (CT)
Part Status Active
Resistance 1.5 kOhms
Tolerance ±1%
Power (Watts) 10W
Composition Wirewound
Features Moisture Resistant
Temperature Coefficient ±20ppm/°C
Operating Temperature -65°C ~ 250°C
Package / Case Axial
Supplier Device Package Axial
Size / Dimension 0.375" Dia x 1.780" L (9.53mm x 45.21mm)

 

[Guyfang]

This is a very normal fault with this set. Before replacing R3, and installing the SP/Relay box, do check K7, and CR4. Its easy. apply 120 volts on pins A5-18, and A5-22. You should hear and feel the K7 click as it opens and closes its contacts. Open up TM9-6115-464-12, to PDF reader page #338. At the top right corner is a schematic for the A5 card. You can also test K7 when its not plugged into the A5. Its in the TM also. If you cant find it, say something and I will post something. Like Kurt posted, its a stink normal resister. Easy to replace.

 

[pf.hal1984]

This is a very normal fault with this set. Before replacing R3, and installing the SP/Relay box, do check K7, and CR4. Its easy. apply 120 volts on pins A5-18, and A5-22. You should hear and feel the K7 click as it opens and closes its contacts. Open up TM9-6115-464-12, to PDF reader page #338. At the top right corner is a schematic for the A5 card. You can also test K7 when its not plugged into the A5. Its in the TM also. If you cant find it, say something and I will post something. Like Kurt posted, its a stink normal resister. Easy to replace.

I will do just that but one question before I break out my laptop. 120v or 12v?

 

[Guyfang]

If you mean the relay, it's 24 volt

 

[pf.hal1984]

If you mean the relay, it's 24 volt

So I applied 12v to a5 22 and a5 18 and nothing. But I pull the relay and test it, it works. I swapped the K1 out as well. And same thing. Also CR6 has resistance. About 500 ohms.

 

[Guyfang]

So I applied 12v to a5 22 and a5 18 and nothing. But I pull the relay and test it, it works. I swapped the K1 out as well. And same thing. Also CR6 has resistance. About 500 ohms.

No, apply 120 VAC to pins 22 & 18.

 

[peapvp]

Next thing would be to check A11.

The Relay on A5 is operated by 120VAC through a bridge rectifier and a resistor as voltage step down to 24VDC

 

[pf.hal1984]

No, apply 120 VAC to pins 22 & 18.

I applied 120v to 18 and 22 on a5 and there is a click. I soldered in new resistor and still nothing.

 

[peapvp]

Now comes the time to dissect A11

 

[pf.hal1984]

I assumed that the A11 would be the issue when I first assessed the generator. I also assume that the K5 relay on the A5 card is an issue because both battery generation and the generator set itself have power supplied to through this relay. The schematics I look at tell me nothing to look for. Any hints?

 

[peapvp]

pf.hal1984,

The most common issue with those Genset's is as follows:

At one point Genset does no longer produce Output Power. At first, if the Voltage Regulator in the A11 is OK, the Genset will excite the Output on the Volt Gauge up to 120 VAC as long as S1 is held in start position. If the Voltage on the Volt Gauge does not increase while in start then two issues need to be checked.
1. Does the S9-1 speed switch closes and activates K5 after reaching app. 600 to 900 rpm?
2. If it does and volt gauge shows voltage then Capacitor C2 and Transformer T2 in A11 have to be checked - C2 ages and eventually fails causing T2 to burn out
3. If it does not show Voltage then the two SCR's on the Voltage Regulator Card are probably toast, besides this C2 is probably due for a change too and hopefully T2 hasn't burnt out yet
4. There is a remote issue that the connections between A11, Cubilcle and Relay box are corroded, loose or disconnected
5. You may want to check resistance on your exciter coil

I assumed that the A11 would be the issue when I first assessed the generator. I also assume that the K5 relay on the A5 card is an issue because both battery generation and the generator set itself have power supplied to through this relay. The schematics I look at tell me nothing to look for. Any hints?

 

[Guyfang]

Open up the A11. See if the Volt Reg card has a burn on it. See if anything looks toasted.

 

[pf.hal1984]

Open up the A11. See if the Volt Reg card has a burn on it.
No burns on the card.

 

[pf.hal1984]

pf.hal1984,

The most common issue with those Genset's is as follows:

At one point Genset does no longer produce Output Power. At first, if the Voltage Regulator in the A11 is OK, the Genset will excite the Output on the Volt Gauge up to 120 VAC as long as S1 is held in start position. If the Voltage on the Volt Gauge does not increase while in start then two issues need to be checked.
1. Does the S9-1 speed switch closes and activates K5 after reaching app. 600 to 900 rpm?
2. If it does and volt gauge shows voltage then Capacitor C2 and Transformer T2 in A11 have to be checked - C2 ages and eventually fails causing T2 to burn out
3. If it does not show Voltage then the two SCR's on the Voltage Regulator Card are probably toast, besides this C2 is probably due for a change too and hopefully T2 hasn't burnt out yet
4. There is a remote issue that the connections between A11, Cubilcle and Relay box are corroded, loose or disconnected
5. You may want to check resistance on your exciter coil

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Very detailed. Thank you. The only issue I found is R2 has 52 ohms which states it should be 510. R3 has 498 ohms which should be 510. Both my transformers are good with no resistance across the H and Xs. Would R2 be my issue?

 

[peapvp]

The only way you can tell for sure if the A11 is OK or not by doing the 3 tests outlined in the TM Number is this picture

Very detailed. Thank you. The only issue I found is R2 has 52 ohms which states it should be 510. R3 has 498 ohms which should be 510. Both my transformers are good with no resistance across the H and Xs. Would R2 be my issue?

 

[Guyfang]

Stop. Before you get ahead too far.

Go back to post 14. Peter asked you if the S9-1 contacts had been made. That has to happen for K5 to light off the main gen. Have you checked the S9-1 contacts. There are NOT, just one set, there are two sets of contacts. One set allows the starter to engage, and then kicks it out, at approx 580-620 RPM. When this happens, and the contacts open, (pins A&B on the S9) another set CLOSES, energizing K5, (pins A&C, if I remember right).

 

[pf.hal1984]

Stop. Before you get ahead too far.

Go back to post 14. Peter asked you if the S9-1 contacts had been made. That has to happen for K5 to light off the main gen. Have you checked the S9-1 contacts. There are NOT, just one set, there are two sets of contacts. One set allows the starter to engage, and then kicks it out, at approx 580-620 RPM. When this happens, and the contacts open, (pins A&B on the S9) another set CLOSES, energizing K5, (pins A&C, if I remember right).

How do I test this? I know it turns off the starter. I get 5v out the accessory plug and shows about 25v on the gauge only when I hold it in start and at full throttle. I'm thinking about adding a switch to jump A and C. I put my finger on K5 but I can't tell if it is K7 next to it operating.