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Generators & Electric Motors General Discussion

Powermate PM0496504 low Frequency

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Old 05-20-2013, 07:15:37 AM
Boblouder Boblouder is offline
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Default Powermate PM0496504 low Frequency

I have a Powermate 6500 generator that should run at 60hz. I have had this generator for about 6 years but there is only 6 hours on it. I have it in case of Hurricane outage (live in Central Florida). I run it occasionally to exercise, although probably not as much as I should run it. This year I removed it from the shed to start it up and found that there was a lot of rust on it. So I cleaned it up and replaced the electrical connectors, and sprayed the governor links with PB Blaster and removed the rust. I started it up. Started up right away (love those Honda engines). The problem I have is that after getting everything back to what I thought was normal. The Hz reading is only 53hz at 126. When I adjust up to get 60hz, the voltage is up to 145v. The meter works fine on my generator in my RV (Onan). So I do not believe that that is the problem. Question, Is there anyway to adjust the hz without affecting the voltage? If not what would have gone bad to cause this problem? If I cannot fix the problem, is this close enough to run a refrigerator and lights in an emergency?
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Old 05-20-2013, 11:09:55 AM
Fred M. Fred M. is offline
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Default Re: Powermate PM0496504 low Frequency


Based on your generator's history, my first thought is not to trust your voltage and frequency meters. I would want to try different meters and compare results.

If that model is capacitor regulated, you could try a new capacitor to see if it corrects the high voltage. If it has an AVR, see if there is a voltage adjustment.

Unless you can figure out the problem and fix it, I suggest adjusting no-load speed so voltage is 132 VAC (120 plus ten percent). That should bring your frequency up to about 56 Hz. This may still be a little low for your refrigerator, but I'd try it in an emergency.

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Old 05-20-2013, 11:15:33 AM
armandh armandh is offline
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Default Re: Powermate PM0496504 low Frequency

you did not mention load
try it with a load first
over voltage with no load is not unusual

caps usually open with age resulting in low voltage, not high
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Old 05-20-2013, 04:50:17 PM
Arkie Arkie is offline
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Default Re: Powermate PM0496504 low Frequency

sorry I overlooked your PM numbers, but I did not have that model in my manuals.

Here is a link that shows little bit of info about your model coleman gen plus others!

and more info

Here is some Coleman contact info that is about 1 1/2 years old.
I got some service manuals and could download owners manuals sometime back and the owners manuals had some useful info! They also emailed me some info!

Coleman Powermate generator info! (now owned by Pramac America) (download owners manuals)

Generators / Home Standby:
• Customer Service: 1-888-977-2622
• Technical Service: 1-800-445-1805
• Email:

Also test your Hz meter calibration on a utility powered 120 v recept and should read 59.99999999999 Hz.

Also 145 at 60-63 hz is normal on some without any load. I would apply at least a 1500- 2500 kw 120v load and look at the output volts. Small emergency gen's try to AVERAGE around 110volts at 60hz loaded to unloaded. I would try setting to 135v unloaded and then test with load and not be concerned about the freq unless it's less than 55Hz and the voltage should not be less than 108.
Although I would not operate high dollar TV or senstive electronic equipment at 145 volts. Their are other voltage options for operating Tv's, etc, instead of from the 145v gen output!

Last edited by Arkie; 05-20-2013 at 08:20:44 PM. Reason: typo
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Old 05-20-2013, 07:47:11 PM
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John Newman, Jr. John Newman, Jr. is offline
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Default Re: Powermate PM0496504 low Frequency

Frequency is directly related to engine speed. Get that right first. 62 hz (3720 rpm) unloaded, and 58 hz (3480 rpm) with full load is considered normal. The closer you can keep it to 60 hz (3600 rpm) the better. With 1/2 the rated load (in this case, 3000 watts) applied, then check your voltage.
John Newman, Jr.
Saint Louis, MO

I Can Probably Fix That
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Old 05-22-2013, 01:57:38 PM
Bassplayer1985 Bassplayer1985 is offline
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Default Re: Powermate PM0496504 low Frequency

Bob, there is no adjustment pot on the AVR. Its part#0052627

The capacitor is part# 0034819.01 Which is rated at 130uF 200V. 85/C. This is an oil filled running capacitor, not a starting.

There is also two diodes part#

Sadly I cannot find a schematic on this machine, but I would first start on changing the cap, it may be worn or dried out. The AVR may also have a failing component to cause a higher voltage. I agree 145 at no load is not good for any appliance.

Typically I see these powermate units run at 128VAC at 60HZ no load. 62hz will make the voltage slightly higher.

***Actually wait, I may have mi-spoke, look at the AVR, to the left of the large capacitor, there is a white component, just below Q1, is that a variable resistor adjusting potentiometer? Picture isnt clear, but if that is a pot you can probably adjust voltage to the field. Just a thought.
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Old 06-21-2013, 05:34:23 PM
Joe Romas Joe Romas is offline
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Default Re: Powermate PM0496504 low Frequency


I blew the picture up using paint and that white thing sure looks like a POT to me
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