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Old 7th September 2011, 07:37 PM   #1
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Default EV 1.5kW Amp Not Powering Up

Hi all

This is a newbie looking for any "been there, done that, fixed it." input that I can find. From what I've read so far, this forum covers the planet.

I have 4 of these class H amps from the turn of the century era (1997) with all presenting identical symptoms. I have the user manual / drawings for this monster and also recall having sent these in for the same problem while they were under warranty.

Of course the factory modification was a secret, though I worked for an EV dealer at the time. One tech told me it had to do with some capacitors... That certainly narrows it down.

They lasted a couple of years after the refurbs. Maybe the caps dried up again...

Hopefully I can save these from the landfill. They're too light for boat anchors. Any thoughts from out there?
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Old 9th September 2011, 03:35 PM   #2
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If the power supply transformer is not burned, and the heat sink is not melted, they are worth repairing if you need 1.5 kw.
Does it have a SCR crowbar on the output? does it look melted?
When you remove the output transistors, do they pass the double diode test with a DVM?
If you unplug the output transistor assembly, does the power supply produce +-95 or so at the big capacitors?
A schematic link would be convenient if you want help. If you can't find one, scan yours and upload them with title to eserviceinfo.com. They keep up to 3 mb files.
I'm fixing a PV1.3K. Rugged but sensitive to shorted speaker wires. No output transistor protection against shorted speaker wires. one half unplugged 1/4 phone plug will short it.
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Old 9th September 2011, 04:20 PM   #3
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Indianajo- I hope no one uses 1/4" phone jacks for speaker connections on an amp with that much power, but then again I know that they do. I have seen much smaller amps with the phone connector carbon/burnt. Just how much power can a phone connector handle anyway?
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Old 9th September 2011, 05:36 PM   #4
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My Peavey PV1.3k has 1/4 phone jacks in parallel with dual banana jacks on the output. Hard to miss a sale just because the customer is inexperienced. The guy that sold it to me was using hard soldered dual banana plugs for the speakers, so he had been around the block once, but the O.T.'s were still blown, 14 of 20. The CS800 amp, somebody had plugged something hot, like a guitar amp, into the input 1/4 phone jacks, and toasted the 1/8 watt input resistors. Got me a bargain that way. Too many 1/4 phone plugs being installed in the dark on stage, ya know.
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Old 9th September 2011, 09:28 PM   #5
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The OP has the manuals + schematics, but does not post them. The OP does not really tell us the trouble experienced. The OP does not give us info on model or make.
Well, that narrows it down (a bit)! E
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Old 10th September 2011, 06:27 AM   #6
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Default The OP posted a followup...

earlier today but since the OP is a newbie it either hasn't been reviewed yet or possibly disappeared. If it does appear, it will outline my recent communication with EV tech support and the revelation that EV didn't build or design them, and rarely serviced them in-house. They were custom labeled by E&W (EWI) in Korea. EV has completely abandoned the series.

The pdf of the manual the EV tech sent me is 5MB and rather fuzzy but someone had circled some caps in the parts list, which gives me something to go on.

When I get time to scan my manual I'll gladly upload it. It is very small print and not an easy one to follow without viewing w/ a magnifier lens. But that's all there is.

Rather than go into great detail in the OP, I was hoping to find someone in this forum who either had an experience with operating the EV 1.5kW amp (that's the make and model) or blowing one up and hopefully repairing it... Or has experienced the anomaly, where it slowly powers up and back down one second later, over and over. No fuses are blown and no shorted semiconductors found...yet.

Meanwhile I'll keep looking as I narrow it down a bit more.
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Old 12th September 2011, 06:46 PM   #7
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Quote:
Originally Posted by Brucester View Post
earlier today but since the OP is a newbie it either hasn't been reviewed yet or possibly disappeared. If it does appear, it will outline my recent communication with EV tech support and the revelation that EV didn't build or design them, and rarely serviced them in-house. They were custom labeled by E&W (EWI) in Korea. EV has completely abandoned the series.

The pdf of the manual the EV tech sent me is 5MB and rather fuzzy but someone had circled some caps in the parts list, which gives me something to go on.

When I get time to scan my manual I'll gladly upload it. It is very small print and not an easy one to follow without viewing w/ a magnifier lens. But that's all there is.

Rather than go into great detail in the OP, I was hoping to find someone in this forum who either had an experience with operating the EV 1.5kW amp (that's the make and model) or blowing one up and hopefully repairing it... Or has experienced the anomaly, where it slowly powers up and back down one second later, over and over. No fuses are blown and no shorted semiconductors found...yet.

Meanwhile I'll keep looking as I narrow it down a bit more.
Here is most of the EV-supplied owners manual I uploaded to eserviceinfo.com. Some of the parts pages didn't upload properly but might not matter since they're obsolete anyway.

ElectroVoice kW 1.0, 1.5, 2.0 Service Manual free download,schematics,datasheets,eeprom bins,pcb,repair info for test equipment and electronics
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Old 13th September 2011, 02:03 PM   #8
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Okay, looked at the spec and schematic. It is a switch mode power supply amp, so there is not likely a burnt transformer. First thing to check is that the input storage caps are charging up to the 200V or whatever. These are time expired components, and typically get low value or leaky at 20 years for cheap ones, even 2 years for really cheap ones. If one shorted it could have taken the input power rectifier with it. This is an area of dangerous voltage, read aikenamps.com tech button technician safety button about one hand rules, no jewelry rules, etc for not killing yourself electrically. Get a clip lead at R**** S**** for your DVM negative to attach it to the neutral input for measuring. Report back with the input cap brand and number, we'll have some opinion about whether to try to measure orjust shotgun replace. I don't think teapo ever made a long life cap- all their quality is at delivery time.
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Old 13th September 2011, 05:14 PM   #9
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Thanks indianajo.

I think that might well be the capacitor issue the factory mentioned.

I flipped the p.s. board and noticed a tell-tale ring of rework flux around C324 and C325 (1500u 160v). A quick test with my B+K 820 cap meter showed less than rated capacity on both. All caps are Daewoo brand, a name I tend to associate with cheap.
The bridges and fast diodes checked okay w/ the meter but I probably need to update the 14 yr. old caps. C301 and C302 (1000u 200v) measured at listed value but that's not to say I shouldn't probably replace them all.

Each p.s.b. has its own brain, the controller chip KA3525A (that I assume is monitoring the output) and cycling the power on and off. So it all likely boils down to a p.s. with a brain versus a repairman with half of one
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Old 13th September 2011, 06:05 PM   #10
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Andrew makes fun of me but if I intend to fix something over 20 years old, I replace all the electrolytic caps before I hook up the scope. Transformer check is important on trans-rect-filter equipment like my PV1.3k, but switchers tend to blow $1 fets diodes and optoisolators, according to my survey of blown PCAT power supplies. Probably all caused by the leaky Teapo caps. Don't know about daewoo caps, except they will probably build anything EV want them too. 5 year life rubber cap seals? no problem. Shipping from Newark is $7, mouser is $10, so buy a bunch of caps, these will be $2 each or under. Newark has the life rating in the selector table, 2000 hour up is my requirement. At mouser panasonic ECA or NHG is 2000 hour, nichicon UPT is 5000 hour at 105 deg C. You have to download the datasheet at mouser to see what you are buying. Both of them sell 500 hour caps if you don't watch what you are doing.
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