REPAIRING an Electro voice 1144 - diyAudio
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Old 7th June 2011, 02:52 AM   #1
dickl is offline dickl  United States
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Join Date: Apr 2011
Default REPAIRING an Electro voice 1144

I dug out my old Electro Voice EV 1144, and found out that one channel is not working. Right channel is fine, left is weak and scratchy. I traced back from the speaker terminals, and the speaker switch is OK, output fuses ok. Traced the signal to the output on the amp board and the right is fine, left is weak there. Power supply seems to be OK.

I am a decent electrician, but not an experienced repair guy. Not sure the next steps.

I do have a repair manual .pdf and that is mostly a schematic diagram and how to take the cabinet apart.

Any suggestions would be appreciated.

Here is the link to the service manual .pdf schematic is at the end of the document.
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Old 7th June 2011, 03:48 AM   #2
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Location: Los Angeles
Is it for sentimental reasons? As far as performance goes it's really uninspired. Enough raining on your parade.

Since you have one good channel you can compare the voltages between the channels. They should natch pretty closely - <10%. Electronics tend to fail where things run warm or hot. This is usually final power transistors, drivers and power supplies. On a unit that old plan on removing the power transistors, cleaning off the old dried out heatsink compound and re-greasing the transistors with white heatsink compound.

Do you have a scope? Multimeter? Is there any DC on the speaker outputs? The speakers are scratchy but are the headphones? If the headphones are clean look for open emitter resistors, those 0.47 ohm units connected to the emitters of the power transistors. The power transistors _could_ go open but shorts are much more common. Are all the transformer windings good? They would read fairly low ohms with your meter. An open winding would require a new or rewound transformer.

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Old 7th June 2011, 04:18 AM   #3
dickl is offline dickl  United States
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Status. Thanks for the answer. Yes it is for sentimental reasons. I bought new in 1967 and have had it since.

I have lots of other stuff around here like a couple of GAS Son of Ampzillas and NAD ETC.

I will try the headphones, but it is just a resistor in the final output circuit and the problem is upstream from that.

I do have a scope and a meter. I will follow your suggestion of measuring voltage in the amp. And will also check the transformers.

Thanks for your tips. I will try them tomorrow.

I am in LA as well
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Old 7th June 2011, 05:08 AM   #4
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Location: Dona paula, Goa
Attempt only if it has high sentimental value or if u want to learn.

If u switched it on after many years, then u need to check the electrolytic capacitors that r not common for both channels.

Gajanan Phadte
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Old 7th June 2011, 01:03 PM   #5
dickl is offline dickl  United States
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Thanks. I will check the electrolytics. I have used it on and off over the last 20 years. It probably has been 8 years since I tried to set it up in a system.

It does have a lot of sentimental value as it was my main system in my 20s.......lots of great music run through that amp.

I am planning on using it in small bookshelf system in my library......near my reading chair.

I know it is not exotic, but the design in interesting and it was one of the first solid state amps.....and I like the small package
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Old 7th June 2011, 01:17 PM   #6
Orit is offline Orit  Italy
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Location: Milano

I respect your harsh opinions on these ancient little amps, and I agree that they distort quite a bit, but on the other hand I must say that in my opinion they sound beautifully, particularly with rock, jazz and blues.
It could be for the very low feedback, or simply the effects of 2nd harmonics...

So before you throw away these little "wrecks", let me know !
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Old 7th June 2011, 01:42 PM   #7
dickl is offline dickl  United States
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I am NOT throwing it away.......lots of Stones, Janis, Cocker, Butterfield.... etc played on this thing. Lots of beautiful young things wooed with this EN 1144 in my apartments over my young years including my wife of 42 years!!

If this amp could only tell stories! We have been to Illinois, Indiana, New York, Quebec, California together.

It is part of the family.......I just have to fix it so I can use it again!! This is not a project, but a mission!!
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Old 7th June 2011, 01:44 PM   #8
dickl is offline dickl  United States
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By the way I still have the Fisher speakers from that old system!!! Much modified and a couple of sets of woofers and mids and tweeters least part of the boxes are original!!

Call me sentimental!!
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Old 7th June 2011, 04:03 PM   #9
llwhtt is offline llwhtt  United States
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There are several electrolytic capacitors in the signal path, those need to be replaced. If you have an ESR meter it would 2 seconds to find they are bad. They all look to be 5UF, axial? Mouser has TVA-1303s in stock at $2.50 each.

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Old 7th June 2011, 04:17 PM   #10
dickl is offline dickl  United States
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Thanks......I don't have an ESR......maybe I should get one. How is the BLUE ESR METER. Is this a good one???
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