Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

ev p3000 repairable ?

Status
Not open for further replies.

AZZTECH

New Member
Hi there, i acquired this amp and wondered what went wrong and if it looks repairable, it still switches on but in protect mode.

pics;

**broken link removed**

**broken link removed**

damage to resisters

**broken link removed**

i think these 3 leg'd chips blew

**broken link removed**

**broken link removed**

**broken link removed**

the resisters look ok so far down.

**broken link removed**

would also like to know whats the best way to discharge the caps, so i can remove the amp circuit board to inspect further.

how do i check stuff with my multimeter ?

any help would be great.
cheers aaron
 
this is a 1800 Watts @ 2ohm amplifier.. :O meaning it outputs killer voltages!
the best way to discharge the capacitors is with a resistor...watch out
what you're doing!
 
I have a zip file containing the owners manual and the service manual with schematics of all the boards along with the parts listing if you want.

just send me your email address and I will sent it to you.

There is a free program called "7 ZIP" if you do not have a ZIP file program to open the Zip with.
Just Google "7 ZIP " download install and then you can open zip files.
 
Here is a thread I found on a typical fix: https://forum.speakerplans.com/ev-p3000-protection-issue_topic33159.html

An amp this powerful I do not recommend that it's your first repair. I haven't seen the schematic, but it looks like it's available for a donation and from the generous person at ETO here in this thread.

I worked on a commercial amp where the components "puddled" on the circuit boards. No shop would take it in and there was a total of five asked.

It's likely that transistors that are in parallel have to be matched in current gain.

I have done extensive repairs on high power amps and other high power things such as 30 KW (15,000 V @ 1A) power supplies and 100 KV @ 0.1 A power supplies and repair of tube devices such as 1 KW 15.56 MHz RF transmitter. My tube experience stared when I was a 10 year old kid or so. My amp experience started when I decided to build one (google The Leach Amp) in the mid 80's from scratch. I started doing amp repairs for a local consumer electronics repair outfit. I typically only did their hard ones. One particular amp had come in for a warranty type repair and I had never worked on it. I found a minor design problem and all has been well.

Not replacing all of the defective components or not matching the transistors can result in premature failure.

Minimum tools are oscilloscope, signal generator, ability to measure transistor gain, and a Variac and a DVM and the service manual obviously helps.

Nearly all the catastrophic repairs require output replacements, driver replacements and attention to the bias network. The small resistors <300 ohms always have to be checked.

The xistors are about $2.50 to $7.00 USD, but you have to buy enough to assure a decent match in Hfe.

There is 12/side or the possibility that 3 have to be matched. That's also judged by the 6 emitter resistors.

The rust suggests moisture and that's in line with the cause presented in the link I posted. It's even possible that the transistor mounting screws rusted and shorted.
 
Last edited:
Zip file containing P3000 info - SEE Warnings in email before opening ZIP file

The info in zip "P3000 amplifier-service manual and schematic.zip" is for educational READING use only - use at your on risk- WARNING !!!! actual unit has VOLTAGES and AMPS that are HIGH !!!!! AND can be LETHAL !!!!

DANGEROUS !!!!!!!! - Do NOT Attempt ANY TROUBLE SHOOTING or REPAIR UNLESS you are experienced or have someone experienced in working on these type of devices NEXT TO YOU and ADVISING and SUPERVISING you at all times AND THEN STILL BE EXTRA CAREFUL !!!


--------------------------------------------------------------------

"KeepItSimpleStupid" or others - here is zip in case you also want to view it.
 

Attachments

  • P3000amplifier-service manual and schematic.zip
    3 MB · Views: 766
Last edited:
helloo

thanks for the pdf's, I've saved them :)

I've still got the amp
i hope to get it repaired 1 day

aaron
 
this is a 1800 Watts @ 2ohm amplifier.. :O meaning it outputs killer voltages!
the best way to discharge the capacitors is with a resistor...watch out
what you're doing!

The DC voltage to the finals is +- 132v and max. output is 138 v when bridged
So, no he won't die but, an accidental shock would feel fairly nasty. This isn't a microwave oven nor a 2-5kw RF amplifier where voltage and current levels are very nasty and life threatening.
 
true.

It could, however. melt a small probe or screwdriver and make a big bang.

Compared to the 100 kV, 0.1 Amp and 15 KV at 1.5 A supplies I worked on, this is child's play. The 1KW RF tube amp had a 3 kV supply in it. RF is an entirely different animal. Microwave ovens suck too.
 
nev23;
You said you repaired lots of these amps. I've got one on the bench that's driving me nuts! Been going on and off into and out of protect on channel A. The SOAR circuit is triggering the protect.

Have you found instances of leaky transistors on the SOAR driver circuitry? It's not a current limiter issue, as I can pull down the B-E junction on the curr/lim transistors and nothing changes. I can also short out the 2.2uF cap at the + rail and the amp will stay out of protect mode.

Have you run across this in your journeys?
 
Please note that nev23 has not logged on here since 10th November 2015.

JimB
 
Just in case one of you happen to be looking for some repair news on an EV P3000 power amplifier, I was having the same type of issues with one here in my shop. You turn it on to see the protect LEDs staying on.

If there are no burnt components internally that you can see, it may be related to some leaky current limiter / overload sensing transistors.
Firstly, when you isolate which channel is causing the issue, I would just replace all 8 (4-MPSA42 & 4-MPSA92) transistors in the SOAR circuit. Contact me through the forums if you need some further details and I'll email you my notes.

NOTE!! If you can't diagnose which channel is at fault, take the unit to a reputable electronics tech! Diagnosing it to that level is a must and with DC voltages of +138, +70, -70, and -138 volts inside the unit, if you can't diagnose to the channel fault, you really shouldn't be 'under the hood' as it were.
 
Last edited:
It is big and it uses an unusual topology (grounded bridge), but it may well have a simple problem. This picture and the one after it
https://www.facebook.com/zenworksen...754270164033/1057230377683080/?type=3&theater
show one I fixed with the same problem recently.
It is usually the first transistors in the SOAR circuit.
To discharge the capacitors, put some sleeving (or insulated crocodile clips) on the legs of a 100 Ohm, 3 Watt resistor and hold it across the two halves of the heatsink.
I have also found a number of these amps that have a lot of failures, but keep on working as the short circuited output device(s) blow their emitter and base resistors and remove themselves from the circuit. So, when you have the board out, check all the large white resistors. If any are more than 1 Ohm, you have a bigger job on your hands. As well as the output transistors, there will be blown transistors and resistors in the current limit circuit.
But the fact that it switches on and doesn't blow fuses is a good sign.
 
nev23;
Big and different topology...I'm used to it from working on Crown Macros & Micros.. =O)

My biggest problem anymore is finding the dual 0R22 and 0R47 emitter resistors. Many times I've had to "kluge in" a pair of of MF 3W FP's in their place. But they're awesome sounding amps.

Thanks for the reply!
 
Parts Express has the usual 5W singles: **broken link removed**[endeca%3Amatches%28.%2C%22P_PortalID%22%2C%221%22%29+and+endeca%3Amatches%28.%2C%22P_Searchable%22%2C%221%22%29]&Ntt=resistors*&PortalID=1&showMoreIds=10025

Not duals, unfortunately.
 
I'm sure EV can supply the dual 0R22 and 0R47 emitter resistors. For a price.
I think the design of the limiting in the Precision series is deeply flawed. The proper limiting circuit only senses current, not voltage, and the SOAR protection operates via a delay and a relay. I'm sure that is why I have had to repair so many. Something this expensive should really be doing this properly. The Macro-Tech series do: they actually measure the current through and voltage across the output devices and feed these into an analogue multiplier to give a precise reading of power dissipated. Sounds nasty when it limits, though.
 
Nope. EV won't even talk about individual components. They will repair the assembly for $425 (at last notice). Otherwise, no assemblies available and techs won't even talk to you. They've become very independent as of late.

The SOAR circuit only "approximates" what they think it might be seeing under load and based on the air temp blowing past the heatsink fins. Basically you might have a better go at it if you were blindfolded and throwing that dart....
 
This article shows how to do it properly.

It won't let me upload a 2Mb rar file.
How do I get a file larger than 2Mb on here?
The publishers don't have it available any more.
The second part of the article is uploaded. It won't make much sense without the first part.
 

Attachments

  • 02100050.pdf
    767.3 KB · Views: 681
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top