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Schematic for KRK E8 Monitors
Old 4th June 2013
  #1
Gear Maniac
 

Schematic for KRK E8 Monitors

Does anyone have a schematic for the original E8 Expose' monitors from KRK?
Old 4th June 2013
  #2
Lives for gear
 

Hi
If they happen to use an 'IC' for the power output section then the chances are that the circuit for that part will be pretty close to the chip maker's 'proposed schematic'.
Presumably you are looking at repair rather than 'tinkering' then relatively simple DC voltage checks on various parts may be sufficient.
Matt S
Old 4th June 2013
  #3
Gear Maniac
 

I need to look back inside

Quote:
Originally Posted by Matt Syson View Post
Hi
If they happen to use an 'IC' for the power output section then the chances are that the circuit for that part will be pretty close to the chip maker's 'proposed schematic'.
Presumably you are looking at repair rather than 'tinkering' then relatively simple DC voltage checks on various parts may be sufficient.
Matt S
Yes, repair is what I want to do. One monitor has a low level hum, which I suspect is a dried out electrolytic cap. The other monitor has the high frequency board broken loose on one side. Transportation damage most likely. This one has high frequency distortion. I hope reattaching the board will fix it. But no hum.
The boards need to be pulled out through the drivers holes. The boards are mounted to the sinks.
I wish it was chips. But looks like all discrete. The schematic I found for the V8 was chips, five OPA2134 opamps and three LM3886 chips for power.
I have seen mention of repair shops setting the bias for the output transistors. May need adjusting after 15 years.
KRK directed to a service center, four hours away. Called them and they recommended replacing the boards with some generic power modules that are more wattage. Found a place in Huntington Beach that seemed to know these. Just hate to ship to California to get looked at.
I think I can fix without a schematic. But having one will help. Would love to get them sorted out this summer.
Old 5th June 2013
  #4
Lives for gear
 
MarkF48's Avatar
Me thinks this might be what you want (maybe?)....

Service manual, eprom result list | ElektroTanya | Service manuals and repair tips for electronics experts

Enter KRK in the search, click on "KRK-SYSTEMS E8T SCH".

On new page and below preview wait until you see "Get Manual" and click on it....

"This file is downloadable free of charge: Get Manual
(You are not logged in, only 2 downloads per day possible for you.)"

Edit... after looking at the schematic and reading through your post again, maybe you already have this one.
Old 5th June 2013
  #5
Gear Maniac
 

Many thanks!

Edit... after looking at the schematic and reading through your post again, maybe you already have this one.[/QUOTE]

This is the input stage schematic. It is much more complicated than V8. This is 10 OPA2134 per channel. But is way more than I started with.
I will try to get a schematic for the output stage and "biasing" procedure. Hard to believe it takes 10 dual opamps in each input stage.
But many thanks for finding this info. I may get these running like new soon.
Old 3 days ago
  #6
Here for the gear
bringing it back to KRK one more time...

Hi,

I have been using a trusty pair of E8s (with silk tweeters) for nearly 20 years. OK, I realise there are better options now but my old ears are used to them and I know where I am with their limitations.

I recently moved my studio around and they were in storage for a few weeks. Now I have sporadic crackle, low level 50hz hum and high end distortion on one of them :(

I have a great engineer who says he can probably save it, replace all the capacitors etc. but I need a schematic for this...

Any chance anyone here has one? (or any for sale...?)

thanks in advance!
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