Wanted: Crown K2 service manual or schematics

[Maxxarcade]

I'm still having trouble figuring out how to fix the output boards, I have little understanding of how they work. I have one good amp to use as a test jig, but these things are fragile and I hate to kill the one good amp I have. Anyone know what the HP2601 and HP2611 IC's are? I found a datasheet for the MC34151P, but not the other chips.

[lumanauw]

Contact Toino

[TOINO]

Originally posted by Maxxarcade
I'm still having trouble figuring out how to fix the output boards, I have little understanding of how they work. I have one good amp to use as a test jig, but these things are fragile and I hate to kill the one good amp I have. Anyone know what the HP2601 and HP2611 IC's are? I found a datasheet for the MC34151P, but not the other chips.

Originally posted by lumanauw
Contact Toino

Hi Maxxarcade

The HCPL2601//2611 ARE optocouplers... http://www.alldatasheet.com/datashee.../HCPL2601.html
I don’t know the physical aspect of the K2 output board, but reading the schematics, the circuit is very simple.

They are some parts of the circuit you must check.

First thing is confirm if power mosfets and diodes are ok.
If you are not sure, simply take it of the circuit and confirm all the remaining parts as follow:

A- The left part (on schematics) of output board has their own local floating power supply. You must first check if it works.
Is the transformer T01, diodes D01 and D02, voltage regulator U01 and associated passive components. This power supply provides 5V for the HCPL2611 optocoupler (U02) and you could check it with a voltmeter on pins 5 and 8 of U02; must read about 5Volt.

The right side (of schematics) is supplied from somewhere else but has also the regulator for the U52 optocoupler and you must check it also.

B- You must check also if the MC34151 driver is properly supplied with about 12V on pins 6 and 3.

Please follow the steps above and come back to tell us the results…

I presume you have the schematics …?

[Maxxarcade]

Thanks, I just got the service manual from Crown, I still need to find the schematics though. Maybe I'll call them back and see if they can send those.

[Maxxarcade]

MOSFETS on the left side (by U53) are shorted. U53 MC34151P is shorted as well. Diodes are ok.

Problem is, I am having trouble finding a source for the MOSFETS. I already ordered some MC34151's from Digikey.

[TOINO]

http://www.mouser.com/search/refine.aspx?Ntt=fqp16n25
at $1.33 each one

http://www.mouser.com/search/Product...y863-MC34151PG
at $1.53

[TOINO]

By the way... I am interested on that service manual…
Could you send it by email, please?

[len_scanlan]

Hi Maxxarcade,

Have emailed you a copy of the schematics... Enjoy!

regards,

Len.

[Maxxarcade]

Thanks Len and Toino!

Making good progress here... Gotta order the FETs and a couple other things and I can start the repairs on the other two amps.

Digikey is going to love me this week, I've already placed 3 separate orders for parts, because I keep finding more things I need.

At least these amps have some resale value if I need to get back some of my investment. We got 3 of them (nonworking) in a package deal with some old EAW FR-153 speakers for $500.

From what I hear, the original MSRP on these amps was ~$2800, and Musician's Friend still sells them for $1,249 last I checked.

Also FYI, the caps I used to replace the old ones are low impedance, 105c high temp caps, I used Panasonic FC and FM series, and United Chemicon KY series. I also upgraded the voltages a step. Only drawback is the 100uf 35v caps I used were a slightly larger diameter, so they were a tight fit in a couple places. Kind of detracted from the "perfect" look I was going for on the board repairs. I'm a bit of a perfectionist when it comes to replacing caps

While I'm at it, maybe I'll use one of these amps to test the Cerwin Vega 152W 15" woofer that I picked out of the trash a while back, I'm replacing the foam this weekend, and hoping to use it and build a subwoofer to match my other CV speakers in my home theater

[Maxxarcade]

Toino, do you still need the service manual?