swapping op-amps in a vestax pmc-55 - diyAudio
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Old 28th April 2006, 10:14 AM   #1
sr126 is offline sr126  United States
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Location: los angeles
Default swapping op-amps in a vestax pmc-55

i'm looking to mod my dj mixer, a vestax pmc-55.

it has a bunch of NJM4580L's, and several NJM4580D's.

i see that i have several options for replacing the 4580D's, but i haven't come across a TI/BB (or other more high end) replacements for 4580L's.

since the 4580L's are the only op-amps on the imput section of my mixer, i would like to start w/these first.

i saw this adapter/chip combo

i like the idea of using the OPA627, or something in that direction soundwise, because it said to have a warm sound. this is very much in line w/what i want to do w/the mixer. increase fidelity/detail, but give it a very warm/thick/deep sound. i would like the mixer to sound more bozak/urie'ish.

but something like this may/may not work depending on the actual size of the pcb. does someone know of a high end chip that is linear like the 4580L and compatible spec wise? i really don't want to mess w/the transformer at this point... but i will be will to do so in the future to make more mods possible.

thx
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Old 2nd May 2006, 06:36 AM   #2
sr126 is offline sr126  United States
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after doing a little research, and considering i'm pretty new at this sort of thing... i've decided to replace the NJM4580D's in the mixer w/the Texas Inst. equivalent, the RC4580.

just one problem. the mixer has more NJM4580L's than anything else. looks like TI doesn't offer the RC4580 in the straight 8 package to replace the NJM4580L.

i was speaking to someone at digi-key. i asked them if they had anything available to allow me to do something like this "AD825 Type 3" if you see on the left the picture on the right w/the two chips mounted on the board and the pins in a straight 8. they said the offer the pins in that configuration, but i would have to source or fab the boards.

now i'm kinda stuck, i don't know where to go to get a quote to create (or buy premade) an adapter/socket to mount the RC4580 to be able to solder it to the board where the NJM4580L are.

in a worst case senario, i have a bunch of canare L-4E6S star-quad mic cable. i can solder a strand of cable to each pin on the chip, then solder the other end of the strand to the appropriate place on the main pcb board.

any other ideas?
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Old 5th May 2006, 11:09 PM   #3
sr126 is offline sr126  United States
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Join Date: Apr 2006
Location: los angeles
right now i'm still in the process of breaking down the mixer... the only problem i have right now are these little demons...

2.5mm screws, i have jeweler's screwdrivers. but these things don't budge.
Click the image to open in full size.

i thought of spraying something like wd-40 onto the screws, but something tells me that pcb board along w/the the stuff soldered onto it will not like it one bit...

Click the image to open in full size.

i tried hitting it from behind... to tight... ;p
Click the image to open in full size.

any ideas on how to remove them? is using a drill my only option?

here are two pics of the main input card of the mixer, where the turntables, cd players, drum machines, etc... get hooked up.

does this look well designed? or well implemented? seem like something worth upgrading?

the black caps are TK 16v 22uf, and the brown caps are KME 50v 10uf.

if i decided to replace the caps w/panasonic FC... then i need to sub something for the 16v 22uf, because the FC come in either 16v 15uf or 16v 27uf... which one would work best?


Click the image to open in full size.

here's a pic of the underside... is there a reason for allowing to two solder joints to touch? is it good, bad, or just crappy craftsmanship?
Click the image to open in full size.

yes, my camera has barrel distortion.

thx in advance
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Old 26th June 2008, 02:00 PM   #4
djmike is offline djmike  United States
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Default What mods did you ever do on this unit?

Hey -

What mods did you do on this unit?

Mike
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Old 26th June 2008, 04:23 PM   #5
flshzug is offline flshzug  Antarctica
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what abunch of ********...

replace opamps to somthing that wont oscilate , even 5532 is better than 4580
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