Fixing a Yamaha PM1000?

briank

briank

analog for the people!
So as the story goes, we've got a PM1000 that started out life as a 32ch console which my studiomate bought, sold half the strips and the frame, and loaded the other half plus the master section and supply into a 16ch "sidecar."

He then re-capped the whole thing with Panasonics and modified the EQs for better semi-parametric mid centers...and wired it so that all channels are summed to the masters, plus channels 1-12 are direct out, while the last four are only summed to the masters.

He put one cap in the each of the four masters in backwards so they blew when he powered up...and then gave up on it and left it sit for five years. I got sick of it collecting dust so recently i replaced those four caps (right way around this time :D ) but the masters are still out...

I haven't worked on a PM1000 before; the circuits are pretty simple but I would appreciate some pointers on where to look/test with these modules...the 12 direct channels work fine as direct preamps, in fact I tracked through several of them at a session yesterday....but I'd really, really like to get the masters going so I can submix with this board as well as mix down with it...I can confirm that the masters as well as chs 13-16 are getting power, but otherwise I can't get any signal through them except for a very, VERY faint signal through Master-1 by cranking it through another gain stage in another console...any suggestions on where to start in getting the masters back in action knowing that it did have one cap in each module blow?

Haven't got an original service manual as such, but I've got some schematic printouts of mediocre quality, they're hard to read!
 
Lots of info on PM-1000 over on prodgy-pro. The PM-1000 mods are well documented as that people often take 2 channel strips and make it into a dedicated 2 ch mic pre. Due to the inductor based EQ and discrete gain stages it has often been called Neve-ish. (heck I even have 2 channels of PM-1000)

Google is your friend. Do you have any specific questions? I only know about the strips that I have....

In general you can supply a 1KHz tone to the input and trace it through each stage till it fails. You can also hook up to the output and work toward the input stage at a time. Inject the signal just after each blocking cap (through a blocking cap of your own). These are C1, C9 and C19 and the like. THe gain switch is a likely cause of problems provided none of the transistors are blown.

Manuals are available online in PDF format.

--Ethan
 
Not sure about the 1800 manual...I did download the PM1000 docs from Yamaha (I'm shocked that it's available) so I'll poke around and see if I can get some specifics. I didn't know if my best approach would just be to start tracing out from around the caps that blew or just start "at the top" and work my way in. As always, your info is helpful Ethan! And yes, the stepped gain pots are a little dodgy on this one.

The circuit boards are elegant/simple in a geeky sort of way and I think this is an interesting piece. I tracked through the direct channels some this week. I was expecting that Neve sound that everyone talks about but I have to say the mids were more aggressive than I would have guessed and the bottom not as loose/big as I expected...I have Neve Portico and API preamps also and I'd put this PM1000 somewhere between the two, not as refined as either but a cool vibe, not a bad thing at all! I particularly enjoyed putting electric guitars through it. The EQs are cool, nice for some sculpting on the way in and the modified mid centers are "just right." Fun tactile experience too with those funky faders and big "upside down" knobs. I look forward to being able to sum with it!

BTW what's the smartest way to clean the faders?
 
As with all PM series consoles the seating of the strips have to be done every so often would this be the case in your new configuation?
 
moresound said:
As with all PM series consoles the seating of the strips have to be done every so often would this be the case in your new configuation?
Click to expand...


I'd pulled the modules to clean and then after I put them in and didn't get any masters, I re-seated them again, so doesn't appear to be the case, but yes that's a good point! I also made sure the modules are all getting power.
 
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