Amek m2500?

[ilfungo]

Hi
I've opportunity to buy an Amek m2500 in very great shape...
I've now an Amek m2000 ( 2016 modules)
I  want to do this upgrade essentialy for the paramertic eq.
Just little help:
it's m2500 automation usable?
There are direct out on all channells?
How is the  sum?
6000 euro Could be a good price ?
Thanks!!!
Suggestions please...

 

[jensenmann]

I bought mine totally damaged for 5000€, a lifelong refurbishing project. No automation, it´s a pre-series model with Allison VCAs. 6000€ might be a bit steep for a large desk in 2015. There´s not much demand after these current sucking space eaters these days
Each channel can be configured with several insert points. If you don´t fear soldering a wire to the bus-PCB then it´s done easily in case it´s not already done.  Those desks were made on special order, so you got what you ordered. This means there´s no general answer as to what is installed in your desk. Make sure you get the schematics and repair/modification  history with it. Otherwise it might turn into a nightmare to figure out what others changed in circuits and signal flow.

 

[ilfungo]

Thanks  jensenmann
Could be the vca usable or is best to bypass them?
Thanks!

 

[jensenmann]

The desk is entirely based on the VCA concept. All faders are linear, not logarithmic, because they generate the VCA controlvoltage and don´t pass audio. So you´d have to change the faders, if you plan to get rid of the VCAs. The master fader is VCA as well. You´d lose the VCA grouping on top of that. All these are very nice features you´d have to give up just for the sake of sonic "pureness". If that´s what you seek then it´s the wrong desk anyway. You get great preamps, the best EQ ever and a lot of features with distinctive sound.
Depending on the age of the desk you have Allison ECG101 VCAs (installed until ´83), which have a nice sound to them, or in later desks dbx2151 were used. Not shabby either, but these can be changed to modern That2181 if you want less mud and distortion.

 

[ilfungo]

Thanks for great info!
Next weeks i will pick up the console and i want to recap and check all,
Some advice?
Some upgrade or change?
THANKS!!!

 

[jensenmann]

Check it out first before you think about upgrades. Occasionally one may like the desk the way it is ;-)

It´s a good idea to resolder all relays. Especially the black ones (Hamlin CCRPI/J) get intermittant  because of bad solderjoints.

Rework the PSU! Recap it of course. The rectifiers are bolted to the bottom of the case. They can get lose, reducing the thermal coupling to the case. Hence they get baked and are prone to failure. Renew these rectifiers. Renew all thermal grease at the all rectifiers, regulators and power transistors. The TO3 sockets of the regulators and power transistors sometimes have contact problems. Renew these or solder the pins directly, omitting the sockets.

After all that you should get rid of all tantalum caps on the channel strips, which are across the power rails. They sit close to the fader in the logic section. 2 of them are across the audio rails and another one next to the 5V regulator in the logic section. IIRC  there´s another one across the 11V rail somewhere... Replace them with at least 10uF/25V low ESR electrolytics with 105 deg rating.

 

[ilfungo]

Thanks jensenmann!!!

 

[gar381]

Check it out first before you think about upgrades. Occasionally one may like the desk the way it is ;-)

It´s a good idea to resolder all relays. Especially the black ones (Hamlin CCRPI/J) get intermittant  because of bad solderjoints.

After all that you should get rid of all tantalum caps on the channel strips, which are across the power rails. They sit close to the fader in the logic section. 2 of them are across the audio rails and another one next to the 5V regulator in the logic section. IIRC  there´s another one across the 11V rail somewhere... Replace them with at least 10uF/25V low ESR electrolytics with 105 deg rating.

Thanks for the tip on the Hamlin relays jensenmann.  My Blue Angela uses the same ones.  This may fix
a small intermittent problem I am having on an A10 module.  BTW.. I second getting rid of the tants
on the power rails.  You don't want to start any fires

GARY

 

[ilfungo]

Hi
The console is at home!!!
For now I can't fire up ,because I'm in the middle of a mix, but I've pulled out one channel and VCA are Allison.
The man says me that the console was recapped in 2008, but inside, I see some caps that for me are the originals ...
It could be?
The great thing is that there's
a board diary with all the maintenance over the years...
There are also, very big images with all the schematics!
Now I will try to scan them and if someone need them I will be very happy to share ...



Thanks Jensenmann for all the info...

 

[ilfungo]

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[ilfungo]

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[ilfungo]

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[ilfungo]

4

 

[jensenmann]

It´s not recapped. These are the original caps.
I´d happy to get a copy of your scans. My schematisc are old, very used, barely readable and have a lot of handdrawn "modifications" on it.

 

[ilfungo]

Hi
I'm starting to compile the buy list for the recapping and I need some help...



"After all that you should get rid of all tantalum caps on the channel strips, which are across the power rails. They sit close to the fader in the logic section. 2 of them are across the audio rails and another one next to the 5V regulator in the logic section. IIRC  there´s another one across the 11V rail somewhere... Replace them with at least 10uF/25V low ESR electrolytics with 105 deg rating."

Sorry Jensenmann are you talking about C1-C2-C3?
at least 10uf/25v = could be better to use big value? (22uf?)
I've read that if change tantalum for electro need to  add a parallel capacitor like .1uf? Ceramic or poly?
For all the other tantalum I nedd to replace them with same type o can leave the old one  in place?
(Some say that tantalum caps have infinite life).
Some advice about other caps?
For PSU I've seen 4 x 33000 uf capacitors, could be better to use  small values in parallel?
Last question:
The console have automation installed ( the man say Optifile Tetra) but I don't have a original external computer. It's possible to find something that could work ?
If not it's better to remove the automation system?

P.s. I will receive the schematics scans in the next two days, after that I will share...
THANKS!!!

 

[ilfungo]

Automation connection?

 

[ilfungo]

?

 

[jensenmann]

I´m of no help regarding the automation. My desk is a pre series version without automation.

IIRC C1+C2 are used on the audio rails and C3 is next to the 5V regulator which brings the 11V logic rail down to 5V.  Anything from 10uF to 100uF is fine. Bypasscaps are fine, too, no matter if ceramic or poly. But never use ceramic bypasscaps on caps in the audiopath.

Some tantalums in this desk are in the audiosignalpath. If you want to stick with the original sound then replace with the same cap. If you want it to sound more clean and modern then replace these caps with electrolytics und increase the capacity value by 2x to 4x.

Replacing the big PSU caps with something else will be a mechanical problem. You can try it but I´m not sure if it´s worth the effort. Definitely recap the regulator boards and get rid of the tantalums over there.

Your copies are on the way.

cheers
Jens

 

[ilfungo]

"Definitely recap the regulator boards and get rid of the tantalums over there."

Same as tantalum caps on channels  (c1-c2-c3) ?
1uf tantalum= 10uf with 0,1 uf ceramic in parallel?
ceramic nedd to be multilayer?
I've also a new spare cap 10000uf, could use it for 4700uf on psu?
Thanks!!!

 

[jensenmann]

1uf tantalum= 10uf with 0,1 uf ceramic in parallel?

yes

ceramic nedd to be multilayer?

Not necessarily, but that´s the cheapest part for that job and does what it´s supposed to do.

I've also a new spare cap 10000uf, could use it for 4700uf on psu?
Thanks!!!

IIRC the 4700uF cap sits on the +48V  regulator board. That´s sufficient for that purpose. Worst case your desk will draw 500mA from that rail. 10000uF will work but don´t expect any improvements. The disadvantage of too large caps is that the rectifiers have to work harder. They need to pass the charging current in a shorter period.