Need photos of REV H MS275 Board

Post by **Eric D** » Wed Oct 31, 2007 2:26 pm

Does anyone own a REV H MS275 which they can take a photo or two of the board?

I have seen or have photos of REV F, G, and I, but no H, and I need to know what changes were made for the H version.

tristan20 · Post by **tristan20** » Wed Oct 31, 2007 2:50 pm

I will check my 275's when I get home

brenzbmr@sb · Post by **brenzbmr@sb** » Wed Oct 31, 2007 7:22 pm

ill check mine to i think i have rev h boards
shoot.

tristan20 · Post by **tristan20** » Wed Oct 31, 2007 7:57 pm

sorry mines are G and F

Pedi · Post by **Pedi** » Sat Nov 03, 2007 6:02 am

Where can I find out what boards I have ??

Post by **Eric D** » Sat Nov 03, 2007 8:37 am

Look by the terminal...

Pedi · Post by **Pedi** » Sat Nov 03, 2007 8:39 am

Ahh.. I see.

Are there any REV's that are preferred?

Post by **Eric D** » Sat Nov 03, 2007 8:48 am

I would say the newer they are the better they are, but that is not fully true.

Some people like the power supply synchronization feature to reduce heterodyne noise, I personally do not.

I am interested in the newest versions of the MS275s, which do not use clamp bars to mount the transistors. I am fairly certain REV I boards use clamp bars, and I know REV G does not.

My hope is REV H boards do not use clamp bars, and also do not have power supply synchronization.

If this is the case, then I will be looking for a pair of REV H MS275s. But, if these features are not as I guess on the REV H model, then I will look for another REV G, or F board to give me a pair of MS275s.

Pedi · Post by **Pedi** » Sat Nov 03, 2007 8:55 am

Thanks for the info..

As far as I have heard from Nico, there are several editions of the 2125 aswell... I believe that he told me that the older ones are preferred??

Post by **Eric D** » Sat Nov 03, 2007 9:09 am

There are many editions of the MS2125 and its family members (MPS2500, MS2250, etc).

I personally prefer the newest versions of these amps, as they are far more reliable than the older ones.

Each REV of these amps adds new components, or changes paths of circuitry. In the case of the MS275, a REV F board has minimal power supply filtration on its rails. The REV G version has a bunch of hand soldered components for filtration, with black goop all over them. Then, skip ahead to the REV I version, and you see places for these parts were added to the board, and they are now soldered in place.

Component for component, all of these amps are the same, but how the parts are used and arranged on the boards kept improving with each revision. The newest amps are the most refined.

All of this also applies to PGs other models, like M, ZX, Ti, etc.

Pedi · Post by **Pedi** » Sat Nov 03, 2007 9:13 am

Thank you for this useful info....

marko · Post by **marko** » Sat Nov 03, 2007 10:28 am

Eric D wrote: The REV G version has a bunch of hand soldered components for filtration, with black goop all over them.

both mine have rev g boards, one for each midbass for good measure! always wondered why the black gunge stuff

brenzbmr@sb · Post by **brenzbmr@sb** » Sat Nov 03, 2007 12:16 pm

hey doc
i have two rev h boards.

what did you need to know?

they dont have clamps or gooey stuff on them.

these are the ones that i replaced the caps in that you guided me about the via on the boards a while back.

phonixx · Post by **phonixx** » Sat Nov 03, 2007 4:49 pm

Here is 3 pictures of my White Rev H and 2 pictures of my grey Rev G

It`s cellphone pictures so let me know if you need better pictures and i`ll take some in daylight with a real camera.

REV G:

1moreamp · Post by **1moreamp** » Sun Nov 04, 2007 4:26 am

marko wrote:
Eric D wrote: The REV G version has a bunch of hand soldered components for filtration, with black goop all over them.
both mine have rev g boards, one for each midbass for good measure! always wondered why the black gunge stuff

Those black items are Zobel type noise filters placed there to prevent diode switching noise from reaching your ears. Diodes make switching noise as they turn on and off rectifying AC to DC.

It would appear that the board used in your amp was "Old Stock" and they added the filters by hand, and did this till all of those Rev boards were gone. Most probably the next rev had the spots to add these on the board like normal. I seen this before on M series amps. Its a after-mod < the boards were built prior to the mod being included in the boards original Gerber file.

Post by **Eric D** » Sun Nov 04, 2007 8:05 am

Marc, if you can snap some photos, that would be most helpful.

The only specific things I am looking for are green and black output transistors, and old or new style speaker and power terminals. My hope is the REV H amps still use green output transistors, but have the newer (and nicer) power and speaker terminals.

If this is the case, then REV H amps will be what I seek to purchase.

phonixx, those photos don’t work for me, I cannot see them…

phonixx · Post by **phonixx** » Sun Nov 04, 2007 8:22 am

Eric D:

Dont know why you cant see them but here`s the Url`s to them. If that dont work i`ll mail them to you.

http://www.steinsland.org/Bilder/Bilder ... 275_H1.JPG
http://www.steinsland.org/Bilder/Bilder ... 275_H2.JPG
http://www.steinsland.org/Bilder/Bilder ... 275_H3.JPG

And 2 pictures of my grey Rev G.

http://www.steinsland.org/Bilder/Bilder ... 275_G1.JPG
http://www.steinsland.org/Bilder/Bilder ... 275_G2.JPG

Post by **Eric D** » Sun Nov 04, 2007 12:23 pm

Phonixx, thanks for those photos.

Now I am eve more confused. It looks like PG has done some random stuff with these amps, and I guess that is to be expected.

Your REV H amps have clamp bars, and have white optoisolators, yet the G version has black.

Maybe PG found some more parts stashed away in the corner!

phonixx · Post by **phonixx** » Sun Nov 04, 2007 1:33 pm

Eric D:

I was wrong; My grey MS275 is a Rev F, not G as i told you, but my white is a Rev H as i said.

Post by **Eric D** » Sun Nov 04, 2007 1:37 pm

Ok, that makes slightly more sense, but still is a bit odd.

brenzbmr@sb · Post by **brenzbmr@sb** » Sun Nov 04, 2007 6:47 pm

here are some pics of the rev h i have

keep in mind i chaged all the caps.

Post by **Eric D** » Mon Nov 05, 2007 3:53 am

It looks like REV H is what I am going to have to try and get my hands on. They have the most modern design and parts, yet still do not use clamp bars in all models. I think I will have a hell of a time finding specific ones which do not have clamp bars in them.

brenzbmr@sb · Post by **brenzbmr@sb** » Mon Nov 05, 2007 7:49 pm

both of mine are like that.