Simple Great River MP-2 questions...

[disorder]

I have two DIY MP-2 boards populated and ready to get wired up. I have a few questions before I continue however, hopefully there's still some help available as it's a fairly old project. Ok first question...  ???

On the audio card layout, it shows the R13 position having 47R5 resistor and R12 position having 49R9. The schematic has these reversed. Which one is correct? Most pictures of circuit boards (including original MP-2 boards) match up with the layout image.

Next involves the four tall 470uF caps. These will not fit in my case what so ever so I ordered shorter, common Nichicon 470uF 63V caps, is this ok? From what I can tell these caps simply provide more power filtering for the final transistor stage? So I think they will be ok, perhaps not as high quality as the original Panasonics..

Finally... I ordered a black 19" rack enclosure from ebay; one of those overseas units from Hong Kong. It's decent enough quality however it includes a 1 3/4" front face plate along with two 1 1/4" front and rear panels. Do I need to use both the larger front face plate and the smaller front panel simultaneously? Holding the two together via the switches and jacks?

Any help appreciated, thanks!

 

[Sredna]

Nope, my PCBs, wiring diagram, schematic and BOM all have the same designations and values.
R13 has the value 49R9 and is parallelled with R46(TBD). R12 is 47R5.

The big caps are part of the voltage regulation, same values is of course ok.
(Maybe check the temperature rating, 105C is better)

 

[disorder]

Thanks. Which Layout file are you using? This one here...

http://www.matt-allison.com/diy/greatrivermp2/audio%20card%20placement.pdf

Shows from left to right... 47R5 then TBD/R46 then 49R9 and following the traces on the board shows that the very most left spot I listed is the one that is in parallel with R46.

 

[Sredna]

Yes, I have this layout also.

Check this picture, R13 is clearly parallell with R46:
http://www.twin-x.com/groupdiy/albums/userpics/GR_components.JPG

 

[disorder]

Sorry for the confusion, my board is laid out differently! Perhaps there was a revision...

Mine is from left to right.. R13 - R46 - R12 with R13 and R46 in parallel... so I will switch mine and follow the schematic not the layout.

 

[Sredna]

Strange, I have my PCBs from Ptownkid.

Yes, R46 is supposed to be in parallell with the 49R9 value, that way the total value could be greater or lesser than 47R5.

I did put a trimmer instead of R46.

 

[okgb]

The nich are decent caps , i second checking the temp rating
voltage should be o.k.
if you're using all i/o transformers + the psu
that could be some extra stress on the panel
[ my quad is heavy  but it's held to the case with 4 bolts
which i have to retighten every so often .

there is a thread already running for MP-2 questions

 

[disorder]

sorry about this thread, the long running MP-2 thread hasn't seen any action in quite some time. I only have one more question (for now)..

Did most people just sand down that "wedge" on the Elma 24 rotary switch and possibly use a lock washer? Or should I go ahead and drill a small hole directly on the top of the main switch hole to accommodate the wedge?

 

[Sredna]

If you post in the "old" thread, itll come on top again.

So dont be shy to do that!  ;D