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those 2 big 1.5k resistors that get hot an MS2250!
Posted: Tue Aug 31, 2010 8:41 am
by marko
does anyone know what wattage is the ideal upgrade for these? just doing the caps on my latest 2250 and want to upgrade them, one of my others has bigger resistors but not sure what wattage they are

Posted: Tue Aug 31, 2010 1:29 pm
by Eric D
I would use 4, 5W ones in parallel (two groups of two). Double the resistance of course, as you will be halving it when you go parallel.
I am pretty sure they are 3W from the factory, but that just does not cut it.
Posted: Tue Aug 31, 2010 4:04 pm
by valeks1
Yes its three watts.
Posted: Tue Aug 31, 2010 4:22 pm
by The Golden One
would the same apply to the 2125?
Posted: Tue Aug 31, 2010 6:48 pm
by valeks1
No. MS2125 has different rail's voltage.
Posted: Tue Aug 31, 2010 8:00 pm
by The Golden One
would there be a higher watt resistor that you could use for the 2125?
Posted: Fri Sep 03, 2010 8:52 am
by marko
just pulled my other 2250 out with the upgraded resistors, they are huuuge by comparison, 1" in length, what size wattage are these anyone?
think it's a worthwhile upgrade as they can handle the heat better, on the one i'm going to change you can see where the heat has shrunk the film on the nearby cap
also, does anyone know which transistors i need to change to fix the clip light scenario?
Mark.
Posted: Fri Sep 03, 2010 9:43 am
by longboard
pics of these areas would be great guys !! im not sure which ones you are on about marko and would like to carry out this check on mine!
Posted: Fri Sep 03, 2010 9:50 am
by marko
will get some pics up soon, just found out they are 5watts the big ones and i'll order 10 so we'll have plenty between us

they're chip to buy but will have to wait to get them delivered from hong kong, farnells want a minimum £20 spend these days
you'll know which ones they are when you turn the amp on, they get quite hot!!
hows your resto coming on mike?
Posted: Fri Sep 03, 2010 9:57 am
by joerg
I have a parts board here that might have the same huge resistors! Just to let u know the Nickel has those big suckers too

Posted: Fri Sep 03, 2010 9:59 am
by marko
well a nickel is 2x 2250's internally so that makes sense, just ordered 10 pieces now so will have enough to do 5 2250's!
Posted: Fri Sep 03, 2010 10:10 am
by longboard
the restos on hold making a big push with the install at the moment
bought andys f1 system and have nearly got the front end somewhere near made lots of filling and sanding now lol
trouble is im building with newth and me and him like things 110% so theres been many changes to make things spot on lol
Posted: Fri Sep 03, 2010 10:21 am
by joerg
Hers´s a picture of them

Posted: Fri Sep 03, 2010 10:29 am
by marko
that's the bad boys! looks like yours have the upgraded 5 watters in their, you can tell the difference when you compare them to the smaller 3 watt gate resistors in that picture!
Posted: Fri Sep 03, 2010 10:42 am
by valeks1
It's not 5 watts its regular 3 watts resistors not space savers.
Posted: Fri Sep 03, 2010 10:43 am
by joerg
I talked with Matt about those resistors and i think those are the ones that have to eat lot´s of juice when the amp is running in bridged mode. The very same resisitors in the circuit on the other side of the board are the same size as the gate ones
Posted: Fri Sep 03, 2010 10:47 am
by marko
joerg wrote:I talked with Matt about those resistors and i think those are the ones that have to eat lot´s of juice when the amp is running in bridged mode. The very same resisitors in the circuit on the other side of the board are the same size as the gate ones
yeah, the other ones don't get no way near as hot even running in stereo mode
will be posting some pics this weekend on why ALL psu caps should be changed even if they look ok on any old school PG amp.
Posted: Fri Sep 03, 2010 10:50 am
by joerg
marko wrote:
will be posting some pics this weekend on why ALL psu caps should be changed even if they look ok on any old school PG amp.
Thanks! I know why

Isn´t the sound of boiling fluid horrible when u take them out?
Posted: Fri Sep 03, 2010 10:54 am
by marko
joerg wrote:marko wrote:
will be posting some pics this weekend on why ALL psu caps should be changed even if they look ok on any old school PG amp.
Thanks! I know why

Isn´t the sound of boiling fluid horrible when u take them out?
it's suprising how many amps are still running on original caps because the owner says "yeah, my caps are still good and dry", i'm yet to do an amp where all the caps were dry, it's a time bomb waiting to off

Posted: Fri Sep 03, 2010 11:07 am
by marko
just found an old thread by me about these very resistors, might be of use to someone
http://phoenixphorum.com/new-toy-ms2250 ... ght=shroud
Posted: Fri Sep 03, 2010 11:21 am
by Eric D
These resistors are part of the circuit which powers the 3 op-amps on the board. They get even hotter if you upgrade to Burr-Brown.
Only one side of the board powers the op-amps, the other side does not, hence the reason one side is larger than the others. If you run the amp bridged or stereo, these will get just as hot.
Posted: Fri Sep 03, 2010 11:23 am
by joerg
Eric D wrote:These resistors are part of the circuit which powers the 3 op-amps on the board. They get even hotter if you upgrade to Burr-Brown.
Only one side of the board powers the op-amps, the other side does not, hence the reason one side is larger than the others. If you run the amp bridged or stereo, these will get just as hot.
Thanks for coming in and explaining that Eric!

Posted: Fri Sep 03, 2010 11:35 am
by JK
i have those on my 220821. it has 4mm twist on it as well. on my 220018 they are boxie and brown.
Posted: Tue Sep 14, 2010 9:08 am
by marko
longboard wrote:pics of these areas would be great guys !! im not sure which ones you are on about marko and would like to carry out this check on mine!
got them and fitted, i have 6 left, 2 have your name on them if you want them they arn't going anywhere, FOC of course
