those 2 big 1.5k resistors that get hot an MS2250!

marko · Post by **marko** » Tue Aug 31, 2010 8:41 am

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

Post by **Eric D** » Tue Aug 31, 2010 1:29 pm

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.

valeks1 · Post by **valeks1** » Tue Aug 31, 2010 4:04 pm

Yes its three watts.

The Golden One · Post by **The Golden One** » Tue Aug 31, 2010 4:22 pm

would the same apply to the 2125?

valeks1 · Post by **valeks1** » Tue Aug 31, 2010 6:48 pm

No. MS2125 has different rail's voltage.

The Golden One · Post by **The Golden One** » Tue Aug 31, 2010 8:00 pm

would there be a higher watt resistor that you could use for the 2125?

marko · Post by **marko** » Fri Sep 03, 2010 8:52 am

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.

longboard · Post by **longboard** » Fri Sep 03, 2010 9:43 am

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!

marko · Post by **marko** » Fri Sep 03, 2010 9:50 am

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?

Post by **joerg** » Fri Sep 03, 2010 9:57 am

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

marko · Post by **marko** » Fri Sep 03, 2010 9:59 am

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!

longboard · Post by **longboard** » Fri Sep 03, 2010 10:10 am

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

Post by **joerg** » Fri Sep 03, 2010 10:21 am

Hers´s a picture of them

marko · Post by **marko** » Fri Sep 03, 2010 10:29 am

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!

valeks1 · Post by **valeks1** » Fri Sep 03, 2010 10:42 am

It's not 5 watts its regular 3 watts resistors not space savers.

Post by **joerg** » Fri Sep 03, 2010 10:43 am

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

marko · Post by **marko** » Fri Sep 03, 2010 10:47 am

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.

Post by **joerg** » Fri Sep 03, 2010 10:50 am

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?

marko · Post by **marko** » Fri Sep 03, 2010 10:54 am

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

marko · Post by **marko** » Fri Sep 03, 2010 11:07 am

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

Post by **Eric D** » Fri Sep 03, 2010 11:21 am

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.

Post by **joerg** » Fri Sep 03, 2010 11:23 am

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!

JK · Post by JK » Fri Sep 03, 2010 11:35 am

i have those on my 220821. it has 4mm twist on it as well. on my 220018 they are boxie and brown.

marko · Post by **marko** » Tue Sep 14, 2010 9:08 am

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