Rumble 100 SMPS

[SCAMP_2052]

Thanks for the tip! I've opened a new thread under "Class-D Amplifiers", http://music-electronics-forum.com/g...iscussionid=10

[Enzo]

We have a section just for class D amps?

[The Dude]

Enzo: From what I can tell he started a new "Group" instead of just a new forum thread.

Scamp: To my knowledge, posts from specific groups don't show up in the normal forum legend (New posts, Today's posts, etc.) So, few are going to see your new Group or posts within it. You'd be best just starting a normal thread in the forum for your amp- like all others.

[SCAMP_2052]

I killed the group 'Class-d amplifiers'. Thanks for the tip.

[Enzo]

Oh.

Well, nothing against it, I just never knew we had "groups". What is it, like a side chat room or something?

[lowell]

I received the new ICE module. After installation, I may use it as a reference to fix the original one. Depending on how much of a priority I make it.

I'll report on my findings if any.

[lowell]

Installed the ICE module. The aux supply fuses, 400ma, are blowing. Ive narrowed the short down to the preamp pcb, which is mounted with the pots on the front panel.

The ICE datasheet says the aux is +/-25v. If the max design current is 200ma (per ICE data) then I'm thinking that inserting series resistors will allow me to track down the short without blowing the fuses. Which I calculate as.

25/.2 =125ohms
25 x .2 = 5watts

Maybe use 10watts

Is this how you all would go about this repair? I predict I can find a hot IC as a culprit with this approach.

[nickb]

Installed the ICE module. The aux supply fuses, 400ma, are blowing. Ive narrowed the short down to the preamp pcb, which is mounted with the pots on the front panel.

The ICE datasheet says the aux is +/-25v. If the max design current is 200ma (per ICE data) then I'm thinking that inserting series resistors will allow me to track down the short without blowing the fuses. Which I calculate as.

25/.2 =125ohms
25 x .2 = 5watts

Maybe use 10watts

Is this how you all would go about this repair? I predict I can find a hot IC as a culprit with this approach.

Personally, I would run the preamp off a current limited bench supply. If something is very low resistance it will take a lot of current to heat it. In such a case it might easier to start pulling likely suspects i.e. decoupling capacitors.

[lowell]

Right on Nickb. Thanks. And to clarify P105 connector, if disconnected, does not blow the fuses.

I'll report back.

[lowell]

What model bench supply do you use?

I think this would work but am unclear on if can get bipolar 40 or bipolar 20v.
http://www.mcmelectronics.com/produc...RoCyLoQAvD_BwE

[nosaj]

What model bench supply do you use?

I think this would work but am unclear on if can get bipolar 40 or bipolar 20v.
Tenma Variable 0~40VDC Switch Mode Power Supply w/Current Limiting | 72-7295 (727295) | Tenma

If you don't need more than 30v 5amp current limiting. reversing the polarity of the plugs gives you a +- voltage.
30V 5A Switch Mode Power Supply with Dual LCD Readout | PS3005 | Distributed By MCM

nosaj

[lowell]

Yes, however I would like to use + and - simultaneously.

[nickb]

What model bench supply do you use?

I think this would work but am unclear on if can get bipolar 40 or bipolar 20v.
Tenma Variable 0~40VDC Switch Mode Power Supply w/Current Limiting | 72-7295 (727295) | Tenma

Something like this Variable Dual 0-30V, 3A and Fixed 5V, 3A Benchtop Supply | MPJA.COM

or http://www.mcmelectronics.com/produc...335A-/72-8335A

[darkfenriz]

Wow, a very interesting thread.

Why would major manufacturers stick to either Bang&Olufsen modules or chips amps (both hi-fi-ish products) when building a semi-discrete own and guitar-tailored solution is on board?

[nickb]

Wow, a very interesting thread.

Why would major manufacturers stick to either Bang&Olufsen modules or chips amps (both hi-fi-ish products) when building a semi-discrete own and guitar-tailored solution is on board?

To save money.

These things integrate the power supply and amp on a single small module plus all the regulatory issues have been dealt with hugely reducing project risk and time. They are sold to many OEMs and so made in large quantities at a low price.

The loser is the end user and the cost of replacements is high.