Question about Audio Players & Recorders

Open Question

No sound from NHT sub amp

Have an NHT sa-3 sub amp. Few years old and went dead with a pop. Fuse did not blow so thought less likely output transistors? Big output capacitors all leaky. Pulled them and cleaned up the board. Replaced with new capacitors. Identical (2) and 2 that had same specs but slightly higher voltage rating (60's vs 50's other specs same). Powers up as before, but still no output. Have not gone over the rest of the output board. Nothing really looks fried. Is it very unlikely to be an output transistor without a blown fuse. How to proceed? I have a volt/ohm-meter. Can return it to NHT's repair co. but what fun is that. Plus they charge $150 plus the cost of shipping both ways and the only parts that cost anything are the Caps I already replaced. Thanks.Jeff Hartford

Posted by on

Ad

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

NHT sa-2 amplifier won't go into standby mode after 10 Minutes of no signal


Does the NHT sa-2 have it's own pre-amp? Because I'm wondering if the power off only works when it's own pre-amp is used? So when your receiver is connected it's shut off.

You could try something connected to it's own pre-amp (if it has one) and see if it goes off when there's no signal from that.

Jan 30, 2015 | Audio Players & Recorders

1 Answer

It doesnt turn it on . I read that it could be bad capacitors . Is this true ?


This T.V. is less likely that capacitors made it go bad. There is probably a MOSFET that went bad or the H.O.T. (Horizontal Output Transistor.) There could have even been a power outage that caused the main fuse to blow. You never know unless you look inside of a dead T.V. if it doesn't have a blink code.

Jun 07, 2011 | Samsung TXM3281HF 32" TV

1 Answer

My LG microwave went completely dead. I is only 3


under the outer cover,its either a 10-15-or 20 amp ceramic safety fuse avail at most hardware stores, the amp rating is on the side of the fuse, if the new one blows then either the H.V. diode/capacitor or the magnetron can be suspects

Oct 03, 2009 | LG LMV1630ST Microwave Oven

2 Answers

Nht subtwo blowing f1 fuse on ac input module. found shorted Q16 2SA1302 and Q15 2SC3281 transistors what was the reason for these parts failing and what else should i be checking.


Try turning on the unit without the two transistors installed. Measure the DC voltages on the 3 pads to ground. These should read .6V,40V and 0, both +and -. If you read anything else, the driver circuit has a problem.

Dan

Mar 01, 2009 | Audio Players & Recorders

1 Answer

NHT SA-3


Appreciate the direct "Ask Me". With reference to your post here;

Voltage checks are done with the power on whereas resistance/continuity check are performed with the power off and preferably the component out of circuit. The VOM would do.

You posted that the fuses have not blown and therefore you are assuming that the output transistors are not defective. Pls confirm this by performing a check on the base to collector to emitter of the output transistors. This page would illustrate how to check a transistor using a VOM. The output transistor once removed from the circuit (pls mark which goes to where), laying flat with the pins/feet pointing towards you would be base, collector and emitter. Although the real outputs if 2SA1302/2SC3281 would be larger.
c05c37f.jpg
Most NHT sub amps are standard design amplifiers. To my knowledge, NHT amps (but not all) uses a unique design to supply power to the output transistors. The fuses does not tie directly to the output transistors from the +/- of the power supply. Instead the fuse goes to several power MOSFETS (IRF640) that regulate/control/monitor the current/voltage supplied to the output transistors. If any of the IRF640 is blown, the output would have no voltage even if the fuses are good.

To be more specific and to confirm the above, would appreciate if you could post/share the schematic diagram.

May I also inform you that there are posts made by other members of the community (our co-experts, I am aware that you have provided solutions yourself in some other posts) that would be of additional help. ginko has posted the method/manner by which you could test the transistors and other components, while bunnydawg addressed the fuse not blowing. welcomejee has posted with an amp schematics of an NHT Subtwoi.There were however and I would expect more posts that are too general/generic to be of any real use to you. I would leave it to your discretion to filter through the flood of information.

As a site policy, once you rejected a solution or give it a "Thanks for Trying", that particular post/expert would no longer be viewable. For your benefit, may I suggest that you copy and paste the "workable solutions" to a document that you would have a record of previous or no longer viewable postings.


Jan 04, 2009 | Audio Players & Recorders

1 Answer

Infinity Entra Sub 150 no sound or power


I had the same problem. When I opened it up, the fuse was blown, and it was a pain to find the fuse it needs (3 Amp, 250 V slow-blow fuse, 5x20 mm). Also, the 2 large electrolytics (big purple things near the amp) and one small capacitor were all blown. For 4 fuses, bought seperately from, and the 2 electrolytics and 1 capacitor, it cost about $20, plus almost 20 more in shipping, which still isnt bad considering the original price of the sub. However, the tricky part is that you have to know how to use a soldering iron to take out the old components and put in the new ones.

Jan 01, 2009 | Infinity Entra Sub Subwoofer

3 Answers

Power Acoustic A3000DB mono amp problems


Broken legs on the rectifiers or an intermittently shorted common mode inductor would be the likely suspects. The common-mode inductor is just to the right of the capacitors in the photo. Install a single 15 amp fuse in ONE of the 4 fuse holders (other 3 fuse holders empty) and power up the amp. Twist the inductor to see if the amp draws excessive current (which would blow the fuse) or to see if it sparks.

Let me know if you have any other questions.

Oct 31, 2008 | Power Acoustik A3000DB Car Audio Amplifier

2 Answers

One fuse keeps blowing


what size fuse is it usually you use at least a 40

Feb 09, 2008 | Sony XM-2252HX Car Audio Amplifier

1 Answer

Amp Issues


1) Make sure a bridged load of no less than 4 ohms is applied.
2) make sure both the left & right channels are working.

Jan 29, 2008 | Rockford Fosgate Punch P2002 Car Audio...

4 Answers

I turn on the amp then the fuse blows??


If the fuse only blows after the remote voltage is applied, the amplifier probably has shorted output transistors.

Dec 01, 2007 | Kenwood KAC-X401M Car Audio Amplifier

Not finding what you are looking for?
Audio Players & Recorders Logo

Related Topics:

129 people viewed this question

Ask a Question

Usually answered in minutes!

Top Audio Players & Recorders Experts

 Grubhead
Grubhead

Level 3 Expert

5699 Answers

The Knight
The Knight

Level 3 Expert

76173 Answers

Marvin
Marvin

Level 3 Expert

85216 Answers

Are you an Audio Player and Recorder Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...