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Question

I have a nikko 230 amp that keeps blowing fuses

Submitted: 220 days and 13 hours ago.

Category: Electronics

Value: $9

Status: CLOSED

Posted by Paul 220 days and 13 hours ago.

Answer

Hi there.
Acts like final output transistors are shorted. This happens when the speaker wires get shorted. chews etc. If you want to get into it, let me know.
Thanks
Paul

220 days and 6 hours ago.

Reply

The amp has been sitting unused for a few years and it was working when I stop using it. now I need it

Posted by Paul 219 days and 17 hours ago.

Info Request

Hi there.
Do you want to take it apart?
Paul

219 days and 17 hours ago.

Reply

Yes I can. I'm a computer tech so its no problem

Posted by Paul 219 days and 16 hours ago.

Answer

Great!
Disconnect the unit from power.
Take the cover off.
Find the power heat sink.
Test the output transistors for no continuity, collector to emitter.
If no shorts, test the power supply main diodes.

If need be, send me a picture.
Thanks
Paul

216 days and 15 hours ago.

Reply

I have the schematic for this amp but its 9 meg do you have an email I can send it to???

Posted by Paul 216 days and 15 hours ago.

Info Request

9 meg. Must be the whole manual. I have dial up so rather not.
You have a multimeter? Can you see the main heatsink? Refer to my last post.
Paul

216 days and 14 hours ago.

Reply

yes I do have a multimeter. I checked some of the transisters but wasn't sure if was was doing it right. The file is a 1 page schematic in jpg format. I can send you a .gif file of the drawing and if you need a sect blowed up I can send that

View Full Image

Posted by Paul 216 days and 14 hours ago.

Info Request

This is great.
Ref: "POWER TR PCB". This scetion contains the output transistors and their drivers. Check for shorts. Any pin to any pin on any given device should NOT be shorted.
Any shorts?

216 days and 13 hours ago.

Reply

View Full Image

Posted by Paul 216 days and 13 hours ago.

Info Request

I'm not surprised at 250 watts. Nice amp.
Can you probe to the transistor leads going through the PC board? The heat sink may be in the way.

Did you see the TO-220 pigie-backed on the big transistor?

216 days and 12 hours ago.

Reply

This is what I found when checking continuity. it checked across all pins

View Full Image

Posted by Paul 216 days and 12 hours ago.

Info Request

You are good!
How are you at soldering?

216 days and 12 hours ago.

Reply

Pretty good had to do some in my earlier days of woking on computers, Haven't had to pick up a meter or solder in almost 20 years. Could all of these transisters be bad? if so were can I find replacements since this is an older amp.

Posted by Paul 216 days and 12 hours ago.

Info Request

Good you can solder. Do you have a solder sucker or solder wick?

You will note a lot of parallel transistors. One of the pair could be good and the other bad.(not likely though.) Take out one at a time. and check for shorts.

Paul

216 days and 12 hours ago.

Reply

I think I have a solder sucker around here somewhere. Where can I find replacement parts??

Posted by Paul 216 days and 12 hours ago.

Answer

RadioShack, mouser.com
Take out the easiest transistors first.
Let me know when you are ready to go.
Thanks
Paul

216 days and 12 hours ago.

Reply

There is no easy way to get at them. There are a number of wires connected under the heatsink that's connected to the PCB. I need to figure out the best way to get at them without taking everything completely apart.

Answer

You may have to take the main board out of the chassis.

Accepts:
Expert:	Paul
Pos. Feedback:	87.5 %
Answered:	4/20/2009

Engineer

40 years experience in technical areas.

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Electronics

Have your own Electronics question?

Question

I have a nikko 230 amp that keeps blowing fuses

Answer

Hi there. Acts like final output transistors are shorted. This happens when the speaker wires get shorted. chews etc. If you want to get into it, let me know. Thanks Paul

Reply

The amp has been sitting unused for a few years and it was working when I stop using it. now I need it

Info Request

Hi there. Do you want to take it apart? Paul

Reply

Yes I can. I'm a computer tech so its no problem

Answer

Great! Disconnect the unit from power. Take the cover off. Find the power heat sink. Test the output transistors for no continuity, collector to emitter. If no shorts, test the power supply main diodes. If need be, send me a picture. Thanks Paul

Reply

I have the schematic for this amp but its 9 meg do you have an email I can send it to???

Info Request

9 meg. Must be the whole manual. I have dial up so rather not. You have a multimeter? Can you see the main heatsink? Refer to my last post. Paul

Reply

yes I do have a multimeter. I checked some of the transisters but wasn't sure if was was doing it right. The file is a 1 page schematic in jpg format. I can send you a .gif file of the drawing and if you need a sect blowed up I can send that View Full Image

Info Request

This is great. Ref: "POWER TR PCB". This scetion contains the output transistors and their drivers. Check for shorts. Any pin to any pin on any given device should NOT be shorted. Any shorts?

Reply

View Full Image

Info Request

I'm not surprised at 250 watts. Nice amp. Can you probe to the transistor leads going through the PC board? The heat sink may be in the way. Did you see the TO-220 pigie-backed on the big transistor?

Reply

This is what I found when checking continuity. it checked across all pins View Full Image

Info Request

You are good! How are you at soldering?

Reply

Pretty good had to do some in my earlier days of woking on computers, Haven't had to pick up a meter or solder in almost 20 years. Could all of these transisters be bad? if so were can I find replacements since this is an older amp.

Info Request

Good you can solder. Do you have a solder sucker or solder wick? You will note a lot of parallel transistors. One of the pair could be good and the other bad.(not likely though.) Take out one at a time. and check for shorts. Paul

Reply

I think I have a solder sucker around here somewhere. Where can I find replacement parts??

Answer

RadioShack, mouser.com Take out the easiest transistors first. Let me know when you are ready to go. Thanks Paul

Reply

There is no easy way to get at them. There are a number of wires connected under the heatsink that's connected to the PCB. I need to figure out the best way to get at them without taking everything completely apart.

Answer

You may have to take the main board out of the chassis.

Related Electronics Questions

Hi there.
Acts like final output transistors are shorted. This happens when the speaker wires get shorted. chews etc. If you want to get into it, let me know.
Thanks
Paul

Hi there.
Do you want to take it apart?
Paul

Great!
Disconnect the unit from power.
Take the cover off.
Find the power heat sink.
Test the output transistors for no continuity, collector to emitter.
If no shorts, test the power supply main diodes.

If need be, send me a picture.
Thanks
Paul

9 meg. Must be the whole manual. I have dial up so rather not.
You have a multimeter? Can you see the main heatsink? Refer to my last post.
Paul

yes I do have a multimeter. I checked some of the transisters but wasn't sure if was was doing it right. The file is a 1 page schematic in jpg format. I can send you a .gif file of the drawing and if you need a sect blowed up I can send that

View Full Image

This is great.
Ref: "POWER TR PCB". This scetion contains the output transistors and their drivers. Check for shorts. Any pin to any pin on any given device should NOT be shorted.
Any shorts?

I'm not surprised at 250 watts. Nice amp.
Can you probe to the transistor leads going through the PC board? The heat sink may be in the way.

Did you see the TO-220 pigie-backed on the big transistor?

This is what I found when checking continuity. it checked across all pins

View Full Image

You are good!
How are you at soldering?

Good you can solder. Do you have a solder sucker or solder wick?

You will note a lot of parallel transistors. One of the pair could be good and the other bad.(not likely though.) Take out one at a time. and check for shorts.

Paul

RadioShack, mouser.com
Take out the easiest transistors first.
Let me know when you are ready to go.
Thanks
Paul