Well SHIT... Sunfire Jr. Took a Dump :(....

My POLK MicroPro 1000 will not produce music. It is getting power, so it is not the fuse.
Beyond that I have no clue.

Lucky I don't need it right now, but I hate that.
No way I can pay shipping + repairs and come out ahead.
I envy you guys who have knowledge.

Bring it to CF with you, Bill. I'm sure SOMEBODY there can figure it out~

Gary, it's a surface mounted board.

Your IRF640's are prob. shorted as well.

Bill, have you tried calling Polk customer service? They can assist you with the MP1000. I used to have that sub back in the day but it has been to long for me to remember the things to look for when troubleshooting it. BTW, call. Don't e-mail.

Also, you will not have to ship the entire sub. If the issue can not be isolated and corrected over the phone, all you have to do is unscrew the plate amp and send that in. You don't have to send the entire sub. If it was purchased under an authorized Polk dealer and it is still under warranty then it won't cost you a dime to repair besides that of shipping the plate amp. If it isn't under warranty, then sign up at Club Polk and mention that you are a member of the forum to receive a discount [I think it's 5%...not sure] on your repair costs. Either way, this should help you to get it back up and running. It's too beautiful a sub to be just collecting dust.

Thanks Tom.
I will look into that. It is a good sounding sub and to me it was expensive.

I used to play it here on the deck and was so happy with it. I replaced the 1000 with the 4000 which is more than all I will ever need here. Polk MicroPro can take on most subs as an addition to 2-channel audio, at least in my systems. I think they would be up to any task, but I don't play movies, rap, new country, or new pop on these.

When I took it below, it was perfect. Just because some of my stuff is on the deck, does not mean it is not protected. These things cost a lot of money.


I used to play it here on the deck and was so happy with it, I replaced it with the 4000 which is more than all I will ever need here. I think it can take on most subs as an addition to 2-channel audio.
When I took it below, it was perfect. Just because my stuff is on the deck, does not mean it is not protected. These things cost a lot of money.

My POLK MicroPro 1000 will not produce music. It is getting power, so it is not the fuse.
Beyond that I have no clue.

Lucky I don't need it right now, but I hate that.
No way I can pay shipping + repairs and come out ahead.
I envy you guys who have knowledge.

Bring it to CF with you, Bill. I'm sure SOMEBODY there can figure it out~

Thanks, I will.
I think it is just not seeing the signal.
Maybe I should just hit it with a bigger hammer.

Yeah, I know what you mean about the 4000. I had that in the rig for a stint as well. That will dig low. Really, really low and with authority.

I wouldn't bother bringing it to CF though. It's not a board that's repairable in the field. It's a surface mounted board that we [or anybody else attending] will not have the parts and equipment to repair. Surface mounted boards are generally referred to as "disposable" boards. Unless you are an extremely lucky guy and it ends up being a resistor that isn't a surface mounted one, nobody will be able to repair it at CF. Even Bob.

Let me ask you this...if it's not seeing the signal, have you tried both the line level and speaker level inputs?

Let me ask you this...if it's not seeing the signal, have you tried both the line level and speaker level inputs?

Not line level as I just have not got around to messing much with it since I have no need of it right now.
My new mains are all I need in the bar.

I will try that this week and see if it shocks the thing to life.

Bill, the power is ON, correct?

I know this is an old post - but what the heck. have been gone for a while....

Regarding the junior sub repairs, I contacted Rita about 1.5 years ago for a super junior sub I had with the same exact failure as in the picture. (resistor burnt by the sine filter capacitors.) she told me I need to send it back to Sunfire for repair. At that time, she did not work on the juniors because she stated they were a completely different design than the other Sunfire subs. So......
Called Sunfire, it was about $350.00 to repair and i had to ship the entire sub to them for the board repairs!!!! No way!

referencing the NHT sub 2i schematic (I believe but I would have to check - it has been a while since I repaired mine) the circuitry is very similar, but not exactly the same. A very good start to troubleshoot the board.
What I found was:

The +12V regulator IC (LM7812) in the power supply section failed - in turn causing the +/- tracking supply rails (+163Vdc and -163Vdc) to temporarily short, causing the output transistors and FET's to fail (which took out the rail fuses as well - but a little too late!). During the repair, both output transistors were replaced including all of the FET's (IRF640), all gate drive transistors (the small surface mount trannys burnt on the picture), power diodes, LM7812 and 7912 regulators, and since I was at it - all electrolytic capacitors.

I know it may be too late for this post...but hope it helps!

Great post !!! Thank you.

Any chance you would want to take a crack at it ?

A friend took the amp board home with him yesterday to take a look at it.
If he can't get anywhere, I'd be glad to send it to you to see if you could work a little magic on it.

James

Hi James,

If your friend does have luck with the main board, the LM7812 and LM7912 regulators on the power supply board must also be replaced, otherwise the main board will smoke up again!!
You may have to replace some tracks on the board as well by the burnt resistors and several smt 0805 resistors.

I repaired both of my subs - a super junior and a std junior sub. Both boards failed in the exact same way!! Now they are as new. Can your friend solder surface mount components (sot23, 0805, so8 parts)? Must be careful when removing smt parts to avoid damaging tracks / vias on the board)

We might be able to work something out. Is Rita still not able to work on these? Only Sunfire?

Chuck