Let me give you a bit of advice.
Forget about those cheap made in china crap amps in those subs.
Even Polk won't support repairing them.
And there are loads of people complaining about those Polk subs failing.
And I've given up on attempting to service cheap crap amps.
Not worth the aggrevation.
A reasonable work around is to get a decent plate amp like this one, do a little trimming of the opening, and mount it.
MS 8A 100 Watt Amp
You'll be far better off and it's much more reliable.
Forget about those cheap made in china crap amps in those subs.
Even Polk won't support repairing them.
And there are loads of people complaining about those Polk subs failing.
And I've given up on attempting to service cheap crap amps.
Not worth the aggrevation.
A reasonable work around is to get a decent plate amp like this one, do a little trimming of the opening, and mount it.
MS 8A 100 Watt Amp
You'll be far better off and it's much more reliable.
wiseoldtech,
I agree 100% and thanks for the advice. Nowhere info available, the boards are really bad, extremely thin tracs, smoothing caps mounted next to heatsinks that dries them out faster. I got it up and running for a friend after replacing bad caps, I'll advise him to get rid of it asap. Gladly I will never buy any Polk stuff after what I have read.
I agree 100% and thanks for the advice. Nowhere info available, the boards are really bad, extremely thin tracs, smoothing caps mounted next to heatsinks that dries them out faster. I got it up and running for a friend after replacing bad caps, I'll advise him to get rid of it asap. Gladly I will never buy any Polk stuff after what I have read.
wiseoldtech,
I agree 100% and thanks for the advice. Nowhere info available, the boards are really bad, extremely thin tracs, smoothing caps mounted next to heatsinks that dries them out faster. I got it up and running for a friend after replacing bad caps, I'll advise him to get rid of it asap. Gladly I will never buy any Polk stuff after what I have read.
Polk's reputation WAS for years, quite credible.
But it seems that they went the way of cheap manufacturing (greed) and now I wouldn't give them even a one-star rating.
A good friend of mine has older (1980s?) Polk speakers, built well, quality materials, sound great.
He bought that same Polk sub, which lasted only 3 years, then started failing.
I was not about to deal with the cheap amp, and knowing full well of its bad reputation.
So I enlarged the amp opening a bit and fitted in the Apex plate amp.
Much better! - he's been pleased since, and should not have issues for a long time.
Attachments
The smps is a minute wimpy thing, there are lots of posts moaning about the "heartbeat problem". Thump thump thump, seems there are a couple of their subs that are up to maggots.Bad smoothing caps. 47uf 63V. No thanks. I fixed a smallish PSB sub awhile ago, smps also wimpy. Money saving stuff from we all know where.I have a Martin Logan Dynamo1000 that have served me without troubles. Then again I do not listen to music the same way as I did 15 years ago !
I have a Martin Logan Dynamo1000 that have served me without troubles. Then again I do not listen to music the same way as I did 15 years ago !I agree with all, the amplifier is not hi-end but the first problem of this subwwofer is it is always ON, also when it is in standby state, the switching power supply is running, so some capacitors run out, electrolytic capacitors have a limited life time, is normal. My advise is unplug the power cord when the sub is not in use. Fully electrollitics recap can solve some problems. Unfortunateli on my SUB also one mosfet is died, I just order it and I'm waiting for replace.
Two transformers can't be compared, Apex have a linear power supply, Polk ( with Sonavox amp) have switching power supply.
And yes, those failure-prone switching supplies are crap.
They've been a problem since the beginning, I've had to repair hundreds of VCRs, etc., over the decades for SMPS failure problems.
A guy spends almost $200 for a sub, same brand as his older early 1980's (and well-built) Polk speakers, and winds up frustrated after a short time due to the crap build quality in that lousy sub.
I can guarantee you that now the guy can enjoy his (modified) sub without having to worry that it will break down any time soon.
Besides that, I added a "sensing" relay circuit which completely kills power to the sub supply transformer after 5 minutes of non-audio use. - basically the same as "pulling the power plug".
In that condition, it only uses 3 watts in "standby" mode.
I ag
I agree, I hate smps power supply, expecially when is used only for budget, in this plate have no sense a switching power supply and AB class amplifier (among other things with a ridiculous heatsink), normally is used a linear power supply and a class D amplifier, to use less power, so on the PSW110 the only reason is for built a budget sub.
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I'm happy for you. In my amp there is a defective IRFZ14 N channel mosfet, I'm looking for to replace it. Afther i think to replace all the low impedance power supply electrolytic capacitors and mont an additional heatsink
I have only replaced some el caps that gets heated due to the heatsinks IIRC. Might just as well replace all EL caps around those sinks, yes a bigger heatsink may help.
Easy enough to bolt a decent finned heatsink to the output transistors side of the cheap aluminum chassis.
Smear on some thermal grease and voila.... done.
First I try to repair it, I hope that the cause of the malfunction is only the mosfet, unfortunately I have the schematic but the reference voltages are not declared, now they are too low, I only have +5 + 5V on the final transistors, I hope both for what it is switching supplies a wrong voltage and I would not like to blame the oscillator module, which is not found and of which I do not have the schematic, except the mosfet all the other components on the main pcb seem ok.
I will mount the heatsink on the aluminum face opposite the transitor, it is impossible to interpose it behind the mosfet, but I think it will help anyway.
Anyway, i fear the problem on my sub amp is also in a mini PCB mounted in vertical over the main pcb, I have not the schema of it, it drive the mosfet on the primary of transormer. I already give out one of the four power mosfer of the bridged stage, one IRFZ14, but the supply voltages are still too low, I have a little bit more the +12V and -12 on the collector od the two stabilizer transistors for the -10 and +10 supply of the pre and driver stage, are too low! On the power stage there is only arround 10V, for the same cause becouse All these voltages com from the secondary of the transformer and after rectified by a MUR diodes, My hypothesis is that in standby the amp must work under the right voltages, for lower the power consumption, and when there is a signal applied to the mini pcb (on the AUDIO-TRACK pin) see it and increase the voltages driving better the MOSFET. The mini pcb is impossible to find and the scheme is unknown, so i think to give to the power stage an external voltage but need to know what are the voltages when ampli is running. Nobody have misured the voltages in the heatsink of the two stabilizer transistor and the power stage when the ampli is running?
UPDATE, i discovered this amp use BASH topology, the switching power supply increase voltages when the amp need it, so 10 Volt without signal could be normal, but on my amp the voltage dont increase also when signa is applied, i think the problem is on PWM controller SIP module solded on the pcb.
