Infinity PS-12 Powered Subwoofer Fired Amplifier

[budm]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

I think you may be confused on the marking LO= ON marking at the output of U4B, ON means the speaker relay is ON. HIGH = MUTE speaker relay OFF. May be you want it to say - or + instead.

Circuit function: U4B which is setup as a comparator, the DC voltage at pin 6 (- input) will be at 0V when there is no audio is present to charge up the cap C37.
The pin 5 (+) input is bias with + Voltage from the voltage divider R63 10K (FED BY +15V) and R64 2.7K, so the + input is being fed by +3.19V, so the output pin 7 will be positive which will make RED LED D1B to come on - Cathode of RED LED is connected to ground.
When the audio signal is present, C37 will be charged by U4A,when the cap voltage reach 3.2v, the the output of the U4B will swing negative, the Green LED the anode of green LED is connected to Ground so green LED D1A will come on.

Q1 PNP will also be ON when U4B output is LO (-) which turns on the speaker relay.
The delayed time before it goes in to MUTE mode is the RC discharge time of R121-C37 time constant.
BTW, fault triggering by the PROT signal can also cause the relay to turn off, this is done by Q7.

[DoubleD14]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

OK well got it reassembled and now it sits in standby(red led) and doesn't go into on mode(green LED). I have line level rca's to it and I got nothing, same setup I had when it was jumping in and out of standby mode. Not sure what to do now. Unfortunately the 9v in my multimeter is dead and I dont have any spares. I'll have to get one and report the voltage on C2 & C37 for you. Thanks again for the help!

[budm]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

BTW, do you have soldering iron, etc.

[DoubleD14]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

OK got my battery for my multimeter, I'm pretty clueless about what settings to use on this meter. Can you please guide me. Yes I have a soldering iron.

[budm]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Show us good clear pictures of your meter, also make and model.

[DoubleD14]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier



Not seing a model number on here, cheapo digital multimeter

[budm]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Set it to DCV 20 and test the meter by checking a 1.5V battery to see what it shows.

[DoubleD14]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

shows 1.53

[budm]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

OK, then start taking voltage readings, just do not let the probes slip on you.

[DoubleD14]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

ok these are bouncing all over the place on both capacitors:
C4 hovers around 14.5
C37 bounces from .4-1.1 or so
LED on unit is still red like its not getting a signal to turn the amp on...so it's not even doing what my initial complaint was, seems worse now. I only took it apart and put it back together

[budm]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

How about C2 Voltage s marked in post 56?
https://www.badcaps.net/forum/attach...1&d=1413344894

Also check the DC Voltage on either C71, 72, 73, or 74 to make sure it is not the power amp output is causing the shutdown.

[DoubleD14]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

How about C2 Voltage s marked in post 56?
https://www.badcaps.net/forum/attach...1&d=1413344894

Also check the DC Voltage on either C71, 72, 73, or 74 to make sure it is not the power amp output is causing the shutdown.

My appologies for the delayed reply, been entirely too busy as of late.
OK got the following results"
C2 reads about 6.25 but bounces a bit to a few tenths above or below that
C71-C74 are all 0.0
Thanks,
Derek

[budm]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

OK, on C2 Voltage reading does not look right.
Do you have 100~1K resistor?
If you do, put the resistor on the two legs of C2 and see if the relay will come on

[DoubleD14]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

I don't have any resistors, where can I buy one locally? Radio Shack?

[budm]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Yes, any 1/4W or larger will be fine.

[drakulina]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

OK, on C2 Voltage reading does not look right.
Do you have 100~1K resistor?
If you do, put the resistor on the two legs of C2 and see if the relay will come on

I am really sorry to revive an old thread, but I have an Infinity PS410 (same amplifier plate it seems as PS-12) with the same fault as DoubleD14's.

I have measured the C2 voltage and it is 5.82 - 6V. It drops to 4.5 V if I manage to make the relay click by setting the plate horizontal with the discrete components on the bottom.

I tried your advice to use a resistor on the C2 pins and the relay clicks nicely and the sub works. I do not understand what component is faulty? The C2 cap?

Thank you

[drakulina]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Well, it was the C2 cap.
Replaced and now the amp works fine.

[hepha3stus]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Hi All,

I hope you can help! I have a PS210 (Service Manual Attached) which will not produce any sound. The power supplies look good, and I have been applying a signal to the Amp, and following it with an O-Scope. Here is where Im at so far:

The signal looks good on side 1 of R84, then is pulled low on the other side side 2. Scope images attached. I dont think the signal should be Low on side 2 of R84 should it? what should I do next?

I am a DIY-er, but am new to electronics and repair, Help is much appreciated!!!

[DarDar]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

I also have a PS12 which had died a while back. Started off making popping noises on occasion then quit. When I first opened it up I immediately noticed that the C6 cap (3300uF) had a bulging top. (black plastic but definitely pushed up) I made an assumption that was the problem and ordered two new caps. Got them in and swapped them out. When I moved the cap that was bulging back and forth I could feel something inside moving around, definitely not normal so I figured that was the problem. However when I installed the new caps it still didn't work. That's when I searched the net and found this thread! My LED also fluttered between red and green, (95% red). I cranked up the volume and adjusted the bass output +10 db from the receiver and it just fluttered away between red and green (now about 50/50), relay clicking madly. I tried putting an 820 ohm resistor across C2 as suggested in the thread and it went to green. It appears the caps that failed were all SAMXON, so I'm going back with Nichicon. The new C6 and C8 were 25mm instead of 22mm but they fit just fine! You can definitely notice where the board has been heated up due to those 5 watt resistors! So in addition to C2, I'm going to change out C4 and C9 while I'm at it due to excessive heat... and C78 and C12 to replace the bad actors ( SAMXONs)! Soooooo, I have ordered a few more caps and hopefully in a few days I can give you the results!
First pic shows new 3300uF Nichicons caps already in place (albeit tight)! Second photo better displays heat problem!

[DarDar]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Yeaa.... PS12 is FIXED!!! Thanks for the information! Burned it in yesterday with about 5 hours of hard rock thumping! Changed out all caps in high heat area and all Samxon caps. Total of 8! Hopefully I want have to go back in, but it would still be advisable to help solve the heat issue!