Infinity PS-12 Powered Subwoofer Fired Amplifier

[Tecchris0516]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Hello All,

Well I reinstalled the old Q2 and Q3 with the original ones - when I measure between C5 (+) and C10 (-) i only get about 8v.

If i measure the voltage after the (R6-&A) and (R9& R9) I have about 10v ( before the resisitors (51.6V)

I also checked the voltage through the FB1 and FB2 an it is the same on both sides..

[Tecchris0516]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Bud, - JR

Thank you for the response - the fuse is not blowing right now due to me removing the Mosfets. But the 15v is not anywhere near 15V - I will check Q2 and Q3 as I did replace those as well with a cross NTE128P (NPN) & NTE129P (PNP). The only reason why i chenged them as to multiple posts about issues with them. I might put the old ones back and see what I get.

[budm]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

It is linear bi-polar power supply to produce +/- 60VDC with ref. to circuit GND as shown in service manual PDF page 33.
Q2 and Q3 are for linear regulator circuits (they take +/- 60VDC input to produce +/- 15V outputs) to produce +/- 15VDC for running the OP-AMPs as you can see in same page number. So do you still have the + and - 15V as shown in the schematic? or it is still blowing the main fuse?.
So look at the schematic then you will see what/where the circuit GND is for your meter.
Page 32) +15Mod is fed by the +15V through Ferrite Bead inductor FB1.
Page 32) -15Mod is fed by the - 15V through Ferrite Bead inductor FB2.

Q18. 22 are blown is probably due to drive circuits are bad and not switching the MOSFET's ON and off bu they are stuck fully on, there are many parts in the GATE drive circuits that you need to test. This is class D amplifier not linear amplifier.

[Tecchris0516]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Hello JR,

Yes I do have the service manual and have been going through it until my eyes crossed, along with reviewing the data sheets for components - the fuse it correct (2.0a/250v) slow blow)

the voltage out of the rect bridge is 121v DC - the voltages at the MOSFET's are 70v along with the same voltage at the MOSFET driver - (IR2111)

I am trying to find out what controls +15v - MOD and -15v - MOD and +15VSW

[Jr_ece]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

I asked about the fuse due to some similar klipche subs being shipped with incorrect/faulty fuses. The service manual and probably users manual should state the correct size fuse.

[Jr_ece]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Tecchris,
Have you located the service manual? The schematic and parts list are included at least for the PS-12. With the parts list you can get data sheets to determine if the voltage makes sense. I didn't have to mess with the power supply circuitry or transformer so I don't have any specific data that I can recall without digging into the documentation mentioned.

Do you know for sure the fuse rating including voltage, amperage, and speed are correct?

It seems like there was some discussion on here about the expected bridge output, but would need to search for it. Maybe this weekend a couple of the others can jump in and help.

Wanted to let you know we saw your post and to encourage you to stick with it. It should sound good when it's repaired.

[Tecchris0516]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Hello all,

I was wondering if someone can help me out with the above post

Thank you

[Tecchris0516]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Hello All,

New to hear - but a huge wealth of information - I just got a PS-10 from a Garage sale - that didnt power up - Internal fuse was blown - replaced the fuse and immediately blew- did some preliminary checking and form the Q18-22 MOSFETS were bad - replaced and powered up but lasted for about 3 sec and fuse blew again - check and mosfets bad again !

I began checking some voltages and i have some questions

What is the output voltage (DC) from the bridge- i have over 100vDC
What is the voltage After the (R6-&A) and (R9& R9) I have about 10v
What controls the 15V rails - I checked C5 and i have approx 8v but on C10 it is less then 1V

I also replaced TIP31C with the orig Q18,22 to be safe
There were also a list of CAPS that were know issues - replaced all of them as well
and Q2 and Q3

And help would be appreciated

[jiari]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

BTW, Q2, 3, and 4 for the power supply regulation will not affect the Audio amplifier gain, it will affect the maximum audio signal level before clipping. The gain are set by the negative feedback, so if you have to turn up the gain then something has change in the gain stages. Since we are also dealing with low frequency only so if the coupling caps with between each stage has lost it capacitance the you will lose Low frequency.

Thanks Bud. That's helpful. I wouldn't have guessed about the bypass caps and passing low frequency.

[budm]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

BTW, Q2, 3, and 4 for the power supply regulation will not affect the Audio amplifier gain, it will affect the maximum audio signal level before clipping. The gain are set by the negative feedback, so if you have to turn up the gain then something has change in the gain stages. Since we are also dealing with low frequency only so if the coupling caps with between each stage has lost it capacitance the you will lose Low frequency.

[Jr_ece]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Good times but tiring.

[jiari]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

I stuck with the TIP31C part number. I thought you did too based on your parts lists:

You're right. I'm going crazy. Too much work plus 9 month old. Thanks for verifying.

[Jr_ece]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Aw crap. I just realized that I didn't vet TIP41C vs TIP31C (original) like I vetted the MOSFETs. The gain on TIP41C is lower than TIP31C and it is used to set the VCC of IR2111. That drives the downstream circuitry that actually powers the speaker. I would hazard a guess that is the source of the lower output.

I'm working on fixing a different amp. When I buy parts, I'll replace TIP41C with TIP31C. I'll let you know how it goes.

I stuck with the TIP31C part number. I thought you did too based on your parts lists:

Here's my order (quantity in parenthesis) [Description; board references]:


(2) 942-IRF640NPBF [MOSFET; Q18, Q22]
(1) 610-CEN-U07 [BJT NPN; Q2]
(1) 610-CEN-U57 [BJT PNP; Q3]
(1) 863-TIP31CG [BJT Bipolar, Q4]
(2) 647-UVY2A332MRD [100V 3300uF; C6,C8]
(1) 647-ULD1H4R7MDD1TD [50V 4.7uF; C2]
(2) 647-USV1E220MFD1TE [25V 22uF; C4, C9]
(1) 647-UVZ1C331MPD1TD [16V 330uF; C12]
(1) 647-UVY1C221MED1TD [16V 220uF; C37]
(1) 647-UPW1E100MDD1TD [25V 10uF; C35]
(1) 667-ECQ-E1475KF [film capacitor 100VDC 4.7uF; C73]
(1) 667-ECQ-E1685KF [film capacitor 100VDC 6.8uF; C72]
(10) 749-9911-312 [.312 standoffs, nylon]

[jiari]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

You are probably right. We'll see how it performs over the next few months, and if it continues to be solid clean Bass then we'll probably just use it. Really appreciate the help! It was very good having someone else walk through the repairs at the same time. We could not have timed that any better.

Aw crap. I just realized that I didn't vet TIP41C vs TIP31C (original) like I vetted the MOSFETs. The gain on TIP41C is lower than TIP31C and it is used to set the VCC of IR2111. That drives the downstream circuitry that actually powers the speaker. I would hazard a guess that is the source of the lower output.

I'm working on fixing a different amp. When I buy parts, I'll replace TIP41C with TIP31C. I'll let you know how it goes.

[Jr_ece]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Honestly, it's probably not worth the time to investigate. Glad everything worked out for you (and me).

You are probably right. We'll see how it performs over the next few months, and if it continues to be solid clean Bass then we'll probably just use it. Really appreciate the help! It was very good having someone else walk through the repairs at the same time. We could not have timed that any better.

[jiari]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

I've been busy so no time to pull the amp back out and investigate.

I agree that my sub also sounds good especially after tweaking it more (gain, phase, freq), but I'm having to run it with a +6.5db input wheras before repairs it was at +1.5db. Actually +5db is probably closer to equivalent, but I think it sounds better with the input a bit higher and the gain dialed back. I guess the input difference is okay just puzzling. One of the side effects of turning up the input (from receiver) appears to be less standby mode. I guess this could make sense with higher signal levels making it to the sub.

I think you are right about the long leads on the caps. I didn't think about that.

I'm happy with it right now and plan to just use it until I can get another opening to work on it.

Honestly, it's probably not worth the time to investigate. Glad everything worked out for you (and me).

[Jr_ece]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

I just checked my speaker settings and my subwoofer was set 10 dB lower than my fronts. I set them to be equal... I actually think my sub is working perfectly and the situation was really just my setup.

I think Budm was suggesting upping C35 so that the sub stays on longer between the times it sees a signal. I'm still wondering if there's a problem with the sub's signal sense circuitry.

I'm not sure the long legs of the Caps makes much difference in this case. From what I've read, the long legs will act like inductors, which will reject high frequency. However, we're working at pretty low frequency. I feel pretty confident that's not the cause to the issue you're seeing.

I've been busy so no time to pull the amp back out and investigate.

I agree that my sub also sounds good especially after tweaking it more (gain, phase, freq), but I'm having to run it with a +6.5db input wheras before repairs it was at +1.5db. Actually +5db is probably closer to equivalent, but I think it sounds better with the input a bit higher and the gain dialed back. I guess the input difference is okay just puzzling. One of the side effects of turning up the input (from receiver) appears to be less standby mode. I guess this could make sense with higher signal levels making it to the sub.

I think you are right about the long leads on the caps. I didn't think about that.

I'm happy with it right now and plan to just use it until I can get another opening to work on it.

[budm]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

You need to check or replace C37.

[sachs]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

You do realize that the PS410's auto on/off circuit turns off after ~10 minutes of no signal. Dialogue should be going through your centers and I doubt your sub gets any signal during that time. The behavior you are describing sounds normal.

As Budm noted, you could change a capacitor so that the sub stays on longer after receiving a signal.

https://www.badcaps.net/forum/showpo...&postcount=140

Ok, thank you but the problem is the clic,clic of relay in long dialog time...sorry my bad english.

[jiari]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Thank you. The sound of my PS410 is very good, no flaws and the only flaw is that the relay turns on and off in long dialogue movies. Any tips?

You do realize that the PS410's auto on/off circuit turns off after ~10 minutes of no signal. Dialogue should be going through your centers and I doubt your sub gets any signal during that time. The behavior you are describing sounds normal.

As Budm noted, you could change a capacitor so that the sub stays on longer after receiving a signal.

https://www.badcaps.net/forum/showpo...&postcount=140