Jump to content

Extremely Low Volume from ProMedia 2.1 Sub ???


DEC

Recommended Posts

A few weeks ago, I moved one of my ProMedia 2.1 set-ups from my Dell computer to my wife's new iMac in another room. When I got it hooked back up, I got good sound from the right & left satellite speakers, the green light was on the right speaker control pod, but I was getting no sound from the sub. Mr. Clean had previously replaced the DIN plug on the control pod back in 2008, and up to the time I moved the set-up, everything was working just fine.

I checked the fuse on the back of the sub and it visually looked OK, so I thought the DIN plug repair had gone bad. I sent it back to Mr. Clean, but after he checked it, he gave it a clean bill of health. While waiting to get the control pod back, I checked the sub fuse with a voltmeter, and despite it looking OK, it was bad, so I thought I had found the problem.

I got the control pod back, put a new fuse in the sub, and turned the system on yesterday, but I was still not getting any sound out of my sub. I then went on YouTube and played several bass testing videos. What I found on the heaviest/loudest bass passages, was that the sub was in fact moving air and putting out some low-level sound, but only when I had the sub volume level control potentiometer cranked to maximum. However, on "normal" recordings with "standard" bass passages, no noticeable sound was coming out of the sub even with the sub volume level control potentiometer cranked to maximum.

What's next?? I have previously heard that there are other fuses inside the sub unit, but I don't know where they are, what type they are, or if they are even the problem. Can anyone give me some pointers on this before I mess with the innards of the sub?

Beyond that, does anyone know if there is there anyone out there who can trouble-shoot & repair a ProMedia 2.1 sub like Mr. Clean does for the control pod DIN plug? (I am mechanically inclined, but I am not much of an electronics guy).

I really love the ProMedia 2.1 set-up, but between the control pod DIN plug issues and issues with the sub, it does seem like this computer speaker system definitely has its problems. In any regard, if anyone has some insight or suggestions on my sub problem, I would sure appreciate hearing from them.

Thanks,

Don

Link to comment
Share on other sites

Bill,

I appreciate the suggestion, however, if you will note in my original post, I already sent in my control pod to Adam Costa (aka "Mr. Clean") and he gave that a clean bill of health (and I had already made him aware of my subwoofer problems). Moreover, it has been my impression that while Mr. Clean has done a lot of work with ProMedia control pod DIN plugs and premium speaker wires, he doesn't do much in the way of supporting the subwoofer part of ProMedia systems. I am also aware that Mr. Clean is contemplating the closing down of his repair business due to increased demands on his time from his main job and family commitments.

Don

Link to comment
Share on other sites

OK, here's a pretty big update on my ProMedia 2.1 subwoofer sound output woes.

I finally opened up my sub cabinet and got an up close & personal look at the innards yesterday. First off, I found the two internal fuses (2.5-amp/250-volt) and did a continuity check on those and they were in good shape.

ProMedia21fuses.jpg

Then, due to the several other threads in the forum describing no/low volume coming out of the subwoofer as a function of fried resistors, I took a very close look at the 6 internal board assemblies looking for any obvious damage. Sure enough, resistor R120/J113 was partially burned on one of its ends (although the slight damage to mine was far less than others have suffered with their R120/J113 resistors) :

ProMedia21resistor-1a.jpg

This is exactly the same resistor that others have reported fried along with little or no sound coming out of their 2.1 subs. On another related thread: http://community.klipsch.com/forums/t/132217.aspx ("Promedia 2.1 extremely low volume"), Zortrium identified this as a 1/4-watt, 82 ohm, 5% tolerance resistor from a schematic. However, when I called Klipsch tech support earlier today, they said they had no publically available schematics for the ProMedia 2.1 sub/amp assembly. In a follow-up exchange in Zortrium's original thread later today, he was good enough to provide a link to a complete set of the ProMedia 2.1 schematics from Dale Thompson. I posted up the link and schematic diagrams in a new thread: http://community.klipsch.com/forums/t/137146.aspx ("Full Set of Schematic Diagrams for ProMedia 2.1 System!"). The specific diagram for the circuit board and damaged resistor in question is:

Full%20Set%20of%20Schematic%20Diagrams%22-1_supply-714x785.gif

Anyway, I did an in-situ resistance check of the slightly damaged resistor R120/J113 and it read out as 80.4 ohms. Then for a comparison, I did a resistance check of the adjacent undamaged resistor R107/Q106 (which is the same rated resistor as the damaged one), and it read out as 81.2 ohms. Let me say here that I am no electronics guy, but I was surprised at how close the two readings were. So here's a question for those more experienced in such things ... do those close resistance readings imply that slightly damaged resistor R120/J113 is not in that bad a shape, or is this a case where even a small drop-off in relative resistance potentially causes deliterious electronic effects & issues? In other words, does 80.4 ohms versus 81.2 ohms for 82 ohm nominally-rated resistors fall into the category of acceptable statistical variation for such a resistor type? If the latter, it makes me wonder if going to the trouble of replacing the "bad" resistor is going to gain me anything if it is in fact operating within the range of its tolerance. Does anyone have any comments on this?

Then on another related thread:
http://community.klipsch.com/forums/t/126402.aspx ("ProMedia 2.1 fried
resistor - I think"), razzz42 suggests going with replacement 1-watt 82
ohm resistors for both R120/J113 as well as the adjacent R107/Q106
resistor (which he reportedly did with good results in terms of getting full volume back from his subwoofer). I get what razzz42 is suggesting, but is it really OK to move up from a 1/4
watt to a full watt on those two resistors? Would it perhaps be better
to split the difference and just go up to 1/2 watt instead? Does anyone care to weigh in on this one?

Finally, when I was talking with the tech support rep from Klipsch earlier, he said I could purchase a replacement board for $78.98 (P/N 118557) if my repair job did not end up working (which would sure beat buying a new subwoofer unit or entire ProMedia 2.1 system).

I have to order the resistor(s), but once they get here, I hope I can bring my sub back to life as others have successfully accomplished. I will report back as to what happens.

Don

Link to comment
Share on other sites

Well, I unfortunately have bad news to report.

After I desoldered and removed resistor R120 (which previously looked like it was damaged), it turned out that a small amount of the over-sprayed brown foam stuff that is slopped around in quite a few places on the various internal boards in the sub was on the end of the resistor in question, which made it look like it was damaged when it actually wasn't. Anyway, I went ahead and replaced the two 1/4-watt 82-ohm resistors R120 & R107 with 1-watt 82-ohm versions and nothing changed. I still get no sound from the subwoofer unless I crank the sub volume level control potentiometer to maximum, and then I just get the same anemic low-level volume even with a heavy bass passage, so there is obviously something still wrong with one or more components on one of the circuit boards inside the sub unit. The trouble is, nothing else looks burned, discolored, or obviously damaged, so I guess it could be anything at this point.

I am going to have to think about what's next. I would definitely like to get my 2.1 sub working again, but I also don't want to spend an arm and a leg doing it. I am also not willing to start buying replacement circuit boards from Klipsch, as with my luck, whatever I started with wouldn't be the right board. I may have stpeteshepherd from eBay (aka Klipsch forum member "stpete cooling"), take a look at it, although he typically focuses more on ProMedia 5.1 systems as compared to 2.1 systems.

Don

Link to comment
Share on other sites

  • 2 weeks later...

Argh, I have exactly the same symptoms. I always thought it was my soundcard/Windows 7 because the problem cropped up shortly after upgrading to 7. I assumed it was something wrong with the soundcard driver (soundblaster audigy bass management). Well I finally unplugged and tested on a nother computer, same thing, very little bass. I've had these 2.1's since they came out in like 2001. So it's probably time they died. Though a lot of my electronics are that old or even older and still working fine.

Link to comment
Share on other sites

Have you opened up your sub to check on resistors R120 & R107? If one or both of these are damaged, you may be a good candidate for swapping those original 1/4-watt resistors out for 1-watt versions. On the other hand, take a look at this outcome (from page 2 of the "ProMedia 2.1 fried resistor-I think" thread: http://forums.klipsch.com/forums/t/126402.aspx?PageIndex=1 ) ...

DEC, I was able to successfully repair my speakers tonight. Here is my solution:



**SOLUTION**


My symptoms were no green light, volume very soft when knob is lowest,
decreases to no volume as you turn it up. Seems to occur only to people
who have replaced their DINs... suspicious. I too have replaced a
faulty DIN.


The problem was a faulty connection with the repaired DIN on one of the
+/- 14V supply lines that connects the I/O board to the Control Pod. I
suspect it was a poor solder joint to begin with and degraded with heat
exposure over time. After taking a voltmeter and testing the +/- 14 V
supply voltages on the Control Pod board, I noticed a discrepancy in
voltage on (for me) the +14 V supply on the Control Pod board. -14
worked properly when compared to GND (P501:2 - P501:1), but +14 to GND
(P501:9 - P501:8) read a different voltage (-12.1 for me). After
tracing connections starting from the power supply and ending up at the
Control Pod, I found that the missing link was the connection between
P3:6 on the I/O Board and JK201:1 on the I/O Board. That is the
connection from the +14 V line going to the DIN plug. By doing a simple
continuity test with my multimeter, I detected that there was no
electrical connection between the two terminals, despite a visible path
on the PCB trace. After resoldering the connection, full functionality
was restored.


TIP: when soldering this joint, apply the soldering iron tip directly
to the trace on the PCB to ensure proper solder flow and hence good
electrical conduction. The problem was caused by a flux bubble between
the DIN pin and the PCB via. These pins are especially prone to this
problem because of the brown glue/gunk on the other side of the board
which act as a heat sink when soldering. As a result, the trace doesn't
heat up properly when the soldering iron tip is place only on the pin,
so the trace repels the molten solder, causing an accumulation of flux
between the pin and the trace, and no electrical connection.


The problem may be either in the +14 V pin, or in the -14 V pin on the
DIN connection, but either way, that is the likely source of the
problem.


@DEC, since your problem is with the subwoofer, use a continuity tester
to check that pin JK201:2 on the I/O Board (the DIN connector) is
making a connection with R209 and R210, which are connected to JK201:2
via a trace on the PCB. This will test that the solder connection is
good. Alternatively, you can turn the device on and test that the
voltage difference between the two pins is zero. If there is no
connection, resolder the connection and see if that fixes it up for you.



Cheers,

Dan



cross listed here: http://forums.klipsch.com/forums/p/122989/1394942.aspx#1394942

Link to comment
Share on other sites

By the way, in terms of what I ended up doing, I ordered a new ProMedia 2.1
system from Klipsch. I had
previously contacted stpeteshepherd, but he was too swamped with 5.1
system repairs (his meat & potatoes), and he additionally felt that
he wasn't that far ahead of me in terms of trouble-shooting the 2.1
system to get to the bottom of what was wrong with my sub boards in any
cost-effective manner. Mister_Clean subsequently suggested that I keep
my old 2.1 satellite speakers, control pod, and sub for parts, and
that's what I finally decided to do (which should allow me to keep one of my two "old" ProMedia 2.1 systems up and running for some time).

Anyway, I installed the new set-up a couple of days ago in conjunction with my wife's iMac, and other than a minor problem with the mini stereo plug, it sounds great. I think I will open it up though and replace the two 1/4-watt resistors with 1-watt versions just to be on the safe side.

Link to comment
Share on other sites

  • 8 years later...

Did you guys get your systems repaired and working? 

I have a low volume subwoofer and am suspecting the capacitors around the 1000(1K) ohm resistors above the MOSFET and in the transitor area on the LF board. 

I tested the MOSFET's and Transistors out of circuit and they seem OK. I tested all the other components on the LF board also other than the capacitors. 

Edited by nonionizingemf
Spelling typo
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...