Monsoon PM-9 Transformer

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
I moved from the US to Singapore about 10 years ago. I had my Monsoon PlanarMedia 9 system shipped with our household items and I'm just now digging it out (yeah, it takes me a while to unpack).

My PM-9 is rated for 120 VAC 60Hz but here in Singapore, the supply is 230VAC at 50Hz. I assume that the frequency difference in this particular application won't be critical (is that correct?). I'd like to swap out the onboard transformer for one that will work with the local supply. I'm not a complete novice, but I haven't done much electronics DIY since moving to Singapore, so I suppose it would be appropriate to respond as though I am a novice.

The markings on the transformer are:

HK76H-129
TTI1201C014
BUILT IN THERMAL FUSE
0233

And on the side:

DAR PLUS A

I can't find any info on this part, and therefore, I don't know what the output should be. I also don't have an external step-down transformer in order to be able to power up the unit and test the output.

Does anybody know if I can simply swap out the transformer in this application? Any idea of the transformer output or how I could measure it?

(I have a few pics of the transformer if that will help--just let me know if it's necessary to post them)
 
I suppose that my questions are more general in nature. Sure, I happen to have the planar speakers, and that's why I posted in this section, but I suppose this question could be asked of any brand of speaker subwoofer. Not sure if I posted in the best place to have the most eyes see this.
 
Am I correct that a brick is an external device that is inline with the AC line, similar to a laptop? If so, I don't have a brick.

I have a typical US grounded blade plug (2 flat blades, one ground prong) that runs through a line directly to and through the back of the subwoofer, to a main on/off switch, then to the transformer in the pics.
 
Ok, cool.

Just to confirm then, I'll need a mains transformer for 50Hz that steps down from my supply voltage of 230VAC to 15VAC correct? I assume the rectifier will have no problem with a 50Hz input instead of the original 60Hz input. Is that correct?

I've attached some more pics in case anybody needs these in a future search. In the thread that Sangram linked, handrew shared a schematic in post #86. However, the schematic is for the PM14 whereas I have the PM9. Similar but some differences if you compare the schematic to my pics.
 

Attachments

  • Monsoon6.jpg
    Monsoon6.jpg
    829.8 KB · Views: 43
  • Monsoon1.jpg
    Monsoon1.jpg
    1,022.4 KB · Views: 124
  • Monsoon2.jpg
    Monsoon2.jpg
    1,016 KB · Views: 120
  • Monsoon3.jpg
    Monsoon3.jpg
    990 KB · Views: 121
  • Monsoon4.jpg
    Monsoon4.jpg
    991.4 KB · Views: 123
  • Monsoon5.jpg
    Monsoon5.jpg
    1,008 KB · Views: 115
  • Monsoon9.jpg
    Monsoon9.jpg
    749.6 KB · Views: 49
  • Monsoon8.jpg
    Monsoon8.jpg
    639.9 KB · Views: 43
  • Monsoon7.jpg
    Monsoon7.jpg
    911.9 KB · Views: 48
I'm hoping to not have another external component, hence the desire to change out the internal PT. However, I'm not sure if it's possible with currently available parts and with this specific circuit. It doesn't bother me to replace parts with non-OEM--again, if possible. I'm just not sure of all the ramification of swapping the PT.

Would something like this work?

https://www.newark.com/block/st-100-23-12/transformer-iso-12vac-100va/dp/55X2492
 
I found an old wall-wart style voltage converter that I used to feed 120V into the sub's internal power transformer. Measured 12V across the secondary winding. I guess it's a 10:1 ratio for anybody who may need this info in the future.

I also measured the mains supply voltage and it was 240V, although Singapore is (I believe) listed as a 230V grid. I'd think that I should be able to find a relatively cheap 240V-to-12V power transformer rated for 50Hz. But then again, I haven't really started searching, apart from the link that I provided in the earlier post. I hope it doesn't turn into a needle-in-the-haystack search, lol.

Anybody with experience want to opine whether transformers rated at 50Hz and 220V, 230V and 240V at the primary would all work in this particular case?
 

Attachments

  • Monsoon9e.jpg
    Monsoon9e.jpg
    988.8 KB · Views: 61
I finally had some time to look around the local shops for a power transformer. Plenty to be had in the USD20-25 range.

However, the 100VA PTs that I came across are quite a bit larger than the original. This leads me to believe that:

1) the original Monsoon PT is a high-density special PT and therefore can pack 100VA capacity in a much smaller and lighter form (I highly doubt this based on the price point of the system)

or

2) the Monsoon PT is not 100VA, even though the subwoofer nameplate says 100W (see earlier picture)

I assume that if I undersize the replacement PT, then it could easily overheat or worse. Is there some way that I could determine the VA rating of the original PT so that I can confidently fit a properly spec'd replacement? Also, the original PT has a thermal fuse while most of the PTs that I saw at the shops did not have one. How critical would this be?
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.