Monsoon PM-9 Transformer - Page 2

Sangram · 23rd November 2020, 06:04 AM

Safer to use 13V. The 25V cap will be on the edge for 15VAC.

yorab · 23rd November 2020, 07:10 AM

Ok, great. Where is a good place to start searching for one? Are there new parts for sale on this site?

planet10 · 23rd November 2020, 07:20 AM

Easiest might be to get a 220 to 110v transformer/autoformer.

You will not likely find a Monsoon part.

PM14 is not likely the same as PM9.

dave

thoglette · 23rd November 2020, 11:42 AM

What Planet10 said. Given the low power level it should be not to expensive. And unless .sg has radically changed in the last decade, there'll be plenty of places with them (Mustafa's comes to mind)

yorab · 23rd November 2020, 11:44 PM

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-...0va/dp/55X2492

yorab · 24th November 2020, 12:02 AM

oh, and thoglette, Mustafa's is a good place but not too far away is Sim Lim Tower and Sim Lim Square. They are the ultimate DIYer's paradise for electronics. Shops packed wall to wall, floor to ceiling with goodies

thoglette · 26th November 2020, 01:17 PM

Quote:

Originally Posted by yorab

Would something like this work?

Probably: it's 100VA which is the magic number, according to the label on the back of my PM-9

I can't honestly remember what the secondary voltage was but if you feed a a dozen volts AV into the primary & measure the secondary, then you'll be able to confirm what the correct voltage should be.

yorab · 29th November 2020, 04:36 AM

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?

thoglette · 29th November 2020, 05:16 AM

Quote:

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?

Generally not a problem.

yorab · 3rd December 2020, 01:32 AM

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?

23rd November 2020, 07:20 AM	#13
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III	Easiest might be to get a 220 to 110v transformer/autoformer. You will not likely find a Monsoon part. PM14 is not likely the same as PM9. dave __________________ Stay safe. Stay home. Respect the 2m bubble.

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23rd November 2020, 06:04 AM	#11
Sangram diyAudio Moderator Join Date: Sep 2002 Location: India	Safer to use 13V. The 25V cap will be on the edge for 15VAC.

23rd November 2020, 07:10 AM	#12
yorab diyAudio Member Join Date: Nov 2020	Ok, great. Where is a good place to start searching for one? Are there new parts for sale on this site?

23rd November 2020, 11:42 AM	#14
thoglette diyAudio Member Join Date: Dec 2008	What Planet10 said. Given the low power level it should be not to expensive. And unless .sg has radically changed in the last decade, there'll be plenty of places with them (Mustafa's comes to mind)

23rd November 2020, 11:44 PM	#15
yorab diyAudio Member Join Date: Nov 2020	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-...0va/dp/55X2492

24th November 2020, 12:02 AM	#16
yorab diyAudio Member Join Date: Nov 2020	oh, and thoglette, Mustafa's is a good place but not too far away is Sim Lim Tower and Sim Lim Square. They are the ultimate DIYer's paradise for electronics. Shops packed wall to wall, floor to ceiling with goodies

3rd December 2020, 01:32 AM	#20
yorab diyAudio Member Join Date: Nov 2020	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?