Anyone here own a Rel Sorm III sub?

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#83
Hi all! My REL STRATA 3 makes a popping sound when turned on and off. Specialists in my city offer only delay relays. But I don't think REL makes their subwoofers with this feature. Thanks to your site, I was able to get rid of rustling sounds during playback by replacing the resistor. And I don’t know how to solve this problem. I will be grateful!
 
#87
Hi Guys,
I've a REL Storm III with this problem. The sub work but with low amplification. I've dismantled the plate amp for a test and this is the result on 8 ohm dummy load. The signal is good until a 10Vrms (12 Watt RMS) and then distorts a lot. The plot show output at max level of knob. No DC output.
I've tested all junction of Bjt and diode and they seem good (on PCB).
What could be the cause?
It seems that the voltage amplification is missing and therefore it could be the driver stage even if the transistors seem ok?
The output of preamp PCB on yellow cable it's 900 mVrms before saturation. It's OK?
The big 12K resistor it's OK.
Thanks in advance for the support
 

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#91
Buriedcode said:
Wow, those were the exact repairs I did.... the SOT89 BF469's/70's to MJE340/50 and R8 to 15K - used a 3Watt too.

I used a machined piece of aluminium for a heatsink for all four transistors, with isolating mounting kits, and fixed it to the board with M3 bolts.
Click to expand...

@Buriedcode, are you still around? I had saved off this image some time ago. I no longer see it in the thread, but assume that it's your machined heatsink.

I'd like to replicate it to improve the cooling of the MJE340/350 transistors. I'm trying to find a suitable quad TO-220 heatsink like yours. Or a suitable starting point heatsink that could be machined like you did.

Suggestions by @Buriedcode or anyone else welcomed.

qRSyS7jh.jpg
 
#93
Ulver said:
You could use a piece of aluminum in an L shape of the appropriate size. Simple and cheap. Of course you have to isolate the transistors very well.

Or look in PC power supplies if you have a broken one. You can find something to adapt.
Click to expand...
That's a good suggestion, thanks. Perhaps I'll go with aluminum L stock if I don't find anything better. (I'd rather not hunt for one-offs from old equipment, as I have multiple Storm IIIs that I would like to retrofit. So I'm hoping to find a commercial heatsink as a starting point, even if it requires some machining to shorten it or remove some material)

Otoh, I really like the fins on @Buriedcode's heatsink.

I came across the Ohmite CSM223-50AE: https://www.radwell.com/Buy/OHMITE/OHMITE/CSM223-50AE

Ohmite CSM223-50AE.png


The center holes are spaced perfectly, and it just needs a couple more holes drilled into it, in order to make it a quad TO-220 heatsink.

However, it's apparently manufactured on demand only, which would require a commercial-size order. Unsurprisingly, I can't find it in stock anywhere (I tried Mouser, Digikey, Newark, Radwell, eBay & Amazon).

I just called Ohmite directly, and they asked me to follow up with an email. I'm not optimistic that it will lead anywhere, but we'll see.
 
#97
tangoextreme said:
You could get this on ebay:
Heatsinks - for Transistors / Diodes / SCR / IGBT - 4.5"W x 2"H x 1"D - lot of 4
Click to expand...
Much obliged @tangoextreme !

LOL, because Ohmite got back to me early today, and let me know that there's no stock of CSM223-50AE around, either at Ohmite, or at any of their official distributors. So I tried hunting on eBay (again), spotted that exact listing myself, and already ordered the shorter ones by the same seller!

The shorter ones are 3" W, instead of 4.5" W, but are otherwise the same. They will still require some modifications, but are quite similar to @Buriedcode's heat sink, as you already noticed yourself.
 
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