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Internal rewiring of Parasound Halo A21 120V --> 230V voltage conversion

Hello everyone,
I recently acquired a gorgeous Parasound A21 which I imported from the US, and as I am really into DIY and opening things to check how it's made, I deliberately looked for a 2nd hand amp from the US, so I would have to switch the voltage operation by myself. I believe I have almost solved the problem, but considering the different sources I found online (none were exactly for the A21, rather for A52), I came to doubt the final moves.
The circuit board is a B4170A, I have already moved the jumper cable JP13 to JP14, the former being for AC120 V and the latter for AC230 V.
Now I'm facing the change into the big transformer wiring. I have a red wire on P4 and a white on P1, both connections labelled as AC120V. The target connectors are P5 and P6, labelled as AC 230V.
The last two transformer wires, yellow and black, are plugged onto "To Transformer TP12" and "P3" respectively, along with a "AC120V" written above both.

There are 2 more wires, P2 and TP11 which connected to the external fuse. ( I have already swapped it for a 6.3A slow blow one)

I know that for 120V operation, the transformers are connected in parallel, and they must be linked in series for 230V operation. The thing I do not know which one exactly are primary and secondary and all the cable are pretty well coated with plastic and I'm not sure how could I do an efficient continuity test.

I believe that I should plug P4 to P5, and P3 to P6. Does anyone know exactly which cable must be switched to please ? Also, I think I could/should change the internal fuses but I have not thought about those yet...
As a safety measure, I have created a power outlet linked in series with a 500W incandescent light bulb, to avoid surge on the A21, if I would come to mismatch some cable, which I'd rather avoid, thanks to this forum hopefully.
Thank you all for reading and hopefully understanding my issue, I wish you all a very pleasant day !
Zeka
zeka
zeka OP
5 posts
 
Hello Jea48,
thank you for your help ! I hope that  Parasound could give a hand to a distant customer, even though there is no warranty anymore.. I also mentionned that I technically qualify as a technician for operating this change since I have two degrees in electronics, but whatever !

The topic on stereo.net seems perfectly fitted, however I "do not have the permission to view this content" even though I registered and verified my account !

Thanks for giving me someone's contact, I will send him a PM shortly
imhififan's avatar
imhififan
2,181 posts
 
The thing I do not know which one exactly are primary and secondary and all the cable are pretty well coated with plastic and I'm not sure how could I do an efficient continuity test.
Based on the photo provided by @jea48

https://www.stereo.net.au/forums/uploads/monthly_11_2013/post-106386-0-69609600-1385421328.jpg

Those two green and two yellow wires in between the power transformer and four rail fuses are secondary.The red, white, black and yellow wires go to the B4170A circuit board are primary.
Also, I think I could/should change the internal fuses but I have not thought about those yet...
No, the four rail fuses should not be changed to lower rating.

I believe that I should plug P4 to P5, and P3 to P6. Does anyone know exactly which cable must be switched to please ?
If you can provide some close up photo of the connections, maybe we can give you more help.

As a safety measure, I have created a power outlet linked in series with a 500W incandescent light bulb, to avoid surge on the A21, if I would come to mismatch some cable, which I'd rather avoid,
Good idea!
zeka OP
5 posts
 
Hello everyone ! Thank you very imhififan for your answer and details. Excellent news, I called Parasound on the phone, explaining my situation and they emailed me with the procedure for the conversion.

Imhififan, yes, after reading some more on the transformers I realized I had misunderstood primary and secondary wire and continuity test for identification.

Changing the railed fuses is definitely not on the menu indeed, a seller from Germany I called probably tried to prevent me from the operation, saying stuff about internal fuses ratings. Well since I am naïve I immediately thought about those 4.

I can upload some pictures I have taken for others who'd need to do the same procedure, though they are not perfect

It turns out I was right, but not completely as the connector labels do not matter as much as the color code of the cables. These instructions are for B4170 board only.

-jumper JP 13 to JP14 
-white lead should go to P5
-yellow lead should go to P6
-Red and black leads should stay connected where they are
-rear panel fuse should be changed accordingly from the writing on it, 6,3A slow blow


imhififan's avatar
imhififan
2,181 posts
 
@zeka
Great, thanks to let us know, it will help other members if they need to do voltage conversion. Also kudos to Parasound of their great customer services!

corteng
2 posts
 

@zeka , I am in the same situation. I need to do the power conversion . I wonder if you can send me the squematic and some photos. Thanks

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