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

I’m adding to this thread because the information above was helpful. Hopefully Google will help others to find this.

I have a Parasound HCA-1200, purchased in the mid 1990s in the USA, which was designed for 117VAC, and is marked that way on the back of the unit. I now live in Germany where the line voltage is 230VAC, and have been operating the amplifier using a voltage conversion transformer. I got tired of that and decided to convert the amplifier to operate directly off 230VAC.

The good news is that the power supply torroidal transformer has two primary windings, which are wired in parallel to run on 120VAC. To convert the amplifier to run on 230VAC is very simple: rewire the primary coils in series. Here are the steps, which closely parallel those above.

WARNING: I ASSUME NO LIABILITY FOR THE INSTRUCTIONS BELOW. IF YOU DO NOT HAVE EXPERIENCE WITH ELECTRICAL WORK AND ELECTRONICS, AND DO NOT KNOW HOW TO WORK SAFELY WITH LETHAL AC VOLTAGES, DO NOT ATTEMPT THIS. FIND SOMEONE QUALIFIED TO HELP YOU.

(0) Remove power from the amplifier and open it up.

(1) Locate the transformer primary wires. These come from the transformer in a bundle of four wires, which are black, red, clear and yellow. (The clear insulation is transparent.) You are not going to touch any other wires than these four! The red and clear wires are connected together to the mains power coming from the front panel power switch. The yellow and black wires are connected to the central (power supply) circuit board near a 10 ohm 30 watt resistor.

(3) You are going to leave the red and black transformer primary wires connected as they are.

(4) Disconnect (unsolder or cut) the clear transformer primary wire from where it is connected to the red wire and the incoming electrical power.

(5) Cut the yellow wire near the power board. Fold over the end of the stub of yellow wire coming from the power board and put some heat shrink tubing over it to prevent it from shorting against anything.

(6) Strip some insulation from the yellow wire coming from the transformer, and use a sharp knife to scrape off the insulation varnish.

(7) Solder the yellow wire to the clear wire. Insulate with heat shrink tubing.

That’s it! If you want to test this in a safe way, I put a 100 - 200W incandescent bulb in series with the power plug when you plug it in. The lamps will flicker from startup current then should dim and the amp front panel lights should light up.

Here is a schematic, the relevant part is the power supply transformer wiring in the bottom left.  (The schematic in the forum has the wrong aspect ratio, but if you download it in a separate window it is correctly proportioned.)

Best regards,

Bruce

thank you, ironically the amp didn't arrive and my purchase was refunded.

@mikhailf 

Hey there Bud,

sorry for the late reply, been busy as hell and I just remembered this.

So I looked on google and nothing really useful, but my guts tell me it's completely fine. My guess is that the transformer is wired the US way and Japan voltage is acceptable for this wiring scheme. I guess since you asked you must have made a choice. If not, you can always turn it on while having a 500W light bulb wired in series so that any malfunction would be damped by the bulb.

Have fun !

Zeka

@zeka 

I just purchased A21 from Japan and realized that they are 100V. I will be using it in US (120V).

Do you know if I need to make alterations using your initial post details as a reference (since you has a US market unit) or it's a simple plug and play between Japan and US?

Thank you!

@zeka Thanks for your comments. I will try the power convesion this weekend following your advise. 

I' ll let you know the results. 

@corteng  Hey mate,

Welcome to the parasound family ! So, I'm curently not very much in my house and trying to move in another place urgently. I did not have any schematic with me. Opening the amp is not quite possible right now :x

Did you already take a look inside the beast ? First thing is to identify your board number, the instructions I received from Parasound were litteraly a mere word file with the instructions I quoted last year 😂

However if you have basic knowledge in the field that should do it right. Since I cannot really open my amp in the coming days, here are my advices

- Open the amp on a large table, sit comfortably and start scouting the main board. There is a jumper cable where you can read JP13 next to the plug on the board, this one should be rewired on JP14 which is very close if I remember.

Then it's all about finding the P5 and P6 plugs, and plugging on it the white and yellow cable respectively.

Then you need to change the fuse which you can order on ebay easily.

Take your time, don't rush anything yet. Take pictures and post them here if you are unsure !

One great thing at the time I built and still use whenever I'm not sure about my wiring, is a powerful filament lightbulb in serie to your device. The  idea is that as long as the filament is cold, it has a very low resistance. Hence, if everything is normal in your wiring, your device will be powered and the lamp should remain off. It is important to use a lamp that requires much more power than the device you want to protect. For the A21 I bought a 500W filament lamp.
If there is a default on your circuit, the power lightbulb will take on the charge and avoid frying your circuit. You'll notice it gets bright instantly, meaning you have done something wrong.
Here is a link explaining it, in french, in case you'd want to do that with more details.

Cheers and good luck mate !
Zeka

http://pafgadget.free.fr/bidouillages/astuces-bidouilles.htm

@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

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.

Also, I think I could/should change the internal fuses but I have not thought about those yet...

I believe that I should plug P4 to P5, and P3 to P6. Does anyone know exactly which cable must be switched to please ?

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,