Cinepro Amplifier Voltage Change

mmcepaj

Novice Member
Hello, New member, I thought this would be a good forum to educate myself on building a home theater system from scratch. So looking forward to reading lots of threads.

I know this could be a longshot, but I now need some help with an issue. I purchased a used 6 channel power amplifier, a Cinepro 3K6 II. The company no longer exists and this has been out of production for some time. I do know these amps can be converted from 120 VAC to 240 VAC power supply, by only switching some wires internally. I thought I had a wiring diagram explaining how to do this, however this does not match any of the actual terminal wiring inside the amp. It is probably for another newer model made by a subsequent owner of the Cinepro brand (long sad story).

I have read previous threads on this forum related to this issue, and one referenced a Bob at AB service having the correct wiring diagram. Unfortunately he and AB service must also be out of business.

Attached is a picture of the terminal inside my unit. I have a pdf copy of the voltage conversion wiring diagram, if someone can tell me how to post this in the forum (maybe this will help someone else?).

Anyone have a correct wiring diagram that explains how to do this? Much appreciated.




20210821_151847.jpg
 

oaklandraiders

Well-known Member
It’ll be the windings on the transformer that need changing. There’s prob a 240v one.
I know nothing about how to do it, but that the principle.
If you can find a local repair place thy could prob do it
 

mmcepaj

Novice Member
Thanks for the response, yes there are multiple windings on the transformer, unfortunately knowing which wire is for which winding is impossible without a legend key or perhaps ohm readings of the windings. But even so someone smarter than me on transformers would need to know how to interpret those results.

I do know it is only a matter of switching the wires on the terminal strip in the picture.

When I purchased this amp, it was advertised as having been wired for 240 VAC supply, however the permanently attached power cord has a NEMA 5-15R plug ( 15 amp 120 VAC prong arrangement) which makes me suspicious. How could it be powered on 240 VAC supply with that cord prong, unless someone violated electric codes (and risked a fire) by wiring 240 VAC to a 15/20 amp 120 VAC wall receptacle?
 
Last edited:

mmcepaj

Novice Member
Well only got one response to my query (which was basically correct), so I investigated myself to try and uncover the answer. I am documenting my results here to benefit others, as I could find no other source on the internet or on any forums that explain how to convert these from 120 VAC to 240 VAC (US power systems). Since these are longer in production interest is very low as evidenced by lack of response to this thread.

Anyway my amp is indeed wired for 120 VAC not the 240 VAC advertised (what a putz seller!). I determined this by tracing every wire related to the power supply in this unit, and disconnecting the wires from the toroidal transformer and measured for continuity and resistance. I also have a Cinepro 4K6 IV Gold and did the same thing. It is wired for 240 VAC from the factory and has the correct power plug (NEMA 6-20P). I was able to determine which transformer windings were connected and which are not. I also checked for continuity between all terminals on the power terminal strip. From that, and how the unit was wired, I could conclude my power configuration. Basically if the two primary windings of the toroidal transformer are wired in parallel, its set up for 120 VAC; series connection of the primary windings gives 240 VAC.

That's simple enough but rewiring for 240 VAC is a bit more complicated than just juggling the wires on the terminal to reflect this transformer wiring. There are two 120VAC circuits on my unit that have to be powered correctly - a relay which appears to cut power to the amp if some bad conditions are present (there could be many), and some sort of power board which I surmise takes 120 VAC and steps it down to perhaps 15 VAC ( a guess) then rectifies it to DC for use in the PCB's of the amp. The tricky part here is the neutral wires of these circuits must be connected to the center tap of the primary toroidal (the point where the two windings are connected in series).

Additionally, the old neutral (white wire) in the 120 VAC scheme becomes the L2 wire in the 240 VAC wiring, meaning it is a power supply wire now and that I believe it must pass through the combination circuit breaker / main power switch. Not doing so would allow 120 VAC to be present in various places even with the power switch off (between L2 and any center tap wiring connected mentioned before). Not a good thing. I searched down my power switch and found it is capable of providing switching and circuit breaker duties of both L1 and L2 wires (two pole single throw with overloads) and is rated at 250 VAC and 16 amps. Cinepro just had to specify this switch for the 240 VAC and L1 and L2 switching service option, as it is overkill for 120 VAC.

Lastly, my power plug has to be changed out from a NEMA 5-15P to a NEMA 6-20P style plug, otherwise it will not plug into a National Electric Code 240 VAC rated 6-20R receptacle (or 6-30R for 30 amp service). I also need to check the wires in the power cord to ensure they are rated for the new service as well. I would hope that is the case if Cinepro was advertising the dual voltage capabilities (which they did).

I could find no reason to believe wiring changes are needed on the secondary side of the toroidal for the voltage conversion, but I am not 100% positive. All of my investigation on the internet and the readings I took on these secondary windings gave me no reason to believe any are needed. But please comment!

Well that's it, lots of words I know but I hope it helps someone. I have attached a Cinepro wiring diagram that is apparently ONLY VALID for amps made at Mt Sinai New York, by the subsequent owners on Cinepro - Mark 4 and above amps perhaps. It does match my 4K6 IV perfectly. Amps I've checked made in San Francisco by the original company don't match this drawing. I have also attached my sketches of my 3K6 II amp wiring for 120 VAC and 240 VAC.

A WORD OF CAUTION - I HAVE NOT CONFIRMED THE ABOVE BY REWIRING AND POWERING IT UP. I AM PROVIDING THIS TO GIVE OTHERS A PLACE TO START FROM. YOU MUST CONFIRM YOUR AMP IS SIMILAR TO MINE, WIRE COLORS AND COMPONENTS. I AM NOT AN EXPERT OF ALL CINEPRO PRODUCTS AND THE VARIOUS MODEL DIFFERENCES. For example, my 4K6 Gold amp wire colors are all different and it does not have the power cutoff relay my 3K6 II has. Terminal numbers are all different and there are other differences. YOU WILL HAVE TO DO YOUR HOMEWORK TOO OR RISK FRYING YOUR AMP AND BURNING YOUR HOUSE DOWN! AGAIN THE ABOVE IS JUST A STARTING POINT.

Any intelligent, informed comments on anything I've written and posted are welcome. I would like confirmation of what I concluded!
 

Attachments

  • Cinepro 4K6 IV Power Wiring.pdf
    374.9 KB · Views: 13
  • Cinepro 3K6 II 120 VAC Power Wiring.pdf
    628.8 KB · Views: 16
  • Cinepro 3K6 II 240 VAC Power Wiring.pdf
    532.2 KB · Views: 15

MickB

Active Member
Hi,
That's great info. I've had my Cinepro 3K6 III since 2002, here's the info I got back then to re-wire:

Malcolm, just to make sure that we are talking "apples to apples" before you start the conversion check to make sure that all of the colors that I make reference to below are all the same colors wires that you have in your actual AMP.

They are: Red, solid white, solid black, white with a black stripe, brown, and powder blue.

The reason I ask you this is sometimes we get different transformers from our transformer vender. Same power ranking but different color leads.

Should all of the colors match then you'll be fine as long as you follow
all of the steps to the letter.

Ok here we go.

The RED wire coming from the transformer is to be attached to the TOP RIGHT TERMINAL BLOCK BLADE. Note: should already be in that position.

The WHITE POWER WIRE SHOULD ALSO BE IN ITS PROPER POSITION AS WELL, THAT BEING JUST BELOW THE RED. This is the wire that runs from the Terminal Block to the amplifiers ON/OFF BREAKER.

Next down that same side of the Terminal Block is the BLACK WIRE coming from the transformer that is to be placed right under the WHITE POWER WIRE. That being the third position down the right side of the terminal block.
Note: should already be in that position.

Next is the WHITE WIRE with the BLACK STRIPE. Still on the right side of TB.
This is to be positioned directly under the BLACK WIRE. Note: there should be nothing attached to this blade as it sits before you now. And this is actually the first wire that you should be moving. It should be located on top of the TB next to the RED WIRE as it sits before you now.


***VERY IMPORTANT Now, remove the BROWN WIRE from its current position, that being right next to the Black Wire as it sits before you at this stage.
And place the BROWN WIER "ON THE EXTREME BOTTOM LEFT SIDE BLADE OF THE TB".
Note: should end up across from the White and Black Wire at this stage.



The POWDER BLUE WIRE should be in its proper position as well, that being right under that big black round MOV on the left side of the TB.


CHECK AND RE-CHECK YOUR WORK MALCOLM!! EVEN HAVE ANOTHER PERSON READ THE INSTRUCTIONS AND SEE IF YOU GOT IT RIGHT. I'M SURE THAT YOU'LL BE OK.

LET ME KNOW.

TRAVIS
CINEPRO
 

mmcepaj

Novice Member
Thanks much MB! I'll study the instructions and will compare to my setup, hopefully to confirm they are identical. Did you actually make the conversion?
 

MickB

Active Member
Yes, as I purchased it direct from the States back in 2002, & had to do the re-wire when it arrived here. Has worked perfectly for nearly 20 years now :)
 

mmcepaj

Novice Member
Well, I compared these instructions to the setups in my 3K6 and 4K6 and they do not appear to apply to either of my amps. I say "do not appear" as interpretation of these instructions could vary (such as - what does "below", "under", "next to", etc. mean in terms of electrical connectivity and position on the terminal block?). Cinepro should have provided drawings clearly showing the before and after connections (like the one file I attached that they did for the later 3K6 and 4K6 models).
Seriously, congratulations to you for correctly interpreting and re-wiring your amp from these instructions! I would have been hesitant to if I were you. But perhaps seeing your terminal block and wiring layout would have made these instructions very clear, but I don't see how...
 

MickB

Active Member
Hi,
Here's the matching picture:
 

Attachments

  • thumbnail.jpg
    thumbnail.jpg
    23.4 KB · Views: 35
Last edited:

mmcepaj

Novice Member
Fantastic MB thank you very much! If you opened up your 3K6 and sketched this, I am in your debt, very much appreciate your effort. I'll take a look at this and compare against my setup.

I actually have another Cinepro a 2K6 III and just got access to it today to open it up for a look. It is definitely wired as a 120VAC (I operated it on 120 VAC) and I did similar continuity testing and wire tracing; the resulting sketch is attached. At first glance it appears similar to your 3k6 III having 8 terminals on the strip. The biggest differences with my 3K6 is that it does not have the power cutoff relay, no separate board for the 15 VDC supply, and the SG-240 surge suppressor is wired to the hot wire (in the 120 VAC setup), while my 3K6 II SG-240 is wired to the neutral wire in the 120 VAC setup. Converting this to 240 VAC would simply be juggling wires on the terminal strip, wire L2 to the power switch, and changing out the plug to a NEMA 6-20P

My only guess for the differences between the 2K6 and 3K6 is that in 120 VAC mode on the 2K6, the relay protects the amp by breaking the hot wire when a surge condition is detected; the SG-240 does nothing in 120 VAC mode (its on the neutral). In 240 VAC mode, the SG-240 surge protects L2 (a new hot wire), while the relay still protects L1 (the other hot wire). For that to work, the 15 VDC separate power board must be powered before the relay contact, as any surge sensing circuitry in the amp must be powered to operate the relay correctly. Again this is just a guess. If that isn't it, someone modified the amp!

Other differences is that the 2 red and 2 orange wires on the 2K6 secondary are actually wired to a PCB, while on the 3K6 the red, orange, and yellow secondary wires are wired to nothing.

I powered up the 2K6 and also confirmed: the power switch is a two pole, single throw unit; the white and grey wires (unconnected) register 100 VAC with the hot wire, and 20 VAC with the neutral wire. The grey wire appears to be a tap off one primary coil, while the white is a tap off the other primary coil. I am guessing this is to provide 100 VAC for other service markets such as in Japan. I also confirmed the yellow secondary wire is a "neutral" for that side as multiple neutral wires from circuit boards and speaker terminals connect to it, and the PCB board is labeled "Ultra Noise Star Ground" at that connection.

I posted all this information here as virtually nothing exists on the internet for the Cinepro voltage conversion. I hope this helps others in the future.

Well thats it, any comments are appreciated.
 

Attachments

  • Cinepro 2K6 III 120 VAC Power Wiring.pdf
    314.8 KB · Views: 15

laup

Member
2k6III

240volt set up if this helps

just got a blown psu though :(
 

Attachments

  • WhatsApp Image 2021-10-31 at 23.16.32 (1).jpeg
    WhatsApp Image 2021-10-31 at 23.16.32 (1).jpeg
    328.7 KB · Views: 17
  • WhatsApp Image 2021-10-31 at 23.16.32 (2).jpeg
    WhatsApp Image 2021-10-31 at 23.16.32 (2).jpeg
    276.9 KB · Views: 17
  • WhatsApp Image 2021-10-31 at 23.16.32.jpeg
    WhatsApp Image 2021-10-31 at 23.16.32.jpeg
    313.4 KB · Views: 16

The latest video from AVForums

AVForums Movies Podcast: Streaming Theatrical Releases And The Future Of Cinema
Subscribe to our YouTube channel

Full fat HDMI teeshirts

Support AVForums with Patreon

Top Bottom