Onix & soap needs a re-cap - diyAudio
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Old 15th August 2003, 07:34 AM   #1
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Default Onix & soap needs a re-cap

Hello,

I own a amplifier and power supply that is based on Naim audio's Nait 1 integrated amp. They are both due for a re-cap but i don't know what capaciters to use. Here is a discription of whats inside. Onix
I have found 40v 22000uf Phillips caps that would fit the power supply but don't know which ones to use. I have also found 63v 4700uf panasonic caps that would fit the amp but don't know if they are any good.
So far i've looked at the Rs catalogue, Farnell, Kendeil and Audiocom but find all the different cap specifications a bit confusing
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Old 17th August 2003, 06:12 AM   #2
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Hi Fatmarley

My name is Tony Brady and along with Craig Hill, formed Onix Audio in the late 1970's to initially build MC head amplifiers and then went on to build the first OA20 integrated amplifiers in early 1981 (I'm sorry I don't remember the exact date - many years have passed)

First of all I'd like to correct your ascertion that the Onix Integrated amplifer is based on the Naim Nait1 - it is not. Actually the Nait came out about 1983 IIRC. The OA20 and the OA21 which replaced it in jan 1982 featured a differential VAS with current mirror load which was inspired by a Hitachi application note for MOSFET power transistors! The input stage was a differential with a constant current source. The output stage was fully complementary.

anyway back to your question:
I presume that you have an OA21 as you have the external (SOAP 1?) power supply. Later versions ( OA21S) were fitted with custom made BHC capacitors in the power supply, 4700uF 63V diameter 25mm and 40mm high, the highest that you will be able to fit to the pcb will be 50mm. The pitch for the pins is 10mm if your amp is fitted with these and they are not leaking then I wouldn't bother to change them as the Panasonics are likely to sound worse...Kendiel I haven't tried so cannot comment on the sound but as long as the can size is ok then the spec to look at is the ripple current - anything over 2 Amps each will be ok. You can safely fit 50V caps as well...be careful to observe correct polarity as the pcb isn't marked.
where you will be able to make a good improvement is in the external power supply. Later SOAP 2 supplies were fitted with BHC 15000uF 63V caps, these again were custom parts with screw terminals. The Kendiels have a good reputation so may be worth a try here.

I hope that this has been of some help to you

Tony
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Old 17th August 2003, 06:43 PM   #3
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Thank's Tony,
I will phone a Kendiel distributer tomorow and order some caps.

On the link i left a guy suggested that i replace the volume pot to a panasonic one.
Are they a standard fit?

Also is there anything else that may need replacing or would benefit from being replaced?

Cheers
Matt
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Old 18th August 2003, 12:51 PM   #4
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Hi Matt
the panasonic pot is not quite a standard fit - you will need to drill out the mounting hole to 9mm.
I saw your question about using ALW's super reg on the pfm forum but this would only improve the phono stage if you are using it. The OA21S (and OA21E) has no pre-amp stage - just the passive 10K log pot straight into the power amp section.

Does the amp have 1 relay or 3 under the phono board? if they are not red in colour (NEC MR62) then it is definitely worth changing to NEC type...If there is 1 relay the amp is a 21S and if there are 3 relays it is a 21E. The S is the better version to have as it has no speaker fuses, if it is the E version then change the speaker fuses to new F3.15A fast blow and tighten up the fuse holders, I don't recommend shorting out the fuses in case of disasters!

You might want to change the wire to the volume control while you're at it and solder directly to the pcb pins if a connector is fitted - twist the wires in the same way as original i.e. separate left and right channels.

It could be worth tightening the bolts fixing the output transistors to the heatsink, but don't go too mad or the bolts will break.

ciao
Tony
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Old 18th August 2003, 09:39 PM   #5
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Thanks again Tony,

I must have the E type because i can remember seeing 3 fuses inside the case, 2 were near the speaker sockets.
I will double check to see if they are red before puchasing a new relay.

Do you know where i can get an (NEC MR62)?

If it sounds like i don't know what i'm talking about it's because i don't but don't worry i'm not going to do the work myself, i hear capaciters have a nasty habit of blowing up if you fit them the wrong way round.

I'm glad you advised me not to do away with the fuses because the thought did enter my mind.

Sorry if i'm being a bit personal but what happened to Onix Audio?

Matt
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Old 19th August 2003, 12:48 PM   #6
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Hi Matt
the third fuse under the red cover is the mains fuse, value T2.5A obviously disconnect the power cord before this point! again tighten up the fuse holder.
the MR62 relay you can get from Farnell 309-2860, you'll need 3 off.

to cut a very long story short Onix, which was already partly far eastern owned was sold fully to them in 1996, this was the end of my involvement so amplifiers such as A60, 120 are nothing to do with me...

good luck with the re-build!
cheers
Tony
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Old 19th August 2003, 07:53 PM   #7
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Thanks for all your help Tony, I am very grateful for the advise
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Old 11th April 2006, 06:51 PM   #8
konst is offline konst  United Kingdom
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Hi,

Would be great if anyone can help

I have a poorly oa21e with blown output transistors on one channel and intend to replace these with mj15003/4 pairs. can anyone tell me what the required bias setting should be and where to measure it? Is there a schematic available?

Also, if anyone has any spare BC416C's please let me know.

Cheers
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Old 14th October 2006, 04:57 PM   #9
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Default Just found this

I took a chance on an ONIX OA20/2 for parts or repair on ebay. The seller did not know its problems. I have always wanted a brittish integrated, so I bit on the auction.

I got it for a pretty low price and I am hoping to be able to resurrect it. It won't be a great loss if I cannot.

Does anyone know the speaker fuse values? Is there a place where I might get a manual or schematic?

I am not too hopeful for for much help considering the age of this unit, but if anyone is out there that can help I would greatly appreciate it.

Many thanks in advance.

Leonard
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Old 14th October 2006, 05:19 PM   #10
hacknet is offline hacknet  Singapore
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hey! its great to see tony brady on the forum!

i've heard so much bout onix but i haven't seen them here in singapore..

is there any chance i can get hold of a set of the schematics?
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