MCI JH636 Powersupply Question

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MCI JH636 Powersupply Question

Postby MCI Chris » Sat Jan 16, 2010 10:40 pm

Hey everyone. I have picked up a MCI JH636 and have joined the MCI family. to be honest i was looking for one for a while to completely bring back to like and I found it.

My question is this:

on the power supplies, one is perfect and the other is a little off. Seems like all of the voltages are off , but only by a volt or two. my first question :

Is this ok?

second question

one on of the leads (i think its the 18v) its only reading 1 volt.
what could be the problem and how do i go about fixing this? I know how to replace caps and resistors, etc.

thanks very much!!
MCI Chris
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Re: MCI JH636 Powersupply Question

Postby todd_d » Sun Jan 17, 2010 3:13 pm

Hi Chris,
I'd say if you are in Tulsa, you've got a great resource in your backyard! :mrgreen:

Those voltages need to be ON. In the big scheme of things, a volt isn't that big of a deal, but the question is "why"
Why is it off in the first place... I'd track that down, because it might be a bigger issue causing it.

Have you trimmed them internally? Then have you checked it again under load?

Power supplies are important, don't more forward with anything else until they are SOLID
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Re: MCI JH636 Powersupply Question

Postby MCI Chris » Sun Jan 17, 2010 10:12 pm

Well,

I finally got around to taking the power supplies apart. aside from being totally filthy , they actually look pretty good.

I did find 2 fuses on one of the power supplies poped. I am wondering, would this be the reason for the bad volts? or the low volts?

thanks..
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Re: MCI JH636 Powersupply Question

Postby mikethebike » Mon Jan 18, 2010 9:16 pm

Hi Chris,

if the power supplies are pretty dirty, then it may be that they are also quite old and so changing the main smoothing capacitor would be a worthwhile exercise. If you have access to an osciloscope measure the ripple on the power supplies dc rails - they should be down at the millivolt level - this will also give a measure of how well the regulators are working.

The power supplies also use remore voltage sensing, meaning that as welll as the cable delivering the main current to the desk, there will be a cable measuring the voltage at the desk so as to overcome any voltage drops down the cable - I would check those for continuity and if necessary, reterminate the crimps.

Best regards

Mike
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Re: MCI JH636 Powersupply Question

Postby brianroth » Tue Jan 19, 2010 8:50 am

Chris in Tulsa and I have visited/yacked on the phone now, and he has "homework" to do (he seems totally cool with meters, digging around, etc)...and we are now friends, I hope.

We will keep everyone posted as this 628 comes back to life.

BTW...any 30 pin male "Tuchels" around here? I found some Telegartners in the UK at RS....

Best,

Bri
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Re: MCI JH636 Powersupply Question

Postby mikethebike » Wed Jan 20, 2010 9:42 am

Brian

Canford Audio do the 10 rows by 3 pin Tuchels as DIN 41622/41618 connectors. Worth having a look there.

http://www.canford.co.uk/Browse/82378.aspx

Mike
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Re: MCI JH636 Powersupply Question

Postby brianroth » Fri Jan 22, 2010 2:04 am

Dear Mike,

Yes...and pricey!!!

RS-UK has Telegartners listed, but I don't know if they are even interested is shipping to the USA...

Best,

Bri
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Re: MCI JH636 Powersupply Question

Postby guy_4 » Wed Jan 27, 2010 3:20 pm

Hello All,
This is my first post on the Analog Console forum 8)
In US, Redco has some 30 pin Tucher connectors :
http://www.redco.com/shopexd.asp?id=398
Cheers,
Guy
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Re: MCI JH636 Powersupply Question

Postby brianroth » Thu Jan 28, 2010 11:37 pm

Hello Guy,

Indeed, it looks like Redco will be the source for the Tuchels that Chris requires. I hit an dead-end trying to order the Telegartner equivalents that RS stocks in the UK, even through their USA subsidiary Allied Electronics.

Best,

Bri
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