Dragon's Lair Fans - Arcade Lifestyle

General Chat => Technical Area => Topic started by: kroustibat on September 07, 2010, 10:48:19 PM

Title: mtc9000 cap kit n00b
Post by: kroustibat on September 07, 2010, 10:48:19 PM

Hello all,

i'm looking to do my first capkit for my hantarex mtc9000. but i'm a bit confused, for example if i check the manual online C59 is a 100u for 50v
but on the pcb i can see 47u for 50v. C14 is 47u for 16v but on the pcb it's 47u 25v and so on ....

so i'm a why such a difference in the capacitors ...?? is there any explaination ? coz i suppose , all the capkit available refer to the manual..

thanks to help a n00b ^^


ooops sorry being such a noob, i should have post in the technical forum

Title: Re: mtc9000 cap kit n00b
Post by: italiandoh on September 11, 2010, 09:43:21 PM

The manual is the official reference and one should replace the caps with those values.
If voltages are higher it is not a problem, so in the second case 16V is the minimum allowed voltage by the manual but they mounted a 25V one which works just fine.
Sometimes modifications to the capacity values were done to adjust the electronics to a particular CRT model (for instance when passing from 90° to 110° tubes), so usually it's safer to replace them with the same values found on the monitor pcb if that tube originally came with that electronic.

Matteo

Title: Re: mtc9000 cap kit n00b
Post by: level42 on September 11, 2010, 09:57:17 PM

Quote

C14 is 47u for 16v but on the pcb it's 47u 25v

That is never a problem. A cap may always have a HIGHER voltage value then specified. The voltage is an indication of the maximum voltage that certain cab can handle.

So, if you need like a 47uF 16V but all you have is a 47uF 25V, go on and use it.

NEVER do it the other way around though !

So, you ask, why are not all caps able to handle 1000V ? Well, that would make them a LOT bigger AND more expensive.

In GENERAL it is also OK to use a slightly higher value uF cap. It depends on how it is used in the circuit however !!!

I would never use a lower value then specced though.

Title: Re: mtc9000 cap kit n00b
Post by: kroustibat on September 14, 2010, 12:17:53 PM

thanks both for your advice, it's clearer now :) i'll go to my local electronic shop ;)

Title: Re: mtc9000 cap kit n00b
Post by: baritonomarchetto on September 15, 2010, 02:33:06 PM

Just a little warning: pay attention to insert the capacitors in the right direction (polarity). It's not so trivial: sometimes wrong polarities are reported on manuals AND/OR ON THE PCB ITSELF! So, be sure to insert the capacitor in the exact position and polarity of the cap you are substituting

Title: Re: mtc9000 cap kit n00b
Post by: kroustibat on September 15, 2010, 04:45:14 PM

thanks , i'm aware of the polarity , but always good to remember it ;)