Help with rail caps on ZX475ti

Twonks · Post by **Twonks** » Sat Jul 10, 2010 9:29 am

Hi all,

I have aquired a 475 and found that whilst it appears to power up, the internal workings leave a lot to be desired.

The biggest problem is the rail caps have been replaced by some 2200uf, 63v 86 degree C caps on flying leads

I want to get it back to how it should be but can't find any info on what rating the rail caps should be.

Does anybody have the figures for rating and size required?

The height is a problem as it fits under a daughter board, and I can't get in to measure the distance properly.

Any advice would be appreciated.

Thanks.

dBincognito · Post by **dBincognito** » Sat Jul 10, 2010 9:54 am

2200uf
50v
105*

I will have to look in my notebook for the size.

Most likely the same height as the input caps.....I will check though.

tonym · Post by **tonym** » Sat Jul 10, 2010 9:58 am

caps were to tall I would think is why someone would do some crap like that

dBincognito · Post by **dBincognito** » Sat Jul 10, 2010 10:17 am

Ok, I got 22mm x 25mm written down for the rail caps on a ZX475

2200uf
50v
105*C
22mm x 28mm

Twonks · Post by **Twonks** » Sat Jul 10, 2010 10:51 am

Very swift replies

Many thanks for your help.

I'll sort some caps out, get it fixed and post some pics here

Post by **ttocs** » Sat Jul 10, 2010 10:56 am

NICE!!!

16v and 86 degree! can't imagine why it quit. I would remove the entire board and see what else has been done to that amp as there is no telling...

Twonks · Post by **Twonks** » Sat Jul 10, 2010 11:06 am

ttocs wrote:NICE!!!

16v and 86 degree! can't imagine why it quit. I would remove the entire board and see what else has been done to that amp as there is no telling...

oops, just realised it was 63v not 16

Maybe the spec of the installed caps isn't too far out, but not to source the correct height ones is a bit silly imho.

dBincognito · Post by **dBincognito** » Sat Jul 10, 2010 11:11 am

ttocs wrote:NICE!!!

16v and 86 degree! can't imagine why it quit. I would remove the entire board and see what else has been done to that amp as there is no telling...

I would change the input caps while I was in there.....seeing as how those are the one's that actually have problems. If you want to change the input caps, you will be looking for.

Input Caps
2200uf
16v
105*C
18mm x 32mm

Twonks · Post by **Twonks** » Sat Jul 10, 2010 11:27 am

Thanks. I will do that.

May I ask which measurement you believe is correct for the height of the rail caps, as the post says;

Ok, I got 22mm x 25mm written down for the rail caps on a ZX475

2200uf
50v
105*C
22mm x 28mm

I am looking for capacitors now and it is a minefield

Do I need to look for anything specific in the specifications, other than Aluminium Electrolytic?

dBincognito · Post by **dBincognito** » Sat Jul 10, 2010 11:30 am

Twonks wrote:Thanks. I will do that.

May I ask which measurement you believe is correct for the height of the rail caps, as the post says;

Ok, I got 22mm x 25mm written down for the rail caps on a ZX475

2200uf
50v
105*C
22mm x 28mm

I am looking for capacitors now and it is a minefield

Do I need to look for anything specific in the specifications, other than Aluminium Electrolytic?

Sorry, the 8 is above the 5 on my numeric keypad.

it is 22mm x 25mm

Aluminum Electrolytic
Radial - Snap In
Through Hole

Twonks · Post by **Twonks** » Sat Jul 10, 2010 12:48 pm

Thanks. Do you think 85 degrees will be ok instead of 105?

I can't find any the right size and 105 degrees, but can readily access 85 degrees here in the UK.

Nico156 · Post by **Nico156** » Sat Jul 10, 2010 12:56 pm

I think it will sound a lot better when you have changed them

Size doesn't matter as far as you can install them

I would reccomend you some Panasonic FM for the 16v (12,5x25 mm)

dBincognito · Post by **dBincognito** » Sat Jul 10, 2010 9:25 pm

Twonks wrote:Thanks. Do you think 85 degrees will be ok instead of 105?

I can't find any the right size and 105 degrees, but can readily access 85 degrees here in the UK.

This has been a debate in the past, so I can only say that 105*C is ok......I looked on digikey.com but the closest thing I found was 1800uf.

This one
http://search.digikey.com/scripts/DkSea ... e=P6673-ND

I don't have a ZX475 on hand right now, maybe someone who does could measure the maximum allowed height for the rail caps. If you can get a 22x30 in there you could use these.....but I don't know if they will fit without someone measuring.

http://search.digikey.com/scripts/DkSea ... e=P6675-ND

Nico156 · Post by **Nico156** » Sun Jul 11, 2010 3:00 am

I think that in that place you will never reach above 85° so you can use 85° caps imho.

Post by **ttocs** » Sun Jul 11, 2010 4:14 am

a zx amp can/will hit 85 degrees at idle wouldn't it?

Nico156 · Post by **Nico156** » Sun Jul 11, 2010 6:05 am

maybe the mosfet can reach 50° at full but there is a fan for them. I don't know exact temperature but I think board would do max 40°.

look some cap near there and watch what temperature they are!

dBincognito · Post by **dBincognito** » Sun Jul 11, 2010 6:12 am

ttocs wrote:a zx amp can/will hit 85 degrees at idle wouldn't it?

It's 185*F, I do believe inside a car that temperature is reachable. A lot of other companies use 85*C caps without a problem, I mentioned them here once before and it was a all out argument. That's why I said 105*C is the only suitable choice......cause I don't want everyone biting my head off.

Post by **ttocs** » Sun Jul 11, 2010 6:57 am

I can tell you my octane has got up to 140 but then it shuts off into thermal protection. I have the temp gauge on my truck modified to tell the amp temp and monitored it regularly when I was in phoenix.

Nico156 · Post by **Nico156** » Sun Jul 11, 2010 7:35 am

140° F? so 60° C

My zx350 running my 4 ohm sub it's warm (35°C) even with my car under sun and system running for hours..

str3atwarrior · Post by **str3atwarrior** » Sun Jul 11, 2010 8:08 am

Wow sorry just saw this, can't believe someone's done this to this amp! I would've waited to order the correct parts instead of doing something this stupid...

Good luck with this one, it should be a fun and easy fix!

Twonks · Post by **Twonks** » Sun Jul 11, 2010 8:57 am

Thanks for all the comments guys

Now, without wanting to induce a war, it seems likely that 85 degrees C caps may be ok.

I am really struggling to find the correct rating for 105 degree caps that will fit where they need to go.

I know for PS caps the bigger the capacitance the better (to a point), but for rail caps how important are exact specifications like voltage and capacitance?

If for sake of argument I could get 3000uf, 50v, 105 C rated caps, or 2200uf, 60v, 105 C, would either of them be too far away from the original spec of 2200uf, 50v 105C to make the amp unusable?

Nico156 · Post by **Nico156** » Sun Jul 11, 2010 9:32 am

I would recommend you to use same capacitance (max plus 20%).
Take over voltage doesn't give you improvements.. Because amp would do same voltage on that cap.
Cap with upper voltage are more solid and have better shield.

use 2200uf 60 v

oldschoolfan · Post by **oldschoolfan** » Sun Jul 11, 2010 9:43 am

My understanding is that you can increase capacitance, voltage, and temperature rating without issue as long as they are at least what was originally required. You just don't want to go down in ratings.

I would also be surprised if you could not find original rated caps that are smaller in height than the originals. Caps get smaller every year with the same rated capacitance. For example, the input power supply caps on the old MS series were originally 2200uf and were 18mm X 35mm tall. I think the current size for that rating is like 18mm X 18mm. This is by memory so don't quote me.

Just keep looking, you will find what you need if not with a higher rating.

dBincognito · Post by **dBincognito** » Sun Jul 11, 2010 11:27 am

Twonks wrote:Thanks for all the comments guys

Now, without wanting to induce a war, it seems likely that 85 degrees C caps may be ok.

I am really struggling to find the correct rating for 105 degree caps that will fit where they need to go.

I know for PS caps the bigger the capacitance the better (to a point), but for rail caps how important are exact specifications like voltage and capacitance?

If for sake of argument I could get 3000uf, 50v, 105 C rated caps, or 2200uf, 60v, 105 C, would either of them be too far away from the original spec of 2200uf, 50v 105C to make the amp unusable?

If you can get 3000uf 50v 105*C caps those would be just fine.

use 2200uf 60 v

Why use 60v when it calls for 50 ?

Nico156 · Post by **Nico156** » Sun Jul 11, 2010 12:30 pm

because he ask which between ''3000uf, 50v, 105 C rated caps, or 2200uf, 60v, 105 C'' so I recommend the second.
I know that increase too much capacitance would maybe affect the amp so I prefer the second.
But if I was him I control if I can give 18x35 mm caps to that amp and I use panasonic FC 2200uf 50V 105° C.