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ZX500 w/ blown resistors, HELP!
Posted: Tue Feb 08, 2011 5:10 pm
by shadeNZ
Hi guys,
I have a ZX500v2 that I've had for a while, it has recently developed a turn off pop, and a bit of noise.
So I opened her up to have a look and I found two blown resistors on the input board (pic attached).
Picture is a bit average as I only have a cellphone camera but I'll try sort out a better one.
Problem is I cant read what value they were as they're now burnt out.
So if anyone knows what to replace them with that would be awesome.
Cheers, Phill
Re: ZX500 w/ blown resistors, HELP!
Posted: Tue Feb 08, 2011 6:21 pm
by ttocs
if you look next to the componants they are numbered. R12, R13, R14. As good as the pic is if we had the r number it would help.
Re: ZX500 w/ blown resistors, HELP!
Posted: Tue Feb 08, 2011 6:26 pm
by Jacampb2
I'm pretty sure they are 100K, 1/8w, but scott is right, if you can get a decent photo with a real camera, or give us component locations we can verify.
It is VERY common for these to burn when there is DC on the signal or shield, or when the input is seriously over driven. They can cause all sorts of different issues, pops and thumps as well as the amplifier breaking out in low frequency oscillation.
Good Luck,
Jason
Re: ZX500 w/ blown resistors, HELP!
Posted: Tue Feb 08, 2011 6:27 pm
by Jacampb2
BTW, forgot to mention, welcome to the phorum!
Re: ZX500 w/ blown resistors, HELP!
Posted: Tue Feb 08, 2011 7:06 pm
by shadeNZ
thanks
I found some numbers underneath R1 and R51.
Re: ZX500 w/ blown resistors, HELP!
Posted: Wed Feb 09, 2011 4:34 am
by Jacampb2
They are 100k 1/8w, and check your signal. Your HU is either jacked up, or you were overdriving the input. If it is a lower end HU, then it might just be that the input signal was in hard clipping for a while, but check your stuff out, there are only a few likely scenarios where these resistors go open, and it is not simply a defect or design flaw.
Later,
Jason
Re: ZX500 w/ blown resistors, HELP!
Posted: Fri Feb 11, 2011 11:49 pm
by valeks1
Check voltage between Audio Ground (two inside connectors on speaker terminal) and B-, B+. R1 and R51 is 100 ohm 1/8 watt
Re: ZX500 w/ blown resistors, HELP!
Posted: Sat Feb 12, 2011 6:09 am
by Jacampb2
I apologize, I just checked one of my zx500s and valeks is correct. Earlier I just checked the schematic-- must have been a misprint, but the one I have does show 100k.
Re: ZX500 w/ blown resistors, HELP!
Posted: Sat Feb 12, 2011 6:16 am
by Jacampb2
Pic for reference
Re: ZX500 w/ blown resistors, HELP!
Posted: Sat Feb 12, 2011 10:38 am
by rolandk
Jacampb2 wrote:I apologize, I just checked one of my zx500s and valeks is correct. Earlier I just checked the schematic-- must have been a misprint, but the one I have does show 100k.
They were originally 100k, then got switched to 100 ohms as part of the V2 update.
Re: ZX500 w/ blown resistors, HELP!
Posted: Mon Feb 14, 2011 2:19 pm
by shadeNZ
thanks very much guys your replies have been extremely helpful.
I haven't replaced them yet, I just temporarily replaced the amp with an M50
but I will put 100 ohm ones in when I do it, since it is a V2 anyway.
will replace the resistors over the next couple of days and let you know how it goes.