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FRANZONI
Double Platinum Member
Ireland
3543 Posts |
 Posted - 06/10/2008 : 04:05:51
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Sorry if this is a bit off topic.....but my dynacord CLS22 rotary speaker simulator blew one of these on the gig the other night and i can't find a schematic for it to find the value ...i'm taking a bit of a leap on faith as the ones the same size are all 10uf 35 volt....when these things burn out they really do sizzle... .. i think i can get one close to home and and replace it fairly handy...my questions are (as my knowledge is limited when it comes to electronics)
A/ can these caps blow due to age as in a electrolytic cap in an amp through usage and age.....(the dynacord is over 25 years old...)
B/if not the above how would i trace the fault...?..(i can hopefully with a bit of the ol' Franzoni charm rope in the brother in law who is a electronic enginneer but who thinks i'm .... dabbling in old valve and analog stuff.....
c/ if A is correct is it likely that the others are going to start to pop as soon as i fix one,or would i be better of changing them all as most people do on amps...??...from what i understand about bead caps is that there is now other caps on the market that are better quality,but i'm a bit afraid as the dynacord soundwise is really great and i love it in my rig...i don't want to mess it up too much but at the same time don't want to f**k it up through neglect.... |
Edited by - FRANZONI on 06/10/2008 04:38:38 |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 06/10/2008 : 05:19:06
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A/ can these caps blow due to age as in a electrolytic cap in an amp through usage and age.....(the dynacord is over 25 years old...)
Yes. Or through a circuit fault.
B/if not the above how would i trace the fault...?..(i can hopefully with a bit of the ol' Franzoni charm rope in the brother in law who is a electronic enginneer but who thinks i'm .... dabbling in old valve and analog stuff.....
Normally a big sizzle is caused by overvoltage / reverse voltage. I'd chedck the power supply rails are OK first thing... how to do this without a schematic? Take some good close-up pics and let us have a look.
c/ if A is correct is it likely that the others are going to start to pop as soon as i fix one,or would i be better of changing them all as most people do on amps...??...from what i understand about bead caps is that there is now other caps on the market that are better quality,but i'm a bit afraid as the dynacord soundwise is really great and i love it in my rig...i don't want to mess it up too much but at the same time don't want to f**k it up through neglect....
Yes. I'd change them all if it has blown due to age (and not due to a fault). Tantalum capacitors haven't really been overetaken by anything. Just use regular tantalums and it will be fine.
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 06/10/2008 : 11:55:46
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Hi FRANZONI & guys
At the expense of sounding negative, & while I will admit, that Tantalum caps are a great invention.
I have found that some brands of tantalum's. will go totally short circuit, for no apparent reason.
I have replace many over my career, & tend to see them as "first suspects", if they are in a bit of gear that I am working on, & there is an indication of heavy current draw, or shorted power supply.
Remember that tantalum caps generally have their Positive leg marked,
while standard electro's have their Negative Leg marked.
Just another thing to be aware of, when performing electronic repairs.
Please keep us informed of your progress.
Regards Dr. Bob |
Edited by - Dr. Bob on 06/10/2008 11:57:55 |
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bossFan
Bronze Member
Portugal
97 Posts |
Posted - 06/10/2008 : 12:14:19
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quote:
Originally posted by Dr. Bob
I have found that some brands of tantalum's. will go totally short circuit, for no apparent reason.....
I have replace many over my career, & tend to see them as "first suspects"...
Right on, Dr.
I have also replaced hundreds of them over the years and they are 1� suspects to me also, and I�ll say it�s easyer to find a shorted tantalum than a blown one..
Regards..
Sorry about that carriage return excess- I got carried away  |
Edited by - bossFan on 06/10/2008 12:24:20 |
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FRANZONI
Double Platinum Member
Ireland
3543 Posts |
Posted - 06/10/2008 : 23:56:50
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i changed the cap and ran the unit earlier for about 30 mins and everything seems ok....touch wood..!! i noticed some of the other bead caps were yellow and the originals seem to be blue in colour so i'm assuming that others have been changed out in the past..i took a couple of photos of the area..the original tantalum cap really melted down..you can see where it scorched the side of one of the other components but i think it's only cosmetic..i was lucky enough to be able to make out the positive marking on the original before installing the new one......
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 06/11/2008 : 01:42:46
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quote:
Originally posted by FRANZONI
i changed the cap and ran the unit earlier for about 30 mins and everything seems ok....touch wood..!! i noticed some of the other bead caps were yellow and the originals seem to be blue in colour so i'm assuming that others have been changed out in the past..i took a couple of photos of the area..the original tantalum cap really melted down..you can see where it scorched the side of one of the other components but i think it's only cosmetic..i was lucky enough to be able to make out the positive marking on the original before installing the new one......
Nice photos!
Couple of suggestions....
- Change out all the tantalums. If it's working OK now, then the cap didnt fail due to a fault, it was just old.
- replace that 0.22�F cap with the scorch marks. It took a lot of heat and I wouldnt trust it.
Regards,
Laurie. |
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FRANZONI
Double Platinum Member
Ireland
3543 Posts |
Posted - 06/11/2008 : 10:59:11
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Thanks laurie......i would change it if i knew what it was.....!..it took me a while with the help of google to figure out that what had blown was a tantalum bead cap..... ...i think i'm getting a bit of a electronics bug and i'm starting to find this stuff interesting so please bear with my lack of knowledge in this dept.....i had a little bit of experience with control valves and circuit boards in boilers as i come from a mech background but most of that stuff is just a board swap usually involving some sort of clip connectors...the fact that people who are either interested or bothered in fixing stuff like this and valve amps are in short supply in this country it seems..... there is only one guy in the whole of dublin(you have been here so you know it's a big enough place)that i know of who does this stuff and his prices would fund a new NASA mission to mars....not his fault as no one else seems to be bothered giving him competition.....maybe i should go back to college to do electronics...... |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 06/11/2008 : 11:25:16
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Hi Franzoni
If you don't change the other tants.
At least mark down there values & voltages,
as well as their polarity orientation on the PCB.
Good long term insurance.
Mail me a copy, for an off site backup, if you need to. 
I'll take you up on the drinks, from the other thread, but I'll go a few Red Wolf's with you.
I Know you have a soft spot for those wolf's
Regards Dr. Bob |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 06/11/2008 : 14:14:31
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quote:
Originally posted by FRANZONI
Thanks laurie......i would change it if i knew what it was.....!..it took me a while with the help of google to figure out that what had blown was a tantalum bead cap........i think i'm getting a bit of a electronics bug and i'm starting to find this stuff interesting so please bear with my lack of knowledge in this dept.....i had a little bit of experience with control valves and circuit boards in boilers as i come from a mech background but most of that stuff is just a board swap usually involving some sort of clip connectors...the fact that people who are either interested or bothered in fixing stuff like this and valve amps are in short supply in this country it seems..... there is only one guy in the whole of dublin(you have been here so you know it's a big enough place)that i know of who does this stuff and his prices would fund a new NASA mission to mars....not his fault as no one else seems to be bothered giving him competition.....maybe i should go back to college to do electronics......
No worries! The white capacitor with the scorch marks looks like a 0.22�F polyester flim capacitor. You should be able to get one at your equivalent of Radio Shack (or where ever you scrounged the tantalum from ). I can't recall seeing something like a Maplins/Radio Shack etc there - but then I was probably more focused on other stuff
If you can't get one that looks exactly the same, no worries. Just don't use a ceramic disc or mono-block to replace it. As long as it's about the same size as the one that's scorched, and if it is in the rectangular plastic case (like the original one), or looks like it's been dipped in green/orange/brown goo it will be OK.
If you really have the bug and a few extra Euro, I would suggest buying:
- a temperature controlled soldering iron (Weller and Hakko are the two name brand ones, and the lowest cost one should be about 80Euro)
- some de-soldering braid to remove the old solder. (there are some videos on Youtube about desoldering)
- a book on basic electronics (or there is downloadable suff on the WWW).
Anyway, please excuse my rambling! I get more satisfaction than I can tell you from fixing stuff!
Regards,
Laurie.
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Edited by - Laurie on 06/11/2008 14:15:27 |
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FRANZONI
Double Platinum Member
Ireland
3543 Posts |
Posted - 06/11/2008 : 15:01:27
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nice one..... ...yes we have maplins and a couple of local suppliers....peats and radionics......i got the tantalum caps in peats as i find them a bit friendler and not looking down their nose at you,if your not 100% what your looking for...watch this space on the musicman amp repair coming soon.............. |
Edited by - FRANZONI on 06/11/2008 16:48:08 |
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Tantalum bead capacitors..........
