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Elekit TU-882 coupling cap needed voltage ratings??

post #1 of 11
1/19/12 at 1:18pm
Thread Starter 

Looks to me that (c1 c2) have almost zero voltage and I can't tell what the voltage across (c5 and c6) is.Can someone tell me what the lowest safe voltage ratings for these caps is. Also for your info  c14 and c13 , upgraded would have great benifit. Can someone tell me if there is a max cap value for these (14 and 15).??Thanks, Tweaker

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post #2 of 11
1/19/12 at 2:27pm

Do you have a schematic? 

 

It is rarely a good idea to reduce the voltage rating on a cap without knowing for sure that its safe. 

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post #3 of 11
1/20/12 at 11:51am
Thread Starter 

Yes I have a schematic but have not opened it up yet . I got the unit used. My question has not been answered by your reply.

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post #4 of 11
1/20/12 at 12:00pm

You didn't give enough info to give you an intelligent reply.

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post #5 of 11
1/20/12 at 12:56pm

Preferably a schematic with voltages marked on both sides of the caps:)

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post #6 of 11
1/21/12 at 2:17pm
Thread Starter 

I can't tell what the voltage is from the schematic.. Ok I'll try this. Does anyone know what the (max?) voltage is across the .1 coupling caps (c1c2) and (c5c6). Would a cap that met that voltage  be enough or do you need say double it in case there is a short or something. I have not taken this apart yet and don't want to until I have decided on the caps. I don't know what the indigenous caps are rated. Also, can I assume without making an ass of myself that all resistors are 1/8 th watt( RN55D) unless labled otherwise?  I could use the assembly instructions if  some one is willing. Does a parts list come with this?? Thanks, Tweaker

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post #7 of 11
1/22/12 at 11:19am

I would assume it comes with a parts list, but you have one, I don't, and I am sure NG doesn't either.

 

He (vkung) has a forum on audioasylum.

 

http://www.audioasylum.com/cgi/etv.mpl?forum=elekit&v=c&s=U&Last_Select=&t=25&n=25&y=12&mon=01&d=c&lts=0&last=

 

I noticed a couple of threads re: coupling caps, and he is using 600 or 630Vdc caps. Normally you spec coupling caps in a tube amp to handle B+ if it were to get across them. Ari can confirm if this is his experience as well (and he is much more experienced with tube gear than I am).

 

I am guessing that you asked the question because you had a particular cap in mind? If so, what?

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post #8 of 11
1/22/12 at 12:48pm

It really depends what the caps are for. 

 

Cathode caps can usually be rated for fairly low voltages. Kind of depends on the circuit but its not uncomon to see stuff in the 25-50V range here.

Coupling caps are usually B+ rounded up to the next value.

Output caps for parafeed amps with choke loaded output stages go any which way. Best bet is to get "who a lot" (B+ *1.5) or more. 

 

Ooh, if the caps you are considering as replacements are known for having iffy voltage ratings include that too. Or just get different caps unless you REALLY like them.

 

I'm kind of curious if the amp has input caps that can be removed. No cap is as good as no cap at all.....

 

Be sure to discharge all caps and measure twice before working on a tube amp. HV can hang out in very interesting places. 


Edited by nikongod - 1/22/12 at 12:57pm
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post #9 of 11
1/22/12 at 2:13pm
Thread Starter 

I asked because I want the most flexability in choice of caps. The obbligatto aluminium foil and the Mundorph zn are on my short list , both given very good reviews and don't cost $70 each. There is 185 v coming directly from the power supply (B+? ) and 350v in other parts of the circuit. I have the schematic but no parts list with brands, ratings... Thanks, Tweaker

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post #10 of 11
1/22/12 at 2:21pm
Thread Starter 

Yo nikogod, My thoughts exactly about the high voltage and the no caps vs caps. Been a long time since I worked on tube stuf. If the PS cap is discharged does that mean I'm in the clear.  I acctually dont kno the reason for coupling caps but was curious if the first input cap was "necessary". My guess that anyone who could design an amp so natural and fun to listen to with what is likely to have no premium parts wouldn't have used it if he didn't have to. When I was strictly solid state, DC was the only way for me. Then I here this. Thanks, Tweaker

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post #11 of 11
2/1/12 at 1:47pm
Thread Starter 

Nikongod, I can now satisfy your curiosity. I'm being told that the input coupling caps cap be removed because of the near extreame unlikelihood of dc coming in. The second set of caps can go down from .1 to .047 mf. No more than 70 to 80 volts, so a cap 100v or more can be used. Took me awhile but I got the answer I wanted and needed. Tweaker 

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