I recently replaced some 1uF capacitors in a 6DJ8 SRPP stage with these ones:
1UF 300VDC SELF HEALING PAPER IN OIL CAPACITOR fd1f9 | eBay
I installed them and 120v dc went straight into my power amp! Luckily there are capacitors at the input of my power amp.
I checked with my multimeter, the continuity tester is signalled straight away, it appears there is no capacitance at all in these paper in oils!
Does anyone have some suggestions as to how I can test if they are used/damaged?
1UF 300VDC SELF HEALING PAPER IN OIL CAPACITOR fd1f9 | eBay
I installed them and 120v dc went straight into my power amp! Luckily there are capacitors at the input of my power amp.
I checked with my multimeter, the continuity tester is signalled straight away, it appears there is no capacitance at all in these paper in oils!
Does anyone have some suggestions as to how I can test if they are used/damaged?
They are feed-through capacitors, meaning the capacitance is between the wires and the metal case.
They are not even PIO. From the datasheet:
MKP technology (dry, self- healing)
Dielectric: polypropylene, metallized
Metal case with synthetic resin terminals
They are not even PIO. From the datasheet:
MKP technology (dry, self- healing)
Dielectric: polypropylene, metallized
Metal case with synthetic resin terminals
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where did you find the datasheet for these capacitors? I've been looking all over the place for it!
OK - so to connect it correctly:
(1) run a flying lead from the pcb hole to the top of the capacitor - it has a washer/nut that can tighten on the lead
(2) the wire from the capacitor (either end) can be soldered to the other hole in the pcb
does the polarity matter?
OK - so to connect it correctly:
(1) run a flying lead from the pcb hole to the top of the capacitor - it has a washer/nut that can tighten on the lead
(2) the wire from the capacitor (either end) can be soldered to the other hole in the pcb
does the polarity matter?
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No, these are used for de-coupling mainly. The two wires are connected internally--ie, shorted together.
The capacitor is formed between the Case--Thats intended to be grounded, and the wires....
Feedthrough caps are used to pass supplies into a metal box containing sensitive oscillators and such like.....
They aint really intended for audio coupling....
The capacitor is formed between the Case--Thats intended to be grounded, and the wires....
Feedthrough caps are used to pass supplies into a metal box containing sensitive oscillators and such like.....
They aint really intended for audio coupling....
The guy selling them prolly doesnt know--Or Care-- exactly What they are....
21 quid is a rip-off in my opinion, for a cap thats not really intended for coupling in audio!
Personally, I would send 'em back and find a proper PIO cap intended for coupling!
21 quid is a rip-off in my opinion, for a cap thats not really intended for coupling in audio!
Personally, I would send 'em back and find a proper PIO cap intended for coupling!
Darn it...you like and learn!
Another option....I do have some of these:
2PCS 4.7uF 250V B&W Nautilus 800 Customize ClarityCap | eBay
Might be a better choice (although they appear to be for speakers).
The Siemens "paper in oil" (supposedly) might come in handy for something else (god knows what, though!)
Another option....I do have some of these:
2PCS 4.7uF 250V B&W Nautilus 800 Customize ClarityCap | eBay
Might be a better choice (although they appear to be for speakers).
The Siemens "paper in oil" (supposedly) might come in handy for something else (god knows what, though!)
What value does the circuit call for...?
You've gone up from 1uF to 4.7uF.....
In some cases, a drastic increase in value may cause you issues...
You've gone up from 1uF to 4.7uF.....
In some cases, a drastic increase in value may cause you issues...
Schematic attached - we're talking about C4 in the tube output stage. The unit shipped with a 1uF capacitor, however the schematic appears to read 22uF(!). Surely this should be 2.2uF? I think it is actually there to block the DC.
I'll try the 4.7uF and see the result - any other suggestions would be great!
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Personally--And, this is just my opinion....
Be better off ditching that pile 'o' iron on the front end, than messing with the coupling-cap!
Whats the original type in there?
Providing its Value is suitable for the application and that its not faulty, there will be very little difference in changing it to a different di-electric type--NO MATTER what the daft hi-fi mags say!
Much more depends on topology than type of component!
removing That iron will make a big difference, Not keen on interstage tx. generally--The Transformers MUST be Extremely GOOD--read, Expensive-- quality to perform, and I suspect that they are not in this device--Much better ways IMO....
Thats rather an uninspiring 6DJ8 SRPP front-end as it is....
I cant see who made this thing, but suspect Chinese origin--appologies if its a alledged 'good' machine...
Be better off ditching that pile 'o' iron on the front end, than messing with the coupling-cap!
Whats the original type in there?
Providing its Value is suitable for the application and that its not faulty, there will be very little difference in changing it to a different di-electric type--NO MATTER what the daft hi-fi mags say!
Much more depends on topology than type of component!
removing That iron will make a big difference, Not keen on interstage tx. generally--The Transformers MUST be Extremely GOOD--read, Expensive-- quality to perform, and I suspect that they are not in this device--Much better ways IMO....
Thats rather an uninspiring 6DJ8 SRPP front-end as it is....
I cant see who made this thing, but suspect Chinese origin--appologies if its a alledged 'good' machine...
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I opened the Word Doc and see only one page with a +5/-5V PSU schematic and 3 blank pages. Can someone post it as a PDF?
Ah, Merci! Indeed that is a 2.2uF cap on the output. A little hard to see the decimal.
But what a strange thing. Why the step up transformer at the input? What is that, about a 1:6 ratio? Odd.
But what a strange thing. Why the step up transformer at the input? What is that, about a 1:6 ratio? Odd.
Indeed, besides having unneeded and unwanted gain, it's connected so as to toss out one of the principal advantages of an input transformer- galvanic isolation. To make things worse, it presents an unreasonably low load to whatever is driving it.
This reminds me of those cut and paste designs that are posted here from time to time, where part of one circuit is glued into another will-nilly.
This reminds me of those cut and paste designs that are posted here from time to time, where part of one circuit is glued into another will-nilly.
For me it looks good design. The AD1865 DAC needs a LOW load impedance, indeed (1.4 k in this case - perhaps a bit high).
Yes - I see what you mean.
The circuit useds the Iout of the AD1865 and not the Vout. R4-R5 look like the I/V conversion. Then the transformer+SRPP stage is used for voltage gain. Could work OK.
The circuit useds the Iout of the AD1865 and not the Vout. R4-R5 look like the I/V conversion. Then the transformer+SRPP stage is used for voltage gain. Could work OK.
Ah, gotcha. It looked like a plain old analog input to me, sorry. For a I-to-V converter, one expects something like a virtual ground for good performance...
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