| WindChill |
Hi all,
Finally finishing up a Pearl I ordered four or five years ago and I'm wondering about a couple of things before I fire it all up and see if it flies.
I just built the suggested power supply and when I power it up I'm reading 51V on the outputs. I've seen posts that indicate 50V is no problem so I don't really think 51V is a problem either. The problem is that the caps are rated 50V so I'm worried about running them over their rating. Once it's connected to the boards would the load drop that voltage under the cap's rating?
Some other posts suggested that grounding might drop the voltage some and that might bring it down within the cap rating too. Any thoughts on that?
The other thing I'm wondering about are the C14 and C16 caps. I'm not clear on what values to try here and what they actually do. Any help on those would be appreciated.
Thanks |
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| wuffwaff |
Hi,
is the 51V without a load? Try it with a load first. If it isnīt under 50V you can always raise R2 and R3 to 10 ohms.
C14/16 are loading caps for an MM cartridge (50-XXXpF) to change the high frequency behaviour. These ar normally not needed on (high output) MC cartridges.
William |
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| WindChill |
Thanks for the reply.
I looked at a lot of power supply schematics and it seemed to be pretty common to put a resistor across the output caps. So I put a 1K across both outputs and that dropped the output voltage to about 47V which I'm more comfortable with.
The power supply was unloaded and I didn't power up the boards with it. Really didn't want to have it on very long with the voltage over the cap's ratings.
As for C14/16 I thought I saw something here that mentioned a range of 200-400uF. But once it's up and running I can try out various values if needed.
I'll be using a Grado Red which looks like it's a pretty high output cartridge -- 5mV on the web site and 4.5mV on the datasheet that came with it. I had thought the MC cartridges were much less than that at around 0.5mV.
But then, I am a noob. |
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| vinylkid58 |
WindChill,
Congrats on finishing your Pearl. Be sure to post some listening impressions.
I'm almost finished mine. Just have the PS to do.
Jeff |
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