Restoring a Threshold FET 10e - a few questions

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#41
Lavcat said:
Perhaps an 'L' shaped hex wrench would be better?
Click to expand...
Yes - you want something like this. It will give you the leverage you need to loosen the screws.
---Gary
 

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#45
Hoping the participants in this thread are still around...

I am a long-term FET 10/e owner about to take delivery of a FET 10/e phono ("cartridge gain") stage with balanced and unbalanced outputs. I figure it's time to bring both units up to date. While I have plenty of experience at electronics repair and maintenance, I don't have the knowledge of how to extrapolate from this thread as to how specifically to update the components in these units.

Is anyone here at all interested in helping me offline? Maybe a pointer to the locations and values of capacitors to be changed?

I'm also interested in replacing the PSU's; it seems to me it must be possible to find off-the-shelf units with enough capacity and filtering to replace the stock units as opposed to trying to source new transformers and fit them into the chassis. Does this seem like a possibility? Do the two units use the same PSU's?

Many thanks in advance for any assistance. PM's are fine.
 
#48
I've posted most of what you need to know already.
Replace all the electrolytic caps and the tantalum caps. Upgrade the power supply with a really big transformer, good diodes, and a lot of capacitance. The phono power supply is the same as the preamp power supply, so you should build 2. If you want to go further on the line stage, considering upgrading the volume pot and playing with the feedback resistors.

As Zen mod suggested, post your questions here and you'll get lots of support. That way, everyone can learn with you.
---Gary
 
#49
Thanks guys. I hope you understand how much I will be asking here.
Let's start with the PSU since it will be quite a while before the phono pre rolls in.
Upgrade the power supply with a really big transformer, good diodes, and a lot of capacitance.
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That's what I took from this thread (it mostly discusses batteries and I don't want to go that route), and looking at all that I asked why not just use existing supplies better suited to the job? Does that run against the culture here? I would rather have untouched original supplies to sell later if the time comes. and just get my 24V from another box.

If upgrading practically everything insie Threshold's box is the way to go, what are the parts, please, and where do I get them? I'll be doing this twice, so I'll get better at it.

Thanks again...
 
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#50
Etnier said:
Let's start with the PSU since it will be quite a while before the phono pre rolls in . . . why not just use existing supplies better suited to the job? . . . I would rather have untouched original supplies to sell later if the time comes. and just get my 24V from another box.
Thanks again...
Click to expand...

I built a separate external 24 power supply so my original power supplies look stock although I also upgraded their capacitors as an experiment.

In post 19, I discussed what I built. Here is the relevant quote: "The final supply is the 300VA toroid 18v/18v to separate Fairchild soft recovery bridges (one for plus and one for minus) to 4700uf + 22000uf. I included snubbers on the transformer secondaries to damp out any diode reverse recovery noise. And I bypassed the electrolytics with 10uf, 1uf, and 0.2uf Russian military caps. "

Transformer was bought from Antek, diodes from Digikey or Mouser as were the electrolytic caps. Russian caps from ebay.
Hope that helps.
---Gary
 
#55
It honestly doesn't matter, as you are going to want an over-sized transformer for regulation as well as the simple fact that bigger ones are usually mechanically quieter. 100-200VA is likely right in the butter zone. Antek has them shielded in that size... 🙂
 
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