if you need to change just caps, there is no need for rebias
anyhow, if you have more questions, best to write directly to Nelson, and ask him whatever you need to ask
no need to do it in public
anyhow, if you have more questions, best to write directly to Nelson, and ask him whatever you need to ask
no need to do it in public
I recall some bulging PSU caps in FW amps, with Papa replying that this was purely cosmetic (wrapping shrinked by heat, with no need of doing anything).
Ah, good point. Now that you mentioned it, I remember reading that comment as well.
Edit: Couple of comments from Papa on bulging caps.
https://www.diyaudio.com/community/threads/firstwatt-j2.151909/page-96#post-6573978
https://www.diyaudio.com/community/threads/rawson-repair-reflections.361593/#post-6375830
Edit: Couple of comments from Papa on bulging caps.
https://www.diyaudio.com/community/threads/firstwatt-j2.151909/page-96#post-6573978
https://www.diyaudio.com/community/threads/rawson-repair-reflections.361593/#post-6375830
Surprising that there would be issues for lack of age and the fact that F7 runs cooler than most FW amps. What tells you that you have a problem?
Mr Pass I don't know how to tell you this but your amp is no longer as it left the factory. It's a mess. It has a larger power trans fitted, I Am trying to source the original trans and return to as original as possible. I fear they have messed with the bias when they changed the trans. I don't even want to turn it on until I know what they should be set too. Maybe the capacitance is ok. It's in far north queensland with very high temperatures. I Am trying to contact his tech to find out why he changed the trans and hopefully get the original trans back.
Mr Pass I have made further inquiries the power trans is original. He was referring to the additional bank of capacitance added. So my job is a lot easier. Only the signal wiring will needs replacing. There is one power resistor that's been changed so the bias maybe off still. He said the resistor was running too hot but why? The additional capacitance probably ruined everything.
I really can't show the inside. Unless I Am authorised to do so. No user serviceable parts! It's just so far away from california and in such poor shape. He actually gave it to me for parts to build a diy pass amp. I just want to fix it for him. Especially now that I know the pt is original and caps might be ok. I'm only 2 resistors from original. They are nickel ww probably inductive between the output devices.
That was nice of him. I think if you are concerned about not showing the circuit, you can put pieces of paper over the amplifier boards. That is the important part.
If you decide to take pics, maybe circle in MS paint or something the areas of concern.
Take some pics. The extra cap bank may not be a terrible thing if properly implemented. Although it probably doesn't need it.
If you decide to take pics, maybe circle in MS paint or something the areas of concern.
Take some pics. The extra cap bank may not be a terrible thing if properly implemented. Although it probably doesn't need it.
Is it really illegal to photo and show nude amplifier-parts in far north Queensland???
Well. This is the world wide interwebs! I hereby give you the FULL autorisation to post nude amplifier pictures.
🔫😎🤚
I’d take this dialogue directly with Papa through e-mail. His address is readily available publically.
WW does not sound like Papa’s recipe for an OS.
Yes, restore to original state. These are rare seldom output devices and a cool circuit.
The RCA and binding posts in post #1 also don't look like what I have seen on other Firstwatt amps.
The one binding post clearly visible looks corroded to me. 🙁
6moons has a review of a pilot run F7 with a lot of photos. It might not be exactly the same as what you have but
should give you an idea of what an original would look like.
Good luck with your restoration.
The one binding post clearly visible looks corroded to me. 🙁
6moons has a review of a pilot run F7 with a lot of photos. It might not be exactly the same as what you have but
should give you an idea of what an original would look like.
Good luck with your restoration.
Could it be a clone, as indeed the sockets look wrong, and the label is too close to them, compared to published production photos?
It's real my friend bought it new. He put those big ugly things on with silver cable. I guess all I need to know is the optiman bias current. Everything else I can restore to original.
Depending on what the mods are, you may not have to worry about returning it to original per se. Extra capacitance isn't going to hurt anything. A larger transformer is not going to hurt anything...
Silver signal wiring is not going to hurt anything either. I suppose if you're restoring it as a conservationalist, then I could see the appeal of putting in the effort. Otherwise...
Silver signal wiring is not going to hurt anything either. I suppose if you're restoring it as a conservationalist, then I could see the appeal of putting in the effort. Otherwise...