C-800G noise

[sodderboy]

I have a C-800G that is making a hissy/spitty noise. I get to check
it literally between takes, as it is still usable except on a ballad,
and find that all PSU voltages are flat DC and cable/ connectors are
all solid. It is down to the tube or a cap in the mic.
I read through past threads regarding the 800, especially the current
one, and have a schematic of the mic, but not the PSU. I found two
6au6 tubes on the PSU board with heaters on, and figured they were
regulators. But then I see thet 6au6 is also used as the amp in the
mic.
Are there two spare 6au6 tubes designed into the PSU, with their
heaters powered? That would be quite cool! Next chance I get I am
going to swap a tube from the PSU into the mic- hopefully the thin
copper shield on the mic tube is not adhesive. . .gulp! Miseur
Peltier? se vous plait?
Anyone have a link for the PSU schematic? merci!

[Scott Dorsey]

sodderboy > wrote:
>I have a C-800G that is making a hissy/spitty noise. I get to check
>it literally between takes, as it is still usable except on a ballad,
>and find that all PSU voltages are flat DC and cable/ connectors are
>all solid. It is down to the tube or a cap in the mic.

It's the tube.

>I read through past threads regarding the 800, especially the current
>one, and have a schematic of the mic, but not the PSU. I found two
>6au6 tubes on the PSU board with heaters on, and figured they were
>regulators. But then I see thet 6au6 is also used as the amp in the
>mic.

The problem is the goofy refrigeration thing. It cools the 6AU6 way down,
and the 6AU6s tend to get noisy when operated that way. If you take it
out and operate it at normal temperature in a table radio (most of the AA5
radios use 6AU6es), I bet it's fine.

>Are there two spare 6au6 tubes designed into the PSU, with their
>heaters powered? That would be quite cool! Next chance I get I am
>going to swap a tube from the PSU into the mic- hopefully the thin
>copper shield on the mic tube is not adhesive. . .gulp! Miseur
>Peltier? se vous plait?

Try it and see what happens. The 800G runs through tubes like nobody's
business, but the 800, which is basically the same electronics without
the Peltier cooler, does not.

>Anyone have a link for the PSU schematic? merci!

No, but Sony only charges five bucks for the full service manual, and you
should have got one originally with the mike. Rag on your Sony rep if you
don't have one.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

sodderboy > wrote:
>I have a C-800G that is making a hissy/spitty noise. I get to check
>it literally between takes, as it is still usable except on a ballad,
>and find that all PSU voltages are flat DC and cable/ connectors are
>all solid. It is down to the tube or a cap in the mic.

It's the tube.

>I read through past threads regarding the 800, especially the current
>one, and have a schematic of the mic, but not the PSU. I found two
>6au6 tubes on the PSU board with heaters on, and figured they were
>regulators. But then I see thet 6au6 is also used as the amp in the
>mic.

The problem is the goofy refrigeration thing. It cools the 6AU6 way down,
and the 6AU6s tend to get noisy when operated that way. If you take it
out and operate it at normal temperature in a table radio (most of the AA5
radios use 6AU6es), I bet it's fine.

>Are there two spare 6au6 tubes designed into the PSU, with their
>heaters powered? That would be quite cool! Next chance I get I am
>going to swap a tube from the PSU into the mic- hopefully the thin
>copper shield on the mic tube is not adhesive. . .gulp! Miseur
>Peltier? se vous plait?

Try it and see what happens. The 800G runs through tubes like nobody's
business, but the 800, which is basically the same electronics without
the Peltier cooler, does not.

>Anyone have a link for the PSU schematic? merci!

No, but Sony only charges five bucks for the full service manual, and you
should have got one originally with the mike. Rag on your Sony rep if you
don't have one.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Eric K. Weber]

The two in the power supply are of different manufacture and are used as
rectifier diodes.
What you may be having trouble with is condensation on the tube socket
caused by the Peltier device...

Rgds:
Eric
www.webermusic.com

"sodderboy" > wrote in message
om...
> I have a C-800G that is making a hissy/spitty noise. I get to check
> it literally between takes, as it is still usable except on a ballad,
> and find that all PSU voltages are flat DC and cable/ connectors are
> all solid. It is down to the tube or a cap in the mic.
> I read through past threads regarding the 800, especially the current
> one, and have a schematic of the mic, but not the PSU. I found two
> 6au6 tubes on the PSU board with heaters on, and figured they were
> regulators. But then I see thet 6au6 is also used as the amp in the
> mic.
> Are there two spare 6au6 tubes designed into the PSU, with their
> heaters powered? That would be quite cool! Next chance I get I am
> going to swap a tube from the PSU into the mic- hopefully the thin
> copper shield on the mic tube is not adhesive. . .gulp! Miseur
> Peltier? se vous plait?
> Anyone have a link for the PSU schematic? merci!

[Eric K. Weber]

The two in the power supply are of different manufacture and are used as
rectifier diodes.
What you may be having trouble with is condensation on the tube socket
caused by the Peltier device...

Rgds:
Eric
www.webermusic.com

"sodderboy" > wrote in message
om...
> I have a C-800G that is making a hissy/spitty noise. I get to check
> it literally between takes, as it is still usable except on a ballad,
> and find that all PSU voltages are flat DC and cable/ connectors are
> all solid. It is down to the tube or a cap in the mic.
> I read through past threads regarding the 800, especially the current
> one, and have a schematic of the mic, but not the PSU. I found two
> 6au6 tubes on the PSU board with heaters on, and figured they were
> regulators. But then I see thet 6au6 is also used as the amp in the
> mic.
> Are there two spare 6au6 tubes designed into the PSU, with their
> heaters powered? That would be quite cool! Next chance I get I am
> going to swap a tube from the PSU into the mic- hopefully the thin
> copper shield on the mic tube is not adhesive. . .gulp! Miseur
> Peltier? se vous plait?
> Anyone have a link for the PSU schematic? merci!