Adcom GFA-555 Feedback DC-Blocking Cap?

[EchoWars]

Got an original 555 on the bench, and was getting ready to replace the two small caps on the driver board. I noticed the feedback DC blocker is a 47µf 100V(!) cap. This is in a place where you'd expect to see a 6.3V or 10V cap, not 100V.

Is there a reasoning here that I'm missing?

 

[infinia]

Hi
Adcom probably already had that part on the parts list, so they used it instead, ie without adding another line item. Purchasing in quantity et al. I don't know its your call, but there is something to said about remaining in "stock" condition.

 

[Nelson Pass]

Just as likely it was on the prototype I gave them, and they
religiously used the same type.

 

[EchoWars]

Can't think for themselves?

I got no 47µf 100V caps here, but I have some 100µf 10V ones. Any reason I should not use them?

 

[mlloyd1]

maybe higher voltage ratings implies lower leakage current?

mlloyd1

 

[Nelson Pass]

Naaaah.

 

[Zen Mod]

use 100uF/47V .......

 

[EchoWars]

Serbian humor?

Thanks anyway guys.

 

[Zen Mod]

Serbian humor?

Thanks anyway guys.

Papa is Serb , too ?

 

[EchoWars]

I think you missed your calling.

 

[allanhard]

anyone have a schematic or perhaps a service manual for the GFA-555?

Thanks

Allan

 

[canyn]

Generally odd to tag such a request to a nine month old unrelated thread, but..

There is a pdf posted here:

http://www.diyaudio.com/forums/solid-state/157682-another-high-dc-adcom-gfa-555-a-18.html

...post #176.

 

[stratus46]

Generally odd to tag such a request to a nine month old unrelated thread, but..

There is a pdf posted here:

http://www.diyaudio.com/forums/solid-state/157682-another-high-dc-adcom-gfa-555-a-18.html

...post #176.

Be aware of typos in the print. R3 is 33.2 ohms, not 33.2 K ohms. Q6 is a 2SA1207, not 2SA1270

G²

 

[fredlf]

I have documentation from Adcom that shows two versions of the input board. One, labeled "earlier versions" shows 10v caps while another, later revision of the board shows the 100v. There are a couple of other small variations too...

 

[Nelson Pass]

Be aware of typos in the print. R3 is 33.2 ohms, not 33.2 K ohms. Q6 is a 2SA1207, not 2SA1270

and R11 is 68 ohms.

This appears to be the earlier (my) version.

The 100V rating on the feedback cap is of no consequence.