Ca 810 Power supply caps

Audi2014

Active Member
Hello all,
Thinking about replacing the 2 big power supply caps in this 70's era amp.
The unit is working fine currently.Looks like the only ones out there is a
71 volt/12000 uf cap versus the 51 volt/ 12000 uf original.
 
Why if it's 'working fine'? If you must poke around with PSU capacitors, test them first for capacitance and ESR and if they are fine leave them alone.
 
Caps

Hi,
Thanks for the reply.They have been in the unit since the 70;s and I wanted
to spruce it up.Have noticed ( in both channels) when I increase the volume
and a strong bass note hits, I see both lights inside the meters react to the
hit.I was thinking maybe that the power supply caps were getting tired and
as a result I saw the effect in the meter lights.
 
That's a reasonable assumption you've made, but the lamps are run from a separate tapping on the transformer, rectifier and filter caps.

Your loud big bass notes are causing a big surge of current from the transformer secondary and in turn a big flow of current from the primary side. That drop in flux density causes the separate windings that your bulbs are connected to, to have a momentary drop in secondary voltage. As the bulbs are all in series any small voltage drop will be manifested as a visual fluctuation. There are 470uF 50v capacitors across the rails (+/-36v) and increasing their value would make a change for short duration transients- you could safely increase those caps to 2200uF and other benefits would flow from that as the regulated front end and preamp is also run from that supply.

Your main caps essentially just supply current for the power amp stage when the transformer isn't.
 
Last edited:
Back
Top Bottom