zoeffiex
Active Member
Hi Guys,
(hope my englisch is ok, normally i speak dutch.)
I am looking to restore and "upgrade"a AU517.
Inspired by a recap and upgrade of a AU717 done by @Leestereo i would like to do some upgrades to the regulated power supply.
I agree with him that the most benefits can be made here .
Except for the power supply and the tone control boards of the AU517, the pre/main switch board, the equalizer board and the driver circuit boards are allmost identical to the AU717.
(in a few places other resistor values are used.)
So i can do the upgrades leesetereo did on the "shared" (allmost identical ) boards. (BONUS!)
Next the schematic of the 517 psu
(hope my englisch is ok, normally i speak dutch.)
I am looking to restore and "upgrade"a AU517.
Inspired by a recap and upgrade of a AU717 done by @Leestereo i would like to do some upgrades to the regulated power supply.
I agree with him that the most benefits can be made here .
Except for the power supply and the tone control boards of the AU517, the pre/main switch board, the equalizer board and the driver circuit boards are allmost identical to the AU717.
(in a few places other resistor values are used.)
So i can do the upgrades leesetereo did on the "shared" (allmost identical ) boards. (BONUS!)
Next the schematic of the 517 psu
Main power supply uses 30D2 diodes.
The 4 power supply main capacitors (C701-C704) are rated at 12,000µF/63VuF. I would like to upgrade them to the same value as the 717, 15000uF/63v, If the 30d2 diodes are up to that. Or should i replace them? MUR1520G are recommended by some. Same reverse en forward voltage etc.
The 4 power supply main capacitors (C701-C704) are rated at 12,000µF/63VuF. I would like to upgrade them to the same value as the 717, 15000uF/63v, If the 30d2 diodes are up to that. Or should i replace them? MUR1520G are recommended by some. Same reverse en forward voltage etc.
Now on the regulated supply:
As we can see raw DC is filtered by C5-C6-C7-C8 and are rated at 220uF/63V
Next capacitors are C9-C10-C11-C12 rated at 100uF/35V. (These shunt the zeners?)
Then come TR01 + TR 03 and TR 02 + TR04. These are 2SD438 + 2B560 pairs.
C25-C26-C27-C28 are 220p ceramics
The zeners ZD01 + ZD03 and ZD02 + ZD04 are RD33E(B)
R13 - R16 says 22 on the schematic. I guess it is 22R
After that C13-C14-C15-C16 rated at 100uF/35V
And final are C19-C20-C21-C22 rated at 47uF/50V
Now, this is it! And it is way different then the AU717 .
If i am correct, the 717 uses local decoupling on the tone control board.
The 517 does not. Hence the extra 47uf capactors?
Ok, now to my question (s)
Can i upgrade C5-C6-C7-C8 to 820uF or more?
If i read the schematic correctly, C9-C10-C11-C12 shunt the zeners? If so i would like to upgrade them to 120uF.
Can i upgrade C13-C14-C15-C16 to 330uF or more?
Can i upgrade C19-C20-C21-C22 to 150uF or more?
Can i do these upgrades without any harm to the other components or do i need to upgrade these also.
On the zeners, i was thinking of replacing them with BZX55C33 (2%) or 1N5257B since the original RD33E(B) zeners are Min 29.68v/Max 33.11V according to the datasheet.
Also, need to look for the fusistors...And replace them.
Well, that is the story. Hope some of you can advise me on this,
Best Regards,
René (Zoef)
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