Hipocrates
Super Member
Nah..... you did the work, crank that bugger up, to mask the white noise
New project. Sansui 8080 recap. Advice appreciated.
petehall347
the brandy coffee man
i missed lots of this but picked up on bits of it .. was all the corrosion dealt with ?
RR--
Active Member
99% of the corrosion has been addressed. I soaked and cleaned a lot of the rusted parts in vinegar and repainted what needed doing, rusted capacitors were replaced, the relay was replaced and the front metal trim was draw filed down.
Most of the bad rust was on the base plate which was easy to remove, I also repainted the top of the rusty transformer but managed to keep the original Sansui logo on the side.
The Mofsets covers (I think) on the power supply board are still a bit rusty but I'm leaving them alone at the moment as I don't know much about them.
Even the before pictures was after I initially cleaned inside, I unfortunately didn't take any photos on the day I bought the amplifier.
Before:
After:
Hipocrates
Super Member
Nicely done!! Now let's listen that 8080 with a cold one!
dapbmw
Active Member
I also successfully completed my modification to the bass frequency. Figuring out the schematics took a while especially since it had a few famous Sansui typos.
On the 8080 tone control board F2544 instead of a frequency selector switch and several capacitors the 8080 has these 4 capacitors, they are the same capacitors as the "150HZ" option in the 9090 at 0.033uf, they are C20, C21, C23 and C24.
The schematics for the switch position for S01a is a misprint, it should have the numbers in the reverse order as 3, 2, 1.
In a 9090 0.012uf capacitors alter the bass frequencies at 300HZ and 0.033uf capacitors alter the bass frequencies at 150HZ. I don't think this is entirely correct as my AU719 bass controls at 150HZ sound much deeper.
What I did was solder some 0.012uf capacitors in parallel with the existing 0.033uf capacitors in place. I used MuRata MLCC C0G 50volts 0.012uF capacitors. Part number: RCE5C1H123J1A2H03B
https://au.mouser.com/ProductDetail/81-RCE5C1H123J1A2H3B
I did this on the reverse side of the board as there was more room and it is easily removable if needed in the future.
So far I'm very happy with this mod. With them installed it sounds exactly the same as my AU719 does when in 150HZ mode. For me this really completed the amplifier, it removes the high bass boom and replaces it with a deep curve boosting only the lowest frequencies needed on my Monitor Audio RX1 bookshelf speakers.
Would not it be simpler if you replaced the .33uf with a .47uf cap?
MIJ_Pioneer
Super Member
You forgot a zero in there
Maybe a 0.047 cap does not exist? If it did then yes it may be easier but size may be an issue as well.
RR--
Active Member
Potentially easier but this way the modification is easily reverse able as the original film caps are still installed.
