• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Finally fixed my 771

R

rkgren1

Super Member
I bought a 771 from a flea market last year and enjoyed it for a while. It started popping and cracking on the left channel, and near the same time I stumbled upon a Realistic STA-90 that work fine. So I swapped it in and set the 771 aside.

I recapped the 771 ~6 months back, but a hiss remained, again in the left channel. I set it aside as other things took my time for a while.

I ordered transistors for the driver board and I received them this week.

Today I finally replaced those designated in the manual as 2SA640. They were actually 2SA726.
I replaced those 4 and plugged it into the dim bulb test and ... nothing. No relay click.
I pulled the driver board back out and I found them to be installed backwards.

I removed them and reinstalled them in proper orientation.
Lifted 3 solder pads in the process....AHHHHH!

Patched those with the clipped ends of the transistor leads.

Tried again with the dim bulb tested and SUCCESS!
I ran it at low volume for ~1 hr. on the DBT. without incident.
I pulled it off and I have been listening to it now for 8+ hours and it sounds sweet as can be.
Dead silent with volume off now. I don't plan to touch the transistors on the board unless they show signs of failure.

I am very much a novice at this, but am very pleased with the result.

The 771 has bumped the presently resident Pioneer 950 out of the living room system so it can have a recap of the power supply.

Feeling good tonight and enjoying the music.
 
Register to hide this ad
Good work. Those 726s do go noisy. And yes, different pin out than most replacements.

Rob
 
Great work, glad you are enjoying your ''new'' silent receiver, l really like that series, hope to own a 771 or 881 one day.
 
Yeah. I replaced the 2SA726s with KSA992FBU.
The pinout is simply backwards, EBC vs CBE, left-to-right, viewed from the flat side. So you just install them with the flat side facing the opposite direction, and all is well.

I hear good things about all of the XX1 series.

I would not hesitate to buy any of the lower-end models.

I swear, my best sounding receiver is a 10W/ch Realistic STA-430.

Not a pretty as the 771 though, and the tuner is way out of alignment. So it sits in the corner while the Sansui sings.
 
Ah, I have a 441 with a channel out. May have to do transistors in it too.

My first real HiFi was a 771 - I loved that receiver.
 
Yes l think many of the lower wattage receivers/amps are overlooked, l don't doubt what you say about your sta-430. I have a sansui 441 that l recapped/replaced transistors on and it sounds great.

SiliconTi the 441 uses stk modules so you may have one of these faulty? The 771 uses all discrete components.
 
You must log in or register to reply here.
Back
Top Bottom