In anticipation of the in-wall Revel speaker system I’ve started installing in the den (thanks employee discount!), I decided to rebuild my 1974 Sansui 771 stereo/quad receiver/amplifier.



I think my dad purchased it new, while in high school, which is crazy considering it sold for the equivalent of $2000 in 1974.
Either way, it was due for a refresh. Outputs were noisy, bulbs were burned out.

• Blew out dust
  Ultrasonic cleaning of knobs and pushbuttons
  Cleaned front panel
  Cleaned and lubed all pots, switches, and connectors
  Replaced all electrolytic and tantalum capacitors
  Replaced all commonly problematic transistors
  Replaced all bulbs with LEDs
  Added preamp output on 1/8" jack on back panel, to feed subwoofer power amplifier

Waiting on a few remaining transistors, but it should be good for another 40 years after this. These things are fairly highly regarded. 32 W RMS / ch, all discrete. I’ve always liked the sound of it, even with it being slightly noisy.
The innards remind me of the Yamaha PM-1000 channels I used to work on all the time. Same PCB style, same hand-soldered connections, same type of interconnecting wire, very similar component selection.
Planning on hooking up my dad’s old Sanyo TP-600 SA turntable after a good cleaning and lubricating.

Last March my TB2000 split in half. A few months went by without doing anything about it, we were in a tiny apartment and the pandemic was in full swing so I wasn't going to a luthier. Eventually we moved in with my girlfriends parents and her father had some clamps and some glue. I stuck it back together and it's been solid ever since.

Nate Dort wrote: Wed Jun 23, 2021 8:09 am In anticipation of the in-wall Revel speaker system I’ve started installing in the den (thanks employee discount!), I decided to rebuild my 1974 Sansui 771 stereo/quad receiver/amplifier.

Ooh, nice. I just got a pair of outdoor Revel speakers for my deck that I hope to hook up this weekend.

I had the privilege of working on a Roland RB-60 the other day. Never even heard of one before, and I think maybe they were never sold in the US. The repair was minor, just swapping the power cord and cleaning, but the amp sounds pretty damn great.
Schematic for the curious: http://lib.roland.co.jp/support/jp/manu ... B-60_j.pdf

Nate Dort wrote: Wed Jun 23, 2021 8:09 am In anticipation of the in-wall Revel speaker system I’ve started installing in the den (thanks employee discount!), I decided to rebuild my 1974 Sansui 771 stereo/quad receiver/amplifier.

I'm about to do the same with my Sansui 5000x. It still sounds good, but the connectors and pots all need a deep cleaning. Might as well do a cap job while I have it open. What led lamps did you end up using?

I used the warm white 8 V LED fuse lamps from Parts Express:

https://www.parts-express.com/5-Pack-8V ... ha-070-121

Looks like they're backordered, but I've seen similar ones on ebay and amazon.

Nate Dort wrote: Thu Aug 19, 2021 2:31 pm I used the warm white 8 V LED fuse lamps from Parts Express:

https://www.parts-express.com/5-Pack-8V ... ha-070-121

Looks like they're backordered, but I've seen similar ones on ebay and amazon.

can't guarantee that they're the same "warm" ones but if anyone needs three of these i have some leftovers from repair of my Pioneer.

Ampeg BA-115 v2:

Go this on ebay for cheap, advertised as having a broken PCB connector for the speakers. Looks like a floor demo or something that was damaged in shipping. No real wear on the outside.


There's some large ferrites on the wire harness that probably put too much strain on the connector. I added some new wires to the PCB with some bullet connectors, and strain-relieved the ferrites by zip-tying them to the chassis. Works fine now.

Ampeg BA-112 v2:



Not to be confused with the 115 above, this 112 arrived at the same time from the same ebay seller. "No output." Also had a gash on the back corner of the cabinet, which was able to glue.

Main amplifier IC was fried (TDA7294). I could see signal going into it, but nothing coming out. When I desoldered it, the plastic body was cracked and broke off. Maybe it was tightened to the heatsink too hard? New one fixed it though. Gonna hold onto this one as a replacement for my little Fender Rumble 40, which sounds good, but isn't quite cutting it in the SPL department for band practice. I think my band is gradually getting louder.

Nate Dort wrote: Tue Aug 24, 2021 9:05 am

Just picked up a free pair of 15" bass cabs from a coworker. He was using them on Halloween for his haunted house display and storing them the other 364 days. Loaded with 350 W 8 ohm Peavey Black Widows. No idea how they sound yet, or what I'm going to do with them. They're pretty huge and heavy, but seem well-built. I'll probably keep one and sell the other.

Turns out that one of these had a Carvin PS15C in it, the other was a Black Widow. I sold the Carvin and one cab separately.

I played the Black Widow cab a few times, but it always seemed way too loose and boomy, so I threw it on CL. Somebody came by yesterday to buy it, but couldn't fit it in their car, so I gave them their money back.

I took 90 minutes today to shave about 8 inches in depth off the back of the cabinet. Pulled the back panel off, peeled the carpet back, and cut it off with a circular saw. Replaced the internal bracing to hold the back panel on, then glued and stapled the carpet back down.

Way less boomy. Much faster response, probably shifted the resonant frequency closer to 50 Hz instead of 25 Hz or whatever it was at. I'm going to keep it for now. I missed having a 1x15 around since I sold my Mesa Diesel last year, and I need something that can handle the output power of my Mesa Fathom.