Ok I’ve got some updates. Some unfortunate lessons learned, and some information that most of you can probably use. I posted in another thread out of frustration with this system. These units are getting up in age and it’s hard to know what’s actually working and what isn’t. Where I left off was a CA-3000 with a weak right channel, a BA-3000 (#1) being used as a mono block that would cut out after about five minutes, and a second BA-3000 (#2) that had a lot of static at start-up.
I’ll start with the bad news. I sourced all of these units over time specifically to be 120v. Unfortunately BA-3000 #1 had been rewired at some point in its life, probably by the crummy tech that left a sticker on the back from Ohio. Lesson learned here is that even if your Sansui powers on, you absolutely need to verify the transformer wiring, especially if it’s a multivoltage unit!!!!!!!!!! When this amp recently started having trouble turning on, an output driver failed and took the right channel output transistors with it. I replaced the outputs and drivers, but the amp continued blowing resistors on the main power board from excessive current draw. When I compared voltages to BA-3000 #2, they were completely different, so I’m confident in my call on the transformer. That amp is now off to the side and I honestly don’t know what I’m going to do with it. Part of me wants to keep it for parts to keep BA-3000 #2 going long term, but I’m still undecided.
The second BA-3000 remains untouched internally and was working great aside from the static at start-up.
The biggest headway was made on the CA-3000. Originally every wire in the unit had been soldered directly to their connector pins, and yes, some in the wrong spots from someone else. I’m guessing a previous tech stole all the original connectors. Over the course of a couple months I pretty much purged eBay of Sansui connectors at a great cost lol, but it was absolutely worth it from a serviceability standpoint. This unit ended up having a couple different issues that was fixed through trial and error. All the troubled resistors that you guys talk about were replaced for longevity and every capacitor replaced. I re-flowed all the through holes, but the right channel was still weak. On top of that, if any meter was selected, there was severe static introduced into the signal path.
The first problem turned out to be on the meter board. The original TA7136P meter amp ICs were replaced with NJM2068D op-amps using BrownDog SOIC-8 to DIP-8 adapters (BrownDog 970601). Once those were installed, all of the meter-related static disappeared completely and all meters began operating identically and silently. No more noise being injected into the circuit just from selecting a meter.
I have no doubt that my second Sansui BA-3000 is suffering from the same meter IC issues. Do yourselves a favor and buy a handful of these ICs for the future. They are literally drop-in if you can solder.
The second problem was the HA24N reed relay, which ended up being the source of the weak right channel. Specifically for CA-3000 owners, if you know your meters are adjusted correctly and you still hear an audible difference in output, the output meter select is monitoring the signal just before this relay. If your meters read perfectly but your audio does not, you can be pretty confident in what it is and not even have to use an oscilloscope.
Now replacing the original HA24N, I installed a Standex-Meder 9007-05-00 reed relay (5V SPST) using a simple adapter setup. The relay itself is a Standex-Meder 9007-05-00, mounted on a DIP-8 style adapter to match the original footprint, with standard 0.1-inch pin spacing. No PCB traces were cut and no board modifications were required. Once installed, the right channel immediately returned to normal and the left channel also improved noticeably in depth and clarity. The improvement was big enough that I’m now considering replacing the HA24N reed relay used in the phono selector as well but that will require loosing the adapter plate and I'm sure it will fit due to height. The replacement drops cleanly into the Sansui board and made the sound return to as good as ever!
As an update to my system, I’ve also been trying out some new speakers. I went to a couple of high-end audio stores and, to be honest, I would stack this Sansui gear against all of it. If you’re a Sansui fan, it’s as good as, if not better than, the three or four $50,000 systems I listened to. If you're not, good stay that way
I trialed a set of Wharfedale Super Lintons for about two months and a pair of Revival Audio Atalante 5s. The Super Lintons were returned. They were great, just not on the same level. This did present a problem though, these speakers are a 4 ohm load, which the BA-3000s aren’t quite happy with.
With the loss of BA-3000 #1, I mourned the loss with an upgrade to a BA-5000. It’s a 100v unit that I thought could be rewired to 120v, but it turns out it’s an early variant without that option. I picked up a proper step-down transformer and I cannot describe how happy I am with this setup. If you have not experienced a ba-5000 but have a ba-3000, it is without a doubt a next level. Opening up the BA-5000, the engineering is definitely a few steps above the BA-3000 to say the least.
I’ve got a couple more upgrades coming once the base system is fully ironed out. If you made it this far, thanks for reading and happy listening. If you find yourself in a similar situation with the meter ICs or reed relay issues and want more details, feel free to shoot me a message. There wasn't too much support from a technical level here so happy to help!!! I'm just not an avid forum user anymore.
There's defiantly more to come here with a BA-5000 restoration coming soon(parts in the mail) and some stuff I know is not well documented as far as rarity is concerned......(Sansui tube to be a teaser!!!!!!)
