Sansui 7070 popping, dumping audio temporarily
- Thread starter Steady Eddie
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- 7070 popping noise rebuild sansui
The 7070 is an amazing sounding receiver. And that Beatles song brings out a lot of detail. I have a 7070 on the bench right now that came in as a literal basket case. The person who "worked" on it should not own a soldering iron! It was a complete mess with wrong components, bad components, shorted transistors, bad soldering, wrong wiring, etc. I may get it powered up today if all goes well. If so, I'll put on Eleanor Rigby as it's first listening test.
Steady Eddie
New Member
That receiver sounds really good through the Bose 501 II speakers, which I’ve heard are rather “meh” but I’ve just gotten some Polk Audio Monitor 10a and 5a. They have the Peerless tweeters. Assuming those speakers are 8 ohms, can I run both pairs? They seem to be much better regarded compared to the Bose and I’m thinking will sound even better.
The biggest problem with the Bose is placement. They are a reflecting type of speaker and must be placed out from the walls accordingly. The tweeters fire backwards at an angle and reflect off the walls. Plus your walls need to be bare with no sound absorbing things like curtains or furniture. I think my 501's sound very good. People have different opinions, and different tastes so trust your own ears, and what makes you happy.
As far as the Polk speakers go, be sure they are 8 Ohm rated. The back of my 7070 states when using both A+B they should be no less than 8 Ohms per pair. When you crank 'em, turn the loudness OFF. Loudness is only to be used at lower volume. 
Then feel the output transistor heat sink to be sure it isn't getting too hot. But just like a car engine, warm it up a bit at lower volume for about 10 minutes before putting the pedal to the metal. That gives all the voltages time to stabilize, and BIAS/Driver transistors to come to temperature to regulate the current.
There's not much information on the 5A or 10A specs online, but the 5B nominal impedance is 4 ohms, the 10B is 6 ohms.
As Skywatcher noted, I would not take that chance unless I knew for sure each speaker's rating.
Agreed. The 7070 will run ONE pair @ 4 Ohms. But 2 pair need to be 8 Ohms minimum each.
Steady Eddie
New Member
Right now I have the heat sinks off. Should I use thermal grease to conduct heat to the sinks? Like a silver grease used for computer CPUs?
Thermal past, yes. But NON-Conductive type only. There are a lot of "silver CPU" type stuff out there that is electrically conductive. It's best to use the white thermal paste (or grease).