New Member with 7070 trouble

[Gregory7070]

Hello Gang, I've recently acquired a sansui 7070

I am getting no sound, I checked commonly known issues on the 2624 board but everything is kosher....I'm getting .0 and .1 dc from my outputs.

Thank you guys

 

[mbz]

.I'm getting .0 and .1 dc from my outputs.

Measured at the speaker posts? I assume you are getting a faint relay click 4-8 seconds after power ON.
Also, you should try different inputs ie, AUX, TAPE,,, and also try speaker set A, B,, and also headphones.
If it has PRE-OUT/MAIN-IN RCA's then connect an iphone/ipod/ixxx at minimum volume to the MAIN-IN then slowly up
the volume. If still no sound then maybe a health check of power supply...

 

[Gregory7070]

Measured at the speaker posts? I assume you are getting a faint relay click 4-8 seconds after power ON.
Also, you should try different inputs ie, AUX, TAPE,,, and also try speaker set A, B,, and also headphones.
If it has PRE-OUT/MAIN-IN RCA's then connect an iphone/ipod/ixxx at minimum volume to the MAIN-IN then slowly up
the volume. If still no sound then maybe a health check of power supply...

Yea I get the faint relay click, I've also ensured all aux, tape selector issues etc. I've checked everything I can find to check

 

[ivandezande]

Gonna need to trace the signal if it’s dead quiet and the switches aren’t an issue. This model
doesn’t have pre-in/outs I think so we’re good there.
Gonna want to replace all fusable resistors anyhow.

 

[cademan]

Make sure the tape record source selector is set on "Source".

Relay click is usually a good sign that the power amplifier section is working.

 

[avionic]

Welcome to AK Greg

 

[sregor]

Eliminate stupid stuff - like make sure knobs are in correct positions (tape selector or input selector), no shorting jacks in anything except unused phono inputs...

 

[Gregory7070]

I've eliminated most of the small stuff, I've determined my amp section is good.. I'm not sure where to go next. Everything I'm suggested to try is fine. Thank you all for the help

 

[AE Bob]

I have seen this issue on many of the Sansui 7070, 8080, 9090, 990, etc receivers. The "flame proof" resistors on the driver PC board just open up. They are not overloaded, they just go bad. If only certain ones go bad, you may have a protect issue, or missing sound in one channel, but if a unit has been out of service for many years, they may all be open, causing your symptom (I have seen this several times). You need to replace R33 and R34 (180 ohm 0.5 watt) on the F2624 driver PC board. I bet they are both open. You also need to replace R41, R42, R43, and R44 (150 ohm 0.5 watt) on the same PC board (I bet they are WAY out of tolerance if not open). I use metal film resistors to replace them. I usually also replace all of the other resistors of that type (greenish gray colored "flame proof") on the board.as I sometimes find them out of tolerance as well, and given enough time they will also likely fail.

 

[Gregory7070]

I

I have seen this issue on many of the Sansui 7070, 8080, 9090, 990, etc receivers. The "flame proof" resistors on the driver PC board just open up. They are not overloaded, they just go bad. If only certain ones go bad, you may have a protect issue, or missing sound in one channel, but if a unit has been out of service for many years, they may all be open, causing your symptom (I have seen this several times). You need to replace R33 and R34 (180 ohm 0.5 watt) on the F2624 driver PC board. I bet they are both open. You also need to replace R41, R42, R43, and R44 (150 ohm 0.5 watt) on the same PC board (I bet they are WAY out of tolerance if not open). I use metal film resistors to replace them. I usually also replace all of the other resistors of that type (greenish colored "flame proof") on the board.as I sometimes find them out of tolerance as well.

Checked what I could as for those resistors, after some research I feel problem is not in my driver board/amp section

 

[Gregory7070]

But the unit hadn't been powered on since 1982. It's definitely set for a very long time

 

[AE Bob]

The protector will still close with the issue I described in the previous post. Believe me, you need to pull the F2624 Driver board and check those resistors. I bet the 180 ohm units (R33 and R34 )are both wide open.They are at the bottom of the board (near the connector) on both the left and right edge of the board.

 

[Gregory7070]

I have

The protector will still close with the issue I described in the previous post. Believe me, you need to pull the F2624 Driver board and check those resistors. I bet the 180 ohm units (R33 and R34)are both wide open.

Pulled it and both 33 & 34 both read fine

 

[Gregory7070]

Yea I gou

The protector will still close with the issue I described in the previous post. Believe me, you need to pull the F2624 Driver board and check those resistors. I bet the 180 ohm units (R33 and R34 )are both wide open.They are at the bottom of the board (near the connector) on both the left and right edge of the board.

i found a video and checked those and they seem to be fine. I really think I have a small issue.

 

[Skywatcher]

Hello Gang, I've recently acquired a sansui 7070
View attachment 1747685
I am getting no sound, I checked commonly known issues on the 2624 board but everything is kosher....I'm getting .0 and .1 dc from my outputs.

Thank you guys

What are you using as a source for the "sound"? If you are using FM, be sure the FM MUTE button is IN. In means muting is off. Also, if you can hear any "hiss" in the speakers, then yes I would say the amp is working at least somewhat. If the speakers are completely silent, then no, the amp is not working.

 

[AE Bob]

You should also check the 150 ohm resistors (R 41 42 43 and 44). If any less than all are open then it won't close the protector, but if all are open the protector will close, and there will be no sound (I really have seen this several times). You don't need to remove them to test them, just see if they read greater than 150 ohms in circuit.

 

[Skywatcher]

Hello Gang, I've recently acquired a sansui 7070
View attachment 1747685
I am getting no sound, I checked commonly known issues on the 2624 board but everything is kosher....I'm getting .0 and .1 dc from my outputs.

Thank you guys

To add to what I said about the FM MUTE button, it is the *only* button that should be pushed in at this time. If the Dolby Adapter button is in (as it appears to be in your photo), you will get silence.