Sansui 8080 Pawnshop Special.

[mattsd]

So after a little bit of cleaning last night it didn’t improve much. I did however notice this morning that while turning the volume up and down all the way. When turned very quiet one channel drops and the other is still producing sound. Using balance no problem.
So my next guess is a dirty volume pot.
I also plan on cleaning the speaker connections on the back.

Now to clean the volume pot can I flip the unit on its top and take the bottom off or do I need to just remove the knob for volume and balance and give it a spray that way or is it more in-depth.
Dan

If cleaning the rest of the pots and switches doesn't solve the channel problem, there's a good chance your protection relay is dirty and needs replaced. Also, that unit has several fusible resistors on the power amp board that can cause problems as well.

 

[Dan887217]

If cleaning the rest of the pots and switches doesn't solve the channel problem, there's a good chance your protection relay is dirty and needs replaced. Also, that unit has several fusible resistors on the power amp board that can cause problems as well.

Thank you Mattsd I hope to do more indepth cleaning soon before I get someone to go in-depth for me for finer work.
I was reading in the faq about same issue on other models and what to do so that is my next plan of attack.

 

[LBPete]

In the 8080 and 9090, the power for the dial lamps goes through the function switch. If it hasn't been modified, the dial lamps are only on when AM or FM are selected. The dial lamps can also suffer from cold solder joints om the lamp holder clips. It's a very common problem and will make even a brand new lamp not light consistently.

Your serial number shows it was built in March '76, making it a very late production unit. It will have all of the factory upgrades made during the production run.

- Pete

 

[Dan887217]

In the 8080 and 9090, the power for the dial lamps goes through the function switch. If it hasn't been modified, the dial lamps are only on when AM or FM are selected. The dial lamps can also suffer from cold solder joints om the lamp holder clips. It's a very common problem and will make even a brand new lamp not light consistently.

Your serial number shows it was built in March '76, making it a very late production unit. It will have all of the factory upgrades made during the production run.

- Pete

This is great news thank you Pete. Wish we could found out the exact date that’s the month I’m born.
Now with the Dolby board I had plug my iPod in to the Dolby NR board and had sound as I do with fm adaptor. So this would mean the Dolby board is fine right.
I ran the stereo for a good amount of time yesterday and it doesn’t smell funny or give off a lot of heat. So this is good to.
Dan

 

[Dan887217]

Is there a number of how many they produced for this stereo?

 

[Dan887217]

So this evening I did some input cleaning on the back and speaker terminals. With the top off and more light I was looking at fuses. One was original in my eyes as it said Tokyo on it. Others just said the amp rating and one was the wrong amperage. These fuses are the ones right in front of the power board. Could this be one of my issues?
It was in a spot that said 125v 5a. But was 4a is all the was on it.
Dan

 

[sKiZo]

Smaller amp fuse would just blow faster and wouldn't hurt the amp's performance till that happened.

Good tip though - ALWAYS check the fuses on used equipment. Never know what you might find in there.

PS - the fusible resistors are pretty much the same thing - either they work, or they don't. If you're getting anything out of each channel, I expect they're not the problem. However - if you do any repairs, I'd consider replacing those, as they tend to be quite brittle from heat as they age. These can be replaced with equal wattage metal film resistors, and DO keep them away from the boards as these suckers get HOT.

 

[Dan887217]

Smaller amp fuse would just blow faster and wouldn't hurt the amp's performance till that happened.

Good tip though - ALWAYS check the fuses on used equipment. Never know what you might find in there.

PS - the fusible resistors are pretty much the same thing - either they work, or they don't. If you're getting anything out of each channel, I expect they're not the problem. However - if you do any repairs, I'd consider replacing those, as they tend to be quite brittle from heat as they age. These can be replaced with equal wattage metal film resistors, and DO keep them away from the boards as these suckers get HOT.

Now I have copied down what’s on the board.
Under what’s a clear label that says 5a 125v it says on the board 125v 7a.
My gut is go with the 5a 125v.
Dan

 

[sKiZo]

Pictures would be nice, but ... if it looks like a factory label that doesn't match the board markings, I'd go with the lower rating to be on the safe side. I'd also think a peek at the service manual would be a good thing. Not sure if AK has one in the library or not ...

** HiFi Engine has the service manual HERE ...

You'll need to set up a free account to download it.

 

[Dan887217]

Pictures would be nice, but ... if it looks like a factory label that doesn't match the board markings, I'd go with the lower rating to be on the safe side. I'd also think a peek at the service manual would be a good thing. Not sure if AK has one in the library or not ...

** HiFi Engine has the service manual HERE ...

You'll need to set up a free account to download it.

About pictures do I need photobucket or a different place or how is it done now was on a guitar forum in the past and needed a URL.

I found manual lib was free to look at manual so I have been going there.
Dan

 

[LBPete]

This is great news thank you Pete. Wish we could found out the exact date that’s the month I’m born.

There is no way to date it to a particular day. The last four digits are a sequential number indicating yours was the 2400th unit produced on assembly line 82 in March of '76.
I just looked up all the units we have on file produced on that line that month. With yours, we have 16 units produced on that line that month. It produced 3 990s, 5 9090s and 8 8080s. Yours was the last one produced so it was definitely produced late in the month assuming the production line ran every day.

It's really hard to even estimate how many in total were built. We have a total of 48 8080s and 890s on file. They were built between August 1975 and September 1976 and most months of production additional models like the 9090 would have been built on the same production line. No easy way to break down how many of each were produced each month.

- Pete

 

[Dan887217]

There is no way to date it to a particular day. The last four digits are a sequential number indicating yours was the 2400th unit produced on assembly line 82 in March of '76.
I just looked up all the units we have on file produced on that line that month. With yours, we have 16 units produced on that line that month. It produced 3 990s, 5 9090s and 8 8080s. Yours was the last one produced so it was definitely produced late in the month assuming the production line ran every day.

It's really hard to even estimate how many in total were built. We have a total of 48 8080s and 890s on file. They were built between August 1975 and September 1976 and most months of production additional models like the 9090 would have been built on the same production line. No easy way to break down how many of each were produced each month.

- Pete

That’s cool Pete how you have all this information.
So it a good chance it was made with the last 2 weeks of March. I appreciate your research and knowledge.
Thank you
Dan

 

[LBPete]

You can upload pictures directly to AK. Just click on "upload a file." If it's producing sound from both channels, there is nothing wrong with the fuses. As far as the values, there should be a sticker under the fuse that identifies the value. If not, check the service manual. What "problem" are you trying to fix? This thread has been rambling. It's not unusual for these units to still produce some sound with the volume control at zero.

- Pete

 

[LBPete]

It's more likely it was produced towards the end of the last week of March. We get this information from people like yourself that post their serial numbers. The serial numbers contain this information. With enough of them you get a picture of production information. We currently have just under 7000 serial numbers on file.

- Pete

 

[Dan887217]

It’s like a

You can upload pictures directly to AK. Just click on "upload a file." If it's producing sound from both channels, there is nothing wrong with the fuses. As far as the values, there should be a sticker under the fuse that identifies the value. If not, check the service manual. What "problem" are you trying to fix? This thread has been rambling. It's not unusual for these units to still produce some sound with the volume control at zero.

- Pete

It’s hiss and static very noticeable at low volume as one channel cuts out. And still noticeable at higher volume. ( I played piano music and was very noticeable with two different sets of speakers. When I played led zeppelin not as noticeable until it was just Robert’s voice.)
Yes their is a sticker saying 5a 125v over the 7a 125v on the board.
The fuses I pulled are blacked on the wire inside. Not shiny and most say Tokyo on them.
The fuse you can take out from the back is really shiny and says Tokyo. I am going to leave this one alone.
I talk to someone through Facebook who works on Sansui and he said hiss may be coming from transistors. And voltages need re adjustments.

I apologize if I have been rambling. 2 other people were making weird comments and I was like huh what.
I don’t want to go to a shop unless I have too.

 

[Dan887217]

Here is a few photos.

 

[Dan887217]

Front lit up and off in daylight.

 

[LBPete]

Hiss could be a component like a transistor. Do you have another amp or receiver? Try driving the 8080 amp with a different pre-amp. That will help isolate the hiss to the amp or pre-amp. Then get some freeze spray and start chilling stuff. If something changes when you do that, replace it.

By the way, your fuses say Toyo, not Toyko.

- Pete

 

[Dan887217]

Hiss could be a component like a transistor. Do you have another amp or receiver? Try driving the 8080 amp with a different pre-amp. That will help isolate the hiss to the amp or pre-amp. Then get some freeze spray and start chilling stuff. If something changes when you do that, replace it.

By the way, your fuses say Toyo, not Toyko.

- Pete

Interesting.
I have a Sansui 881. In the same room on the opposite side.
Oops Toyo not Tokyo.
Okay I admit I am a newbie in someways and have experience in others. How would I do the stated above?
An replacing the fuses won’t hurt it?
Dan

 

[LBPete]

Assuming the 881 works normally, look at the back of both receivers. There are U shaped jumpers. Remove them from both receivers and use a pair of RCA cables to connect the "Pre-out" of one receiver to the "Amp-In" of the other. Connect speakers normally to both receivers. Turn them both on and listen to for the hiss. If you hear the his from the speakers of the 881, it's originating in the 8080's pre amp. If you hear the hiss from the speakers on the 8080, it's originating from the amp of the 8080.

One other thing, what are you using for a media source? If you are only using the tuner, play something through the aux input.

- Pete