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9090db Speaker Selector Switch fuse ?

LongPlay33

LongPlay33

New Member
Does anyone know what would cause this and how to fix this issue on a Sansui 9090db

I had the speaker selector switch on Speaker C and the volume was set at 4, all was sounding great until I heard a loud pop.
The right and left speaker`s quit working. I disconnected the AR3a speakers from Speaker C and tested them on the Speaker B which still had
power and they worked fine, the Speaker A was also working fine too, fyi
The AR3a speakers are new to me , after connecting them to the Speaker B and listening to them I discovered that the tweeters on each speaker
was not producing sound. Honestly I can`t say that they were working while I listened to them when they were connected to Speaker C

Could this maybe be a faulty Selector knob gone bad ? Why would Speaker A and B still have power but Speaker C quit ?
 
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Interesting, I always thought on these particular units you had to have speaker "A" or "B" hooked up for C to play... Didn't know "C" would play all on its own.
 
On the 8080/9090(DB) line, all speaker outputs are in parallel. Hence why a maximum of two sets of speakers can be active at once (A+B, A+C), otherwise it would present far too low an impedance to the amp.

I suspect the issue the OP is experiencing due to an issue in the rotary switch, specifically on the contacts for the C speaker system. These oxidize and require the switch to be cleaned (carefully) to restore a proper signal path through the switch.

Some later models (9900Z for sure) used individual relays to control whether each speaker system was in or out of circuit.
 
I recently was playing my Ar3a`s on the Speaker B and finally they quit working. I then moved the speakers to Speaker C and they worked fine
until the next time I turned on the unit and the speakers were dead on Speaker C. What I finally realized was the speakers are rated at 4 ohm.
I`ve since hooked them up to a receiver that would play 4 ohm and the speakers are now playing well without any issues.
In order to get the Speaker Selector to work and run B and C again I`m wondering if each might have a fuse that blew ?
If their are no fuses what has to be done to get the Speaker Selector Switch to work again ? Fyi.. Both my meters are working as I use the speaker B or C although no sound is heard..
 
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There are no fuses related to the selector switch. And speaker impedance is highly unlikely to have played a role. A, B and C are just speaker connections. One amplifier (per channel) drives all three of them. A, B and C are wired to put the speakers in parallel.

Sounds to me like your selector switch may be bad, or dirty/oxidized/corroded. I am assuming that this issue occurs regardless of input? If not, problem could be the input selector switch as well.

Try cleaning both switches with Deoxit D5. Some folks recommend CRC QD; it is less expensive. Sometimes just working the switches back and forth (one end to the other) can provide at least temporary relief.

Before spending money, hook up a different pair of speakers to confirm the variables of the problem. What happens on A? What happens on B? What happens on C?
 
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Unlike other Sansui receivers, the 9090DB places multiple sets of speakers in Series which increases the rated speaker impedance. So it's not likely that running two pairs of speakers would cause a problem. That said, depending on the production date of your 9090DB there may be fuses in the amp's output. Early production 9090DBs had fuses on the protection board to protect the speakers. These fuses were deleted in later production.

If your unit has these fuses and either one is open, you won't get any sound from that channel regardless of speaker selector position. If you post your serial number I may be able to tell if your unit has these fuses.

- Pete
 
Actually, it just occurred to me what might be happening. Because the 9090DB (and 8080DB) places multiple pairs of speakers in series, if only one pair of speakers is connected they won't play when the speaker selector is in either A+B or A+C. They will only play when the speaker selector is set to the same system terminals, A only, B only or C only.

- Pete
 
LBPete said:
Actually, it just occurred to me what might be happening. Because the 9090DB (and 8080DB) places multiple pairs of speakers in series, if only one pair of speakers is connected they won't play when the speaker selector is in either A+B or A+C. They will only play when the speaker selector is set to the same system terminals, A only, B only or C only.

- Pete
Click to expand...

He said he is having issues with just A, just B, and just C. They work, on one or both channels (R&L), then stop working.
 
If he is having intermittent audio dropping out on individual channels (regardless of speaker selection), I would bet a cup of coffee it is an issue with the Dolby board feed throughs.
 
LongPlay33 said:
I recently was playing my Ar3a`s on the Speaker B and finally they quit working. I then moved the speakers to Speaker C and they worked fine
until the next time I turned on the unit and the speakers were dead on Speaker C. What I finally realized was the speakers are rated at 4 ohm.
I`ve since hooked them up to a receiver that would play 4 ohm and the speakers are now playing well without any issues.
In order to get the Speaker Selector to work and run B and C again I`m wondering if each might have a fuse that blew ?
If their are no fuses what has to be done to get the Speaker Selector Switch to work again ? Fyi.. Both my meters are working as I use the speaker B or C although no sound is heard..
Click to expand...
The OP doesn't actually say anything about speaker A. Although the post does seem to suggest he was killing channels one at a time, until no channels worked anymore.
I personally would have quit after the first speaker postition stopped working.
 
AE Bob said:
If he is having intermittent audio dropping out on individual channels (regardless of speaker selection), I would bet a cup of coffee it is an issue with the Dolby board feed throughs.
Click to expand...

That is certainly a good possibility, but I think first step would be to clean speaker and selector switches (and tape monitor switch for good measure). Eliminate the easy stuff first!
 
DB-7 said:
The OP doesn't actually say anything about speaker A. Although the post does seem to suggest he was killing channels one at a time, until no channels worked anymore.
I personally would have quit after the first speaker postition stopped working.
Click to expand...

I thought he mentioned it in a different thread...but could be mistaken. In any case, B and C are same as A, other than different contacts on the speaker switch, right?

Based on info provided so far, it seems unlikely that he has "killed" either channel.
 
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If there is another thread posted by the same poster about the same problem, he should have bumped their other thread instead of creating a new one to avoid confusion and forum clutter.
Hopefully one of the two threads figures out the problem, and we don't have two threads dangling with no solution.

Cleaning the switch is a good start.
 
The 9090DB and 8080DB are unlike other Sansui receivers. They put pairs of speakers in Series, NOT Parallel. As a result if one pair of speakers is connected there will be no sound in the A+B or A+C positions. The OP now has two threads on this subject.

- Pete
 
LBPete said:
Unlike other Sansui receivers, the 9090DB places multiple sets of speakers in Series which increases the rated speaker impedance. So it's not likely that running two pairs of speakers would cause a problem. That said, depending on the production date of your 9090DB there may be fuses in the amp's output. Early production 9090DBs had fuses on the protection board to protect the speakers. These fuses were deleted in later production.

If your unit has these fuses and either one is open, you won't get any sound from that channel regardless of speaker selector position. If you post your serial number I may be able to tell if your unit has these fuses.

- Pete
Click to expand...
Thank you, I will have to pull the unit out of the shelf and turn it around to look for the serial number. I'll do that asap.
 
LongPlay33 said:
Thank you, I will have to pull the unit out of the shelf and turn it around to look for the serial number. I'll do that asap.
Click to expand...

It worked on B for a while, then stopped working on one channel. You moved speaker wires to C, and again it worked for a while. I fuses were blown, it would not have worked on either B or C.
 
I would tap on the Dolby PC board and see if you are not just seeing a random loss of signal from that board's feedthrough issue. Moving stuff around while changing the speaker wires to another output could be triggering the notorious Dolby board intermittency.
 
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