Difference between 9090db and 9090

[Erich]

Thanks for the reply. That's kind of what I expected :-(

Since the Dolby board is so closely integrated with the tape inputs and outputs, it has been determined that there is no easy way to do this. Bypassing the board would be more difficult than repairing it.

 

[59volvo]

Here are all the differences that I know of in the two receivers

Tone and filter circuits, Identical on 8080/8080DB and 9090/9090DB, the 9090/9090DB versions have crossover selection switches on the tone board that the 8080/8080DB series do not have.

Dolby circuit only on the 8080/9090DB

Speaker selection 8080/9090 places the speakers in Parallel in A+B and A+C, the 8080/9090DB places them in series.

Tuner the 9090 has a noise canceller/multipath circuit incorporated in the tuner. the 8080 and 8080/9090DB receivers do not.

The 8080/9090 tuner lights are on only when the tuner is selected the 8080/9090DB they are on all the time. (Note the 8080/9090 can be modified to do this)

The 8080/9090 has one phono input, the 8080/9090DB has two.

The Amp section on the 8080/9090DBs is more robust, using a standard NPN/PNP complementary Push/pull amplifier. The 8080/9090 use a quasi complementary NPN only amplifier

The power supply on the 8080/9090DB is larger and has a much higher current capability. The filter caps on the 8080/9090 are 6700UF on the 8080/9090DB they are 12000UF.

The 8080/9090DB have two pre-out jacks, the 8080/9090 only one.

can the non-db 9090 be modifed to use the larger 12000UF caps?

 

[sleepyweasel]

can the non-db 9090 be modifed to use the larger 12000UF caps?

Why? When recapping it is ok to go slightly larger on filter caps. Most say 10%(IIRC) is ok....not sure about going that much larger though. also it ait going to make it "more powerful"

 

[sKiZo]

So, how about a sticky listing the current stickies?

CLICK for a list of current stickies

You go from many to one at the top of each forum area.

Probably wouldn't be a bad idea to explain what a sticky is inside the sticky of stickies ...

 

[LBPete]

Why stop at 12,000uf? The rectifiers will handle 15k with no problem. The 10% rule is more for routine substitution when the original value isn't available.

- Pete

 

[CDFixer]

When I Recap 8080/9090 I routinely install 15000uf 80volt caps without any problems. If you are concerned about inrush, install an inrush surge suppressor. They are cheap and easy to build. You need a couple of caps, resistors and a relay.

 

[DCinDC]

A Sticky subforum with all the stickies in it, is a slick solution.

 

[avionic]

Difference between a 9090DB and a 9090--to much DB. I hate working on those boards.