Toshiba RT-9000S - any info/manuals/schematics available?

[jonny]

I'm having some trouble with the preamp section of my Toshiba RT-9000S. It's proving quite tricky to trace a signal through from the phono inputs to the power amp IC input, and to make life easier I'd like to get my hands on a schematic and PCB layout for this boombox.

I've so far failed to find any documentation online, and a hopeful purchase of a manual from Analog Alley for an RT-8700S (a boombox that's outwardly very similar to my 9000S) hasn't proved all that helpful - it turns out that there's quite a lot of difference between the PCBs of the two machines.

Has anyone ever come across any schematics etc specific to the RT-9000S?

 

[jonny]

Quite a few months later but I managed to find a paper manual for the RT-9000S on eBay.

Have taken some photos of the schematic and PCB diagrams and uploaded them here, in case it's any help to others, the full size ones are in the ZIP file attached.

As for my RT-9000S: Turns out that the Hitachi Dolby-B IC in my box is dead, getting power and input signal to it but no output whether Dolby is switched on or off. As an interim measure I've bypassed the IC, which has at least allowed me to test the tape deck (which works, but not well, mech needs further attention) and the tuner (which is fully functional).

 

[Eric]

Johnny what a coincidence the Dolby B left side chip (NE64B) on my National RX-7200 died also. I was having trouble tracing the audio path and used an RX-7000 schematic. I would have never guessed the audio path runs through those chips the entire time (Even if Dolby off). I had audio going in but flat line out. Right side is fine.

Purchased one on Ebay, hopefully its the fix.

 

[jonny]

Yep, I was surprised too! It looks like the Dolby chip (HA11226 in the Toshiba) does some preamplification as well, whether Dolby is enabled or not; with my wired bypass in place, maximum volume doesn't seem terribly high and the VU meter doesn't move much.

The one IC carries both left and right channels, and both were dead before I bypassed it.

I've got a new IC on order from Cricklewood Electronics, just over £11 delivered, hopefully that will restore the box to full output.

Good luck with your 7200, that's a stunning machine!

 

[Eric]

The new IC fixed it. Yes it does look like there is a preamp in these chips. I am sure the person who had it before me was running the box on 120 volts. Some of the chips/circuits were probably stressed.

Good luck on yours jonny

 

[jonny]

Never got round to updating this, I replaced that IC last year, it did the trick and the RT-9000 is sounding good!