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Sansui 9090DB Recap and LED mod

hadrian333

hadrian333

Active Member
Just rebuilt a 9090DB and the results are stunning. i upgraded all electrolytic capacitors in the unit to 105 degrees capacitors. The main filter capacitors were upgraded from 12000uf 85 degrees capacitors to 18000uf 105 degrees capacitors. All lamps were converted to LED except the dial scale indicator. After tuning up the unit, the power amplifier delivered a stunning 134.48 watts (32.8V) per channel both channels driven at 20 hz before clipping at 0.0245% distortion! The LED modification required (6) LED fuse lamps and (10) LED bipin lamps from Northridge Electronics with no electrical modifications required. I had to increase the radius of the hole in the VU meters with an Exacto knife to fit the LED's with minimal physical modification. The unit exceeded all published noise specifications all modes of operation. I also ran solid wire through all feed through holes on the Dolby pcb to avoid intermittent problems. I'm very content with the results.
 

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VERY nice.

When Glenn (echowars) finished my own 9090db, the output was a staggering 161 wpc at clipping. The noise went to .03thd. I am having trouble with the VU led's, as they were siliconed in place, and have somehow wiggled out. Gotta get back in there and fix them.

Great work, man. Looks superb.
 
Very Nice ! - I am sure you will get enquiries for more information about the led conversion especially. ;)
 
Yes, hyperion, you are correct. Glenn used a green led for the normal blue on mine, and it is simply stunning, but the VU meters have never been illuminated enough, so I would be very interested to know the ratings, etc, of the led's used here. It looks so damn good, and damn close to original. Superb.
 
onwardjames said:
VERY nice.

When Glenn (echowars) finished my own 9090db, the output was a staggering 161 wpc at clipping. The noise went to .03thd. I am having trouble with the VU led's, as they were siliconed in place, and have somehow wiggled out. Gotta get back in there and fix them.

Great work, man. Looks superb.
Click to expand...

I measured the power at 20hz because the power typically drops off drastically on the lower end of the audio spectrum. At 1000 hz (mid frequency), the unit clips at 155 watts (35.2V) both channel driven into 8 ohm load (Dale 250W/1%). I always try to specify at the worst power rating from 20-20,000hz and the worst distortion spec to be conservative.
 
onwardjames said:
Yes, hyperion, you are correct. Glenn used a green led for the normal blue on mine, and it is simply stunning, but the VU meters have never been illuminated enough, so I would be very interested to know the ratings, etc, of the led's used here. It looks so damn good, and damn close to original. Superb.
Click to expand...

I used ebay item #19064913819 to replace the meter light and the function lights. You need the 6-8V version. No electrical modification necessary.
 

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That's some surgery I'm incapable of doing, but thanks anyway, may be able to convince a friend I have to do it. Looks VERY authentic.

And I re-read your post, and realized you used the 20 hz wave. That makes sense.
 
Never been terribly happy with the LED solution on the 9090db meters, but all the replacement bulbs I had found up to then looked even worse. These are small (about 3mm or so, IIRC) 7V lamps that I had not found anything that looked like the factory originals. An 8V lamp will work, but there's a resistor on each board that was likely changed to limit current for the LED's and will have to be removed and changed to a jumper wire if 8V lamps are to be installed.

This was Glenn's reply, so if I use those from Ebay, I'll have to run down that resistor.

Man, why didn't I take a few electronic classes while in school??:scratch2:
 
Standard hi intensity 3mm LEDs fit into the holes for the VU meters and they provide plenty of illumination. No need to hollow them out unless you are using the larger 5/6mm LEDs. I did mine in blue but have decided to change them to green. I am not a fan of the standard white coloured VU light, but that would be easy enough to do by putting in white 3mm hi intensity LEDs.

On my 9090 I did a voltage conversion from AC to DC to provide LED power, but still retained the AC and some of the original bulbs. This power conversion is reversible if, for whatever reason, I want to return the unit back to pure AC only (for the illumination).
 
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