9090 or 9090db is one better than the other?

Don't get me wrong. I'm not saying the Dolby board is not an issue. It definitely can be, especially on the earlier production models. What I'm trying to say is it is not the first place to go when you have a channel drop out in one of these receivers. Like any 40+ year old receiver, almost ANY of the switches, relays and pots can cause channel drop and this receiver has a lot of them. In many cases, it just needs to be cleaned, don't jump to the Dolby board.



Absolutely true. The early production units have the green flex pc boards connecting the push switches to the Dolby board. They are very fragile and tear easily when handled. Unfortunately it's hard to get access to the Dolby switch without moving those push switches out of the way.

This discussion has focused on the 9090 and 9090DB. With the excetion of the power supplies and output transistors, it all applies directly to the 8080 and 8080DB.

- Pete

It's been approx a year since i last posted with the Dolby issue with my 9090db.....(which as of yet has not been solved).


Pete how does one distinguish the year date of the improvements to the Dolby board?


Steve
 
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While you bozos were hijacking my thread I was out doin' stuff. JK:D
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It's been approx a year since i last posted with the Dolby issue with my 9090db.....(which as of yet has not been solved). Pete how does one distinguish the year date of the improvements to the Dolby board?

The first improvement is easy to see, the green flex pc board connecting the push switches to the Dolby board were replaced with black ribbon wire. That happened around the time they switched to the yellow zinc plating on the chassis. Somewhere around the end of production they deleted the rivets in the pass thru holes. Don't know when exactly that occurred but my best guess is around the time they stopped shipping multi voltage units to the US.

We have not been tracking these changes in the serial number database but we can. To do so, people with these units need to report which mods their unit has along with the serial number. I can tag this information to newly reported or serial numbers that are already in the database. With enough reports we can narrow it down to the month of production.

Also, sorry about the thread hijack but you opened a can of worms.

- Pete
 
Thx Pete,
I'm not going to take any more of JK's thread, I'll start a fresh thread & supply you with all I can.


Steve
 
Well I just watched BLUEGLOW's youtube video about rebuilding the dolby board. Looks kinda hard but do-able.
My db is smokin' along just fine so I'm not about to fix something that ain't broke yet.
I haven't been able to do a "sound" comparison yet but I'm not worried and I doubt my old ears could tell the difference.
 
The traces on the Dolby board are tiny and lift very easily. You need pretty good soldering skills to service it without damaging it.

- Pete
 
I have my 9090 back from QRX and it sounds huge and lush and detailed.
I'll be dropping off the 9090db this week for the same restoration and dolby bypass.
So it's possible that my comparison won't be fair since I'm told by them that the dolby "colors" the sound somewhat and the dolby bypass eliminates that effect.
I think my original question of which is better has been answered by "J" at QRX. He prefers and uses as his personal rig the 9090db. (bypassed)
BTW: The team at QRX certainly has their customers' satisfaction as their goal. Nice guys too!
 
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I have an 8080DB on the bench as we speak. The right channel is weak and I think I've narrowed it to the Dolby board. Is it the same board as the 9090DB? Is there any component that's notoriously at fault. I've seen a bunch of talk about the ribbon cables but is there anything else?

Thanks
Matt
 
The 8080DB uses the exact same Dolby board as the 9090DB but there are at least three generations of that board so there may be minor differences between what you have and what is shown in that overhaul thread.

- Pete
 
Single voltage units were built exclusively for NZ/AU, GB, which did not have outlets in rear of the unit.
Just reading through this thread, these units were never sold new in New Zealand due to our strict import laws in the 70's and up to 1984. So we missed out on all this great gear....They may have been sold in Australia, but definitely not New Zealand.
Just wanted to clear that up....
 
Just reading through this thread, these units were never sold new in New Zealand due to our strict import laws in the 70's and up to 1984. So we missed out on all this great gear....They may have been sold in Australia, but definitely not New Zealand.
Just wanted to clear that up....
we did miss out on a lot of the good stuff Kev!
 
we did miss out on a lot of the good stuff Kev!
and by the time the law changed, it was all the "plastic fantastic crap".......What about the crappy Technics, Akai, and National Panasonic stuff made here under license!! Just absolute rubbish!!
 
and by the time the law changed, it was all the "plastic fantastic crap".......What about the crappy Technics, Akai, and National Panasonic stuff made here under license!! Just absolute rubbish!!
LOL I made $600.00 on a Technics SA-T670 receivers , it had nothing om my G-4500 at the time.
 
LOL I made $600.00 on a Technics SA-T670 receivers , it had nothing om my G-4500 at the time.
Those Technics were absolute rubbish.....I had a 670, 100 watts pfft..........and they just sounded so awful...very gritty and nasty...
 
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