CurtPalme.com Home Theater Forum

[gjaky]

I have been collecting old Marquee 8000/9000 VIMs for years,those also used the desired AD834 500MHz multipliers, to be honest this was the very reason why I wanted them as well.
The general advice regarding old Marquee boards were the „stay away from those” but I never really cared about these voices.
Anyway I preserved one working M9000 VIM, the latest one I had: made in May 1995, which was quite new for a 9000.
Performance wise this board was not standing out from other Marquee boards, even compared to the newer but less potent -02p VIMs, it was no worse no better.This is no surprise either since it is known for long time that the real bottleneck on the VIM was always the SD5401 analog switches. One day I was bored and had an idea: to substitute the SD5401 switch at the lowest possible cost while retaining the functionality of the original VIM. The SD5401 contains 4 switches of which only one is in the signal path. So I had the idea to bypass that switch with something else. I had a few SN74LVC1G3157 switch laying around: they have ~340MHz bandwidth and cost about 0.2USD while they are in small SOT23-6 package or even smaller packages. I removed the SD5401 switches and cut the legs 11, 13, 14 (in reality this may not be important at all, but I wanted to be pedantic) and put back in, and installed the new switches with just flying wires. Man, soldering was PITA!
The thing is the modification worked, the bandwidth became significantly better than before. The original opamps were HFA1100s, I changed them to CLC449 but I haven't noticed any obvious difference for the first sight.
The card is holding bandwidth up to 1080P 72Hz very well, but above that it somehow falls apart: red holds nice bandwidth (through some phantom peaking effect?), but green and blue rolls off, so there is a red tint on the very high bandwidth material, but again at 1080P 72Hz it works quite well and balanced for what it is. All this from a board that was basically sentenced to recycler or landfill, and for parts cost less than 1 USD.

[Tim in Phoenix]

Too much spare time stuck at home eh? LOL

[gjaky]

Well I started this project in March 2019, but then only modified one channel, to see if it is working at all, upon seeing it was working I happily put the board aside. I was finishing the whole board just a few days ago.
I have two sons: a 5 months old and a 3 years old, a (new to us) house that needs constant renovation, and we didn't even stop working here yet, in fact I have a lot of work, so I don't think I have too much spare time This was just something I wanted to finish.

[nidi]

how much better , bandwidth wise, would you say your latest VIM-DB are compared to this 'el cheapo' mod?

[gjaky]

[Tim in Phoenix]

Mr Gjaky Sir

I have enormous respect for your engineering skills but........who effing cares about modding ancient boards that no one can find? Sir?

[gjaky]