I have an old 8000 that I'm revamping for a backup for one of our remote sites. I found several bad electrolitics gone bad and replaced them. Are there any other things I aught to try to change (that are available easily, etc) in this thing before I press it back into service? Thanks!
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Optimod 8000
- Thread starter OKCRadioGuy
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You might shoot billsacks at gmail.com a quick email. He did an 8100a for me,new caps,much much better chips..running it with an Ariane on classic hits .lovely creamy sound.Sounds as good and more musical than the other boxes in the market..He can do an 8000 ,love that rubber band bass....He had a new PS for the 8100 that is unreal.Bill is sharp,Bob Orban & he are long time friends.
Definitely replace the big filter electrolytics in the power supply. If they go bad, you'll have a high-pitched whine under the audio.
Interesting. Thanks for the advice!
There are several mods that can be made to marginally improve the 8000a. Some are approved by Orban and some fall in the catagory of "hot-rodding". Generally, the box is a good performer, especially if gently pre-processed with a multiband unit like the old audio prisms. I have an LPFM client that runs one exactly that way and it mostly sounds excellent. There's only one unapproved modification that I have done to them. Lift one side of R263 & R264 and insert a .047uF cap in series with each resistor and the circuit board. This acts as an additional high-pass filter on the control input of the HF limiter and seems effective in preventing deep bass from punching holes in the highs.
Orban maintains an excellent FTP site where you can download tech manuals and service information for most products including the 8000a. ftp://ftp.orban.com/8000A/
There is also a paper written by Bob about what are good and what are bad 8000a mods at:
www.orban.com/support/orban/techtopics/GoodBad8000.pdf
Generally, the little 8000a doesn't need much. It just works and sounds good as long as you don't overdrive it.
Orban maintains an excellent FTP site where you can download tech manuals and service information for most products including the 8000a. ftp://ftp.orban.com/8000A/
There is also a paper written by Bob about what are good and what are bad 8000a mods at:
www.orban.com/support/orban/techtopics/GoodBad8000.pdf
Generally, the little 8000a doesn't need much. It just works and sounds good as long as you don't overdrive it.
Thanks for the link. Looks like a few chip upgrades before the 30khz filter and trying out your mod might be about the only thing else I need to try. For our station, as a backup especially, it should do the trick. Thanks again!
You probably want to use the 8000 as the final limiter and clipper and 19khz tone, with a multi-band or 2 in front of it. Prisms or CRLs. Recap it. The boards are pretty robust. You can juice those boxes, but an 8100 will be a little friendlier with a modification. I don't recall an 8000 taking an XT chassis either, so you'll probably want the multi-bands in front of the 8000 so it doesn't sound squishy.
A few educational stations I've worked with still have some of these boxes in the rack.
A few educational stations I've worked with still have some of these boxes in the rack.
So far I've just re-capped it. This one seems to sound acceptable enough with new electrolitics in it to be a good backup for our mainly talk station. I may get around to the chip update, but in our case it's probably not that critical. I do have a friend using a 8000 in a small market for his backup stick, so at some point we should consider the chip updates, caps and other things to improve his unit. It'll make more of a difference for him as he's mainly music.
OKCRadioGuy said:
Orban discusses the chip upgrades in some of his papers. Generally, upgrading the chips doesn't add much, if anything that you can hear. The original chips were chosen with care to be as pure as possible and they are. Yes, you can get a db or two better noise floor out of the box, but it's a lot of work for little gain. Generally, recap the power supply and the outputs of the regulator and then give it a listen. I listen for hum, test for frequency response (below the limiter threshold), and do a quick measure of the stereo sep. If it's pretty flat, limits audio, has no hum and the stereo has at lest 40dB of separation, you're good to go as a backup processor.
Ok. I have another challenge. I've let it "burn in" on my bench for the past few days. All was good until yesterday. With the lid on, the unit went into a bizzare mode where lots of "overload" audio light flashes were persistant. The audio had huge peaks on the output. The input wasn't very high on the L or R input. I turned it off, took off the lid, and waited until this morning to try it again. With the lid off where things can run real cool there's no signs of the failure. All is good. I did notice the regulators in the middle of the board get pretty darn hot inside for no holes in the top and bottom plate to let things cool. Is this a common problem? Has anyone modified these units for the failure I experienced to cool the unit better, or is there a chip I should be looking to change out? While the thing was acting wierd yesterday and still good and hot, I did freeze-spray stuff. I couldn't find anything specificially that cleared the problem up.
The regulators have always run pretty warm. Make sure the filter caps on the rectifier stack are good and also that the filter caps on the regulator outputs are good. Bad ripple control makes the regulators work even harder which increases the heat load.
Next, invest $8.00 in a can of freeze spray. You should find the problem pretty quickly with that. Pay some attention to the potted release time module. If that fails, the control voltages on the VCAs goes away and the unit will overmodulate like it's possessed. Several other componants that are serviceable can also have the same effects.
Next, invest $8.00 in a can of freeze spray. You should find the problem pretty quickly with that. Pay some attention to the potted release time module. If that fails, the control voltages on the VCAs goes away and the unit will overmodulate like it's possessed. Several other componants that are serviceable can also have the same effects.
Thanks.
The regulators have always run pretty warm.
Good to know. Mine is probably the norm then.
Make sure the filter caps
on the rectifier stack are good and also that the filter caps on the regulator outputs are good. Bad ripple control makes the regulators work even harder which increases the heat load.
I had bad caps. I
just replaced them. I ESR'ed them before I insalled them. One big cap was oozing bad and two smaller caps by the regulator were actually open.
Next, invest $8.00 in a can of freeze spray. You should find the problem pretty quickly with that.
Tried that. No dice. I was spazzing out and I hit every solid state compenent in there I could get to. No improvement until I unplugged it for the night and let it totally cool down.
Pay some attention to the potted release time module. If that fails, the control voltages on the VCAs goes away and the unit will overmodulate like it's possessed.
That's exactly how it's acting. I wouldn't be supprised that the potted module had some issue when it got warm. I'll run it for a while with no top on it on the bench and see...
Several other componants that are serviceable can also have the same effects.
Good to know. That's for the tips. I almost thought I got away on this one with just a cap change. LOL! It's never that easy I guess.
The regulators have always run pretty warm.
Good to know. Mine is probably the norm then.
Make sure the filter caps
on the rectifier stack are good and also that the filter caps on the regulator outputs are good. Bad ripple control makes the regulators work even harder which increases the heat load.
I had bad caps. I
just replaced them. I ESR'ed them before I insalled them. One big cap was oozing bad and two smaller caps by the regulator were actually open.
Next, invest $8.00 in a can of freeze spray. You should find the problem pretty quickly with that.
Tried that. No dice. I was spazzing out and I hit every solid state compenent in there I could get to. No improvement until I unplugged it for the night and let it totally cool down.
Pay some attention to the potted release time module. If that fails, the control voltages on the VCAs goes away and the unit will overmodulate like it's possessed.
That's exactly how it's acting. I wouldn't be supprised that the potted module had some issue when it got warm. I'll run it for a while with no top on it on the bench and see...
Several other componants that are serviceable can also have the same effects.
Good to know. That's for the tips. I almost thought I got away on this one with just a cap change. LOL! It's never that easy I guess.
As well as the freezer spray try a hairdryer or heat gun, and alternate between the two. 
LA_Guy said:
I have several 8000As on the air at smaller stations. I've never had to replace ALL of the 'lytic caps. I don't think it hurts to replace them all, but every one of the 8000s that I've done only needed the ones related to the power supply. I think I found one 2.2uF cap on one channel of one board that showed a little bit of degradation below 200Hz. I did replace that one, but the rest all passed with flying colors. Not bad for a 35 year old product. Perhaps mine were previously used in a better environment, but the bottom line is that they all sound fantastic, especially with a minimal amount of pre-processing from some audio prisms or even an old CRL SEP800.
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