ADR Compex Problem

[Preslav]

I was working on something. The compressor was working fine and all of a sudden it died. Basically it gets power ...lights up...etc. However, the only sound coming through it is a high pitched buzz...it's not my cabling because I tested it with several different ones and an independent sound source. Also, the light for the limiter does not light up...only the light for the expander. Is it possible only the limiter section died?

Any help would be much appreciated.

[triez]

Unless you are a tech there is no point going inside that unit. If you have some skills, check the plus & minus supply rails first, if they are OK, then you are probably looking for a bad electrolytic cap or a failed transistor.

[Preslav]

Does anyone have manuals/schematix for these units?

[Hiwatt]

Does anyone know if the compressor circuit in the compex and the vocal stressor are the same?

[Preslav]

I seem to recall that they are but would be nice for someone to confirm it.


p.

[triez]

The compressor in the Vocal Stresser is an F760X Compex-limiter, coupled with an E900 sweep equaliser. I actually put up scans of the service notes, calibration procedure and schematics onto the web at a friend's site about 6 months ago, but I have completely forgotten the URL, so all the info is sitting on the net, I just can't remember where...

I have the service and owners manual right here, so if you have any questions let me know and I will try and steer you in the right direction.

[Preslav]

well the first question is do you think you can send me a scan of the schematic/service manual whichever you have. if it's a problem I'll try to explain the issue with the unit:

basically when it stopped working it seemed that it was not getting any input into the compressor circuit, so consequently nothing was coming out.

I thought it may be a capacitor issue so I tested the ESR on pretty much every cap in the unit - on all the cards + the power supply. Some of them test a little high but nothing excessive. So I don't know what to do from now on. I haven't tested any of the resistors/pots so I think that might be next...any ideas /suggestions?


preslav.

[triez]

Thre are 3 boards in the compressor section, A, B, & C.

A is the compressor sidechain, CV mixer invering amp and FET bias control.

B is the line amp, variloss amp and the peak limiter sidechain and indicator.

C is the expander/gate sidechain and indicator.

The C board will tolerate being hot plugged to access the other boards. Do not try and hot pug the A & B boards.

I suggest checking out the line amp first on the B board. The service manual does not provide any parts map for the PCB's so you will have to trace them yourself.

http://moonpony.net/images/Compressor_board_B.pdf

http://moonpony.net/images/Compressor_board_A.pdf

http://moonpony.net/images/Compressor_board_C.pdf

[Tim Farrant]

Do you have the optional I/O transformers installed in your unit? If not, beware that it will be unbalanced and maybe wired pin 3 HOT, as was the factory standard at the time. The Compex only has a +24V rail, no negative supply. Also, the limit and expander lights are bulbs which blow quite frequently, I usually replace these with leds.

I have hand written alignment instructions from the factory for the Compex, I will try and make the best copy I can from them and post them here shortly.

Cheers
Tim.

[Tim Farrant]

Here are the alignment instructions as promised, the files are quite large as they are hand written and I wanted to make sure you can read them...

http://www.buzzaudio.com/stuff/pdfs/...alignment1.pdf

http://www.buzzaudio.com/stuff/pdfs/...alignment2.pdf

http://www.buzzaudio.com/stuff/pdfs/...alignment3.pdf

http://www.buzzaudio.com/stuff/pdfs/...alignment4.pdf

and the block diagram which may be useful in seeing how the controls connect to the boards in the pdfs supplied by triez

http://www.buzzaudio.com/stuff/pdfs/compexblockdia.pdf

Good luck
Tim

[triez]

Tim, you are a marvel. The alignment procedure in the service manual is poor to say the least, and I really want to replace all the trimpots in my unit, but have not due to the sad ass cal. procedure in the book. Big thanks to you!

[Preslav]

Tim & Triez thank you very much for the posts. This will help a million.

Triez can you please make sure the PDF for board B works again. I have been having problems downloading it. A&C work fine. Thanks again.




NEVERMIND. IT WORKED. MUCH APPRECIATED


Preslav

[Tim Farrant]

No problem, those instructions were used in the factory to align the Compex, I had them sent out from the UK 20 years ago, (or was it longer?), anyhow, the ADR people were very helpful at the time. I've been using them to align Compex's and the procedure always works.

Cheers
Tim.

[Arny]

Originally Posted by Hiwatt

Does anyone know if the compressor circuit in the compex and the vocal stressor are the same?

Dear Hiwatt,
Yes the Limiter/ Compressor are the same except you have internal wiring between the E900 Sweep EQ and the F760, and that is what makes it a Vocal Stressor due to side chain facilities, i.e. the F760 can become a De-Essor as well as the many other tools that this pair open up for the Enginneer. but of course it is mono.
A 2U Steroe Rack version of the F760X-RS and a 2U Stereo Rack version of the E900-RS with a few mods + adding a pair of Transdynamics you then have a great mastering tool (Believe me).

Best Regards,

Tony.
Tony Arnold (Director)
Home

[Arny]

Originally Posted by Preslav

I was working on something. The compressor was working fine and all of a sudden it died. Basically it gets power ...lights up...etc. However, the only sound coming through it is a high pitched buzz...it's not my cabling because I tested it with several different ones and an independent sound source. Also, the light for the limiter does not light up...only the light for the expander. Is it possible only the limiter section died?

Any help would be much appreciated.

Dear Preslav,
Did you get sorted, I know its late but only just came across your problem, and I am sure we can help.

By the way ADR are still making gear, and I do recomend their DMA-2, it has recieved some nice reviews
DMA-2

for one review
Audio & Design DMA2

and
Q. What's the best way to get audio into my portable recorder?

Best Regards,

Tony.
Tony Arnold (Director)
Home

[MatthewleBlom]

Originally Posted by Tim Farrant

Here are the alignment instructions as promised, the files are quite large as they are hand written and I wanted to make sure you can read them...

http://www.buzzaudio.com/stuff/pdfs/...alignment1.pdf

http://www.buzzaudio.com/stuff/pdfs/...alignment2.pdf

http://www.buzzaudio.com/stuff/pdfs/...alignment3.pdf

http://www.buzzaudio.com/stuff/pdfs/...alignment4.pdf

and the block diagram which may be useful in seeing how the controls connect to the boards in the pdfs supplied by triez

http://www.buzzaudio.com/stuff/pdfs/compexblockdia.pdf

Good luck
Tim

Are these files still available somewhere?
I would be glad to have them sonce I've plans to buy an F760X-RS


Regards,



Matthew

[brianroth]

Dear Tim,

While I have some files with hand-written alignment procedures from A+D, I was curious to add your info into my files. However, the links you posted do not work.

Best,

Bri

PS, it is GREAT to be back in my own home again. Oklahoma had a record-breaking blizzard Christmas Eve, leaving my area without AC mains. Between attempting to "do Christmas" with my extended family and many other things related, I am now very far behind....

Originally Posted by Tim Farrant

Here are the alignment instructions as promised, the files are quite large as they are hand written and I wanted to make sure you can read them...

http://www.buzzaudio.com/stuff/pdfs/...alignment1.pdf

http://www.buzzaudio.com/stuff/pdfs/...alignment2.pdf

http://www.buzzaudio.com/stuff/pdfs/...alignment3.pdf

http://www.buzzaudio.com/stuff/pdfs/...alignment4.pdf

and the block diagram which may be useful in seeing how the controls connect to the boards in the pdfs supplied by triez

http://www.buzzaudio.com/stuff/pdfs/compexblockdia.pdf

Good luck
Tim