No Sound from Monitor Out Right Channel

[MartyAckerman]

I'm still working through my 6000E that arrived in less than optimal shape.  Currently I have no output from the right channel monitors. I've done some looking into it, but still no fix.  Here's what I'm experiencing:

• A, B, and C buses all the same result
• "External to Monitors" works in both channels with "Cue Stereo" selected
• Pressing "Mono" or "Mono L" works in both speakers, but "Mono R" results in silence from both speakers
• Patching from the 8 track "ST Record" outputs to the monitor inputs, "Mon LS", works in both speakers. I can use the Bus Comp and main VCA fader, but have no monitor pot control(next to the VCA fader)
• Patching from "Programme" or from the A bus inserts to "Mon LS" I get both speakers, but the right channel is down about 8db from left. No control via main VCA fader, monitor knob, or bus compressor
• Patching from the Monitor inserts to "Mon LS" gets signal on both speakers, but not bus comp, no main VCA, and no monitor knob control
• Using "Mini" switches monitors as expected, but still no signal in the right channel

I've noticed that there is no right channel any time I have control of the volume with the monitor knob. I realize I should have a clearer picture of what is in/out of each patch situation, but the fact that I'm looking at 4k manuals and the patchbay is different here for a 6k, plus the 688v section has my head swimming.

I've also replaced a few components I found to be faulty or was just looking at sideways:
CF82E31 (Cues 1-4 Patch Return, Matrix External QB & TB Input): replaced R108 and leaked caps c15 and c16. Replaced burnt out R33
CF82E162(programme and monitor mix inserts and routing): replaced T1, T2, T4, T8, T12, T16, T17   with NE5534AP
Which brings up another question - is it OK to replace the 5534 chips in these with the newer 5534AP chips that re now available? Looking at the datasheet, it seems the main differences are that the AP chips have higher voltage and temperature tolerance I believe?

I suspect that the lower output from the right channel of the programme bus may just be an issue of needing to be recapped and unrelated to the fact that there is no audio whatsoever getting out to the speakers, but I'm unsure of that as well.

Any guidance you all could give here would really be appreciated. Thank you!

[horizonsound]

Hi Marty,

From the sounds of it, by your comment on leaking caps, the console was not refurbished.
If you're experiencing leaking caps, then I would undertake a full recap of the centre section so that issue can be ruled out.

Would you be able to post some photos to show the condition of the cards, and the console overall?

Anthony.

[horizonsound]

The other thing to look out for is the RF Cut Bus.
It's path comes from the RF monitor cut switch, through to the E24 card. A BC212 transistor then drives the J112 FET on the same board.
I've had plenty of BC212 and J112 fail over time.

Anthony.

[MartyAckerman]

I also talked to someone via phone and they suggested removing every card from the center section and re-seating it, plus swapping the two 26 main VCA cards. While doing that I took a pic of each card and uploaded it to a photo album here:
https://photos.app.goo.gl/DNyFdHr1y9vDQMJi8

Funnily enough, when I opened the bottom panel under the center section, a check fell out from my broker to the tech company they hired to work on the board. So I have proof they at least paid for something to be done haha.

So I reseated the boards and ended up with no audio at all. I sulked for a while, then re-reseated and now I've got audio in both speakers but my issue from the other thread - unable to switch global status is back.

I think the obvious truth here is that I've got an old, dirty board that really needs to be recapped and was not totally refurbished. I believe there's a bill of materials for recapping on the dropbox. I'll refer to that and make an order.  I really hate to waste everyone's time with ghost issues that I could deal with by performing the proper maintenance.

[nycsudio1]

I had a similar problem with my console once, where I would lose the left channel and only got signal when I tilted the 26 card. It turned out that the socket had cold solder joints. Perhaps you should move the 26 cards a little while the console is on to see if the signal comes back or cuts off.

[amillar]

Which brings up another question - is it OK to replace the 5534 chips in these with the newer 5534AP chips that re now available? Looking at the datasheet, it seems the main differences are that the AP chips have higher voltage and temperature tolerance I believe?

Hi Marty,

The "A" in the AP means they are selected for low noise (AFAIK identical chips, they just select the low noise ones). We'd have used "A"s everywhere when we built the desks if we could have afforded it! As it was we only fitted them IIRC in the mic amps. The "P" is just Texas Instruments label for plastic DIP package i.e. exactly the the same as the "N"s we fitted as new - just a different label.

So if you can afford APs rather than Ps go for it!

Good advice from Anthony on your main problem, let us know how you get on, if I get a chance I'll dig out my 6k manual and see if I can think of any other things to try.

Cheers,

Andy

[Chris Simon]

If the problems go away and re-surface with card re-seating, the main culprit is the cleanliness of the fingers on the card edge and their mating socket. While recapping may be in order, I still find the master section will lock up in some weird mode about one time in four after rebooting.

[MartyAckerman]

Good to know I'm not the only one with a console that locks into a mode. And the 5534 chip info is great to know, that puts my mind at ease as I replace these!  I'm going to clean up all of the cards and recap the center section before I start targeting more specific issues for now.

One thing I did notice was this modified CF82B22 card. Does anyone know what's going on here? It appears that T3 was removed along with some transistors. There are also some components re-routed. A 4k-like mod maybe? I wonder if this is related to the issues I'm having.

CF82B22 photos: https://photos.app.goo.gl/tBbZLNwCpxVRK9Y68

[horizonsound]

Hi Marty,

As I understand it, there were some optional mods on the E22 card for Quad to Studio, for the Japanese market. My 651E was ex-Japan and has the switches wired for it, but the E22 card in the centre section was a standard, and has these components removed.
It's not something I use, and will eventually revert it back to stock configuration.

Anthony.