Mackie CR1604VLZ - dead channels - any common problems

[bruce]

Currently looking at a Mackie CR1604VLZ, which has 4 dead channels, and one with significantly less gain than others.

Not consecutive - channels 8/11/12/13

Diagnostics so far has been to stick a tone source into each input and see whether I get any output (on busses or PFL), and to twiddle the gain pot to see if it feels smooth. 

 

Any known faults or suggestions? I'm told the ribbon cables are a good starting point... and the channel inserts...

 

 

[DrV]

Channel inserts are easy to check. Get a stereo jack plug and link the tip and ring together. Plug it into the insert jack and it will link the send and return. If that fixes it the issue is with the switched jack and a bit of switch cleaner plus pushing the plug in and out a few times will sort it out.

[bruce]

I'd done the "check the insert" trick - no joy.

But I opened up the back end, realised that the PFL on the "low" channel changed level if I prodded the bunch of ribbon cables. So I fiddled about with them a little reseated a couple of ribbon connectors, cleaned some of the jacks, and touch wood it seems to be all working...for now.

 

[KevinE]

you may be lucky rearranging the cables but the fault is usually the connection between the cable and the IDC portion of the connector that goes intermittent. And that's quite a few pins!  

[DrV]

When I did work for a Mackie repair shop a few years ago we would sometimes do a blanket replacement of all the ribbon cables using much better quality connectors. The originals were 'single wipe' where the connector contact only touches one side of the pin of the header. We used 'double-wipe' connectors which have metal on two sides of the header pins.

Edit: this was on the big digital desks, if it matters.

Edited November 28, 2022 by DrV

[sandall]

No connection with your problems, but I bought a CR1604-VLZ at one of the BBC auctions some years ago & found one of the VU bar-graphs was dead. I'm not confident enough with SMT to try to fix it, & everything else works fine, so I've learnt to live with it.

[bruce]

OK - a couple of further questions. 

First, is it worthwhile trying to release and re-crimp the IDC? Secondly, at the PCB end, does anyone know if it's a plug-and socket arrangement, or is the IDC header straight onto PCB.

Secondly - a couple of crackly gain pots. Replacement would probably be a soul-destroying task 🙂 

Are any of the "magic lubes" - deoxit etc - likely to help. I've had experience on another mixer where a squirt of regular switch cleaner made things a but better, but obviously removed the lube, as the pot felt very loose afterwards.

 

To be honest, the unit is probably beyond economic repair, but it's a hobby(*) project and I'm not costing my time.

 

(*) Actually, it's a procrastination project - something that I "need to do" when something more urgent, but tedious, comes up...

[DrV]

41 minutes ago, bruce said:

To be honest, the unit is probably beyond economic repair, but it's a hobby(*) project and I'm not costing my time.

 

(*) Actually, it's a procrastination project - something that I "need to do" when something more urgent, but tedious, comes up...

Oh, if I had a pound for every one of those(*) cluttering up my workshop then I wouldn't need to do economically viable repairs 🙄

[sunray]

35 minutes ago, DrV said:

Oh, if I had a pound for every one of those(*) cluttering up my workshop then I wouldn't need to do economically viable repairs 🙄

That reminds me... I really must dig out the parts of the powered mixer that have been languishing in the depths and fit the 600VA toroid transformer I rewound at least 5 years ago. Oh and the pair of HH amplifiers and that 200WPC mobile disco amp my son dumped on me even longer ago. Then I'm afraid what others I may find lurking beneath them

 

I really don't know what you mean DrV🤣

Edited November 29, 2022 by sunray

[sleah]

Any how many of use have various bits of broken or faulty kit lying around that's not repairable, can't get parts, not worth the bother, can't be ar5ed with, might get round to one day but we keep 'just in case' because 'you never know'.

"Not guilty your honour." He says, lying through is a55😁

[themadhippy]

32 minutes ago, sleah said:

Any how many of use have various bits of broken or faulty kit lying around that's not repairable, can't get parts, not worth the bother, can't be ar5ed with, might get round to one day but we keep 'just in case' because 'you never know'.

Nope not me, erm dont open that cupboard.

[sunray]

6 hours ago, themadhippy said:

Nope not me, erm dont open that cupboard.

Granny annex

[KevinE]

Quote

, is it worthwhile trying to release and re-crimp the IDC?

they're a 1-shot thing, recrimping might make it worse. ISTR the headers are proper pcb-mounted receptacles with latches. Some Mackies also have cable-mounted receptacles in addition though I dont know if that applies to yours.

If you dont have any luck cleaning your noisy gain pots I might have some on a scrap panel, I think they're probably specials knowing Mackie.