I have a BX20 that I think is going a little wrong. It seems like on channel 1 some of the dry signal is leaking across to the output, making the output much higher than channel 2, which is only reverb signal. The fault is somewhere in the wiring or the tank because I swapped the two cards over and the problem stayed on channel one.

Has anyone encountered this before, or does anyone have a schematic so that I can figure out exactly where in the chain this is happening?

Thanks,

Daniel.

Somewhat improbably, I've actually managed to download a complete service manual from the AKG website, so I don't need that anymore, but advice would still be appreciated...

Ok, progress:

One of the spring end coils was open circuit (the lower end on channel one.) I dutifully ordered a new spring end from AKG (£OUCH!) and installed it (GRRRRRRRR, six more irritating hours I have never spent) and the sound is better but the echo is still there. I suspect that the coil requires more precise alignment than I am able to acheive without specialised, or at least plastic tools.

Does anyone know of a service person in the UK with extensive experience with these units? I'm only interested in finding someone who has worked on one before, preferably multiple times, because I'm fairly confident that average-repair-man will fair no better than I have and I don't really care to spend a lot of money on not making things any better...

Until then, it can just be mono.

Any ideas? Anyone?

tarandfeathers wrote:Any ideas? Anyone?

Hi, I have a BX20e and have a similar problem with channel 1 - there is about 10db more volume pumping out of channel 1 than 2. It was suggested that I get it recapped when I got it, but haven't had the time/money/manpower that I need to get the project on the go. Have you tried to recap the box that you have? Any luck?

I'm not sure if it's my imagination but the problem seems to be intermittent (but won't completely go away on a good day).

I hope it's an electrical fix, the number of techs that no these units and their springy innards are getting scarce.

oh yeah, I forgot to mention that there is also a distinct echo - kind of an uncontrollable pre-reverb that happens on channel 1 as well.

Hi, yeah, that sounds like the same problem. I've not tried re-capping it since the problem stays on channel one even if I swap the channel cards over. I might get a parts list together and try recapping it just in case. Where did you get yours from? Mine's ex BBC so I kind of wondered if they might have done some kind of modification to make one channel wet signal only and the other one a mixture of dry and wet in case it needed to be used as an insert. Total guesswork though...

Cheers,
Daniel.

Hmm, that sounds like it could be an interesting mod - and probably something the BBC would do - does yours have the original control unit? Has that been modded?

Mine is a well used box from Vancouver, it's been kicking around here from one studio to another for the past 30 years. From being moved several times it might have spring issues, but it still sounds great. HUGE. ...apart from the problem I'm having with it of course.

I have heard that the foam padding in the spring tree could cause the most issues, have you had to replace any of this?

On the topic of the control unit, if you have the original (or not, it doesn't really matter) is there a chance you could post a close up photo of the face plate. I don't have mine, I'm designing and ordering a custom rack face for the control and want to get the dial just right.

Thanks

I do have the control unit. When I get home next week I'll see if I can sort you out a photo.

The foam in mine is pretty badly gone, a crumbly sticky mess. It seems to still perform its desired function if it's not totally squished though and I've not yet found suitable long bits of thin foam to replace them yet. Let me know if you have any ideas about that...