Looking for parts for a D&R 4000

[Logan]

Any D&R 4000 users? Anyone with a master channel and some channel strips to sell? Take care Logan

[Matt Syson]

Hi
Most if not all parts are easily sourced, your terch should be able to sort that out.
Matt S

[Logan]

Originally Posted by Matt Syson

Hi
Most if not all parts are easily sourced, your terch should be able to sort that out.
Matt S

Well I've been trying to find a source for awhile now and searches don't turn up anything useful. Do you know where there are channel strips available? Is Terch meant to be tech? If so the guy I use, because I'm a total twit about electronics, has never even heard of D&R and is in a small town really out of the loop. He did manage to get the power supply running again, after I managed to screw it up, but he has no source of stuff like channel strips.

I've got a huge hum still that I have no idea how to trace and have no meters on the master channel. I have 24 channels passing signal and sound coming out the master but no meters on the master and no meters on a couple of channels.

I have another eight channels that still need to be hooked up but something there is blowing the fuse on the -18 side of the power supply.

I read your thread with the guy who was restoring the same board over at the ACF and wish I had even his skill level of dealing with such stuff. If I wasn't outside of a small rural town in Canada I'd bring it to you. So if you have advice or tips on where to find parts I'd really appreciate any help I can get. Take care Logan

[Matt Syson]

Hi Logan
I don't think that having a few 'spare' modules will help that much as you seem to have a variety of problems which are likely to be distributed between several modules and may include the chassis wiring.
I believe practically all the components for these desks are readily available, (Mouser, Digikey etc.) with no special ICS or whatever, so fixing the whole thing is not impossible.
You really need 'the doctor' to call and sort it all out at one hit as for example the hum and power rail issues are likely to be related to your setup.
Shipping the whole desk and supply is one option! but may still miss hum problems which could well be your room, wiring or other factors.
I feel you could probably replace all the channel strips and could still have a hum issue and if the 'failure' of meters is actually frame wiring related, these may not be resolved either.
From my travelling to look at desks over the years probably around 10 - 20 percent of 'desk' problems are not actually problems within the desk.
Good luck
Matt S

[Logan]

It's not the room, it's definitely the desk, eliminating it eliminates the hum and it was hooked up before I started to clean it and although there was noise from 3 years of storage, which cleaning pretty much dealt with, there was no hum. Unfortunately the desk had been altered, I think, because the power was introduced through a chunk of ribbon soldered to the master channel pins. I dislodged it during cleaning and fixed it and dislodged it again, this time I left a small blob of solder which shorted two pins and fried the power supply. The power supply is fixed but eight channels are still not hooked up, something there shorts the -18 side. And the hum is who knows where.

Yah I got to get someone here but it is almost impossible and taking the desk to someone else involves renting a truck and the costs spiral out of control. I hoped a different master buss might eliminate the hum, just a gut feeling, although I have nothing to go on to justify that, clutching at straws really. Trying to get up and running as I have guys coming for a writing recording session in the near future. Take care, Logan

[Matt Syson]

Hi
A module on it's own CANNOT hum, there will be a source of hum being fed into it.
The main routes would be hum or 'ripple' on what should be a clean DC power going into it, Hum arriving on inappropriate ground or signal wires, or hum which is 'received' from the location, meaning it is picking up magnetic hum field from a power transformer much the same way as a guitar pickup 'receives' hum from it's surrounding magnetic fields.
Simply swapping a particular module will not 'solve' any of these mechanisms.
Has the tech who looked at the power supply REALLY tested it under full load conditions and ensured that there is (practically) NO ripple coming out of it? A typical level would be about 1 or 2 millivolts maximum.
Having the supply connections on the module 'altered' COULD be introducing a loop or if it had been modified 'correctly' your repairs since may have introduced a new loop.
Matt S

[Logan]

Well that's good to know. I just assumed something else was blown on other modules with was producing the hum. The tech who rebuilt the power supply just got it going there were some op amps burnt and other bits that I have no idea about. Maybe a transformer, what ever is in the middle of the heat exchangers on the back of the power supply, see I have no clue, I can do other things but have zero knowledge of electronics ;-). Anyway I thought maybe other op amps along the way might be screwed and causing the hum.
But as far as having it under full load, I'm not sure what that even means but it wasn't hooked up to anything so I kind of doubt it.
I'll have to find someone to come here or just scrap this beast as being something I don't have the resources to deal with. Ripple to me is cheap wine lol but if it's something I can put a meter on somewhere and check if you could give me a clue as how to do that, I'd try it and maybe I'd just have to take the power supply some where again. Fancy a vacation in Canada? I've got 160 acres of swamp you could drive shit through ;-) Unfortunately the fastest thing I have is a 4WD tractor. Take care, Logan

[Sean Sullivan]

D&R is still in business and you can get schematics from them.

I've done some tech work on an Orion and I think the only part that is no longer being produced is the op-amp that drives the meters. I think the studio owner bought the remaining stock that D&R had. I'm sure there is a replacement part out there that would work, though.

Besides that, it's just 5534's and TL072's and electrolytic and film caps. All stuff readily available from Digikey or Mouser.

[Logan]

Originally Posted by Sean Sullivan

D&R is still in business and you can get schematics from them.

I've done some tech work on an Orion and I think the only part that is no longer being produced is the op-amp that drives the meters. I think the studio owner bought the remaining stock that D&R had. I'm sure there is a replacement part out there that would work, though.

Besides that, it's just 5534's and TL072's and electrolytic and film caps. All stuff readily available from Digikey or Mouser.

Thanks, but I have the schematics but they sort of look like Picassos to me. The tech who rebuilt the power supply said that the one provided in the service manual was not that useful in working on it that it really didn't look much like what the power supply really was. Anyway I was looking for channel strips add a master channel strip apparently wrongly thinking that subbing those out might solve problem, because I don't have the ability to really trouble shoot it and start changing out parts on the circuit boards. I'll have to try and get some one here who is competent to look at it. Take care, Logan

[Ike Zimbel]

Hi Logan,
So you shorted the main power leads from the supply, took out the supply, had it fixed, and now eight channels still don't work and cause the rest of the desk to hum?
Where are the eight channels in relation to the master section?
Best,
Ike

[Logan]

Well that's changed a little now. Originally I shorted the power supply (PS) and had it repaired. When I brought it back I hooked it up and it blew the fuse on the -18 volt side. Blew up a few more just to confirm that it was really a problem/ I then disconnected every channel from the middle ribbon which carries the power and then turned on the PS with just the ribbon attached in case there was some kind of short in the ribbon itself, no blown fuse. Reconnected the master section still OK. Reconnected all 24 channels to the left of the master section, still OK.
This board has been altered and there is no patch bay and it has 32 channels altogether 24 to the left of the master and 8 to the right, with 6 blanks to fill out the frame.
The hum remained constant through all connecting of the master and first 24 channels.
I stopped there, assuming that whatever was shorting the board was in the final 8 channels. However I hooked then all up today and the PS did not blow any fuses. There is still a hum though. I had no meters in the master section and the light, on the master section, which indicates PFL/AFL when one of those options is selected, on any channel, was dimly lit even though no P or AFL was selected, it would turn bright, as it should, when when one of those switches was pushed. Then that light stopped shinning dimly and now works as it should. Further fiddling with the connections of the ribbons to the channels brought back my master channel meters and the other meters on 3 or 4 channels which didn't have meters, however they are intermittent and you need to push the ribbon at the place it connects to the channel to get them to work. I'm going to re-clean all the pins on the channels and sockets on the ribbon to see if I can get the meters on the channels that are dodgy to work consistently. But I still need to trace down the hum. Not really sure how to do that. I guess the next thing is to test the power supply as Matt suggested under load to see if there is ripple, still trying to figure that out. Take care, Logan