Dynacord PS2000 schematic

[philly]

Hi All,
A band guy dropped off a dynacord ps2000 desk recently and reported a few problems that he would like sorted. One being no reverb and also a hum on channel 15. So before I get stuck into it I would like a schematic if anyone has one. Please advise if I am looking for trouble taking this job on .
Any advise appreciated.

Philly.

[The Dude]

I just rebuilt an old similar Dynacord MCX24.4.2. I couldn't find a schematic, but they are pretty straightforward mixers. Nothing fancy. Separate cards for each channel, which is something you don't see much any more. You can use the good channels as reference for any bad channels. I went through this one only because it belongs to the company I work for. I wouldn't otherwise have spent much time on an analog mixer. You can't give them away these days.

[philly]

Thanks for getting back to me.
Yes your correct about comparing channels when fault finding. All channel boards are connected with parallel wires soldered across them so I would need to cut these in order to remove the faulty board. You cannot work on the channel boards as they are tightly side by bside. If I want to trace the fault on the board I would need to re-connect it outside the mixer for scope measurements etc. I might just check the 4 or so electrolytic capacitors and replace the few op amp type ic's. Looking in at the channel boards there seems to be little else in there that would cause trouble. The reverb fault is what I needed the schematic for.
Let you know how it goes.

[philly]

Thanks for getting back to me.
Yes your correct about comparing channels when fault finding. All channel boards are connected with parallel wires soldered across them so I would need to cut these in order to remove the faulty board. You cannot work on the channel boards as they are tightly side by bside. If I want to trace the fault on the board I would need to re-connect it outside the mixer for scope measurements etc. I might just check the 4 or so electrolytic capacitors and replace the few op amp type ic's. Looking in at the channel boards there seems to be little else in there that would cause trouble. The reverb fault is what I needed the schematic for.
Let you know how it goes.

Removed channel15 faulty (hum) board and did some cold checks. First two electrolytic caps C1 and C2, 22uf are reading o/c so I decided to check the remaining 6 and see what condition they are in, however the remaining all seem to be non polarity types as there are no marking +/- on them. Here is a pic of one with markings and one without which I removed from the board for testing. Maybe the ones that have no markings are non polarity and are audio coupling etc. I think they are bipolar ????

https://www.dropbox.com/s/67pzs1c2po...05152.jpg?dl=0

[doctor]

Capacitor without marking is non-polar 2.2uF.
Capacitor with marking is polar 22uF.

[philly]

Capacitor without marking is non-polar 2.2uF.
Capacitor with marking is polar 22uF.

Hi Doc,
I thought so. I very rarely come across caps over 1uf that are non polarity as I don't work on audio that much. With this Dynacord and the amount of years on the clock a lot of the caps are a bit on the dodgy side showing high esr values. I bet that any problems with it will be capacitor related.

Thanks.

[doctor]

I will not argue, because the dispute does not produce any results.
Only measurements, knowledge and experience give results.

Find faulty components and replace them.
Pay attention to the voltage of the polar capacitors. This voltage must be
at least 63V, since during operation with capacitive mics, 48V phantom
power will be supplied to these capacitors.

[Helmholtz]

Yes, Roederstein (ROE) EKU series caps are bipolar ecaps.

[philly]

I will not argue, because the dispute does not produce any results.
Only measurements, knowledge and experience give results.

Find faulty components and replace them.
Pay attention to the voltage of the polar capacitors. This voltage must be
at least 63V, since during operation with capacitive mics, 48V phantom
power will be supplied to these capacitors.

Exactly.
Thanks.
Anyone got a schematic as I am from the old school and always worked with a schematic especially if its the first time to see a piece of kit.

[Helmholtz]

https://www.dynacord.com/?language=en

[philly]

https://www.dynacord.com/?language=en

Thanks Helmholtz,
Had a look before at their web site but cannot see any schematic for this old desk.

[Helmholtz]

Thanks Helmholtz,
Had a look before at their web site but cannot see any schematic for this old desk.

I guess you need to email the customer service contact: technical.support@us.bosch.com

[philly]

I guess you need to email the customer service contact: technical.support@us.bosch.com

Good idea,
I will see how it goes.
Thanks again.

[philly]

Good idea,
I will see how it goes.
Thanks again.

Got no feedback from them .

[doctor]

Here is my help during coronavirus:
https://www.dropbox.com/sh/97zkad49b...qUKZ5O94a?dl=0