Realistic 10 bands Equalizer type 31-9081

[rick_noname]

Hi guys, i hope you can help me.

I have a Realistic 10 bands Equalizer type 31-9081.





I have this Equalizer for almost 20 years, but now there where some problems with it. When i put it on, on the first minute in a cold situation it sounds not very well, so i will replace all capacitors with new good one from Panasonic or Nichicon.

Are there people who have any service manual for me.

I will also change the 3 op-amps njm4558D with OPA2134. But the biggest problem is, It sounds noisy when there is no sound. I think the power supply is a little bit weak. Do you have any sugestions for me to make this Equalizer sounds beatiful with a minimum of noise and good components.

Regards Rick...

[rick_noname]

hi guys, nobody

[jaycee]

Do it in stages. The capacitors will most likely want replacement. You may also want to consider cleaning the sliders and switches with contact cleaner.

I would not recommend changing the 4558s for the 2134. The 2134 is a much faster opamp with FET inputs, and will probably oscillate in the circuit. NE5532's would be a good safe bet though.

What are those 16 pin DIP devices on the right?

[MJL21193]

Originally Posted by jaycee

What are those 16 pin DIP devices on the right?

Those look like they may be the M5227P graphic EQ ic. Could be.

[Eva]

Replacing the op amps by JFET ones may reduce noise floor sometimes but not always. RC4558 has the same noise voltage level as OPA2134, the difference is lower noise current, so it will depend on circuit impedances.

What is usually worn out in such an equalizer are the faders. Measuring frequency response with a computer may help.

[event horizon]

Originally Posted by rick_noname

Are there people who have any service manual for me.

Wow, i haven't seen one of those for about 20 years No tone controls in my system nowadays...

If i remember correctly i have the original user manual for that graphic (having owned one) & realistic (tandy) kindly gave a full circuit diagram with their manuals. I'll have a look about, no guarantees as i'm a terrible hoarder & it could be anywhere. It's something i'm not likely to have gotten rid of, but i'll be looking for a needle in a haystack so to speak.

Good luck with the service & i'll do my best in locating the circuit diagram

[rick_noname]

Hi guys, thanks for all so far, The biggest thing with this equalizer is to bring back the noise to a minimum and a better sound. So the first step wil be to replace the op-amps with opa2134.
So even when i recap the whole equalizer is there any guarantee
that it will help to bring the noise back to a minimum level. Also is it a good option to replace resistors with metal films???
They also use a Low Power Quad Operational Amplifier LM324N. Is there a beter replacement for this one?
The graphic equalizer ic`s are a 4X MC14066BCP. Cap`s in the power supply will be 470UF, is it better to replace it with ???? 1000UF.

Sorry for my bad englisch.

Regards Rick...

[jaycee]

Aha - i suspected there would be some 4066's in there ! Try replacing those. They can often get damaged by static from the input sockets (they are very rarely protected by clamp diodes).

Recapping is always a good idea on older equipment. It will definitely help improve sound quality.

The LM324 is probably used for the spectrum analyzer on the front. Don't bother changing it.

If you can fit 1000uF in the main supply, do so. Can you measure what voltages are used ?

[wahab]

no doubt that changing the 4558 for NE5532 will improve a lot
the thing. no possible comparison..the original op amps are just too bad..

[MJL21193]

Originally Posted by wahab

no doubt that changing the 4558 for NE5532 will improve a lot..

I very much doubt that.