T560 Riaa Unit damaged out circuit help!!

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T560 Riaa Unit damaged out circuit help!!

Unread postby Filipe Cruz » Wed Jan 18, 2017 8:33 am

Good day people , does anyone know the reference of the controller chip in the Riaa controller unit of t560 of souris machine ? Mine simply stopped working .
And I can't simple ask him the reference , besides we had a fight and we no longer do business together so I can't even send it to him ...
I just need to know this chip reference to replace it .. I live in Brasil and I don't want to deal with souri anymore...the guy even sanded the reference so no one could copy ... so my maintenance technician can't repair it without the reference to replace the chip ... can anyone help ??

20170112_144335.jpg


Cheers and thank you in advance
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Re: T560 Riaa Unit damaged out circuit help!!

Unread postby Gridlock » Wed Jan 18, 2017 10:00 am

Troll fight! I swear to God I'm going to start making memes about you guys that only 75 people will understand. Just get a freaking analog 12+ channel stereo eq and run your line thru both channels.
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Re: T560 Riaa Unit damaged out circuit help!!

Unread postby markrob » Wed Jan 18, 2017 10:59 am

Hi,

It should be easy to determine something that will work. Most 14 pin dip op-amps use the standard pinout for a quad device. As a reference, use the datasheet for an LM348.

http://www.st.com/content/ccc/resource/technical/document/datasheet/50/11/0f/1c/28/6f/4b/ea/CD00000462.pdf/files/CD00000462.pdf/jcr:content/translations/en.CD00000462.pdf

Start with that assumption and trace the PCB to see if that makes sense. On the quad device pin 4 is V+ and 11 is V-. That should be easy to check. Next look at the 4 corner pins 1,7,8 and 14. These are outputs. Another trick is to power the unit up and see if all of the + and - inputs pins (e.g. pins 2 and 3) are at the same voltage. This assumes that the section being tested is functioning correctly and is being used as an amplifier (as it most likely is). You can also check the DC voltage present on the 4 output pins. If a bipolar supply is used (e.g. +/-15 Volts), you would expect all of the outputs to sit at 0 volts. If a single supply is used, then look for 1/2 of the supply voltage.

Once you have some confidence that this is the correct pinout, you can choose from a large array of op-amps that will work in the circuit. If the circuit is powered by a single supply (e.g. +12 Volts), try to sub in devices rated for single supply operation. However, most amps will work in single supply mode with no problem. The TL074 is a very common quad device that would probably work in the circuit if you determine that it is indeed a quad.

The board looks like it was hand etched, so use caution when unsoldering the old part. I would put a good gold plated screw machine 14 pin socket in place to avoid any further need to solder.

Mark
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Re: T560 Riaa Unit damaged out circuit help!!

Unread postby dubcutter89 » Wed Jan 18, 2017 12:37 pm

Agree with Mark, very likely a quad opamp. But check first....

Another thing is that normally those things don't blow up randomly - probably there was or still is a reason for it! Bad PSU? Short Circuit?
Are you sure it is this IC?

Lukas
Wanted: Stylus for Neumann MS52h
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Re: T560 Riaa Unit damaged out circuit help!!

Unread postby SueDenim » Wed Jan 18, 2017 1:09 pm

Hi Filipe,

If you're using a DAW then I'd apply the RIAA curve with an EQ plug-in and avoid having to route your audio path through the VR main unit altogether.
Depends on how your set up is wired of course but it would probably improve your signal too.

Basically, cut some white or pink noise at around -3dB, then put the playback audio through a spectrum analyser plug-in and adjust your EQ to flatten out the cutting head's response.
I'm currently redesigning my VR cutting set up so I'll be doing just this soon :)
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