Hello,
I have a problem with my Technics SU-V2A This is about the phono preamplifier. Technics uses an IC (SVITA7322P) as phono preamplifier in this amp. One of these ICs is defective in my unit.. The signal comes in at the functional channel at pin 2 into the IC and out at pin 7. At the defective IC only a DC voltage of about 0.7V can be measured at the output.
I would like to replace the IC, and maybe even improve the quality. I found a TA7322P on the internet, which seems to be the same, but I'm afraid to get a fake IC here.
Do you think it would make sense to remove the entire phono input circuitry in its original form and design and install a separate module, for example based on the RIAA preamp here (ESP Google Search Does anybody know an alternative source for this chip where I can be sure not to get a fake IC?
The service manual can be found here (Technics SU-V2A Stereo Integrated DC Amplifier Manual | HiFi Engine), the phono circuitry can be found on Page 13 and 14. I've attached these pages to the post.
Thanks in advance
Lukas
I have a problem with my Technics SU-V2A This is about the phono preamplifier. Technics uses an IC (SVITA7322P) as phono preamplifier in this amp. One of these ICs is defective in my unit.. The signal comes in at the functional channel at pin 2 into the IC and out at pin 7. At the defective IC only a DC voltage of about 0.7V can be measured at the output.
I would like to replace the IC, and maybe even improve the quality. I found a TA7322P on the internet, which seems to be the same, but I'm afraid to get a fake IC here.
Do you think it would make sense to remove the entire phono input circuitry in its original form and design and install a separate module, for example based on the RIAA preamp here (ESP Google Search Does anybody know an alternative source for this chip where I can be sure not to get a fake IC?
The service manual can be found here (Technics SU-V2A Stereo Integrated DC Amplifier Manual | HiFi Engine), the phono circuitry can be found on Page 13 and 14. I've attached these pages to the post.
Thanks in advance
Lukas
Attachments
although the originalIC takes up to +_30v dc soit has virtually no replacement , you're lucky because the supply rails are +18v and -15v so almost anyop-amp will do.Try ne5532,njm2114, njm2043 or opa1642, opa1652...they will certainly work there.just follow the +, - inputs, output and supply rails Vcc and Vee to .In that original capsule...not so many op-amps will do.Find an adapter for those pins or just build one.
I'll give this a try, I've got a few 5532s and some 4558s laying around. Sadly, they are rated for just +-15V, so i'll put a 3V or 5V Zener into the VCC rails, so the IC isn't running at its limit.
The Bias and Phase Compensation Pins would be left unconnected?
The Bias and Phase Compensation Pins would be left unconnected?
ne5532 is rated +-22v and is lower noise.It works without a problem.NJM4558 is not good for phono.
yes.The Bias and Phase Compensation Pins would be left unconnected?
NJM4580 is used nowadays widely including phono sections.NJM4558 is not good for phono
Many amps from the 70s era used the TA7136P for the phono section.
My Pioneer SA-606 uses it and I like the sound. It's a dual channel chip.
Look here, an adapter for 10 bucks.
DIY: QTY 2: TOSHIBA TA7322p ADAPTER PCB, UPGRADE THAT OBSOLETE OPAMP! | eBay
I'll put a 5532 in tomorrow, but I don't want to spend 10 Dollars on a thing, I can make out of a 5 ct header and a piece of perfboard 🙂
Hi,
Suggestion it is to read the pin 7 resistance with no power and compare it with the second TA7136P pin seven. By checking the resistance you will know if something it is loading down the pin 7 output voltage to ground.
Suggestion it is to read the pin 7 resistance with no power and compare it with the second TA7136P pin seven. By checking the resistance you will know if something it is loading down the pin 7 output voltage to ground.
Hello,
I have a problem with my Technics SU-V2A This is about the phono preamplifier. Technics uses an IC (SVITA7322P) as phono preamplifier in this amp. One of these ICs is defective in my unit.. The signal comes in at the functional channel at pin 2 into the IC and out at pin 7. At the defective IC only a DC voltage of about 0.7V can be measured at the output.
I would like to replace the IC, and maybe even improve the quality. I found a TA7322P on the internet, which seems to be the same, but I'm afraid to get a fake IC here.
Do you think it would make sense to remove the entire phono input circuitry in its original form and design and install a separate module, for example based on the RIAA preamp here (ESP Google Search Does anybody know an alternative source for this chip where I can be sure not to get a fake IC?
The service manual can be found here (Technics SU-V2A Stereo Integrated DC Amplifier Manual | HiFi Engine), the phono circuitry can be found on Page 13 and 14. I've attached these pages to the post.
Thanks in advance
Lukas
In both cases pin 2 connects to ground via resistors of value 82k (or is that so with the problem IC?). In equipment this old, solder can go cold. Faults from this cause are the repair man's bread and butter. Properly made solder joints have a shiny finish - to be thorough one would remove the solder from the IC pins and other components connecting to this as necessary and re-solder them.
The solder joints are alright. Swapping the ICs of the two channels moves the problem to the other channel, so the IC is clearly faulty. I'll try the 5532 next.
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