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How to make Sony SQR-8750 real SQ? + something else...

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CZmok

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You seem to have it hooked up right and understand how it should work. I think it needs service. I wonder if the 2/4 channel switch on the back has failed, is very dirty, or bypassed by a previous owner to get a louder 2 channel system when quad failed commercially. If you can get help from the person you bought it from or another tech, that seems the logical step.

So You think the problem is in 4ch/2ch switcher on back side of amp?

It is not possible to get help from person I bought it. I bought amp from Canada and I live in Czech republic, as You can see on my pure english :) . It was long and expensive transfer.

Thans for helping - @par4ken , @Circular Vibes , @LuvMyQuad - Last word, is the amp broken and need service? Probably the 2/4 switcher?
 

par4ken

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Discreet inputs are 4 (LF, RF, LB, RB). Which ones should I connect if I have just 2 cinch?
You would connect a stereo (2-channel) source to the Aux stereo 2 channel inputs (as you did). The internal decoder will split that to four outputs. Use 2-4, SQ or RM, try each one to see which sounds best to you. You only use discrete with a discrete source, tape, Multichannel SACD, DVD-A ect.
 

jaybird100

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The FM will work in the SQ and RM modes. Also, use the RM mode when you're playing records encoded in the QS or EV systems. It will also synthesize quad from stereo better than the SQ mode will.
 

CZmok

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@par4ken , @jaybird100 - it seems my device is not able to play SQ sound. 👎 😢

Befofe I take it to the service ant will pay lot of money, do You have some advice where to look?

@Circular Vibes - You think it can be the 2/4 switcher on back side of amp? Just clean it or some how disassembled the switcher?

Thank You for advice
 

CZmok

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Maybe the rear channels are blown, try connecting a stereo source to DISCRETE LB/RB in DISCRETE mode just to check if the rear channels are working.
@furui_suterioo - good idea. Rear speakers are working. But one of them plays like no bass is there or something... Anyway I will take the amp to service on Saturday. Hope service man fix the SQ trouble.

...after 2 month transport from Canada, stopped in Poland for 1 month in custom Agency, technical troubles with on/off switcher, finding the right transformer of voltage (230/110)... I hope I will finaly hear the SQ sound from it and will see all 4 UV meters dancing.

:phones
 

furui_suterioo

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From what I am reading, the sqr-8750 sq decoder board(s) inside use components from both sqd-2020 and sqd-2010, seems like a rather complicated design, so it likely that the sq decoder is the source of the problem but could be as good as the sqd-2020/2010? I am not sure, can't seem to find a comparison but its definitely a great looking unit, I do love Sonys.
 

CZmok

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I really hope it is repairable. I was looking for the right amp almost 1/4 of year. It would be really pitty to have just stereo device instead of SQ. :confused:
 

CZmok

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btw serviceman ask me for an electric scheme of amp. I just own manual, but not exact el. scheme... Is somehow possible to get it? I even write email do Sony and they told me that schemas are not available to customers...
 

par4ken

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btw serviceman ask me for an electric scheme of amp. I just own manual, but not exact el. scheme... Is somehow possible to get it? I even write email do Sony and they told me that schemas are not available to customers...
Sony wouldn't carry a schematic for a unit of that age. I would suggest hifiengine but I just checked and they don't have it. There are some for sale if you look around. I saw one on eBay but they wanted over $100 for it, you should be able to find one much cheaper than that.
 

MidiMagic

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Check the speaker first (try trading them). Loss of bass is usually a speaker failure.
 

chucky3042

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There's a surcharge to have SQ????
Yep. Originally I had zero interest in doing an SQ version as our main aim is the promotion of our INVOLVE encode format. Then after a bunch of pressure form all the members of this forum we gave in. I thought it would not be that hard and it would be a few weeks work, turned out to be a nightmare and was around 4 / 5 months work to work around the real limitations of SQ. Finally we got it right and it sounded amazingly good!

So given the really limited market for this defunct format we had to add a $50 surcharge to the SM1 with the SQ option in place of our then supplied TSS mode (Two Speaker Surround).

Sorry but it really is a token reimbursement- it cost me say 4 month of engineering wages! I admit I am glad we did it as its nice that it is standard on the SM2.

Regards

Chucky
 

CZmok

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Hi guys,

so the problem is SQ decoder. As You can see on amp block scheme (bellow), if 2CH is choosen, the SQ decoder section is bypassed:

IMG_20200916_172520.jpg



@chucky3042 - do You think is possible to repair decoder? I live in The Czech republic, so it is little bit expensive to buy one from You. Shipping and so on...


Btw... somebody already did something with decoder. Red wire bypassed something. Any idea what? Why? Also integrated cuircuit seems to be changed or something (rosin everywhere)

IMG_20201003_131049.jpg

IMG_20201003_131056.jpg
 

chucky3042

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Hi guys,

so the problem is SQ decoder. As You can see on amp block scheme (bellow), if 2CH is choosen, the SQ decoder section is bypassed:

View attachment 57345


@chucky3042 - do You think is possible to repair decoder? I live in The Czech republic, so it is little bit expensive to buy one from You. Shipping and so on...


Btw... somebody already did something with decoder. Red wire bypassed something. Any idea what? Why? Also integrated cuircuit seems to be changed or something (rosin everywhere)

View attachment 57347
View attachment 57348
Without a circuit diagram I cannot advise. You might try to remove the board and look for obvious problems like poor soldering, damaged capacitors etc
 

par4ken

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May 28, 2011
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Hi guys,

so the problem is SQ decoder. As You can see on amp block scheme (bellow), if 2CH is choosen, the SQ decoder section is bypassed:

View attachment 57345


@chucky3042 - do You think is possible to repair decoder? I live in The Czech republic, so it is little bit expensive to buy one from You. Shipping and so on...


Btw... somebody already did something with decoder. Red wire bypassed something. Any idea what? Why? Also integrated cuircuit seems to be changed or something (rosin everywhere)

View attachment 57347
View attachment 57348
You always mention SQ but do the other decoder functions work? RM and 2-4. Did you check the back speakers on the working front channels?
 
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