some cr-820 questions

[painttoad]

hi, i am going thru a cr-820 and have some questions:

1st: fr701/702. what wattage should these be replaced with?

i've seen 2 suggestions by guys that i trust:

Yamaha CR-820 - Fusible resistor 68R/85mA

Hi, Everybody ... I like to ask for help ... I have this vintage recceiver from my friend and there´s was a blown away left channel, both power transistor are dead, together with 2SA814 ... I have the same genuinne Toshiba transistor, used, but they are fine ... There´s was blown away the...

audiokarma.org

Yamaha CR820 Powers up-no relay click

I'd get rid of that 1.5KΩ 1 or 2 watt carbon composite resistor. Right below TR722 in the above photo. Those two larger caps with the shrunken plastic sleeves in the same photo . Right below the small aluminum heatsink. Are likely toast.

audiokarma.org

i ordered the 1/4 watt but am doubting my choice after reading more on the unit. i have not removed or measured the original yet.

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2nd: i have replaced tr 609/610 and tr707/708 and tr801 - tr809.

replaced all electrolytics, trimmers, relay on the main board. i have all diodes but have not replaced any yet. dc offset is around 5mv. idle current is stable @7mv.

is there any true benefit to wholesale transistor replacement on the amp board like was done here?:

Project: Yamaha CR-820 (Rebuild)

About a month ago... was able to pick up two CRs - both were non-working. Have much gear and only Yammie was a DSP-A1 (beefy) which was included with a purchase of some Infinity RS-IIIb. I really liked it, but I moved it down the road to keep with the silver theme. These were in...

audiokarma.org

i'm all for replacing for reliability but i'm also a fan of letting sleeping dogs lie.

phono stage,tone board have had all transistors and 'lytics replaced.

the unit sounds great and measures to spec(as far as my capabilities go that is)

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3rd: has anyone been able to mod the tuner to raise the muting threshold?

i watched a video on the unit and the one on the video exhibits the same 'issues' that this one does. granted, i am in a basement with only a dipole antenna but stations that i receive in stereo on other units with no antenna will not get past the muting circuit in the yamaha with an antenna.

i plan to haul it upstairs to check reception but have not gotten to that point yet and wanted to ask first.

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that's all for now, i may have a few other questions.

thanks for reading and any input.

 

[mbz]

1st: fr701/702. what wattage should these be replaced with?

Not aware of any problems in this area, working off the schematic and hopefully agreeing with the FR's marking, 68ohms, 85mA gives
0.5W (= I x I x R)

2nd: i have replaced tr 609/610 and tr707/708 and tr801 - tr809.

Looks like a sensible selection criteria, psu and possible troublemakers.

is there any true benefit to wholesale transistor replacement on the amp board like was done here?:

I wouldn't but it comes down to what you are going to do with the amp, perfectly ok to retain OEM transistors if you plan to sell, it will be fine for years to come. If you plan to keep then yeah, understandable that you go a little overboard but then include C0G type ceramics and...

i have all diodes but have not replaced any yet

1N4148's are cents so I'd replace the 1S1555(?) wouldn't bother with rectifier diodes unless you've had preious success of soft recovery/no recovery/UF?...

 

[painttoad]

thank you.


crap. i just realized that i never hit the reply button 2 weeks ago.

@mbz i did not mean to appear ungrateful.