Yamaha R-700 safety relay question.

S

srinath

Super Member
I have a r-700 with a few fried resistors etc, and I had replaced those, so nothing in it should be fried as in resistors caps etc - But I cant get the safety relay click.
The 2 power amp modules have been removed.

Its got the stk3056 in though. The thing lights up and scans stations etc. Just no safety click.

Can this indicate a bad stk3056 - or can it still be something else.
How to test the stk3056 ? does that chip put the voltage to the relay ?
Thanks in advance yamaha experts.

Cool.
Srinath.
 
does that chip put the voltage to the relay ?
Click to expand...
Don't think so. Look over the small caps in the protect circuit.If you have the schematic you need to figure out whats holding the relay in the "reset" state.
 
I have another 3056, I could have a bad 3056 too right, this one in this amp came from an amp that was in a 100 bits.


Cool.
Srinath.
 
Check voltages around TR's 305,306,307 & 308..
Caps C368 and C369 are suspect issues.
 
what should they be

avionic said:
Check voltages around TR's 305,306,307 & 308..
Caps C368 and C369 are suspect issues.
Click to expand...

What voltage should I have for those 305-308 ? B+ - I am still looking over the schematic.

c368 and c369 - let me find those and swap em. My fried resistor had splattered its guts onto a couple of caps, those should be removed so I can clean the board too. So swapping em is better now.

Cool.
Srinath.
 
What is the V-amp ? Is that the stk3056 ?
I suspect the 3056 itself, but I will get those burn marked caps off and swapped.
Cool.
Srinath.
 
I am just starting on the amp. I'll post these in a bit, but I got about 27v dc between pins 5 and 2 (the 2 middle ones) of the safety relay.
Does that mean the relay is bad.
Or does that mean I have DC in output ? Thanks for all your help avionic (and more to come also welcomed.
Cool.
Srinath.
 
Cant find em

Hey man,
I cant find the c368 c369, and worse yet I cant find much of the tr305 - 308.

I am going to see what they are on the schematic and see if I can find em, but if the c368/369 were little square ceramic caps - I swapped em out cos the ones in the amp I intend to ressurect had a burn on em I thought was a spray burn from a resistor that went to heaven ... but maybe not.

Cool.
Srinath.
 
Anyway I am replacing a few items from the parts r-700. Anything that looked suspect. The c368 and 369 I wasn't able to locate, but I dont see any electrolytics with any sign they could be bad.
I will look tomorow, I have a blown resistor in both amps - its on that border where it says "protect" on the main board. Let me see if I can find a location code and hence what it is from the schematic.

Cool.
Srinath.
 
I found all em components thanks to the schematic with all the numbers - page 10 of the manual.
Anyway I have a blown up R412 - in both amps. The c368 and 369 both were little electrolytics - they both looked good.

Cool.
Srinath.
 
srinath said:
I found all em components thanks to the schematic with all the numbers - page 10 of the manual.
The c368 and 369 both were little electrolytics - they both looked good.

Cool.
Srinath.
Click to expand...

Swap them out.
 
Ok thanks, I'll swap em tomorow when I get back to it.

I got readings off the TR305-308.

TR305 B=1.0 vac, C=1.0 vac, E=.66 V DC.
TR306 B=0, C=56 Vac, E=0.
TR307 B=1.7 V DC, C=55 Vac, E=0.
TR308 B=-.66 Vdc, C=-9.8 Vdc, E=-2.66 Vdc.

If these look off to you - as in I may have something measured wrong - like if this is 55 that oughta be 27.5 etc etc - please tell me, I was shivering away in the wind and 40 degree weather trying to measure it. I would get it inside and measure it again.

And on my parts amp, these transistors have been replaced before, they look much smaller than the ones in the amp I am trying to ressurect. It also has those translucent greenish ceramic caps instead of those brown cooked mud looking ceramic.

Anyway the resistor R412 was cooked in both amps, I swapped it with R414 from the parts amp.

Cool.
Srinath.
 
srinath said:
Ok thanks, I'll swap em tomorow when I get back to it.

I got readings off the TR305-308.

TR305 B=1.0 vac, C=1.0 vac, E=.66 V DC.
TR306 B=0, C=56 Vac, E=0.
TR307 B=1.7 V DC, C=55 Vac, E=0.
TR308 B=-.66 Vdc, C=-9.8 Vdc, E=-2.66 Vdc.

If these look off to you - as in I may have something measured wrong - like if this is 55 that oughta be 27.5 etc etc - please tell me, I was shivering away in the wind and 40 degree weather trying to measure it. I would get it inside and measure it again.

Cool.
Srinath.
Click to expand...

Don't know how you come up with AC in a DC circuit.
 
Oooo

avionic said:
Don't know how you come up with AC in a DC circuit.
Click to expand...

OK I saw rapidly changing DC voltage and tried AC in my multimeter. I shouldn't do that ? OK then I'll measure them all only DC, but if its fluctuating - I guess that's it.

Wait a second - this circuit is fed by that little cheese cube transformer behind and to the right of the big transformer right ? does it have its own rectifier bridge ? can that have given up the ghost ... or the smoothing caps.

Cool.
Srinath.
 
OK I got DC off all them

TR305 B=0 dc, C=0 dc, E=.66 V DC.
TR306 B=0, C=27 Vdc, E=0.
TR307 B=-1.7 V DC, C=27 Vdc, E=0.
TR308 B=-.66 Vdc, C=-9.8 Vdc, E=-2.66 Vdc.

All dc - some of these weren't steady. Like the TR305 B and C ones were sorta moving around a bit.

Cool.
Srinath
 
srinath said:
TR305 B=0 dc, C=0 dc, E=.66 V DC.
TR306 B=0, C=27 Vdc, E=0.
TR307 B=-1.7 V DC, C=27 Vdc, E=0.
TR308 B=-.66 Vdc, C=-9.8 Vdc, E=-2.66 Vdc.

All dc - some of these weren't steady. Like the TR305 B and C ones were sorta moving around a bit.

Cool.
Srinath
Click to expand...

Pull and check R380..In circuit it should have 24vdc on one side and 4.6ish vdc on the other. Unfortunately the resistance value is missing on the schematic.Maybe its in the parts list. Parts list says 220kΩ.
 
Last edited:
You must log in or register to reply here.

Similar threads

S
Yamaha R-700 help
2
Replies
29
Views
5K
srinath
S
merrylander
Damned fakes
2
Replies
34
Views
3K
soundboy
soundboy
dowey
yamaha cr 650
Replies
2
Views
2K
merrylander
merrylander
M
Yamaha R-50 Relay Pulsing
Replies
4
Views
3K
avionic
avionic
S
JVC JR-S600 blown fuses.
2
Replies
21
Views
3K
srinath
S
Back
Top Bottom