Kenwood Eleven III Power Issues

I have a Model Eleven III that powers on somewhat...

It turns on, but the only reason I can visually/audibly tell is that the tuner meters respond to tuning. The relay does not engage. No lights work either. No sound output, no VU meter response, no output through headphones.

The timer is OK, but I've temporarily bypassed it to completely rule it out.

All 3 fuses check out fine (out of circuit with a MM)...the 2 main fuses by the transformer and the additional fuse on the power supply board for the lights.

Is it possible that every bulb happens to be burned out? Maybe I suppose, but the other issues might relate?

I've started with checking out the power supply board. I took voltage readings before pulling the board:

Pin 1 (-56v/-49v) -54v
Pin 2 (56v/49v) 51.7v
Pin 3 (-63v) -67.5v
Pin 5 (47vac) 50.4vac
Pin 6 (47vac) 50.4vac
Pin 7 (35vac) 38vac
Pin 8 (35vac) 38vac
Pin 10 (22v) 19.9v
Pin 11 (14v) 13.99v
Pin 12 (33v) 33.6v
Pin 16 (-6.7v) 390mV (For Relay Off)
Pin 20 (7.5vac) 8.2vac

My question is what controls the expected -6.7v on pin 16 that reads low?

I've pulled the board to fully recap it and will replace any needed transistors if something is out of whack on the relay control portion.

All diodes tested good on the power supply board and all of the resistors look good as well.

Any common issues on this board?

I finished recapping the amp board and the power supply board and took new readings with a 100w DBT in place:

Pin 1 (-56v/-49v) -54.5v
Pin 2 (56v/49v) 48.3v
Pin 3 (-63v) -62.7v
Pin 5 (47vac) 47.8vac
Pin 6 (47vac) 47.8vac
Pin 7 (35vac) 36.3vac
Pin 8 (35vac) 36.3vac
Pin 10 (22v) 19.73v
Pin 11 (14v) 13.79v
Pin 12 (33v) 33.44v
Pin 16 (-6.7v) 400mV (For Relay Off)
Pin 20 (7.5vac) 7.77vac

The voltages are a bit closer to spec now and I'm sure the recap was a good thing...BUT, it was not a problem solver (didn't necessarily think it would be.)

I checked the Bias for both channels and they are under the specified 90mV

I also pulled all of the bulbs to take a look and they all test fine, so I think the issue is power supply related.

With the power off I checked the continuity between pin 20 (7.5vac power transformer feed) and pin 19 (output to lamps) and at the connection points on the Fk1 fuse which is in between those two pins and all test fine with good solid continuity. But, with power applied, the 7vac does not supply to the lamps. The schematic shows that the 7.5vac feed is also tapped by the dimmer/LED feed and relay off control feed portion of the circuit. It begs to suggest the problem is in this section.

I've already replaced Ck9 (330uf 80v), Ck10 (100uf 63v), Ck15 (1uf 50v), Ck17 (2200uf 10v) so that leaves Dk9, Dk10, Dk17, Dk18 and Qk10 and Qk11 as being likely candidates for need of replacement. All of the diodes passed a basic diode test when I had the board removed. Testing them with the unit powered will be a challenge for sure. This board has very limited access and requires 20 wirewrap pins to be unsoldered to remove the board. If I pull the board again I'll just replace the 4 diodes and 2 transistors, but I can get to the transistors without removing the board.

Proposed replacements if needed...

Dk9 W06B >>> 1N4004
Dk10 1S2076A >>> 1N4148
Dk17 1S2076A >>> 1N4148
Dk18 W06B >>> 1N4004

Qk10 2SA893 or 2SA750 (a893 installed) >>> KSA1013 or KSA992
Qk11 2SC1890 or 2SC1400 (c1890 installed) >>> KSC1845

Any suggestions from the audience?

is that a typo on pin 1 ?

Pin 1 is the -B voltage and it does read -54.5v...the manual just states 56v/49v (for 8 ohm/4ohm load)

I assumed it a manual typo, but am I wrong?

Looks like a typo in the SM...I looked at the coordinating pin on the Power Amp - Pin 24 and it states it should be -56v/-49v

I also went ahead and changed that above to avoid future confusion...

So I replaced the 2 transistors and the testing still yields the same results

Qk10 2SA893 >>> KSA992
Qk11 2SC1890 >>> KSC1845

Also replaced

Dk17 >>> 1N4148
Dk18 >>> 1N4004

Wire wrap pin #16 reads about +400mv and needs to read -6.7v

Dk9 and Dk10 will be more difficult to get to but if someone thinks they'll impact the lights or pin 16 output then I could put in the effort...remember that they tested OK when I had the board out. Also, all of the removed transistors and diodes have tested OK as well.

few tests for you ...
ac v pins 19 and 20 ..if pin 19 is low then measure voltage drop across fuse .1
acv dk18 anode dk17 cathode
dc v dk18 cathode dk17 anode
check ck15 and ck 17 are in correct way round .
make sure rk34 is 22k ohms .

I don't get AC voltage on either side of the fuse.

With just a ground connected to the chassis I get about 3.7vac

I can test the rest as well but this seems to be something more basic...no?

Ck15 and Ck17 are installed correctly

Rk34 reads 21.5k ohms and was rising as I held it in place...that's without lifting a leg so I suspect it's just fine

For good measure...

dk18 anode .018vac
dk17 cathode no vac (fluctuated under .5vac sporadicly)
dk18 cathode 0.00 vdc
dk17 anode .402 vdc

pull the fuse and check voltage at pin 20 .. then at the fuse holder . 7.5v ac
if the voltage comes up to around 7.5v ac replace fuse and unsolder one end of rk32 or rk33 then see if the other voltages come up .

With just the ground connected to the chassis the AC voltage will read as high as 6vac with a bit of fluctuation between 5 and 6 volts but as soon as I connect to pin 20 it locks in on about 8.2vac with no variation. If I connect to the supply side of the fuse holder with the fuse removed it won't get up to 8.2...it'll get a bit higher than 6vac but not much and again it's a bit flakey and not locked in like you would think it should be. Being irritated with this I decided to jumper test pin 20 to 19 and indeed all the bulbs look wonderful. So, that can definitely be ruled out. Should I still unsolder one of the ends of one of the resistors as you suggested?

pin 20 is the feed .. then the fuse is next in line . then along to the diodes and pin 19 .
so there is a bad connection along the way .. maybe the fuse holder has a poor solder joint . or the board trace is cracked ..
or pin 20 has a poor connection ..
leave the resistors in place .. that was a test to see if the dimmer was shorting stuff out .

did all lights work ? as in position and the led ?

All lights worked tuner indicator and all

I have good continuity along all the points with the power off. I can hook up the probe to 20 and get the signal to 19, 18, and 17 and all the points in between. It's weird for sure. It makes me think it's grounding out or something?

Also, I had already reflowed the solder around the fuse holder and the pins, etc as a troubleshooting measure.

try holding a wire between different points like the fuse to pin 19 .....fuse to pin 20 ..
and try a wire across the fuse

I tested a bit more while carefully jumpering pin 20 to 19 and when I press the dimmer button it actually turns off all the lights except for the led, the source selected, the speaker selected and Dolby selection. Dial and meter lights off. Is that how it would normally work or should it just lower the output? I suspect jumpering it is making it work incorrectly.

lights dimmer operation is maybe written in the manual ..
i am pretty sure there is a bad connection ..its just a matter of finding it