Need help diagnosing a Kenwood Ka-8300

[Bob S.]

I am a newbie with very little electronics knowledge and recently acquired a KA-8300 (my Christmas present to myself) that powers on and the relay clicks but I can't get any output to the speakers. I do see that the rk 6 resistor is burnt, would that have anything to do with no output?

 

[gort69]

- Normal;/separate switch on the back set to normal?

- Tape monitor switch usually overrides any other input selection

- Make sure speaker switch is set to correspond with speaker terminals choice

Can't comment on Re6

 

[mbz]

Any burnt/stressed component should be a red flag. It's the point of failure but why did it fail?
Re6 is in the power amp stage, it would affect one channel, maybe check the other channel/Re6.
Maybe check Ce5 (33uf/10V). Do you have any DIY skills/able to replace these?

 

[Bob S.]

The resitor in question is labled r 6 on the power supply board. Yes i have the skills necessary. I was checking the normal/separate switch and it was in the normal position but decided o pull the switch lock and switch it back and forth and found the switch has separated. Working on getting in there and putting it back together.

 

[jcamero]

Anything through the headphone jack?

 

[Bob S.]

Ok, so power light is out so rk6 is that. The internals to the normal/separate switch are gone, jumpered it to the normal position but still no music. If I touch the connections that are jumpered I hear a hum in the speakers. I don't have an adapter for the headphone jack to test.

 

[Bob S.]

Would a missing ground pin on the power cord cause a grounding problem??

 

[Bob S.]

A/c or d/c? I'm not getting a solid reading on either

 

[Bob S.]

I didn't replace it yet, I will get that done and go from there. Thanks for all your help

 

[SicMan]

This would be a normal setting of the switches. The input selector switch gets get dirty alot.
Like rjsalvi said the signal path may be the problem thru the switches along with your other probs.
Just some info.

 

[Bob S.]

Ok, so I finally got the R6 resistor (1.8kohm 1 watt) installed. I'm getting -30 on # 4 and nothing on #6. I unsoldered one side of each zener and checked them, both are O.L. one way and 0.625 and 0.627 the other way. Do those values sound close? Does anyone have any other suggestions on what to check next?

 

[mbz]

Expect pin 6 to be +30Vdc. Working back, candidates are,
DZk1... passes diode test
Ck4.... remote chance
Rk2.... 120 ohms
Ck3.... remote chance
Rk1.... 120 ohms
Dk1.... rectifier, +ve half, unlikely

Suggest measure resistance Rk1 and Rk2, incircuit ok, amp powered off & unplugged.
Expect one has failed open

 

[Bob S.]

Oooo K, so R1&2 both measure 119.6ish in circuit and about 119.8ish out of circuit. Here is what I get on the pins
#3. +7.3vac
#4. -29.78vdc
#6. -0.67vdc
#7. +7.07vac
#8. -49.7vdc
#9. +36.55vac
#11. +36.58vac
#12. +49.8vdc
i can not find 41v at rk1& ck3

 

[Bob S.]

Tonight as I was waiting for the iron to heat up and I took your advice rjsalvi and started checking continuity, i found that even tho i checked r1 resistor and soldered it back in its trace was broken on the top solder joint. Whooo hooo!!!! It's making sound!!!! Thank you all for all the advice!! While im in here is there anything else i should check or change?

 

[Bob S.]

Thank you sooo much for your help. Its amazing to me that this thing is alive. I came across this gem about a year and a half ago laying in a garbage pile. When I found it it was slightly covered in debris and had dust and dirt in it. Just from the beauty of the face plate I knew I couldn't leave it. I brought it home and it sat in my shop until about 2 months ago, that is when I decided I Wanted to go back to good-true sound in my system. I was looking around on eBay at vintage stuff and then's came on and remembered what I had found.

 

[Bob S.]

I have been using my ka8300 for the last few days and it is more impressive than I could have ever wished for. I have noticed something that is concerning to me tho, when I turn the power on it makes a pop sound in both speakers and if my tuner is on before the amp after the pop sound music is coming out of the speakers before the relay clicks. While listening to the system every once in a while there is a random pop in the speakers. Also when powering down the system it doesn't shut down immediately, it takes about ten seconds for the music to stop. Im hoping someone has some info or advice on what I'm experiencing.

 

[Bob S.]

I think it's been doing it since I got it up and going but have not really used it until this weekend. Before this weekend it was on my bench and I was using small speakers and my phone as the input. when I connected it to my kt-8300 and my Mtx AAL1540 speakers and really started playing with it and paying attention to what was going on is when I noticed it. The relay does click but if the tuner is on before the amp the music is playing through the speakers before the relay clicks