Kenwood KR9600 Protection Mode

Issue started several weeks ago and progressively got worse. After listening to the receiver for about 2 or 3 hours the unit would go into protect. Then it was an hour, ....... I reluctantly decided to take it apart. The volume/balance control had been crackly as well. After cleaning the volume/balance pot I examined the 1860PSB. It had some very slight charring and some of the solder joints looked bad. After reflowing the joints, I tested the unit for two weekends about 5 hours each time and the receiver worked good as new. Before putting it back together I decided I would do the Power Regulator Board / Power Supply B upgrade as some of the members in here did and upgrade the bulbs to LED. I replaced the lights, removed the old resistors, ran my jumper wires under the board and put the new resistors on the chassis wall. I turned the unit on and no relay click. after about 20 seconds I felt the resistors getting hot so I powered the unit down and rechecked everything. After several hours of scratching my head and looking I discovered that I had switched the wires on 3 and 4 and had the resistor switched as well; idiot move on my part. I went ahead and corrected the mistake but the relay still will not engage. Along with the relay not clicking, the signal strength meter is not working either. I have searched several of the threads in here and decided to take some voltage readings. I'll post them below. If anybody can steer me in the right direction I would appreciate any help !


1830 PS

1 1.7 v
2 -.033 v
3 70.8 v
4 NC
5 .47 v
6 NC
7
8
9 -9.2 v
10
11 0 v
12 0
13
14 34.2v
15 70.6v
16 0
17 13v
18 12.5v
19 13.3v
20 0
21 0.8v
22 1.2v
23 -71.1v
24 33.5v
25 49v
26 0
27 .006v
28 35v
29 0.6v
30 57.0v
31
32 0
33 22.8


1860 PS

1 34.5v
2 34v
3 60.5v
4 -68.4v
5 0.6v
6 1.2v
7 34.2v


2400 Relay

1 .002v
2 -.001v
3 .157v
4 .186v
5 -.033v
6 0.3v
7 -9.2v
8 -1.6v
9 0v
10 -.001v
11 -.001v

Hi,AK has some great experts and for Kenwoods, EchoWars is quite an authority. I would think that they will soon respond. Get a Service Manual and start comparing the voltages listed for the boards. Build a Dim Bulb Tester. Rechecking all you work is routine. My very quick check of PS 'A' 1830, shows that #2 ( out to power relay coil ) should have 67v and you have none (-.001). I do not know your skill level, but for now I would wait for the experts to guide you. One spark and you could kill a Power Pack and they are almost impossible to locate (used only).
Qk14 (Relay Driver) should have 67V on ECB. The C feeds #2 and you show 0 volts.
E&B should also have 67V and if they do, a novice guess, maybe Qk14 is no good. First, lets hear from the experts.

Pin 21 and 22 of the 1830 bd is a problem (-33V is missing, so the -13V is also gone). Looks like Qk5 and Qk6 may be due for a swapping. Do check that Rk11, Rk17, and Rk13 are not burned up.

(You can click on the schematic to download a full-size version)

Awesome ! Thanks for your quick replies. I was contemplating rebuilding those boards based of the restoration post in some of the earlier threads. I'll give them a once over and most likely redo the boards based off of those post. I'll keep you guys updated and thank you so much again for your help !

Update! Over the weekend I replaced Qk5, Qk6, and Qk9 as well as Rk13 based on EchoWars recommendation and all is well again. The new LED's I ordered off the Bay look nice as well. I also added the extra resistor to the relay board for the reduced current draw of the LED's. Thanks to all that responded, this site and especially EchoWars for his expert guidance on this.

You are welcome.

If you enjoyed your stay, hang around. And consider becoming a subscriber for a year if you think you got $25 worth of assistance from being here.

Absolutely ! I will be subscribing very shortly. :thmbsp: