Kenwood KA-7100 needs help
- Thread starter Squidward
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Do you hear a relay click a few seconds after turning on the power? Is the power indicator light on?
If you can hear the relay engage, measure the DC offset at the speaker terminals using the 200mV scale on your multimeter. Have a look at the DC-offset thread first if you are not certain how to do this.
If you can hear the relay engage, measure the DC offset at the speaker terminals using the 200mV scale on your multimeter. Have a look at the DC-offset thread first if you are not certain how to do this.
Well... that could mean the relay itself is faulty and doesn't operate... or it could mean that there is a deeper problem within the unit and the protection relay is doing its job - refusing to engage so your speakers are not damaged.
You may wish to remove the cover and examine the circuit boards for signs of fried components, or extreme overheating, but it is not likely that a visual inspection alone will reveal the problem.
I have a spare KA-7100 in a similar state, and haven't yet been confident enough to start following the schematic to check voltages and try to isolate the problem any further... I have checked the fuses in my unit and they seem fine.
Perhaps now would be a good time to start, if some of the more experienced technicians in the crowd that can be enlisted to offer some support and coaching.
You may wish to remove the cover and examine the circuit boards for signs of fried components, or extreme overheating, but it is not likely that a visual inspection alone will reveal the problem.
I have a spare KA-7100 in a similar state, and haven't yet been confident enough to start following the schematic to check voltages and try to isolate the problem any further... I have checked the fuses in my unit and they seem fine.
Perhaps now would be a good time to start, if some of the more experienced technicians in the crowd that can be enlisted to offer some support and coaching.
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The board looks OK, nothing obvious.
I don't have a schematic, if anyone would like to point me to one I'd be grateful.
Yeah, if anyone out there that knows what they're doing would be willing to give pointers, I'd be all ears. I think it's cool that someone else is in the same boat, and we could all troubleshoot together. This might turn in to the KA-7100 repair thread...
I don't have a schematic, if anyone would like to point me to one I'd be grateful.
Yeah, if anyone out there that knows what they're doing would be willing to give pointers, I'd be all ears. I think it's cool that someone else is in the same boat, and we could all troubleshoot together. This might turn in to the KA-7100 repair thread...
Squidward... I have an original service manual for this unit... haven't attempted to scan it into an electronic format, but I will give it a try tonight or tomorrow and see what kind of results I can get.
PM me your e-mail address and I will send you the results...
PM me your e-mail address and I will send you the results...
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mhardy6647
Lunatic Member
Well, one thing you can try is to see if you can get some line level signal from the tape outputs. Unfortunately, sometimes a perfectly dead amp can pass signal (passively, no pun intended) from an input to the tape outputs. I have a Kenwood preamp that's dead as a doornail except tape IN/OUT. http://audiokarma.org/forums/showthread.php?t=26213&highlight=kenwood
Try a phono cartridge IN and see if you get preamplified, equalized signal OUT of the tape outputs. That should tell you if the low-level (preamp) part of the amp is doing anything at all.
Did you check the fuses? They're all inside the 7100, as I recall, but still worth checking. No relay click's a bad sign, though.
Try a phono cartridge IN and see if you get preamplified, equalized signal OUT of the tape outputs. That should tell you if the low-level (preamp) part of the amp is doing anything at all.
Did you check the fuses? They're all inside the 7100, as I recall, but still worth checking. No relay click's a bad sign, though.
Jim H B
Well-Known Member
I have a Hitachi HA-5700 integrated amp in the same condition; no sound from any input to any output, though I've not tried the tape output.
Powers on, but no relay click.
The 5700 has no pre/main jacks either. I've tested all fuses.
I would be interested in how one tests the relay to see if that is the problem. I'm a longtime stereo fan, but new to doing diagnostics.
I have a multimeter, but just have basic questions about meauring voltage; do you need to take the relay out of the curcuit to test it (ie, unsolder it)? What leads to you put where to test it?
So, any help would be very enlightening, and appreciated.
Jim
Powers on, but no relay click.
The 5700 has no pre/main jacks either. I've tested all fuses.
I would be interested in how one tests the relay to see if that is the problem. I'm a longtime stereo fan, but new to doing diagnostics.
I have a multimeter, but just have basic questions about meauring voltage; do you need to take the relay out of the curcuit to test it (ie, unsolder it)? What leads to you put where to test it?
So, any help would be very enlightening, and appreciated.
Jim
hpsenicka said:
You are probably correct sir, most of the time if the output relay doesn't
kick in, then there's usually something wrong in power amp section.
But it doesn't hurt to eliminate the preamp section... as my electronics
teacher told me, "If you eliminate what isn't the problem, then
you're left with what is the problem.".
Glad to see that we're on the same wavelength! :thmbsp:
Scott
It looks like the Tape and Input selector knobs on the face of the unit have rods that extend to the rear of the unit, where the input jacks are physically located. There, a PCB has all of the input jacks mounted on it, and both selector switches are on the PCB, too. I suspect that the signal that goes from the tape in to the tape out never leaves this board at all, and has no bearing on the health of the active stages in the preamp.
mhardy6647 said:
This test was brilliant! I got amplified/EQed signal from the tape outs. But, I think the phono pre-amp is on the board at the back, and still doesn't go through the amp's volume/EQ/active preamp stages.
All fuses are fine.
Thanks for the suggestions so far!
Jim H B
Well-Known Member
Sorry to be dense guys, but just so I make sure - I would hook a turntable up to the phono input, play a record, and see if there is equalized output from the tape outs?
To see if you are getting output on the tape outs, I assume you would hook up a tape deck and start recording. Or is there an easier way?
And, like Squidward, let's say I do get a good signal through to the tapedeck; what does that mean. Does it mean the pre-amp section is probably good, and that the problem is then likely to be in the power amp or the relay itself?
If that is the case, is it easiest to start with testing the relay itself?
I've read some threads about how a little piece of dust can lodge itself between the contacts.
Thanks for the help
Jim
To see if you are getting output on the tape outs, I assume you would hook up a tape deck and start recording. Or is there an easier way?
And, like Squidward, let's say I do get a good signal through to the tapedeck; what does that mean. Does it mean the pre-amp section is probably good, and that the problem is then likely to be in the power amp or the relay itself?
If that is the case, is it easiest to start with testing the relay itself?
I've read some threads about how a little piece of dust can lodge itself between the contacts.
Thanks for the help
Jim
