Kenwood Basic M2A Shuts Down at Higher Volume

[OnThePike]

Hello all,

The subject line pretty-much says it all. At higher volume, my trusty old Kenwood Basic M2A appears to enter standby mode, cutting off the output and flashing the power indicator.

Here's a list of what's running:

Kenwood Basic M2A Power Amp
Kenwood Basic C2 Control Amp
Kenwood GE-1100 Equalizer
Gemini CS-02 Mixer
Gemini iTrax iPod Mixer
Cerwin-Vega CLS-215 Speakers
Technics SL1200 MKII (1983 originals)

The CV's are hard-wired using about 30-feet lengths of 14g zip cord, properly phased and not touching anything but their intended connectors.

I'm using the mixer output gain as my master volume, with the M2A output controls set to 7 each and the Basic C2 output around 12:00. The mixer input gain is set to about 80%. The mixer channel output varies between sources; usually between 5 and 9 (with 10 being maximum).

Any ideas as to exactly what is causing the M2A to drop out? Any suggestions/comments welcome.

Thanks,

Jeff

 

[TLS Guy]

Hello all,

The subject line pretty-much says it all. At higher volume, my trusty old Kenwood Basic M2A appears to enter standby mode, cutting off the output and flashing the power indicator.

Here's a list of what's running:

Kenwood Basic M2A Power Amp
Kenwood Basic C2 Control Amp
Kenwood GE-1100 Equalizer
Gemini CS-02 Mixer
Gemini iTrax iPod Mixer
Cerwin-Vega CLS-215 Speakers
Technics SL1200 MKII (1983 originals)

The CV's are hard-wired using about 30-feet lengths of 14g zip cord, properly phased and not touching anything but their intended connectors.

I'm using the mixer output gain as my master volume, with the M2A output controls set to 7 each and the Basic C2 output around 12:00. The mixer input gain is set to about 80%. The mixer channel output varies between sources; usually between 5 and 9 (with 10 being maximum).

Any ideas as to exactly what is causing the M2A to drop out? Any suggestions/comments welcome.

Thanks,

Jeff

Can you give us more details on the amp? I can't dig up anything. However if my memory serves me correctly, that amp is a type of class H switching rail amp. I think they are a known problem unit with most having bitten he dust. If it is the amp I'm thinking of, it has a Sanyo chip (NLA) that controls the switching rails, that is the cause of the problem. Do you have a manual that will give more details and confirm if my memory is correct. If it is the amp I'm thinking of then realistically is at the end of road.

 

[OnThePike]

Ouch!!

Not quite the response I was anticipating, but I thank you nonetheless for your assistance.

I do have the manual and (I think... schematic). Let me look around and scan that for you. I'll post back again when I dig up the information.

Thanks again.

 

[TLS Guy]

Ouch!!

Not quite the response I was anticipating, but I thank you nonetheless for your assistance.

I do have the manual and (I think... schematic). Let me look around and scan that for you. I'll post back again when I dig up the information.

Thanks again.

Yes, that's the one. I found a service manual at the Hi-Fi engine. It is a 220 watts per channel class G amp. It is known for problems with the switching circuitry, and vital parts, especially a Sanyo chip are NLA, unless you can find old stock.

I would have the amp checked by a good service tech, and if the problem is in the power rail switching circuitry, I think it is time to call it a day.

Switching rail amps are generally more trouble than the more usual AB class.

My guess is that the amp is not switching to the higher rail voltage and then the current limiters come in to operation.

We have had these sorts of problems posted before with this amp. The amp is highly regarded though when working. However these amps are getting far and few between now.

 

[OnThePike]

I have 5 jpeg images of specs to post/share, but I am not allowed to post attachments. I'll try and "text them out" when I get a chance.

Thanks for responding.

 

[Seth=L]

TLS almost always moves to diabolical damage before considering silly things like a basic short. Once upon a time I had purchased some speaker wire that had become defective over a short period of time. I suggest trying a different set of speaker wires. I remember returning two receivers to best buy because of a bad speaker wire.

 

[Lordoftherings]

TLS almost always moves to diabolical damage before considering silly things like a basic short. Once upon a time I had purchased some speaker wire that had become defective over a short period of time. I suggest trying a different set of speaker wires. I remember returning two receivers to best buy because of a bad speaker wire.

This was one of my first guess, I'll get something like 12 gauge speaker wire of decent quality, or even 10 gauge (check Blue Jeans Cable).