Basic M1 won't power on. Fuse?

IanMcI

Active Member
I just pick up a Basic M1 at an estate sale, along with a Basic C1 Pre (and a matching tuner).

The M1 is not powering on, and I'd think the first thing to check is whether a fuse is blown. However there is no access to a fuse without opening it up. Can you give me some idea of of what to expect when this is opened?

Will there be an easily accessible fuse in there?
Will my first step be to replace that fuse if blown?
Is there a reason the fuse is not easily accessible?
Is there a commonly recognized reason for a fuse blowing?

It goes without saying that I'd like to have this unit working, and I do have some minor repair experience, having recapped a couple of things, and soldered, etc. But, other than a multimeter, I have no test equipment, nor the expertise in using any.

Can anyone help with my next move? Thanks!

Ian
SF Bay Area
 
Answers inserted in the quoted text.

I just pick up a Basic M1 at an estate sale, along with a Basic C1 Pre (and a matching tuner).

The M1 is not powering on, and I'd think the first thing to check is whether a fuse is blown. However there is no access to a fuse without opening it up. Can you give me some idea of of what to expect when this is opened?

Will there be an easily accessible fuse in there?

Yes, on a small circuit board where the line cord enters.

Will my first step be to replace that fuse if blown?

look and see if it is blown. But it could also be the protection relay. It was minimally rated from what I've read, and was the issue with my "ugly Betty" restoration recently completed.

Is there a reason the fuse is not easily accessible?

it is...it's just inside the case.

Is there a commonly recognized reason for a fuse blowing?

Too many amps of current going through it.

It goes without saying that I'd like to have this unit working, and I do have some minor repair experience, having recapped a couple of things, and soldered, etc. But, other than a multimeter, I have no test equipment, nor the expertise in using any.

Can anyone help with my next move? Thanks!

Ian
SF Bay Area
 
Thanks very much for the input, jheu02! It gives me some hope, and a bit of confidence, that I can get this thing back up and running.

Ian
SF Bay Area
 
Here's my restoration thread. There's a part number in there for a current production relay that will be an upgrade to the original but has a different pin format (if that's what the problem happens to be) and perhaps even a link to leesonic's instructional thread for wiring the new relay to the board.
 
Fuse is blown. I'll replace it, but must think that whatever caused it to blow might still be an issue.

So... too many amps going through it. Where would those excess amps come from? Would use of 4 ohm speakers cause that? Not that that was ever the case, I wouldn't know - this is a recent estate sale find - just wondering, or looking for reasons to believe I might replace the fuse and call it good.

Ian
SF Bay Area
 
Test the output transistors for shorts. I also suggest that you build a DBT (Dim Bulb Tester) before you power up the amplifier. The C1 preamplifier and M1 power amplifier are very nice sounding designs, and can be made to sound even better when restored/upgraded: Kenwood C1 and Kenwood M1
 
I wouldn't know how to test the output transistors, but I do have a dim-bulb tester, thanks for the tip!

Slow-blow or fast on something like this?

Ian
 
To test for a short with a multimeter, test for continuity between any of pair of pins on the output transistors (power is off).

Use a fast-blow fuse; the DBT will "absorb" any abnormal current draw.
 
Thanks. I do have a multimeter. I'll Google output transistor. However, I did button it up.

I did replace the fuse with a 250v 6a fast blow and it powered up fine. I made the connections between Amp, Pre and Tuner, hooked up a pair of KLH HD 53Bs that should able to handle it, and it sounds pretty good (Local FM jazz station).

I hope this takes. I'm very pleased to have this system up and running!

Ian
SF Bay Area
 
Does anyone know what fuses to use on the EPI M1 power amp? There is one fuse on the main and two more for the speakers.
I keep blowing main fuses and burning one of the other fuses. I have Buss agc 5. 250v fuses in all three plugs.
I have two 8ohm speakers on channel one and two 4ohm speakers on channel two.
Thanks for your help.
BilliamC
 
Does anyone know what fuses to use on the EPI M1 power amp? There is one fuse on the main and two more for the speakers.
I keep blowing main fuses and burning one of the other fuses. I have Buss agc 5. 250v fuses in all three plugs.
I have two 8ohm speakers on channel one and two 4ohm speakers on channel two.
Thanks for your help.
 
Back
Top Bottom