AKAI M8 Reel to Reel right channel off

[treeman]

The Akai M8 Reel to Reel Tape Recorder has 2 separate channels each with its own panel.
i am preparing to sell mine as it is hardly ever used and we are downsizing.
The right channel has hardly any sound output, in power amp mode.
The pre amp output didn't seem to be working yesterday but is 'ok today.
What sound there is on the right channel with the volume on max could be cross talk from the Left channel.
I don't have the knowledge or expertise to rectify the problem unless it is a valve.
I have swapped the power amp valve and High y dual triode from the good channel,but no improvement.
My question is the other valves common to both channels are the Rectifier tube and the Low noise Pentode. They are hard to access with my large fingers, but is it worth doing, as my limited knowledge seems to think they are not the problem.

[Simon Gittins]

You might find the problem by swapping valves but access is limited and a broken valve may result as in the thread below. Logical fault finding is the best way but in this case a dirty headphone socket was mentioned in Post 49:
https://www.vintage-radio.net/forum/showthread.php?t=209475
Information about the M8 is here:
https://museumofmagneticsoundrecording.org/RecordersAkaiM8.html
You might consider a post in the Repair and Restoration Services Wanted section:
https://www.vintage-radio.net/forum/forumdisplay.php?f=145

[Simon Gittins]

Just a further thought:
As you want to sell it, you could just advertise it with the fault described; I don't think this problem would put an enthusiast off and many would prefer to fix this problem themselves.

[treeman]

I think you are correct about selling it as is Simon, it is just how much it will affect the price.
I will have a look at the links, but the problem is definitely not a dirty headphone socket, magnetised or misaligned heads or an other mechanical problem as i am fully experienced on that side of the machine.

The sound via the pre-amps to my external Pioneer Amp is excellent.

[Analogue man]

It is a long time since I had my M8 but I'm sure there was a switch on the back to cut out the internal speakers, this may have gone open circuit, if it has try switch cleaner and work the switch vigorously.

[treeman]

Hello Graham,
The "monitor" switch is on the front panel and switches on and off as it should. The headphones are missing the Right channel as well, so a problem with the circuits inside the unit which I can't do.

[Analogue man]

No it's not the monitor button on the front, there is another switch which I think is where the DIN socket is either on the back or side.

[DMcMahon]

The M8 Operators Manual shows a pushbutton switch on the front right just below the Recording indicator, this is identified as Item 44 "Internal Speaker On/Off Switch" and the associated text says to push it in to switch off the internal speakers. However the machine images identifies the switch as "Push to Monitor" ?

David

[Analogue man]

Certainly my M8 had a switch in the recess where the input and output sockets were, the monitor switch on the front panel allowed the inputs to be heard during record, I don't know if that was as intended or whether mine was got at but the separate speaker switch looked original.

[treeman]

The only switch on mine for the internal speakers is the one on the front panel. There is only the DIN socket on the side. There are no other switches .Mr MCMahon is exactly right as far as my machine goes.

[Analogue man]

Umm maybe mine was got at or there may have been a change in design mid production.

[DMcMahon]

Originally Posted by treeman

The only switch on mine for the internal speakers is the one on the front panel. There is only the DIN socket on the side. There are no other switches .Mr MCMahon is exactly right as far as my machine goes.

But the confusing thing for me is that the Operator's Manual describes the switch as internal speakers on/off, but the images in the manual designate the switch as Push to Monitor.

Is your (treeman) switch actually labelled as Internal speakers ?

David

[treeman]

It is labelled Monitor, which is one of the functions of the internal speakers when recording.
These speakers are quite small., so one would expect to either connect external speakers , and use the on board power amp, or connect to an external amp via the DIN socket.
Interesting to note that plugging the headphones into the unit does not cut out the internal speakers.
This is not a fault, it's always been like that.

[PatriceB]

Could be anything for a machine that old (I have the Roberts 770X, same deck):
- heads (dirty, worn);
- mechanics for switching the two separate amps;
- dirty switches;
- grey caps are notoriously bad…
- tubes

I had to buy at least three of those to have one working!