That's odd.

I had a Roberts 770X (AKAI M8) and never once experienced any hum whatsoever when playing back tapes or using it as a phono preamp. More than likely the hum back then was caused by how these reel to reels were connected to other equipment.

With the AKAI M7 & M8 it is important to make sure all grounds are connected properly particularly the ground wire that runs between the two amps and tape transport (near where the screws on the front that hold the amps in are located) otherwise there will inded be hum. Also there are hum balance pots that need to be adjusted properly before saying the reel to reel has hum issues as a tape head amplifier.



Easiest way to restore these amps is to remove all components related to the record function including the record/playback switch, eliminate the first stage (unless you want it for a magnetic phono preamp), restore the rest of the amp and IIRC the input would go to the first 12AD7 stage. Doing it that way shouldn't cost all that much money only requiring you spend what is necessary for the replacement capacitors and any out of tolerance resistors.

Thanks, Tube Radio. I remember those ground wires very well. I believe they were blue or black in color, and had a tip on the end of them that fit into a hole on the other chassis. I'll dig out these amps tomorrow, and look them over.

Now what, no new tape! Obolete?

The amps are back in the cab and the M-7 is playing well through my nice 8 Ohm bass reflex hi fi speaker I use for some of my loud puch pull boat anchors . I was a little concerned on initial power up since I decided replaced the entire compliment of caps at once before I squeezed the amps back in the cab to fire it up. I did have a little initial belt slipping but after cleaning it with rubbing alcohol the speed now sounds pitch perfect. I have been going through a number of used tapes I purchased for cheap on Craigslist. It's been fun to listen to the assortment of music on these tapes. The machine is holding it's own so far, it will find a nice place in my system. I still haven't done more just play tapes. I will experiment with direct recording and also check out the Akai microphones next weekend. I'm going to need to buy/assemble a number of patch cords so I can integrate it with my Dynaco Pas3 preamp.

Apparently there are still NOS tapes to be found made by Quantegy and occasionally on Ebay but the prices are a bit high for my blood.

If the reel to reel has a DIN jack on the side you can use that to feed the audio signal to your preamp which bypasses some of the internal circuitry IIRC. I did that with my 770X (M8) by using an old computer keyboard cable and rewiring the DIN jack to accomodate the different pinout on the computer keyboard cable. It worked extremely well.

I guess I'm not out of the woods on this set yet. Having no stereo speakers I've just been playing both the left and right channels twisted together powering a single large speaker. Both VU meters work so I assumed both channels were operational but it turns out the left channel's not working. It may just be a funky speaker lead jack on the left channel as I've not had a chance to get back in to it yet.

But here is a real oddity that started to happen last night for the first time. When the volume is real low and the tape is playing I can planely hear a strong local AM station coming out the speakers. If I stop the tape and turn up the volume I can also hear the station bleeding through. I have tried reversing the plug but the problem remains. Any ideas what could be causing this? How is the RF getting into this recorder/player? (This particular station also crops up at various places while listening to different boatanchors short wave receivers)

It could be how close you are to the station.

I used to have the same problem with mine, only it would pick up an FM station. It got better or worse depending on where the power cord was placed. I guess that it was acting like an antenna. I could never fully cure the problem, and it wasn't worth the trouble anyway, being that the heads were very worn out on mine. Hopefully, someone can suggest something to you to get rid of the RF problem.

Elrick, how's the reel to reel coming along?

Update on the Akai M7: It has earned a permanent place as part of my regular vintage stereo system but it's not entirely integrated yet. I picked up some un-opended NOS tape, some brand new Ampex tape, plus some lightly used newer tape as well as about 30 pre-recorded tapes of assorted older music so I'm building my tape library. I tested the two original Akai microphones that came in the accessory bag. They worked very well during a test recording of me punishing my acoustic guitar. For recording LP's I've been running the turntable through my Dynakit PAS3 pre amp and into the Akai. I can report that the quality of my self recorded tapes is just wonderfull with very high output and low distortion. I sometimes hear parts of the music that I've not heard before. The other day I recorded the entire Simon & Garfunkel box set collection I picked up at the Goodwill for $2. Turned out great recorded at 3 3/4 ips. I have not yet been using it through my Dynakit ST70, instead I just power the stereo speakers directly from the deck. For most purposes there is penty of volume, just ask my neighbors.

I'm really happy with the way it turned out. I suppose eventually, I'll replace the capstain belt, but so far the playback speed is spot on. When I get some more RCA to 1/4" phonp plugs I'll see abut patching the ouput back into the pre amp and driving the speakers with the Dynakit ST70. But for now, I'm pleased as punch. I just hope it holds up since I will be using it frequently.

It should hold up very well.

Cannot remember if the M7 is set up this way, but with the M8 IIRC you could plug in a magnrtic phono directly to the unit and at least play back a record or maybe even record a record. Going from memory here.

The manual states that you need a pre amp to record from magnetic cartridge turntables. I do think that a CD player can be plugged directly into the phono input jack on the deck for recordings however. That's next on the list.

One concern I mentioned earlier about how I was able to hear a super strong local sport talk radio station coming through the deck during quiet passages or even when the tape transport was stopped, needs to be explained since I did discover what was going on. Turns out the end of my long wire antenna (170 Ft) just happened to be dangling very close to a remote speaker switch I put together to play various sources through a single hi fi speaker usually used for my boat anchors. The RF was somehow getting into the speaker leads, problem solved just by moving the end of that antenna a few inches away from the seaker wires. I thought that was interesting.

Oh ok. I figured the M7 was different.

Yes that was an interesting fix.

This is my first time on this forum. Great stuff.

I just fired up my Akai Terecorder M7 that I purchased used in 1964 and that I used until 1972 when it was relegated to storage in the garage. Poor choice of storage locations.

After taking the back cover off and manually turning the motor fan blade a bit, the motor came to life. As far as I can tell, it still works just fine. Except 3 of the 4 VU meter lights are burned out. It appears to me to be a monumental task to replace those lights.

I took the cover off the front of the tape player part and all wheels look fine. The real (or is it the reel) question is, the rubber on the Pinch Roller that keeps the tape pressed to the capstan is dried and cracked.

Is it possible to somehow obtain a good used (or new) pressure roller for this wonderful 50-year-old tape recorder?

Cliff

First thing you need to do is find a pinch roller. Then clean all mechanical parts and re-lube them. Then replace the capacitors in the amplifiers. The resistors should be fine.

Thanks for the info. Right now I think the audio is fine. I don't hear any 60 cycle hum nor coupling capacitor crackle. Yet.

I found a website with a manual for the M6. I assume is is almost identical to my M7. Nice instructions on lubricating.

I assume I will not find a replacement pinch roller unless I buy a junker parts-only M7.

I found a website that rebuilds pinch rollers. Have you ever heard of or done business with these folks? Sounds like just what I need. They even have before/after pictures of an M7 pinch roller that looks exactly like my rubber problem.
http://www.terrysrubberrollers.com/

Cliff

Terry's is the best. You should send in your pinch roller for them to rebuild -- anything you find on a junker unit will be as old as your pinch roller and probably in similar condition.

-David

The audio may seem fine, but the capacitors still need to be replaced as they are old and well beyond their expected lifespan.

New capacitors will not be all that expensive.