Akai Reel-to-Reel Acting Up

[Scorpion8]

So I dug my Akai GC-267D out of long term storage (~20 years), and brought her to the work bench. I cleaned out the back, dusted, checked the fuses, sprayed DeOxIt on the contacts and checked the lube (direct drive model).

I pulled out some old tapes, and fired her up. All seems to be working fine on the right channel, but the left channel is dead. I get spurious noises when I flip the Tape Monitor switch from Tape to Source and back, and the left channel meter may move slightly sometimes, but often not at all.

Back when she went into cryostasis she had a scratchy tape monitor switch that you had to move back and forth sometimes to get left side sound, but now I dunn-get-nada.

Any ideas? What should I check next? I've only played her thru headphones, and haven't tried the line-outs yet.

[blooeyz]

hi fellow analoggers; I suggest you pull off the back cover and look for sliding contact switches on the lower mainboard.....make sure unit is NOT plugged in, spray into these best you can contact cleaner/lubricant working the switches back and forth.....failing the remedy by this effort, i suggest you ensure the source /tape monitor switch is working properly... clean and lube the slide contact switch attached to it from behind....i have one too..and will get back to you.... let me know if ny of this helps... blooeyz

[blooeyz]

So I dug my Akai GC-267D out of long term storage (~20 years), and brought her to the work bench. I cleaned out the back, dusted, checked the fuses, sprayed DeOxIt on the contacts and checked the lube (direct drive model).

I pulled out some old tapes, and fired her up. All seems to be working fine on the right channel, but the left channel is dead. I get spurious noises when I flip the Tape Monitor switch from Tape to Source and back, and the left channel meter may move slightly sometimes, but often not at all.

Back when she went into cryostasis she had a scratchy tape monitor switch that you had to move back and forth sometimes to get left side sound, but now I dunn-get-nada.

Any ideas? What should I check next? I've only played her thru headphones, and haven't tried the line-outs yet.

Hello again;
I would ALSO suggest you spray cleaner and lubricant (never wd40) into the tiny access holes in the side of the round pan pots behind the output level control. where the wires contact the panpot (*looks a bit like a mint or landmine) spray the cleaner/lube into the tiny holes into the pot as you rotate the output levels...and input levels...give them a few mins to dry....this should help... make sure the cleaner has dried before powering up the unit... hope this is helpful. BLOOeyz

[Scorpion8]

Well, that didn't seem to do it. I sprayed the two sliding switches quite liberally and worked them back and forth, and sprayed both the inside of the Line Out level and backside of the Tape Monitor switch and let it sit overnite. I have no left channel at all in either direction, but the right channel sounds fine. Oddly, I have about 7 V AC (fluctuating) going to the left channel meter just like the right channel meter, but still no sound. And the meter bounces a little on power-up so I know it's not dead.

What else should I try? Thanks for the help.

[Scorpion8]

Bump.

[Fred Longworth]

I don't recall if this model has plug-in circuit cards for preamps, but I think it does. Two for record preamps, two for playback preamps. (You can identify the playback cards because, if you lightly brush your fingers across them while the set is playing and hooked into a receiver, you'll hear the intrusion of the fingers and see it on the meters with the monitor switch in TAPE mode.)

You might try swapping the playback preamp cards. (I like to mark them with Sharpie pens so I don't lose track.) If the left channel continues to malfunction after the swap, then the problem is OFF card. If the right channel begins to malfunction and the left channel is "cured" after the swap, then you know the problem is in the playback preamps. Akai used some hi-failure single-in-line ICs in their preamps in those days.

Good luck.

Fred Longworth

[dr*audio]

Plug a source into it and see if you get output out of both channels in the source position. I think you have a dirty switch somewhere with crud in it that needs something stronger than De-Oxit. Try this stuff:
http://www.mcminone.com/product.asp?catalog%5Fname=MCMProducts&product%5Fid=20%2D2974
Then use De-Oxit as a preservative.

[Scorpion8]

I don't recall if this model has plug-in circuit cards for preamps, but I think it does. Two for record preamps, two for playback preamps. (You can identify the playback cards because, if you lightly brush your fingers across them while the set is playing and hooked into a receiver, you'll hear the intrusion of the fingers and see it on the meters with the monitor switch in TAPE mode.)

You might try swapping the playback preamp cards. (I like to mark them with Sharpie pens so I don't lose track.) If the left channel continues to malfunction after the swap, then the problem is OFF card. If the right channel begins to malfunction and the left channel is "cured" after the swap, then you know the problem is in the playback preamps. Akai used some hi-failure single-in-line ICs in their preamps in those days. Good luck. Fred Longworth

Thanks. They aren't plug-in circuit cards. All the pre-amp seems to be on the bottom plane mainboard. There is a large circuit board and a line drawn down it that says <-LEFT | RIGHT -> under the sliding metal switch that's activated by the directional solenoids. And believe me, I've blasted the bejesus out of the sliding switch with RatShack Contact/Control Cleaner & Lubricant (very very hard to get DeOxIt up here in SEAK). I also cleaned & lubed any switches on front (rotary or flip).

Of course it's at home and I'm at work right now ....

[Scorpion8]

Plug a source into it and see if you get output out of both channels in the source position. I think you have a dirty switch somewhere with crud in it that needs something stronger than De-Oxit. Try this stuff:
http://www.mcminone.com/product.asp?catalog%5Fname=MCMProducts&product%5Fid=20%2D2974
Then use De-Oxit as a preservative.

Thanks. I'll try the source inputs when I get home. Those always worked fine way back before it went into cryostasis, it's just in the monitor position that was finicky.

ETA: ps - I may be able to get that Permatex contact cleaner at Western Auto. They carry a wide variety of Permatex products.

[Scorpion8]

Okay, some more info. If I hook up a source to the input jacks, I get meter movement and stereo sound from both channels if I flip the "monitor" switch to "source", When I flip the switch to "Tape" and the tape is playing on the RTR, I only get sound out of one channel (right). Sounds like the Tape Monitor switch is faulty on one side? I mean I've gone thru a can of contact cleaner already, and there's no scratchy attempt to get sound thru that sounds like a dirty switch.

Any other ideas?

[dr*audio]

If the bad channel is completely silent, it is probably not the switch. There may be a playback adjustment pot that is dirty, a bad cap, or the head could even be dirty.

[Scorpion8]

So what's my next step? Any ideas would be helpful and appreciated.

[dr*audio]

1. Clean the heads until nothing comes off, even if they appear clean. A smalll speck of oxide in the head gap can cause a chennel to almost completely drop out.

2. Check to see if the channel works in reverse play. If so, the problem is either a dirty head switch, a broken wire or connection on the forward playback head, or a bad palyback head.

3.. If you don't have the service manual you should get one. You need to locate the playback level adjustments on the playback pc board. When You find that adjustment, mark the position of the adjsutment pot, shoot it with some cleaner and work it back and forth. Do it with both channels. See if the channel comes back.
4. If this doesn't work you will need to troubleshoot the circuit. If you can't read a schematic, you will have to take it to a professional.

[Scorpion8]

Well, it's an auto-reverse playback-record RTR so there are separate playback and record heads for each direction. I've cleaned all four, but "yes", the left channel is dead in both directions on playback. I didn't think it was in the heads, as it's always played and recorded fine. As I said, when a source is hooked up there is sound in both channels on the "source monitor", just no left channel sound at all on "tape monitor" in either direction.

Back in the day, before I put it away for storage, it was scratchy on the "tape monitor" switch left channel and sometimes dead, but if you flicked the tape/source monitor switch up and down a few times it would clean the contacts (I assumed) and then play fine. I always meant to clean the contacts back then, but life happens and it got put away in storage for way too long.

I'll check the heads and clean them again, but logically that doesn't sound like the right path. But I certainly do appreciate all the help. Thanks.

[dr*audio]

Since it does it in both directions, that vindicates the heads, head switch and probably the wiring. You are left with the playback amp and the tape monitor switch. I would go back to the switch since it caused a problem on the same channel originally. Re-clean the switch with a non-residue contact cleaner, NOT De-Oxit, it isn't strong enough. Try:
http://www.mcminone.com/product.asp?catalog%5Fname=MCMProducts&product%5Fid=20%2D2974
Inject it into any opening in the switch body and work the switch back and forth 30 times or so. If this doesn't fix it, I doubt the switch is bad, I would go to the playback board next.

[Scorpion8]

Well, I don't think it's the switch. I've cleaned it with everything I can get my hands on to no avail. There's not even so much as a hum thru that side of the deck during playback except when I have a line-in source playing, and then it sounds fine thru that side. I ordered a service manual which should be here in a day or two, so I guess the playback amp is my next area to concentrate.

[Scorpion8]

Doc - this is the SM scan.

http://audiokarma.org/forums/attachment.php?attachmentid=26647&stc=1

Any ideas where to proceed next?

[dr*audio]

The only pins you need to be concerned with are the top pins, the first 6 starting from the left side. You can ignore the far right pin. Each channel is switched by 3 pins, and the middle pin of each group of three is the output. So from the left, measure the resistance between pin 2 to 1 and from 2 to 3, then flip the switch and repeat. In the tape postion you should read 0 ohms from 2 to 3, and in source you should read 0 ohms from 2 to 1.
Now measure from 5 to 4 and from 5 to 6. Flip the switch and repeat. In the tape postion you should read 0 ohms from 5 to 6, and in source you should read 0 ohms from 5 to 4.
If the switch is good, you will have to inject a signal at the input to the board and probe the circuit with your meter on AC volts to see where the signal disappears.

[Scorpion8]

I have managed to procure a TAPE/SOURCE switch for this deck from the Netherlands, and will install that soon. However, with the switch jumpered out right now, I am still getting no signal on the left channel in either direction. If I remove/desolder the long sliding switches on the amplifier PCB (I know there's good signal down to them via the head block leads) I've heard that these have to be disassembled to get cleaner inside. Can a small jewelery-type ultrasonic cleaner be used to get cleaner into these switches instead of disassembling them?

[Scorpion8]

After many months, I replaced TR9 and TR10 in the left channel at the suggestion of dr*audio. An amazing guy, and that was the solution. The left channel issue is all gone (and I've got lots of cleaned and lubed switches as a result of all my troubleshooting and fiddling).

Anyway, I can't than Warren enough. Amazing! The deck lives and is playing Triumph's Rock and Roll Machine recorded on the same deck in 1980ish. Sounds superb!

I'm back in the reel-to-reel era!