Film-Tech Forum ARCHIVE: Ampex AG-440 Tape Deck... Need info.

This is topic Ampex AG-440 Tape Deck... Need info. in forum Film-Yak at Film-Tech Forum ARCHIVE.

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Posted by Bruce McGee (Member # 131) on 11-05-2001, 09:47 AM:

SUCK-UP TIME:

Please dont kill me for posting this here, but I know of no other place with a better group of trustworthy electronics-types on the net.

I rescued the AG-440 from the junk heap, along with a like-new ReVox deck. The ReVox is working fine, after some cleaning/lubricating. The 440 hasblown the 1/2 amp fuse on the power supply unit under the deck control buttons. Just after this fuse is a big wirewound resistor that has overheated, and is checking OK, but 200 ohms higher than the rating.

Before I got it, someone tried the old "Lets put in a bigger fuse and see what happens" trick that I love so. There was a 3 amp-er in there, unblown. The big resistor glows cherry red. but I only saw that once!

The fuse controls the brake operations, and the pinch roller.

It still blows the fuse after all of the solenoids, etc, are unplugged from the power supply, so I know the problem is inside.

There are tons of diodes in this machine. I dont want to just start cutting wires to test all of them.

Has anybody got a schematic of the control circuits on this machine? If you need more info, just email me and I will get it pronto.

I COULD NOT let this machine just go to the dump. It is beautiful!!!

What a piece of workmanship!

PLUS I have lots of 10" reel-to-reel tapes (half-track) that will love to be run on this machine. The ReVox is a half-track, too.

As usual, I appreciate all of you, even Joe R.

Posted by Jerry Chase (Member # 660) on 11-05-2001, 01:03 PM:

Have fun:
http://recordist.com/ampex/apxschem.html

Posted by Bruce McGee (Member # 131) on 11-06-2001, 01:58 AM:

Jerry, THANKS!!

This site is so big, that I need to go log on at work and access it. WebTV couldn't cut it. Thanks A Million.

Posted by Jerry Chase (Member # 660) on 11-06-2001, 10:47 AM:

Glad to help. I used to think the Ampex decks at my dad's radio station were the coolest things. Then I went with him to see the custom McCurdy equipment installation at the CBC in the late 1950s. Awwww jeeze. Take a kid and show him a starship bridge. Then make him go home.

Posted by Mark Gulbrandsen (Member # 72) on 11-07-2001, 04:04 PM:

I just recently sold off my Studer A-80 2 track. It went of all places.....to Alaska. I replaced it with a Technics Closed loop RS 1500 that I got at an estate sale for 30 bucks. The Technics has an amazing servo system, even better than the Studer had.......
Mark @ GTS

Posted by Bruce McGee (Member # 131) on 11-08-2001, 12:28 PM:

Mark:

Our company has a couple of those closed loop Technics machines. They've been through hell, but continue to run like a dream.

I attempted to run the big Recordist site that Jerry sent me last night at work. I had some trouble, so I'll get with the computer guru and work it out. The AG-440 is just screaming for service and will NOT go to the dump.

I let the electronics on it cook for 6 hours last night. Everything had a musty smell for awhile, but it went away. Now, the bias levels on the meters is exactly the same with no adjustments... before, there was a big difference. All the motors and pivots on the deck are clean and lubed. It's going to work... I can feel it in my bones!

Posted by Mark Gulbrandsen (Member # 72) on 11-08-2001, 08:01 PM:

Bruce,
Keep at it! There's no reason it should not work. If you do a rebuild consider using MIT multi-caps (type ppmxf) when you replace the coupling caps. They are the best I've found, but be prepared to spend about 15 bucks a cap. Also replace the power supply electrolytics and bypass them with film caps of about .05mfd. This will efffectively lower the power supply impedence quite a bit and will help lower noise floor even more. To make the rebuild even cooler you could use all film caps in the power supply and forget the electrolytics all together!!
Check out Bob Katz's web site and look at the old Ampex MR-70 electronics that he uses. Its among the last Ampex tube stuff built and even has regulated B+ supplies in it. The stuff's amazing!
His web site is www.digido.com
Have fun!
Mark @ GTS

Posted by Josh Jones (Member # 447) on 11-09-2001, 12:30 AM:

I also need help getting a Akai 280D-SS running. it had a control card failure as far as I can tell. please help, this machine sounded great for the few hours it did work. I first got it to run by tapping the control card with a screw driver, but it quit. It is a quad machine, runs great, or did. a control board schematic would be of great help.

Josh

Posted by Jerry Chase (Member # 660) on 11-09-2001, 09:00 AM:

Josh, jgl6008@juno.com has a spec sheet and user manual he is willing to copy for a few bucks.

Posted by Bruce McGee (Member # 131) on 11-09-2001, 11:10 AM:

Josh: I used to have a 280D!

Try this

Look for cracks in the solder on the control board. You may find some bad soldering too. Mine had a few bad connections, but never messed up after the repairs that I did on the board.

I missed the Guru yesterday. Plus, the Ampex site was down for awhile.

Mark: I was thinking about at least replacing the electrolytics in the power supply for now. The pre-amps will be a more involved project, as you know.

They tell me at work that this Ampex has been in storage for about 5 years in a dry place, and that it quit working a few days before it was to be replaced anyway.

That 3 amp fuse didn't help matters. I've found a 25w wirewound resistor of the same ohms rating as the one that smoked in my junk boxes. I have a feeling that even though the old one still works, the B+ wont be right. This is the 115v DC source. I got this much from the Ampex site that Jerry turned me on to...

Posted by Paul G. Thompson (Member # 655) on 11-12-2001, 11:14 PM:

Bruce, I'll have to check for sure, but I might have some bones that will fit your machine laying around in the radio station junk. I'll email you if I do.

Paul

Posted by Bruce McGee (Member # 131) on 11-13-2001, 10:27 AM:

Thanks, Paul.

Jerry: I'm on the mailing list for the Ampex site. I'm just reading for now. Some of these guys on the list are the designers of the AG-440, and others! I need to compose a really good email to send so I won't look like a spaz. Someone was looking for the "ready" and "record" lamps for a 440... They told him to convert to LED's...

Remember how I do things: On A Budget.

I'd like to find a paper service manual somewhere. I never liked microfilm copies of schematics.

(I KNEW that there would be some magnetic tape-types here at Film-Tech!)

Posted by Jerry Chase (Member # 660) on 11-13-2001, 10:26 PM:

"I'm on the mailing list for the Ampex site. I'm just reading for now. Some of these guys on the list are the designers of the AG-440, and others!"

Cool. Tell them they have admirers.

Now if the old electronic junk shops on Canal street in NYC would just re-open with all the stuff they used to have...

I snagged a lot of fixable stuff out of those bins. Turntable, a couple of amps, tons of early circuit board parts, all MIL spec. Most of the stuff I made didn't work or worked poorly, but it was fun and cheap to play around.

Posted by Josh Jones (Member # 447) on 11-13-2001, 11:29 PM:

well, I e-mailed that guy. I checked the board and couldnt find any broken traces. when the control buttons are pushed the relays dont even fire. It's probably something simple, but I wish I knew what it was.

Josh

Posted by Paul G. Thompson (Member # 655) on 11-14-2001, 01:26 AM:

Josh, check the relay armature rail supply to see if it even exists. Could be you may have a fried diode in a power supply. If nothing works, I would certainly suspect the control logic board or the power supply. If you get a roadmap on that critter, you and I will have that thing running very soon.

Paul

Posted by Gordon McLeod (Member # 33) on 11-14-2001, 09:05 AM:

Well just scoot up to Toronto we have a tone of electronic surplus joints up here (actually Mark G cleaned out one of them

)
Does any one have the drawings for the later AMpex theatre stuff after they were taken over as electrosound

Posted by Bruce McGee (Member # 131) on 11-14-2001, 10:43 AM:

Paul: I couldn't remember if Josh's 280 used a plug-in module or not. It's been a long time since I played with one.

I had an RCA CTC-35 color TV that had intermittent color issues. I could touch the board with anything and the color would pop back on for a minute or so. After days of head scratching, I eventually soldered the entire video/color/demod board and the traces. Fixed it so good, that it is still running every few days 22 years later!

Posted by Josh Jones (Member # 447) on 11-14-2001, 11:07 AM:

This particular control card is removable. It appears to have two card-edge connectors on the chassis. I am beginning to think it is a power supply problem, but at this point in the game, who knows.

Josh

Posted by John Anastasio (Member # 607) on 11-14-2001, 08:13 PM:

I installed and maintained AG440-4s in the Air Force recording studio I built in Germany back in 1970 and then used 440-2s for 14 years in a radio station in Princeton. I always like them. We couldn't get 1/2-inch tape for the 4-track models, so we traded stuff for the tapes the guys in the spook squadron were using on the computers! You've got a popped diode in there and a dried out cap or two. Use an in-circuit transistor tester and you won't have to unsolder everything to find it.

Posted by Paul G. Thompson (Member # 655) on 11-15-2001, 07:27 PM:

Bruce, we have the AG-350 series. Will that be any help? I have manuals on it, too. Jim (the owner) would be interested in selling you all that shit if you are interested. Firesale prices.....

Paul

Posted by Bruce McGee (Member # 131) on 11-16-2001, 09:10 AM:

Paul, I have to decline due to lack of space for anything unrelated to my current projects. The AG-350 is a different baby. A BEAUTIFUL baby, I might add...
John A. is right. I think I will find a blown diode is causing all the trouble. I just would like to have some literature to get this solved. There are several bridge rectifiers on this one.

Dont have an in-circuit checker at this time, but I do have a load of diodes...

I DID run a signal from the machine thru my mixer, to my amplifier last night. There's some slight hiss... on both channels.

There's no big rush to get this baby running. I've only got about 10 different projects going at most times. My Holmes 8's have to be run, too!

Posted by Bruce McGee (Member # 131) on 12-03-2001, 12:20 PM:

Alot has happened since the last posting here. I have been in touch with the Ampex guys on their site that Jerry turned me on to. What a wealth of information!

THEN: My guru at work found the original manuals for MY Ampex!

THEN: My digital meter died. It never was a really good one, but...

THEN: I got a new meter.

THEN: Found that my local parts jobber carries nothing that I can use in the form of caps, etc. anymore. I closed my account with them. I'll be buying on-line from now on...

I got the big filter cap. It arrived on Friday.

This weekend, I looked thru my garage for a Holmes base for a friend here on the site, and worked on the Ampex. I installed the cap, replaced the 4 bridge diodes, and found the total culprit: There was an intermittent diode across the tape-lifter solenoid that would short after a few seconds of "on"-time.

Replaced a total of 6 parts. I've invested less that $30 in this machine, so far.

I cant believe how good this machine is running with no adjustments anywhere, yet. Cooking the electronics seems to be what it needs.

Just so I can keep this thread film related, I didn't locate the Holmes 8 base for you, RICK! This is becoming a nightmare.

I will continue the search...

Ran some 2-track stuff after degaussing and cleaning everything. Sounds good, and smooth. Even my tone tapes sound good.

And to think that it all started on this FILM site. Thank you one and all. (Gush...Gush... )

Bruce