Ampex MM-1000 Story...

[sweetbeats]

Having now read that 1968 AES Preprint in its entirety I can tell you that I am of the firm opinion that the "24-track" machine (figure 1 on page 7 of the pdf) is NOT an operational machine but a mock-up.

The description of it doesn't match the production MM-1000 units in so many ways.

Under the "Console" paragraph on page 2 of the pdf it indicates that all electronics and controls are mounted below the control panel and we know the production 16 and 24-track MM-1000's weren't that way, and even some of the 8-track machines left the factory with all 8 electronics modules mounted in an overbridge for future conversion to 16-track using the empty bays below. The description of the electronics starts in the "Electronics" paragraph on page 3, and what they are describing is closer to what we didn't see until the advent of the MM-1100. It sounds to me like the idea of electronics drawers was there, but the use of the 440 electronics on the Mirasound AG-1000 stuck on into the production of the MM-1000. The MM-1100 and MM-1200 had 440 type amp cards loaded in pull-out drawers and indeed all 24 channels on a 24-track machine fit below the control panel. The piece that did come to fruition on the production MM-1000's was the 8-channel Sel-Sync modules described at the bottom of the second paragraph on page 4 of the pdf, though they weren't in "trays" but in 2U modules mounted above the electronics in the lower left rack. The guts of the Sel-Sync modules basically remoted components already present in the 440 electronics modules, but made the screwdriver adjusted controls accessible at the front of the machine rather than at the back of each electronics module which would be terribly cumbersome with the electronics mounted in the lower racks of the console.

Another interesting mention is on page 5 under the "Accessories" heading...the full-track earase head assembly...that assembly is pictured on both the "24-track" machine as well as the Mirasound AG-1000 in the document...that is nothing more than the full-track erase head assembly off the VR-1100. That assembly was removed from the Mirasound machine at some point, if it was even ever ON the machine when it was delivered as I have yet to see a pic of it at Mirasound with that assembly there...this AES paper is the first time I've seen that assembly on that machine. At any rate I have a hunch it made a convenient mount for an incoming guide to the head block.

Also, no production MM-1000's had a tip-up transport plate. That was a quad VTR thing...can't imagine ever getting it tipped up. That plate with the components mounted has got to be in excess of 150lbs...

 

[lukpac]

No doubt it was a prototype (of course, they *were* still referring to the machines as 'AG' rather than 'MM' at that point), although it would be interesting to know if it was operational or not. I wonder if maybe it *was* operational, but they weren't able to mass produce the new electronics until later for production use. Just speculation...

That does clear up my confusion over the description of the channel modules, though. I was reading and re-reading and thinking "this doesn't sound like the description of the 440 modules".

BTW, I think we determined that the first album recorded on 16-track (or, at least one of the very first) was the Lovin' Spoonful's "Everything Playing", done some time in the fall of '67. I suppose there were probably multiple projects going at the same time though.

 

[sweetbeats]

No doubt it was a prototype (of course, they *were* still referring to the machines as 'AG' rather than 'MM' at that point), although it would be interesting to know if it was operational or not. I wonder if maybe it *was* operational, but they weren't able to mass produce the new electronics until later for production use. Just speculation...

I would bet money that it was NOT operational and here's why: based on narratives of folks that worked at Ampex at the time there was general scoffing at the idea of 16+ track machines at the time...like "who would ever need that?" Mirasound was asking about it...then IIRC Ampex folks heard that 3M was working on one, and then Mirasound was asking if Ampex would at least make up a set of 2" 16-track heads...if Ampex wouldn't make the machine for them they were gonna do it themselves but they needed Ampex to make the heads. That made things look more serious and Ampex jumped to figure out what they could put together to respond to Mirasound's needs, so they grabbed the VR-1100 transport which was tried-and-true in a very pure sense of the phrase, and grabbed the 440 electronics which were very well designed and already well-received. That's the Mirasound AG-1000 prototype. Look at that machine side by side with a production MM-1000 and you'll see finishing details with some of the control panel elements and CERTAINLY with the description of the electronics...the Mirasound AG-1000 is MUCH closer to the production MM-1000's than the "24-track" machine pictured in the AES paper. No 24-track "trays" are shown because I have a hunch they only existed on paper at that point. Development of the MM-1100 didn't start until early 70's along with actual design of drawer-type electronics assemblies. Now take a look at the picture of the "24-track" machine and the pic I put up of the VR-1100E...actually, let me do it for you:

Now you tell me the differences between those two machines? Control panel elements and the "24-track" machine has the newer VR-1200 reel adapters, but the head cover is actually an older version than the one on the VR-1100E. My supposition is that the "24-track" machine is actually earlier/older than the Mirasound AG-1000...so you think they had 24-track heads and prototype "tray" electronics developed before the AG-1000? The '68 AES preprint was part of Ampex's attempt to assert themselves as the market leader of the 2" multitrack market so they were hyping stuff they hadn't made yet. The 16-track heads on the AG-1000 were one-of-a-kind at that point...there weren't even any 24-track heads made up yet.

I bet you if you could lift up the head cover on that "24-track" machine you would find...guess what...a quad VTR head assembly.

 

[lukpac]

Now you tell me the differences between those two machines? Control panel elements and the "24-track" machine has the newer VR-1200 reel adapters, but the head cover is actually an older version than the one on the VR-1000E. My supposition is that the "24-track" machine is actually earlier/older than the Mirasound AG-1000...so you think they had 24-track heads and prototype "tray" electronics developed before the AG-1000? The '68 AES preprint was part of Ampex's attempt to assert themselves as the market leader of the 2" multitrack market so they were hyping stuff they hadn't made yet. The 16-track heads on the AG-1000 were one-of-a-kind at that point...there weren't even any 24-track heads made up yet.

Like I said, you may very well be correct, and that pictured prototype may have been nothing more than a control panel. I just thought *maybe* they had (smaller) prototype electronics working but didn't feel they were quite up to snuff yet, so kept using the 440 electronics for the time being for customers. Just a theory...

As for that machine...I'll defer to you, but from what my untrained eyes can see, the Mirasound 16-track machine had the same head cover as the 24-track "prototype", as well as the older style reel adapters. Even if it wasn't functional, I'd have to think based on that (and the fact that, well, it was 24-track) it was newer than the original Mirasound deck.

It would be interesting to know if Ampex did any actual demos at that convention.

 

[lukpac]

To comment on this:

the Mirasound AG-1000 is MUCH closer to the production MM-1000's than the "24-track" machine pictured in the AES paper.

Well...yes and no. Obviously the MM-1000 went with the 440 electronics like the Mirasound machine, but the track switches on the panel of the 24-track prototype are similar or identical to those used on the MM-1000. In contrast, the Mirasound machine didn't seem to have switches on the front panel at all. From that standpoint, it certainly seems like that prototype (even if it was just the control panel) came after the Mirasound machine.

 

[sweetbeats]

I just thought *maybe* they had (smaller) prototype electronics working but didn't feel they were quite up to snuff yet, so kept using the 440 electronics for the time being for customers. Just a theory...

Well, I can't be a naysayer for sure, I just really doubt it because the timeline between Ampex saying "bah humbug" to anything larger than 1" 8-track and them delivering the 16-track modified quad VTR to Mirasound was a surprisingly short span of time, and the later MM machines were the first to use the drawer type configuration for the amp electronics. Everything up to that point had been the 2~3U single-channel modules.

f...rom what my untrained eyes can see, the Mirasound 16-track machine had the same head cover as the 24-track "prototype", as well as the older style reel adapters. Even if it wasn't functional, I'd have to think based on that (and the fact that, well, it was 24-track) it was newer than the original Mirasound deck.

I was trying to figure out what picture of the Mirasound AG-1000 you were looking at because in the AES Preprint and in the more recent auction pics the head cover is a much smaller black affair...I see now that that pic at the time of delivery at Mirasound that it has that same flat-topped full-width cover...the listing pics for the AG-1000 show it with the later VR-1200/2000 reel adapters utilized throughout the MM-series run, but yeah I see in that pic from delivery day it has the older VR-1100 reel adapters. Good stuff!

I still highly doubt that tray-type electronics physically existed during the MM-1000 production run.

Well...yes and no. Obviously the MM-1000 went with the 440 electronics like the Mirasound machine, but the track switches on the panel of the 24-track prototype are similar or identical to those used on the MM-1000. In contrast, the Mirasound machine didn't seem to have switches on the front panel at all. From that standpoint, it certainly seems like that prototype (even if it was just the control panel) came after the Mirasound machine.

Well excellent points there too. Can't disagree with you. The Mirasound machine required track arming and monitor source selection at each electronics module, and sync level and bias trap adjustments at the back of the modules. Relatively primitive. And actually I believe the AG-1000 did not even have lifters.

I put a post to the Ampex List to see if there is more information, even anecdotal, on this subject.

 

[sweetbeats]

Vr-1100 *not* vr-1000

Whoops!

I made a typo above that stuck and got replicated a number of times. I've known that the MM-1000 was based on the VR-1100E but I typed VR-1000...

I've corrected my posts but any quotes taken from my posts prior to correction will forevermore display my error, so just to be clear the Ampex quad VTR that was modded to make that "Mirasound" AG-1000 was a VR-1100E.

 

[sweetbeats]

24-track heads were around (and other interesting bits)...

I've gotten some great feedback from my inquiry over at the recordist.com Ampex List on that AES Preprint lukpac brought forward.

24-track heads had indeed been made by Ampex by the time of the 1968 Preprint.

This can be verified because on page 4 of the pdf at the bottom under the description of the heads it mentions that the erase head is split into 2 staggered 12-track stacks. This is because the heat cracked the original single 24-channel stack so it was split into the 2 staggered stacks. Obviously if the Preprint touts 2 staggered erase stacks they already had the 24-track heads and had gone through the teething of the 24-channel stack failure.

A couple responses I've gotten assert that as soon as Ampex bit on the 16-track idea they were already thinking 24-track, so there you go.

I haven't gotten any confirmation as to whether or not there are actually 24-track heads under the cover of the "24-track" machine pictured on page 7 of the pdf. The first 24-track heads were fitted to the "Mirasound" AG-1000, but the indication so far is that 24-channels of electronics were NOT installed in the belly of that "24-track" machine; that the "tray" type audio electronics were not developed for the MM-1000 series.

 

[sweetbeats]

Information direct from the source...

I was hoping George Schowerer would chime in on my inquiry regarding the AG-1000/MM-1000 history over at the Ampex List and he did. If you don't know who George Schowerer is, please Google him to get an idea. I believe it would be worth your while.

I asked George if he would be alright with me quoting his responses here as I felt it would be valuable to have included in this body of information on the MM-1000. So with his permission here is what he had to say:

"Cory: The Mirasound AG-1000 was the culmination of many hours, previously, of suffering through sessions requiring multiple, multiple, and more multiple overdubs and bouncing of tracks. Our experience with producers like Bob Crewe (especially), who needed extra layers of foot stomps, handclaps, tambourines, background vocals and even brass and strings led to the exploring of a large recorder with added tracks. We had lived through the 4 and 8 track Ampex recorders by bouncing the various tracks and continuous additions to the recordings. Since the "sync" playback on all Ampex units suffered from restricted response, I chose to bounce all tracks in the regular playback mode to maintain quality during the myriad of overdubs. This placed those "bounced" tracks out of sync with the remaining tracks, so I had to eventually "bounce" all tracks using that method except the last track for vocal. Working with our 8 track AG-300-8, it quickly became evident that we needed more tracks in order to keep things from having to be sub-mixed down several generations. Samples from the AG-300-8 are "Can't Take My Eyes Off You" by Frankie Valli and other late sessions with the Four Seasons and the Crewe "Girl Watchers" albums.

The owner of Mirasound was Bob Goldman. Bob was a good tinkerer, so he and I set about designing a 16 track recorder, and since I had a 2" VR-1000 hulk and between us we had plenty of AG-350 electronics (probably 30-40 units), we came to the point where we needed someone to build the 16 tracks heads. We met Leon Wortman of Ampex at the Cattleman restaurant in New York City, and proceeded to sketch a drawing of what we intended to do on one of the restaurants cloth napkins (which I think Leon must still have). Anyhow, we parted that night with the feeling that Ampex would be the maker of a head assembly for our new idea. Two days passed, and Bob received a call from Leon implying that since the Ampex name would be on the unit, Ampex would prefer to make the whole recorder and lease it to us. The deal was made and I then made cables in order to facilitate the arrival of the unit. Since it would not fit into the control room immediately, we planned to operate the unit from the clients waiting room. Well, the unit arrived at 10am in the crate, and we had it connected and checked out in time to do a session at 8pm that same night. The session was "With This Ring" by the Platters, produced by Luther Dixon. So I became the very first engineer to record in 16 tracks. Sessions with the Skyliners followed the next day..."Dry My Tears". It was no easy task since the Mirasound console was 12 inputs to 4 output busses. In preparation for this doubling of tracks, I set about adding outboard mixers to feed all those added tracks, and literally used the console (with an added 4 track mixer) to become the monitor mixer. Skip Juried, my machine man on the AG-1000 was the backup level protection. He was a best friend who later died unexpectedly at age 45. It was a crushing blow, since he knew of every session of hit records we had done....and since I didn't keep track, we lost the list, because neither of us wrote them down. When I say busy, I mean unbelieveably busy. There were times when each of us slept on the couch for just a few hrs. at times...all because everyone wanted to use the new system. The AG-1000 had NO TAPE LIFTERS, so the outputs had to be muted during fast fwd or rewind. That recorder worked continuously for three yrs. day and night with never a hickup or problem. It was a bare bones recorder that proved to be bullet proof. Our first 24 track unit worked for less than 4 hrs. before the erase headstack (in-line) cracked and then had to be refitted with staggered erase heads, leading me to wonder just how much time the unit ran at Ampex before delivery. All in all it was a hell of a time in the recording industry.

Regards, George S."

 

[lukpac]

Good stuff!

I haven't gotten any confirmation as to whether or not there are actually 24-track heads under the cover of the "24-track" machine pictured on page 7 of the pdf. The first 24-track heads were fitted to the "Mirasound" AG-1000, but the indication so far is that 24-channels of electronics were NOT installed in the belly of that "24-track" machine; that the "tray" type audio electronics were not developed for the MM-1000 series.

Yeah, I wouldn't have expected as much. Still curious if perhaps there was an internal prototype at the time...

I was just about to say "George Schowerer is a person to ask" when you posted his response. Perhaps you want to ask him this...

That AES doc notes the 16-track was installed in the fall of '67, and I've heard that The Lovin' Spoonful's "Everything Playing" (released in January of '68 or so) was one of the first albums recorded on it. George notes "With This Ring" was the first song recorded on it, but that was *released* in early 1967, several months before the (apparent) arrival of the AG-1000. Any ideas? I'm trying to find information on that Skyliners song he mentioned, but I'm having a hard time.

Also, you just mentioned the VR-1100E, but he just mentioned the VR-1000...

 

[sweetbeats]

I can't really comment on the matter of the release date of "With This Ring". Where are you referencing the early '67 release?

On the VR-1000 that was the VTR that Bob Goldman and George Schowerer were going to convert and use AG-350 electronics and they met Leon Wortman to see if Ampex would make the heads. Ampex took the idea and ran with it using the VR-1100E transport and AG-440 electronics.

 

[lukpac]

I can't really comment on the matter of the release date of "With This Ring". Where are you referencing the early '67 release?

Billboard:

Billboard - Google Books

On April 15, 1967 it had been on the charts for 7 weeks.

Feb 11th mention:

Billboard - Google Books

On the VR-1000 that was the VTR that Bob Goldman and George Schowerer were going to convert and use AG-350 electronics and they met Leon Wortman to see if Ampex would make the heads. Ampex took the idea and ran with it using the VR-1100E transport and AG-440 electronics.

Ah, got it!

 

[lo.fi.love]

Does this mean that the Ampex MM1000 is at its heart a sixteen track AG440?

 

[sweetbeats]

Oh Jeff you dog! Now you've got me all fired up to wax all philisophical and whatnot...

Couple different ways to look at it I guess.

From a functional standpoint the MM-1000 and AG-440 have a lot of similarities. Both are fairly basic transports with static tension control (i.e. fixed holdback tensions as opposed to servo control dynamic tension)...good old "drag the tape on through" transports with relay logic. So with the MM-1000's use of AG-440 electronics and the functional similarity of the transports then yes one could say the MM-1000 is like a big overgrown 2" AG-440. A friend of mine very familiar with the 440 series as well as the MM-1000 said of my MM-1000 when I first got it "What you've basically got there is a big overgrown 440-8" (since mine is at present and was at the time a 1" 8-track). It is easier to compare the 440-8 and the MM-1000-8 since they are the same format and the 440-8 includes a critical comparative element with the viscous reel idler flywheel...that flywheel that's full of silicon fluid...as well as an additional rotary guide making the tape paths more similar.

I, however, really see the MM-1000 as a 2" quad VTR at its heart. That's really what it is. The AG-440 series was originally designed to handle 1/4" to 1/2" tape, period. The 1" 440-8 does what it does just fine but upon close study you'll find where Ampex had to beef things up to make it handle 1" tape satisfactorily and some disagree that it was satisfactory, namely some folks that were involved in the original design of the 440 series. The MM-1000 on the other hand was designed from the ground up to "manhandle 2" tape on 14" reels" (quoting myself), so there are vast differences in the transport mechanicals and from that standpoint there really is no comparing the MM-1000 and the AG-440 AFAIC.

So the answer to your question is "yes" and "no". If you consider the heart of the machine to be the amplifier electronics and heads, then you betcha, the MM-1000-16 is akin to a 16-track 440. If you consider the heart of the machine to be the transport mechanicals then no the MM-1000 is a quad VTR converted for multitrack audio mastering. I think the latter description really nails it on the head (no pun intended) since that is, quite simply, how the MM-1000 was born, and those that have used, for instance, both the 440-8 and the MM-1000-8 say the MM-1000 has a sound character unique from the 440-8. It shouldn't, considering the same heads and electronics (up until the 440C), but maybe its the considerable differences in the tape path, the mass of the machine...a more stable transport plate...who knows.

 

[sweetbeats]

George Schowerer at the helm at Mirasound:

 

[lukpac]

More Mirasound...I found a transcription of one of the articles posted on Flickr, and it appears there's slightly more:

Mirasound Studios: First Studio to Use 16-Channel Recording

In 1967, Mirasound recently moved to its new enlarged quarters on 57th Street. Five studios, four for audio, one for video, made up the complex. Always considered a leader at innovation, it was the first studio to put in 16-channel recording with the new Ampex two-inch multichannel recorders. Since receiving the recorder, it operated 10 to 12 hours each day. According to Robert Goldman, President of Mirasound, "When recording today's modern sounds, the Ampex 16-track recorder produces higher quality recordings. We find the new Ampex machine provides the maximum recording versatility and economy." In 1968 Mirasound will increase its multichannel capability even further with the delivery of two new MM-1000 multichannel recorders, one a 16 channel version, the other a 24 channel. "The new Ampex Master-Maker will offer us even more opportunity for creativity," Goldman said. The AG-1000 is a custom version of the new MM-1000 series, built especially for Mirasound. Both use Ampex videotape transports for two-inch tape, combined with electronics from Ampex's top-of-the-line AG-440 recorder.

"With our 16-track recorder," Goldman said, "individual instrument sounds can be recorded on separate tracks, separately equalized, deleted or combined with other sounds on the tape at a later mix-down session." Having many tracks available means that a sound of doubtful quality can be temporarily saved and evaluated later. For example, a drum take can be compared with later takes with only the best one being saved for master recording. "With 8-track recording, tracks sometimes had to be cleared for this type of sound saving," Goldman continued. "Tracks one and two might have had to be combined and recorded on track three so that the second drum take could be recorded on track one. In doing this, track three became second generation, possibly of lesser quality than the original tracks. Tracks often had to be dubbed any number of times with the resultant music diminished in quality from the original." The final master tapes at Mirasound are mixed to two-track stereo for album release and single channel mono for singles on AG-350 recorders.

Some of the groups that recorded regularly at Mirasound are The Lovin' Spoonful, The Happenings, Vanilla Fudge, The Doors, The Charrells (the first group to use 16-channel recording), Frankie Valli, The Bob Crewe Generation, and folk singer Janice lan. The Bob Crewe Generation did the "Girl Watchers Theme" at Mirasound, originally as a Pepsi Cola commercial. It was later released as a successful popular record. At a recent session, the rhythm section of the Lovin' Spoonful group was being recorded on the 16-channel Ampex recorder. This included a bass guitar, a piano and an autoharp on tracks two, three and four. Channel eight recorded a composite of the three other channels. Later in the evening the lead guitar and drums were added on tracks one and five. Just before the session broke up at midnight a second drum was added on track nine for more rhythm. On the following day a vocalist (and possibly a back up vocalist) were to come in to record the vocal part. Then Joe Wissert, the producer on these sessions for Kama Sutra, and the band got together to decide whether any other musicians should be added. Possibly a second lead guitar, another piano, or some brass, for a total of as many as seventeen or eighteen instruments might make up the final recording. This session was for one of a group of songs which eventually will come out in an album. The recording was done at 15 in/sec. In total, some 40 to 50 hours will be spent to record the dozen or so selections for the album.

Flexibility with 16-track recording means that the best of the session can be mixed later to achieve the desired end product. Frequently, these groups haven't decided exactly the sound they are looking for on a particular song. Multitrack recording has benefitted them greatly because with a good sound mixer and control board the song can be re-assembled without interference between channels after the recording is done. Mirasound's board has four output busses and inputs for about a dozen microphones. The microphones include Electrovoice and Neumann condenser types used extremely close to the instrument for maximum isolation between channels. Each member of the recording group wears earphones to hear a composite signal of all instruments so they can get the total effect.

IDM dance & surround production

Interesting how The Record Plant is often mentioned for their 12-track Scully when Mirasound was using 16-track the year before. Another bit farther down on that page:

"On December 4, 1969, the new LA studio on Third Street opened its doors, and a bricklayer built an autographed lobby wall that would stand for 15 years. The tracks increased from 12 to 16, and next, the studio boasted the first 24-track in the world."

Wrong!

 

[sweetbeats]

it figures...

So I've been plugging away with some guidance trying to figure out why the transport won't latch up in PLAY mode anymore. One would think it might be obvious since it is all big fat point-to-point wired relay logic and the problem didn't manifest until I replaced a certain relay blah-blah-blah...the more I dig the cloudier things become.

I'll spare the details but basic troubleshooting measures were bringing bizarre results like, for example, finding a ground wire with 120ohms of resistance where there should be none...put in a temporary jumper wire and *blink* the 24V supply short-circuit protection kicks in, all because I made something correct to the schematic.

This is great...my preference for relay logic TOTALLY being put to the test.

So after a number of hours spanning several days staring at this thing I widen my scope from just the three relays involved in PLAY mode and I start looking at all the wiring annnnd......there is a significant amount of wiring that is non-factory. There are a couple of resistors, some diodes and a dozen or more wire runs that don't match the schematic and I can see the factory solder joints still where wires were clipped. Something strange is afoot in my control box...

Grumble-grumble...pull the control box out again and spread papers all over the floor...

So now I start thinking what a project its going to be to straighten it all out. My friend cautions "Don't do that..." and brings up the very valid point that field engineers made factory updates to machines all the time that may or may not have been captured by later versions of schematics, or maybe not at all.

Urg...what to do...

We get it to work right by hanging another cap on one of the caps on the diode PWA...

And I'm sure you're all shocked and awed when I tell you that even though its working I'm not satisfied. 'Cause its not RIGHT!

Okay...I know...I have a later version of the control box schematic...I'll look at that for changes and see if any match up with the wierdness on my assembly. Nope! The updated schematic is identical to the older one except for some convenient labeling of the connector pins.

Ah! I have a spare control box that came with my machine but it is from a late model MM-1000 whereas mine is very early. This one:

I haven't looked at it in a long time. So I dig it out annnnnd...all the wiring matches the schematic with a couple minor differences which actually make perfect sense.

So I start thinking maybe I can just drop this control box on my chassis and be done with it because the wiring isn't all rats-nested and I recall that the relays actually seemed like they were in good shape on the spare unit. Simple enough, right? But...but...its FILTHY!!! I mean it really is dirty.

Within a few minutes I've got the harness out with the PCB's and the relays:

I clipped the capacitors off the diode board...they looked a bit gamey. I'll have to get some new ones pronto.

Here's the harness and associated components:

Toothbrush, small bristle brush and a hose on a hot sunny day. Scrub-scrub-scrub...took about 20 minutes. Not super clean but MUCH better and good enough for me. Here it is drying in the afternoon sun. I'll let it sit out all day tomorrow too:

I also washed the control box chassis...looks MUCH better now, though I'm going to put some polish on it tomorrow.

So that's where I'm at...need caps, polish chassis, probably open the relays up and wipe down the contacts reassemble, put on the ear protector muffs and safety glasses and see what happens...but I'm pretty hopeful. No more funky control box wiring. I feel I am an expert on the transport control box now though...really.

 

[lukpac]

We get it to work right by hanging another cap on one of the caps on the diode PWA...

How on earth did you come up with *that*?!

 

[sweetbeats]

How on earth did you come up with *that*?!

With a lot of time staring at schematics with the control box in front of me...and some help too of course.

But it makes sense when you understand the circuit.

C3 is the cap that has the extra cap hanging on it.

What C3 does is store a small charge inline with the path that energizes the coil of one of the play relays when you hit the PLAY button. Pressing PLAY also momentarily energizes the stop relay via a separate path. Why does the stop relay energize when you hit PLAY? FFWD, REW and PLAY relays all get their holding current through the stop relay, and in all those cases when you put the transport into any of those modes the stop relay closes momentarily with the respective transport mode button (opening the holding current path) to clear any transport mode present when you hit the button for whatever mode you want to enter. So the stop relay is only closed while you hold the PLAY button...as soon as you release the play button the stop relay opens and when the stop relay is open the path for the holding current to the play relay is closed and that play relay has to ALSO be closed to complete the holding circuit. So C3 stores a small charge so that when you release the PLAY button that play relay lags behind in opening...C3 holds it closed a little longer so there is time for the stop relay to open and close the holding circuit while that play relay is still closed.

C3 was suspect all along because that play relay wasn't latching when I'd hit PLAY, but would latch if I manually closed the relay...that means the wiring that completes the holding circuit was okay but something wasn't right from the energizing circuit from the PLAY button. I'd checked voltage from the PLAY button and the rest of the circuit up to that play relay, to and from C3, etc. I don't have a way to test C3 by itself. Putting that second cap in parallel with C3 tells me something isn't right with C3 or C3 isn't big enough for the new relay...different current draw between the old cap and new cap? Dunno. This process is how I also discovered the 120ohm resistor inseries with the ground circuit for the diode board that the caps are on.

Its all funky.

Somebody, for SOME reason, did a healthy amount of creative re-wiring in there and I'm pretty confident that it wasn't necessary stuff (i.e. kludgey repairs rather than finding root causes and rectifying the issue or issues properly).

 

[lonewhitefly]

i'm a little late to this discussion, but i believe the first 16-track-recorded LP was "Everything Playing" by the Lovin' Spoonful, released Sept '67.