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  • Want To Buy: Lowrey Pac Network / Couplate / PEC Schematics

    I'm looking for the set of schematics describing Lowrey's "Pac Networks". These are the integrated modules containing the passive parts of divider, keying, and filter circuits. They have also been called various other names, including Packs, Couplates, and PECs (Printed Electronic Circuits). In Lowrey's terminology, it seems Couplates are the thin modules with all parts printed on a ceramic substrate, and usually covered with a brown coating. Packs are thicker modules comprised of cylindrical resistors and capacitors wired to a common backing and covered with a thick red coating. I am interested in info on both.

    Organ Service Corporation once sold the schematic set, as can be seen here under part number 949-000001-000, so I know it exists. But that company went out of business a few years ago, and I haven't been able to find the info anywhere else.

    My main reason for wanting the set is for reference in case one of these ever goes bad in my 1960 Lowrey Festival FL. It uses many of them, such as types P-7275-1 (1st divider), P-7273 (F-B keyer), and various filter modules with no listed part numbers in the FL schematics. If all else fails, I could try reverse-engineering (or re-engineering) and making guesses based on other Lowreys, but it would be nice to have the real info if possible!

  • #2
    I cannot help with the exact item you are looking for, but I have a 1968 CMI service clinic technical service manual in my collection that covers the TLS/TLO/HR models and in one of the theory of operation sections it appears to show the keying networks, sustain and non sustain networks. Are these of any use to you? I am only familiar with the Holiday and Berkshire TBO transistor Models but wondered if the filtering would be the same. I’ve attached an example. Once the pandemic is over I plan to scan all of my Lowrey manuals at my wife’s office so that they can be shared.

    Attached Files
    Hammonds; BV, M101, T202, T402, R100
    Lowreys; Heritage DSA, Berkshire Deluxe TBO-1
    Farfisas; Compact Duo MK2, Professional 110R, Compact Deluxe
    Analog Korg CX3
    Leslies; 147, 145, HL822 ​

    Comment


    • #3
      Thanks Dave. It is interesting to compare Lowrey's transistorized designs to their tube ones – from that picture, I can see the principles are basically the same in the generator section, though the details are different. Unfortunately, it is mostly the details that I'm concerned with. The part numbers of those modules don't match anything in the FL, nor do the pinouts seem to match. The component values are also not helpful, being chosen for the lower impedances and voltages of transistor circuits. Too bad that my FL schematics don't diagram the "pacs" like that manual and some of my Holiday manuals do!

      Thanks again in any case. I would be quite interested in seeing the scans of these Lowrey manuals once you get the chance to make them, since even the transistor models have very few scans online.

      Comment


      • #4
        That’s a shame, but only to be expected I suppose. It was worth a shot! We are hoping to go to my wife’s company to check the premises next week and I intend to do my scanning then. I have a TLOR1 mint owners manual, not currently available on the web, a mint service manual for the same which should yield a higher quality transfer to the one currently doing the rounds. I also have a mint condition Berkshire TBO owners manual with TBO-1 supplement which is not currently available, a photocopy of the TBO-1 service manual, not currently available and finally the technical guide for the lower spec mid sixties transistor organs.
        Hammonds; BV, M101, T202, T402, R100
        Lowreys; Heritage DSA, Berkshire Deluxe TBO-1
        Farfisas; Compact Duo MK2, Professional 110R, Compact Deluxe
        Analog Korg CX3
        Leslies; 147, 145, HL822 ​

        Comment


        • #5
          I assume this should be pretty close for the P-5789-x's used on the preamplifier of the Festival. (Capture from the Electric Organ Handbook I found somewhere on the Internet.). This is from an older model using 6SL7's and discrete components instead of the PAC's and 12AX7's, but the differences are probably minor. I just recently ran into an issue on several of these on my Festival FLO effectively causing them to shut off. For a temporary fix, I just disconnected the wire from the PAC to pins 2 and/or 7 (grids) on the corresponding filters and soldered in a jumper resistor (150k in my case, close enough!) from input of the filter (pin 4 on the PAC if I remember correctly). Works fine – the sine waves are not as pure as previously, though, since the filtering is not as effective. I might do some replacement PAC's in the future, but let's see.. Click image for larger version

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          Comment


          • #6
            And here's a bit more, these are from the service manual of the Lincolnwood (SSO-25) of the same era. With the exception of the power supply and amplifier, the circuits are very similar if not identical to the Festival. I am also experiencing some issues with some of these, causing one frequency to play in the background all the time with some registrations. Temporary fix was again to unsolder one lead from one of the P-7719's – now the lowest C of the 2' registration does not play, but the registration itself is usable (with the exception of the lowest C, of course!)
            Attached Files

            Comment


            • #7
              I assume this should be pretty close for the P-5789-x's used on the preamplifier of the Festival. (Capture from the Electric Organ Handbook I found somewhere on the Internet.). This is from an older model using 6SL7's and discrete components instead of the PAC's and 12AX7's, but the differences are probably minor. I just recently ran into an issue on several of these on my Festival FLO effectively causing them to shut off. For a temporary fix, I just disconnected the wire from the PAC to pins 2 and/or 7 (grids) on the corresponding filters and soldered in a jumper resistor (150k in my case, close enough!) from input of the filter (pin 4 on the PAC if I remember correctly). Works fine – the sine waves are not as pure as previously, though, since the filtering is not as effective. I might do some replacement PAC's in the future, but let's see..
              Thank you; this diagram is certainly the best reference I've found so far in lieu of the real schematics. The only likely difference may be in scaling of the component values to alter the input/output impedances. And that is a funny fix – you basically turned those filter-amps into more non-filtering "string" amps. I bet the flutes are especially unusual, with some portions of the manual sounding very pure, while others are practically raw squarewaves! If you ever get a chance, it would be interesting to know the result of directly substituting the PAC with the relevant circuit from the Electronic Organ Handbook. Also, coincidentally, I scanned and uploaded the EOH to my own site just a few months ago. This looks like it's from a different scan, but still, a funny coincidence.


              And here's a bit more, these are from the service manual of the Lincolnwood (SSO-25) of the same era. With the exception of the power supply and amplifier, the circuits are very similar if not identical to the Festival. I am also experiencing some issues with some of these, causing one frequency to play in the background all the time with some registrations. Temporary fix was again to unsolder one lead from one of the P-7719's – now the lowest C of the 2' registration does not play, but the registration itself is usable (with the exception of the lowest C, of course!)
              Now this is quite interesting – those generator and keyer circuits actually use the same couplates and tubes as the DSO (besides adding the 4th and 5th dividers), rather than the FL/CN/CH. I previously suspected that the SS-25 (and hence also presumably the SSO-25) would be nearly identical to the latter models, since functionally it is so close to being the same – just slightly reduced. Anyway, like the EOH's schematics of the filter-amps, these provide the best references so far.

              Also, as for your cypher problem, I suspect that the faulty part may not be the couplate after all, since the keying couplates themselves don't (or should not) receive any DC voltage to leak over to a neon and and cause it to pass signal without a key being pressed. I wonder if it may be a "firing line" problem (check the voltage there with no key pressed), or the same kind of tube "emission" problem I had on my model LS where the keying electrode voltage was drifting upwards as a result of a faulty tube, which you can read about here: http://crasno.ca/articles/LowreyLS.htm

              Anyway, thanks again. I will continue looking for the real schematic set, but it is good to know the basic circuits just in case I never find such a set.

              Comment


              • mattikari
                mattikari commented
                Editing a comment
                Thanks for your reply and sorry for my super-late one! I had to move on to completely another tasks. I have been playing the FLO regularly during the last five months and it is somewhat reliable. Your guess was just right tone-wise...

                At the moment we're investigating on the opportunity to manufacture a bunch of PCB's to easily recreate the PAC's, at least the P-5789-x for now. My assumption is that they should cost no more than max 1-2 €/$ a piece (per pcb). One could of course build them on veroboard for example, but a proper PCB would be so much nicer... I'll let you know if we have any success on this project!

                Your site is wonderful, I wish I had found it earlier! For some reason Google didn't find it in spring (or maybe already in the winter), when I was searching for FL schematics! Thank you anyway!

                Ps. In case you didn't know about Rory More and his band Les Hommes, check them out! A lot of Lowrey on the latest album!

            • #8
              Thanks for your reply and sorry for my super-late one! I had to move on to completely another tasks. I have been playing the FLO regularly during the last five months and it is somewhat reliable. Your guess was just right tone-wise...
              All good; things have been quite busy here too. I have been playing my FL frequently for the last five months as well, so far with zero failures. I haven't even recapped it yet aside from the bumblebees in the tone generator section – it still has all original electrolytics (from 1959/60) and tons of Micamold Tropicap paper caps! The dry and cool climate surely help, but regardless, the quality of these old American parts is excellent.


              At the moment we're investigating on the opportunity to manufacture a bunch of PCB's to easily recreate the PAC's, at least the P-5789-x for now. My assumption is that they should cost no more than max 1-2 €/$ a piece (per pcb). One could of course build them on veroboard for example, but a proper PCB would be so much nicer... I'll let you know if we have any success on this project!
              Absolutely, please keep me updated! By the way, I found a source for some of the P-5789-x packs (and others), which is a company in British Columbia; see bottom of page: http://pacifictv.ca/blowout.htm

              Of course, having a source doesn't help with knowing what's inside, but it may help in terms of a quick and cheap fix. For long-term reliability and serviceability though, it would be best to replace couplates/packs with discrete parts, so I encourage your efforts.


              Your site is wonderful, I wish I had found it earlier! For some reason Google didn't find it in spring (or maybe already in the winter), when I was searching for FL schematics! Thank you anyway!
              You are quite welcome, I'm glad you appreciate it. My Lowrey articles are quite recent – the Festival article was released less than two months ago – so that's why they wouldn't have been found. More to come... I have more tube organs to write about from other manufacturers (Conn, Electrohome-Kinsman, and Wurlitzer), each with their own unique character.


              Ps. In case you didn't know about Rory More and his band Les Hommes, check them out! A lot of Lowrey on the latest album!
              Yes, I know about Rory, and have especially enjoyed his recent solo album Looking for Lazlo, which displays a sort of dreamy and high-spirited beauty almost never heard within the last 50 years. But my favorite use of a tube Lowrey so far has been by Jukka Gustavson of Wigwam, from your native Finland. And remarkably enough, it was your friend Alfred who introduced me to Wigwam (to my great pleasure) when he contacted me a few months ago about my articles! Small world, eh?

              He also mentioned that you are the proud owner of the exact Lowrey DSA played on those great Wigwam recordings (Fairyport and Being particularly), and plenty of live shows! I understand it is extremely road-worn and still in need of work. If you are still wanting to repair it, I promise to contribute whatever help I can!

              Comment


              • #9
                I have just finished restoring a Heritage DSA for my own collection. Let me see if any of these PACs are the same as the ones in my DSA schematics. As far as ciphers are concerned, the few that I experience were cured by manipulating the bus bars gently so that they were in contact (or not as the case may be) with the key contact.

                Edit: I checked the schemo and all my PACs are prefixed 6 or 8. If you want the DSA generator schematic for reference, PM me. the .tif file is to big to upload here.
                Hammonds; BV, M101, T202, T402, R100
                Lowreys; Heritage DSA, Berkshire Deluxe TBO-1
                Farfisas; Compact Duo MK2, Professional 110R, Compact Deluxe
                Analog Korg CX3
                Leslies; 147, 145, HL822 ​

                Comment


                • #10
                  I wonder if I could ask Drawbar Dave, mattikari and JQA a small favour. I'm putting together a package of a Lowrey Timeline of models, 1949-2018, a brief-ish Lowrey history together with a collection of photos of as many models as I can. Good photos of organs like the DSA and the FL are, as I'm sure you can imagine, hard to come by. And chance that you might each be able to post a photo of yours please? Thanks.
                  It's not what you play. It's not how you play. It's the fact that you're playing that counts.

                  New website now live - www.andrew-gilbert.com

                  Current instruments: Roland Atelier AT900 Platinum Edition, Yamaha PSR-S970, Kawai K1m
                  Retired Organs: Lots! Kawai SR6 x 2, Hammond L122, T402, T500 x 2, X5. Conn Martinique and 652. Gulbransen 2102 Pacemaker. Kimball Temptation.
                  Retired Leslies, 147, 145 x 2, 760 x 2, 710, 415 x 2.
                  Retired synths: Korg 700, Roland SH1000, Jen Superstringer, Kawai S100F, Kawai S100P, Kawai K1

                  Comment


                  • #11
                    Here’s my contribution Andy. I’ll find one of the switches too. The speaking and mechanical stops are identical to a DSO except that there is no brilliance tab. Instead there is a Quint solo stop. The brilliance is controlled by a pot in the front rail.




                    Attached Files
                    Hammonds; BV, M101, T202, T402, R100
                    Lowreys; Heritage DSA, Berkshire Deluxe TBO-1
                    Farfisas; Compact Duo MK2, Professional 110R, Compact Deluxe
                    Analog Korg CX3
                    Leslies; 147, 145, HL822 ​

                    Comment


                    • andyg
                      andyg commented
                      Editing a comment
                      Very many thanks, DD! Yours looks great. Perhaps once all this is over, I'll be able to hop in the car and pay you and your super collection a visit!

                  • #12
                    Andy, here are pictures of my Lowrey "Festival" FL (1960) and "Holiday" LS (1957) models from the front. Let me know if you'd like pictures from the back as well. They are not perfect specimens; my FL is still missing the pedalboard, and my LS is missing its legs and music stand, besides that I had to replace the speaker grillecloth (and I chose a light-brown fabric instead of dark brown). I would take no offense if you don't consider these good enough examples.
                    Attached Files

                    Comment


                    • Drawbar Dave
                      Drawbar Dave commented
                      Editing a comment
                      Nice pictures. I'd never seen a decent picture of an FL before.
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