Superscope R340 (no B)

Discussion in 'Marantz Audio' started by quaddriver, Dec 7, 2017.

  1. quaddriver

    quaddriver 120 What's per channel Subscriber

    I just pulled one of these from a living estate auction of an old rock and roller.

    9/10 or better physical condition. Wont know if its dark or lights up or catches fire till saturday.

    Found the R350B SM on hifi, have not found jack on the 340, not even from the russians.

    looking at the SM they are as billed from what little I can find as very marantzish inside, looks like I can unsolder half of a 2215 and dunk it inside a 350.

    So, anyone have any info on the 340 (not B)?

    thanks
     
  2. quaddriver

    quaddriver 120 What's per channel Subscriber

    well here it is....

    plugged it in as brave as can be and it lit up. tunes well, no sound anywhere. off comes the cover and as I am lifting it (its still on) I hear the snap of a fuse...seems the main power line to the amp off the main power cap is just sitting in there. hmmmm

    move things around, re-fuse it, its working, tuner is great, I am using tape out to power my big machine and the tuner is pretty decent, sensitive too. I might see some silicone updating in there but the amp, (P600) hmmm, one of the 150ohm fire-proofs has earned its keep, the amp output wires are desoldered and the grounds unscrewed and one of the emitter resistors is a .47ohm carbon as compared to the .5ohm whatevers that are in there. the outputs are itsy bitsy to220s 2SD365/2SB512 pairs. what is this, 10-15 watts? and no outputs are bolted t o the heat sink, in fact, it seems they were held in place with a bracket that is missing, no individual mica pads and screws - thats easily fixable. anyone know the part number for the nylon shoulder washers that insert in the to220 bolt hole?

    there are no DCO or bias adjustments so should I rebuild it, it will be an exercise in hfe matching. power board P800 is non output adjustable, so I guess its WYSIWYG.

    Im sure I can update the 'power' trans to something acceptably to-220 and add a sink. all the lights are fuse lights, got the leds in warm white in stock.

    totally doable, but Im flying blind..I need to find the SM or a photofact for this...

    this is so weird, but so cosmetically good, Im gonna fix it out of spite. IMG_20171210_144932.jpg
     
  3. quaddriver

    quaddriver 120 What's per channel Subscriber

    got the SM from some fine folk in canada for a decent price. date 1973. will scan and upload to the database as well. looks like this is a cakewalk, p800 and p300 are straight forward and the amp is less optioned than a 2215 given the non-adjustability. worst case is I replace every single item on the board. it has to work. g*d says so.
     
  4. Richs_Trains

    Richs_Trains AK Subscriber Subscriber

    Messages:
    679
    Location:
    Tucson, AZ
    :lurk: Have never seen the insides of a Superscope, how about some internal pics?? Rich
     
  5. quaddriver

    quaddriver 120 What's per channel Subscriber

    sure, post some pics of your trains as well....
     
  6. quaddriver

    quaddriver 120 What's per channel Subscriber

    ok here is a pic of the top off:

    r340 main boards smaller.jpg
    upper right is the amp board, note the to-220s are not fastened to the heat sink. there appears to have been a metal bracket that held them 2 at a time down, I will instead be drilling a clearance hole and bolting each one individually to it. or make my own brackets, I have a lot of heat sink material. have not decided yet

    note the red wire in the upper left of the amp board, it is B+ and is disconnected. not seen is a purple wire for the right side output, that goes to the speaker selector switch, it is disc as well. and of the emitter resistors look close and note that an old tube TV style 1 watt carbon was inserted. I will find some .5 ohm, 1 watt cements or ceramics. note sure what I am gonna replace the outputs with (but I will, working or not) and the drivers will just become a992's and c1845's well, just becuz... the p300/p500 phono/tone amp board have C1327's on them...I could go C1845 (which are hard to replace right now and I only have 85 left) or use 1815 which I have a fresh 100 of. the voltage is low enuf and the hfe of the newer ones is high enuf, to warrant mathing up and guaranteeing the boards stay quiet.

    I ran this on fm for 2 days using tape out to drive my sx890 and the tuner is flawless...just a quick refresh and visit some Ge diodes in the AGC and ratio detector...

    the main big cap is 3000uf 55v, the rails are 38v (I got 41 with the main amp disconnected) so I think a 3300uf-50v that I have in stock will suffice.

    btw, p300/500 are underneath, in the middle to the left is p800 power...aside from a full recap and fresh diodes, 2sc1407 is old, but appears to be working, mouser had it as of 2015, but no longer does, I might use a mouser replacement, or ? dunno yet
     
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  7. quaddriver

    quaddriver 120 What's per channel Subscriber

    superscope 280dpi R-340.jpg ok a question for the marantz gurus, in the rectifier session for the rails, the H802-805 diodes are S-1.5-01 which well, I just find any info other than an NTE designation. I have seen S1501 listed - is this a better format? and I have seen that UF400-something used. Does anyone have a quick xref for this? I am making notes in the SM I got before I scan it upwards for yinz.

    Also, the W06B, have replaced those before with WEP170s, 4005s etc..kosher? the 14v 1W zener is an order item as I only have 14v in 500mw

    on the P300 phono board, the 2SC1327s are suffix S and T, with S being Hfe of 260-520 and T 360-700. I got KSC1815 with a Vceo of 60v (35 on the SCM) and hfe's in the 400's, if the thought was to have 'stage 1' with less Hfe than 'stage 2', I can do that with Hfe matching and 'mismatching', but all 4 the same should be ok no? superscope 280dpi R-340.jpg
     
  8. quaddriver

    quaddriver 120 What's per channel Subscriber

    And another question, on the P600 main amp, and in the SCM are M601/602 - 8v lamps, that measure 15 ohms so, a little over 500ma - why? they feed the base of the PNP outputs wherease the PNP side uses a 10ohm resistor. and on the suspected blown side, the lamp is missing and one of the 150 ohm emitter resistors for the drivers.

    yes, all silicon will be replaced, but why the lamp vs resistor? and where pray tell do I get these?
     
  9. quaddriver

    quaddriver 120 What's per channel Subscriber

    in case this is ever searched, Tom (catrafter) has indicated 8v, 80ma bulbs work for him

    As for the power supply diodes, the W06B are 3/4A, 150V, anything 1N4005 or UF4005 is better so I am using that
    For the S-1.5-01, Im not getting a clear crossref, BUT the larger 2215 can use UF5405 (3 amp vs stock 2 amp) so likely any 2+ amp silicon fast diode should work

    the ones in the machine are not bad, but why chance it...
     
  10. quaddriver

    quaddriver 120 What's per channel Subscriber

    made some changes on the FM tuner board, working the phono board now, looking into 2SC1815s instead of 1845s. I need a combined digikey/mouser order to rebuild the amp board and all is in stock, but whereas mouser ships immediately, digikey takes a day or so to discuss it at department meetings, but they had the ONS output devices in stock (either gonna use MJE15030/31 or 32/33 pairings.

    I am updating the SM/SCM as I go with the modern subs and will scan/upload, only question is, where, here or hifi. It seems no one is minding the store here...dont want it lost.
     
  11. quaddriver

    quaddriver 120 What's per channel Subscriber

    And here we go, this post will serve as the BOM for a Superscope R340 amp bpard I will edit it as I go with the subs in 'MTF format' so in case anyone ever uses google in the future (hey its how I find half my stuff by 'accident')

    Superscope R-340 Main Amplifier board P600

    Capacitors: replace as seen. Modern general purpose caps are superior to every cap in the machine. Spend more at your discretion. This is cap coupled so C601, C602, C613,C614 could stand to be better.

    Semiconductors:
    H601, H602 Marantz part number: HT105651C

    Found: 2SA564 pnp to-92b ECB -25v 50ma 250mw 150mhz hfe 65-700
    Replace with mouser: 512-KSA992FTA pnp to92 ECB -120v 50ma 500mw 50-100mhz hfe 200 min $.22 each

    H603, H604 Marantz part number HT313182B

    Found: 2SC1318(s) npn to-92b ECB 50v 500ma 625mw 200mhz hfe 170-340
    In this case, I do not think power dissipation is of utmost concern, and a KSC1845 *could* work, in the driver stage (which follows this placement) KSC1845 would be underpowered. so...
    Replace with Mouser: 512-KSC2383YTA pnp to-92-3L ECB 160v 500ma 900mw 20-100Mhz hfe 160-320 $.37 each (overkill for this position)

    Now look at H613, H614 waaayyyy across the board such that they look like they are to the heat sink. At first I thought they were a thermal set up, but no, we have:

    H613, H614 Marantz part number HT308281B

    Found: 2SC828 npn to-92 ECB 25v 50ma 400mw 220mhz hfe 130-520 (no suffix seen)
    This is an easy sub,
    Replace with Mouser: 512-KSC1845FTA npn to-92 ECB 120v 50ma 500mw 50-110mhz hfe 300-600 $.21 each (if you can get them, I have 1000 on backorder at this time) I do not think the Ft difference is a problem in this part of the circuit.


    More volts, same current, more wattage, acceptable Ft, comparable hfe

    Now we get to the drivers. Nice part about his place is, once you get this far, you can test it without outputs on headphones, on larger machines with larger drivers even speakers.

    The drivers in this case are 2SC1381/2SA720 compliments. These are to-92B cases and at 625mw, fairly healthy. KSA992/KSC1845 compliments will not do here - go bigger. Online I have seen KSC2690/KSA1220 pairings, but this is *at least* twice everything from the originals. Overkill, but not needed. Aiming smaller, I settled on KSC2383/KSA1013 compliments, hfe matched. Lettuce begin:

    H605,H606 Marantz part number HT31318Q
    Found: 2CS1318Q npn to-92b ECB 50v 500ma 625mw 200mhz 85-170hfe (q)

    Replace with Mouser: 512-KSC2383YTA npn to-92-3L ECB 160v 1A 900mw 100mhz 160-320 hfe .37 ea

    And compliment this at H607, H608:

    H607, H608 Marantz part number HT107201Q (parts lists says 2SC720Q, its wrong, 2SA720Q)
    Found: 2SA720Q pnp to-92b ECB -50v, -500ma 625mw 200mhz 85-170hfe

    Replace with Mouser: 512-KSA1013YT pnp to-92-3L ECB -160v -1A 900w 50Mhz 160-320 hfe .35 ea

    Note that they are not strictly compliments, but in the driver stage of a low power amp, should do fine. hfe match best you can, what I pulled (that was not blown) was all over the place. Could be from the factory, or the fact that I was not gentle doing the de-solder. dunno.

    Next up will be the outputs, they are in but the emitter resistors I expect in a day.

    Resistors:

    Any and all obvious resistors replace and in a complete utter refresh for the 'replace all' crowd replace, but this amp has a number of 'safety fuses' in the form of flame proof resistors and as I said in an earlier post, one was blortlecated.

    Here is the critical list:
    R623, R624, R625, R626 Marantz part number GF0515112 which resolves to 150 ohm, 5% 1/2 watt (flameproof)

    Replace with Digikey: S150HCT-ND (CFM12JT150R)

    and R627, R628 Marantz part number GF0510014 which resolves to 10 ohm, 5%, 1/4 watt (flameproof)
    Replace with Digikey: CF14JT10R0CT-ND (CF14JT10R0)

    The 150 ohm resistors are essentially emitter resistors for the drivers and the 10 ohm resistors are the bias resistor for the NPN output (the PNP using a light bulb)

    I will add to this when the rest of the parts are in
     
    Last edited: Jan 11, 2018
    Richs_Trains and MBuras like this.
  12. quaddriver

    quaddriver 120 What's per channel Subscriber

    As a side note, on phono EQ/amp board P300, I had looked to replacing the 2SC1327s with KSC1815's since KSC1845 is hard to come by - no dice. The hfe on working, "fresh" 2SC1327s is much higher than that of the KSC1815, so I went with KSC1845 and note that the phone stage has listed 2 suffixes, T and S. On the old datasheet, one is higher than the other but when I pulled these, all were good, but all over the place. so I matched KSC1845s left to right AND in the spirit of the 2SC1327 differences, I made a pair of highers, and a pair of lowers. Probably makes no difference, but I went that extra mile.
     
  13. quaddriver

    quaddriver 120 What's per channel Subscriber

    PS: just used a dozen or so jumper wires from machine to my desk and for the first time in 'n' years, the 'Scope played a set of headphones - nice and clear.
     
  14. Richs_Trains

    Richs_Trains AK Subscriber Subscriber

    Messages:
    679
    Location:
    Tucson, AZ
  15. quaddriver

    quaddriver 120 What's per channel Subscriber

    All my parts came in yesterday so I glue in some outputs, emitter resistors and bulbs and I should be good to go, except, I am not hooked up to the heat sink. does anyone have a quickie photo of the type of bar or hints about it, that clamp the outputs to the heatsink? I have a couple large hunks of aluminum from some 100+ watt STKs that I use for stock....
     
  16. tonebells

    tonebells AK Subscriber Subscriber

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    Location:
    Florida
    This is from a 2215B that I had to make a clamp for. It was from some scrap aluminum angle.

    [​IMG]

    Tony
     
  17. quaddriver

    quaddriver 120 What's per channel Subscriber

    Excellent, thanks tony, Im gonna do pretty much the same then
     
  18. quaddriver

    quaddriver 120 What's per channel Subscriber

    ok I got some time so I put the new outputs in (MJE15032/33's) and funky light bulbs.

    I used some jumper wires and a ton of to-220 heat sinks so I could run this outside of the chassis as it is very difficult to assemble/solder in. there is no way to access the PCB with the factory wires soldered on.

    So, before when it worked, the headphones played but ran out of headroom quickly and sounded a bit tinny. likely due to the lack of power, high impedance etc

    IMG_20180117_202819.jpg

    so I put it together and listen on headphones, sounds full and good. when turning way up, I imagine hearing distortion.

    I connect my work speakers up, turn up - volume! then I go more and it starts distorting.

    I poke prod, trace - all seems good. The thing is a ground loop nightmare.

    but I cannot find an apparent reason, so using the SCM, I hook up power and grounds only

    I have all my voltages, off perhaps .25v but the power supply is over the spec by half a volt and its non adjustable. I had slightly low on the base of the bias unit but I wonder resistor differences. MEasured every single one and all were within spec. The PO apparently replaced them all with more modern units.

    So its time to hook up the sig-gen and the scope, I injected 1Khz (1013 according to my meter, its analog controlled and its not like this is an IF or anything), I set my ancient BK scope to read the sig gen, plugged that into aux in, then I tested the pre-amp P400. tested fine. I even jumped the pre-amp over to my sx890 and not one unruly noise.

    so while listening to the output (not a very catchy tune) I started probing legs of various stages. At low volumes see the screen of the scope (sorry, I have 2 laptops, the unit, all my junk on the desk, the scope went on the floor tonight)

    IMG_20180117_202455.jpg

    That wave is the same shape (with soft points) as the generator itself.

    And see what happens when you turn it up a bit over low volume, look at how the upper part of the wave is shaded, it has the shape, but I guess this is representation of noise or breakdown.

    IMG_20180117_202446.jpg

    what the holy heckfire is going on. it should be noted, that the hfe between the MJE15032 and the 33 is almost twice. and a set of MJE15030/31s were even worse. either my meter does not like to switch pnp/npn quickly or wth?

    Im half temped to glue in a set of KSA940/KSC2073s to see what happens (150v, 1.5A 25W, 3Mhz Hfe)

    any ideas? ever see a trace like that? I listened to it on headphones for over an hour and it sounded great, but add speakers with lower impedance and stuff and it falls flat, and yes, I cleaned and tested the speaker switch, checked the resistors on the selector network etc.
     

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  19. quaddriver

    quaddriver 120 What's per channel Subscriber

    We are getting there, I didnt give the whole lead up story because of something else I thought was inconsequential, but it turned out was not. VAS was bad. I noticed that when I applied signal to left only, I got signal path thru left, but a attenuated distorted signal in right. What this was doing when there were 2 signals, the left->right bleed was out of phase and wiped out half of the right amplified signal in the driver/output stages. the images on my scope are gone...

    so I fixed that and being shy on KSC2883s, I used a KSC1845 and it aint even getting hot so we are ok.

    I went ahead and swapped out the driver KSA1013/KCS2883 pairs for larger KSA1220A/KSC2690A pairs. they were easier to match up and are rated twice the current

    however, it sounds good, but when you crank it, or add loudness or base, it distorts early on the volume control

    thru headphones - never, but then again the impedance of the phones plus the 270 ohm resistor in the way, the way this amp is set up it plays speakers OR phones, never both, so on headphones its never really making that much power

    The idle current is just too dang high however, I got 68mv across the emitters right, 50mv left. this is non adjustable, so I need a new solution...stay tuned, time to ask the big guns
     

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