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Thread: full schematic SWR workingsman

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    full schematic SWR workingsman

    Hello from Argentina, im looking for the swr workingsman schematic, i have one part from this thread

    http://music-electronics-forum.com/t7538/

    So im asking id anbody have the other part, especially in need to know all those w points where they go, there is a compression part o something like that.

    Thanks for al the help.

    Saludos.

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    Lifetime Member Enzo's Avatar
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    The schematic in the thread you linked is the whole schematic for the Workingmans 10. There is no more than that.

    Do you have some model different from the Workingmans 10?

    What is missing from your schematic?

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    There is an older version of the Working Man's 10 bass amp that doesn't use the TDA7294 chip, but power transistors (2SA1943 and 2SC5200) in a push-pull configuration for the output.

    I have one of these in my shop and there doesn't seem to be a schematic anywhere for this. The board I have is marked "WKG10 #1 Bottom Rev D" and on the component side is silk screened "WORKING MAN'S 10", "MANUFACTURED BY SWR", "WKG #1 SILK REV D".

    The board was damaged (burnt badly) after one of the power transistors shorted causing the driver transistor to fail, which burnt the resistor to it.

    The customer wants the silly thing fixed(!) even though the repair is going to cost more than what the amp is worth. I'm down to pulling parts off the board so I can trace out the schematic manually (double sided board, with through-hole vias, at least it's only two sides) but was hoping someone might know where the schematic or other info may be. Fender doesn't have it, they only list the TDA chip version

    Thanks!

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    Last edited by HutchAmpMan; 10-29-2019 at 11:04 PM.

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    Supporting Member Jazz P Bass's Avatar
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    Here is a schematic of the WM10 with discrete output devices.
    Workingman's 10 discrete.pdf

    Not too sure about "but power FETS for the output." as this schematic shows bjt outputs.

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    Thanks for the info

    Thanks for the schematic, it's not quite what I have but closer than the TDA output version.

    I edited the post as in my "drain bamaged" state I mixed the outputs up with another bass amp (Carvin) that used FETs.

    The outputs are indeed, BJT, 2SA1943 and 2SC5200. The thing also runs +/- 45 volts on the rails and +/- 15 volts for the op amps (NJM2082L SIP Vs the TLO72 DIP used in the later amps). It would seem to pre-date this schematic also.

    I have it in my office now with most of the larger components removed and a strong light, hopefully I'll be able to see what should go where on the board.

    Again, thanks for the schematic and the quick response!

    Tom

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    Senior Member vintagekiki's Avatar
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    Last edited by vintagekiki; 10-30-2019 at 02:00 AM. Reason: 1)
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    Lifetime Member Enzo's Avatar
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    You know, as a technician you do have the right to decline a repair job.

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    This is a favor for a friend, or I'd have never started it.

    What's probably going to happen to it is when I can the the preamp section powered up, I'll scrap the power section and stick in one of those 100 watt preassembled TDA boards that you can get for about $8.

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    Thanks for the links, unfortunately, they all are much later versions than the one I've been blessed with.

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    Thanks for the links, unfortunately, they are all much later TDA chip amps which the one I've been blessed with uses BJT transistors for output.

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    Lifetime Member Enzo's Avatar
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    SO how diffrent is your 1943/5200 version from the 2SC3281/2SA1302 version?
    Attached Files Attached Files

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    Senior Member vintagekiki's Avatar
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    Quote Originally Posted by HutchAmpMan View Post
    Thanks for the links, unfortunately, they are all much later TDA chip amps which the one I've been blessed with uses BJT transistors for output
    Attached links evidently you not viewed or not understand. It does not matter.
    If it's not difficult specify your SWR model name from the front or back panel.

    By the way Workingman 2X10C is not a TDA chip amps, it's designed in discrete technique.

    https://www.talkbass.com/threads/workingmans-10-schematic.1428121/


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    Last edited by vintagekiki; 10-30-2019 at 05:06 PM. Reason: 2)
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    Lifetime Member Enzo's Avatar
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    kiki, the discrete transistor ones in your links are as far a I can tell, all of the quasi-comp type with the 2SC3284 transistors. The OP has a complementary circuit.

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    Looking at both, the differences seem to center around the transistors with most everything pretty accurate.

    Do you have a diagram for the power supply and preamp sections? I'll look more closely at them when I get of the doggy-dope the docs have me on for this sinus infection!

    Thanks much!
    Tom

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    Thanks. One of these did provide additional information for me.

    Best regards,
    Tom

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    Quote Originally Posted by vintagekiki View Post
    Attached links evidently you not viewed or not understand. It does not matter.
    If it's not difficult specify your SWR model name from the front or back panel.

    By the way Workingman 2X10C is not a TDA chip amps, it's designed in discrete technique.

    https://www.talkbass.com/threads/workingmans-10-schematic.1428121/
    The links were viewed and understood. As I said before, they are not the correct ones. The 2X10C is for the Working Pro which is completely different. There have been at least three versions of this amp, two (or more) by SWR and another one from Fender.

    I have contacted Fender and they sent all the schematics they have, Possibly I will be able to get a complete schematic drawn up from this information and if so, will post it here.

    Best regards,
    Tom

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    WM 10 Full Corrected Schematic - Discrete Version

    Well, I've managed to track down all the schematic sections for the discrete WM10 bass amp. Special thanks to Jazz P Bass for the PA section.

    The other two parts are the Power Supply and the FRT schematics, which are attached. Note there were some errors on the FRT schematic. This is the one with the Input, Audio, XLR and FX sections, plus the Speaker board section.

    The errors were duplicate R35 resistors; the correct one is on pin 1 of IC4: B, the incorrectly labeled one is on the speaker board which is a 1 Watt 100 ohm resistor. I have relabeled that one as R39.

    The other was a duplicate C27/ 47uF/35 cap which is connected to R4 and then to Ground from IC1:A pin 2. My board does not have the cap (shown as the second C25) between pin 1 and R5, it is a direct connection so I deleted this cap from the schematic. Other amps may have this cap, looks as if there were several versions prior to the TDA equipped amps.

    BTW, any of these old amps need to be completely recapped or they will come back. This one had been worked on previously to me getting it and was not recapped, just had the PA and driver transistors replaced. The little C25 2.2uF Non Polarized cap in the PS section was resistive, causing a fault on the +15V supply for the op amps and also the optocoupler drive. There were other bad caps as well. There was lots of circuit board damage where a resistor melted and burned two traces and a chunk of board about 1/4" squarish. Not a hard fix with the right epoxy, replacement traces & through hole rivets.

    I didn't bother renaming the "Woffer" to Woofer on the speaker board!

    Best regards and thanks for all the help,
    Tom
    Attached Files Attached Files

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    Lifetime Member Enzo's Avatar
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    Isn't that the same power amp I put up in post #11?

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    Quote Originally Posted by Enzo View Post
    Isn't that the same power amp I put up in post #11?
    Yes, same power amp, but did not have the FRT or PS schematics.

    Thanks again for providing the schematic.

    Best regards,
    Tom

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    Last edited by HutchAmpMan; 11-10-2019 at 03:27 PM.

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