Hmmm let's take another stab, found some problems 🙁 oops...
Fixed them unless something blew, right now I get 465v over R30, -260-270v over R7 and -80v on the grid 🙂 with GZ34 plugged in.
No voltage over pin 4 on the output sockets.
Plugged in the 5842's and R27 blew spectacularly...
Fixed them unless something blew, right now I get 465v over R30, -260-270v over R7 and -80v on the grid 🙂 with GZ34 plugged in.
No voltage over pin 4 on the output sockets.
Plugged in the 5842's and R27 blew spectacularly...
At this point it's upside down so certainly not a factor right now, when it's done I'll monitor and see, it should be okay.
Here we go again... Okay replaced the Q's or mosfets, and the resistor that blew, from the tubelab checkout page:
"Put a meter from the grid of the output tubes to ground. One meter for each tube. Power up the board. Each meter should read a negative voltage. With ONE HAND BEHIND YOUR BACK carefully adjust one of the bias pots (R12 or R23). The negative voltage for the corresponding output tube should change. Set it to the most negative voltage, and then adjust the bias pot for the other channel."
From what I read on there I adjusted them to the most negative they would go, they went all the way to -140 and -152, is this OK?
"Put a meter from the grid of the output tubes to ground. One meter for each tube. Power up the board. Each meter should read a negative voltage. With ONE HAND BEHIND YOUR BACK carefully adjust one of the bias pots (R12 or R23). The negative voltage for the corresponding output tube should change. Set it to the most negative voltage, and then adjust the bias pot for the other channel."
From what I read on there I adjusted them to the most negative they would go, they went all the way to -140 and -152, is this OK?
Initially they were at -78 and -80.
Before I plugged the 5842's in I measured the plate, I am getting B+ on one of the plates... any idea why this would happen?
Before I plugged the 5842's in I measured the plate, I am getting B+ on one of the plates... any idea why this would happen?
Okay I must have a short, I took the board out, measured resistors R27 and R28, both 540, measured R16 and R17, one 330, the other 1000 as it should be, R27 blew before so this most likely the cause.
Scratch that, R27 260, R28 320, R16 and R17 is ok.
C11 gives a resistance when on the board, when removed it's fine... C9 is fine in the board... I don't know where else to look...
Any help?
C11 gives a resistance when on the board, when removed it's fine... C9 is fine in the board... I don't know where else to look...
Any help?
Got new CSS's, previous problem solved but no voltage at the 5842 plate, I'm using these: eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices
wrong tubes?
Everything else checks out fine.
wrong tubes?
Everything else checks out fine.
Never mind I see some of you guys use these tubes, any ideas why there is no voltage, there is around -110v to -125v on the other side of the caps. On startup the plate reads negative then as B+ starts to turn positive the plate just goes to 0.
Tried new mosfets, no change. Css doesn't seem to be warming up... If I put the 300b tubes in they are dead even though I have proper voltages over the socket, -85v, 452v, 4.85v.
Can someone please check this for me?
Measured on the board I get:
R1=168r
R2=496r
R10=2.5r
R21=2.5r
These are all from the damme supplier, all say 510r on them... I didn't measure them before installing.
Measured on the board I get:
R1=168r
R2=496r
R10=2.5r
R21=2.5r
These are all from the damme supplier, all say 510r on them... I didn't measure them before installing.
Sorted the problem with the socket, but still nothing on the 5842 plate 🙁 Not sure if i should try the 300b's again.
I am hoping that I have mine up an running in about a week, or even this weekend, so then I can compare notes. Not that mine is likely to be better in any way...
Good luck sir, hope you don't have any issues... it's a real problem if you do.
It's my own fault I'll accept that, I only had about 90% of the components at first assembly, I was focused then and installed all correctly, when the rest came I was rushing and doing it late at night because I was very busy, I made some mistakes, it's all been fixed just wish I could figure out what else needs replacement.
Next stop is to start from scratch 🙁
It's my own fault I'll accept that, I only had about 90% of the components at first assembly, I was focused then and installed all correctly, when the rest came I was rushing and doing it late at night because I was very busy, I made some mistakes, it's all been fixed just wish I could figure out what else needs replacement.
Next stop is to start from scratch 🙁
R10 and R21 appear to have a trimpot in parallel with them, I would read the setup instructions to adjust the trimpots as required. At the moment it looks like the trimpots are adjusted for minimum resistance which means max current through the tubes which won't be doing them any good. I don't have experience with the SSE/TSE so can't give more detailed explanation. Hope this helps. BTW, I love your chassis, looks fantastic.
Thank you Ian, I wound them up all the way to check that I installed the correct trim pots in the correct locations, they are 1K and I verified, I didn't adjust them back again when I made the measurement.
After reading some more posts on here, the problem appears to be around the mosfets or CCS's.
the measurement I am getting off the mosfets are(Pin to ground):
-6x(can't remember the exact number, then B+ 450v, then -86v
On the CCS's
0, 450v, 0
One more thing CSS and Mosfets are now mounted off board because I am destroying the PCB with all the removing and reinstalling the components, can this be a factor?
the measurement I am getting off the mosfets are(Pin to ground):
-6x(can't remember the exact number, then B+ 450v, then -86v
On the CCS's
0, 450v, 0
One more thing CSS and Mosfets are now mounted off board because I am destroying the PCB with all the removing and reinstalling the components, can this be a factor?
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Okay
I've narrowed it down to the CCS's or the 5842 tubes, can anyone tell me how to test them(Without a tube tester), it's strange since the CCS's are brand new, problem is they are also $30 a set since it's a difficult part to source locally and I have to bring it in from the UK. I get +-16mV at the side legs...
I'm guessing that a positive voltage from the 5842 is required to switch on the CCS's??????? It is not clear from the data if the CCS's work with nothing applied to the gate.
Good new is that the on the output tubes everything is fine, B+ drops to a nice 374V but obviously no audio since 5842's are down.
Does ANYONE want to give a stab at some advice?
I've narrowed it down to the CCS's or the 5842 tubes, can anyone tell me how to test them(Without a tube tester), it's strange since the CCS's are brand new, problem is they are also $30 a set since it's a difficult part to source locally and I have to bring it in from the UK. I get +-16mV at the side legs...
I'm guessing that a positive voltage from the 5842 is required to switch on the CCS's??????? It is not clear from the data if the CCS's work with nothing applied to the gate.
Good new is that the on the output tubes everything is fine, B+ drops to a nice 374V but obviously no audio since 5842's are down.
Does ANYONE want to give a stab at some advice?
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Checked the tubes, problem found, tubes faulty.... 🙁
I studied the schematic a little bit too, with my very very very limited knowledge of electronic circuits it appears that the CCS passes the negative B+ as the amp warms up, however once B+ goes positive the CCS no longer passes it, is this correct?
Since the tube is not working it isn't providing a positive signal the the CCS gate, hence the CCS doesn't switch on and stays cold. It isn't clear to me why the -60v on the other side of the coupling cap isn't coming through to the plate, but I assume possible that is what the coupling cap does?
So if the 5842's are in and provide the positive signal the CCS will start functioning and warming up and all should be well?
Can I bias the 300b's without the 5842's in?
I studied the schematic a little bit too, with my very very very limited knowledge of electronic circuits it appears that the CCS passes the negative B+ as the amp warms up, however once B+ goes positive the CCS no longer passes it, is this correct?
Since the tube is not working it isn't providing a positive signal the the CCS gate, hence the CCS doesn't switch on and stays cold. It isn't clear to me why the -60v on the other side of the coupling cap isn't coming through to the plate, but I assume possible that is what the coupling cap does?
So if the 5842's are in and provide the positive signal the CCS will start functioning and warming up and all should be well?
Can I bias the 300b's without the 5842's in?
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