Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Smash => Topic started by: galyons on July 04, 2015, 06:24:46 PM
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Got back home and cranked up the Smash to finish testing the AC hum on the PS. Must have shorted something because the LED's didn't light up as usual. One board is fine, all four LED's lit. The other board, the A side LED's light, but not the B side.
Here are the voltages:
IA 180-220V = 205V, 205V
OA 150V ± 1% = 202.4V, 149.4V
+reg (A side) 2.5V = .426V, -1.51V
IB 150V ± 1% = 202.4V, 149.4V
OB 45-75V = 200.9V, 63.5V
Kreg (B side) 3-5V = 1.9V, 4.4V
Breg (B side) 150V ± 1% =202V, 149.4V
+reg (B side) 150V ± 1% =202.2V, 149.4V
B1 0V= 0V
B2 150V= 202V
B3 3-5V= 1.9V
B4 0V= 0V
B5 150V= 149.4V
B6 3-5V= 4.45V
So I blew one or more of devices on the reg board. Please let me know what I need to test to identify the culprit.
Cheers,
Geary
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Your regulator is not working and your 4P1L isn't drawing current. This could just be a damaged ground wire going to the PC board that isn't letting either part function properly.
-PB
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Your regulator is not working and your 4P1L isn't drawing current. This could just be a damaged ground wire going to the PC board that isn't letting either part function properly.
-PB
Thanks PB!
I checked the ground wires to the boards. Both good. Swapped in my spare 4P1L's. LED's are back! Here are the voltages that are still off.
+reg (A side) 2.5V = .644V, .765V
OB 45-75V = 148.3V, 63.5V
Kreg (B side) 3-5V = 2.1V, 4.4V
B3 3-5V= 2.1V
Getting closer!
Cheers,
Geary
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You still don't have 4P1L conduction, can you check the voltage coming off the little filament regulator board?
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PB,
I get:
1.98V from "Out" to board ground.
1.51V from "Out' to chassis ground.
Thanks,
Geary
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1.98V from "Out" to board ground.
1.51V from "Out' to chassis ground.
Yeah, that's a problem. The 4P1L is setup for ~4V to heat the 4P1L. You don't have 4V coming out of that board, so your 4P1L's can't conduct.
What kind of voltage is going into the board? (Measure from Ground to "I" on the PC board)
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PB,
I get:
4.95V from In to board ground.
Thanks,
Geary
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PB,
I get:
4.95V from In to board ground.
Thanks,
Geary
Yeah, that's not enough. The diode bridge will make more than that unless either a diodes is not well soldered/not working, or there's too much current being drawn.
You can lift the red wire at the 10,000uF cap, then retest the low voltage to see how much it pops up.
-PB
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Low voltage goes up to 15.84V measured at terminals 26 & 27, with the red wire going to the reg board lifted.
Thanks,
Geary
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I just performed the same test. On 127V AC line voltage, I get ~9V DC out of the raw supply.
Are you running the stock parts?
I can't really figure out how you'd get 15.8V, unless maybe your meter is seeing a lot of ripple or something, but this is certainly where you need to look for your issue.
-PB
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Hi Paul,
Yes, all stock parts in the filament PS. Line @ 120.7VAC Red wire still lifted, so regulator out of circuit, 13.8VDC with 9.4VAC along for the ride. So, yes, a ton of ripple!
Thanks for helping out on this!
Cheers,
Geary
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You can't get 13.8V from a 6.3V winding without changing from a bridge to a voltage doubler.
I would suggest having a close look at all those 1N5818 diodes and the 10,000uF cap to see what's amiss. Also try a second meter if you have access to one.
-PB
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Already double checked the voltages with my other meter, same. I made no changes to the filament PS, so this befuddles me. I will double check the diodes and the cap.
Thanks,
Geary
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You can't get 13.8V from a 6.3V winding without changing from a bridge to a voltage doubler.
I would suggest having a close look at all those 1N5818 diodes and the 10,000uF cap to see what's amiss. Also try a second meter if you have access to one.
-PB
Thanks Paul! Yet again you called it! The 10K uF cap had one leg loose. I had to add fly leads to get the 10K uF cap away from the terminal strip to add the big film cap. Must have nicked the wire stripping and moving things around broke the wire. Re-soldered. The 1N5818 diodes test fine. With the red lead to the filament regulator board re-soldered all voltages are back in spec with the exception of:
+reg (A side) 2.5V = .92V, 1.1V
So, getting really close.
Cheers,
Geary
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Now we just need a post where PB thanks me for suggesting to him it was ripple...
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+reg (A side) 2.5V = .92V, 1.1V
You should recheck all voltages. What voltage are you getting out of the filament regulator board?
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These voltages are different than I got when I posted 3 hours earlier. I was getting 4.35V from the output of the filament regulator board. Back to not so good! :(
Here are the voltages:
Line =120.3VAC
I to board ground =7.1V
O to board ground =3.3V
L200C pins to board ground
1 = 7.1V
2 = 3.3 V
3 = 0V, continuity to ground
4 = 2.2V
5 = 3.5V
IA 180-220V = 204V, 204V
OA 150V ± 1% = 150V, 149.4V
+reg (A side) 2.5V = 0.89V, 1.1V
IB 150V ± 1% = 150V, 149.4V
OB 45-75V = 130V*, 58V * ranges between 127V and 133V
Kreg (B side) 3-5V = 4.7V, 5.0V
Breg (B side) 150V ± 1% =150V, 149.4V
+reg (B side) 150V ± 1% =150V, 149.4V
B1 0V= 0V
B2 150V= 150V
B3 3-5V= 4.7V
B4 0V= 0V
B5 150V= 149.4V
B6 3-5V= 5.0V
Cheers,
Geary
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Well, you have adequate voltage going into the board now, so that's a good start.
The regulator is set to put out about 4.2V, so your regulator is still not working. There isn't any reason to muck around with the high voltage side of things before your tubes are properly heated.
Try pulling both tubes, then recheck the output of the regulator board.
Do both OB voltages measure at 130V, or is it one side is 130V on OB and the other side is 58V?
-PB
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Well, you have adequate voltage going into the board now, so that's a good start.
The regulator is set to put out about 4.2V, so your regulator is still not working. There isn't any reason to muck around with the high voltage side of things before your tubes are properly heated.
Try pulling both tubes, then recheck the output of the regulator board.
Filament reg board, no 4P1L tubes :
I 7.1V
O 7.5V
Do both OB voltages measure at 130V, or is it one side is 130V on OB and the other side is 58V?
These voltage vary from time to time, but, yes, there is consistently an approximate 2:1 voltage differential at OB on each side.
Current measurement is: 150V, 77V
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Repeat the regulator board voltage measurements with the left tube in, then with just the right tube in.
-PB
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Filament reg board, 1 X 4P1L tube per side:
I 7.26V, 7.26V
O 4.26V, 4.21V
Regards,
Geary
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OK, so this convinces me that your regulator board is probably working OK. Do you have more than two 4P1L's? It's possible that one may be internally shorted somehow, and dragging the output of the regulator down?
Luckily, we have a current limiter on the filament regulator board, so you won't burn it up by loading it down too hard (but the delivered voltage will drop!).
-PB
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Hi Paul,
I switched sockets with my original pair and the lower HV reg board voltages followed. So, yes, maybe an issue with the tube. I put in a new pair of 4P1L's, same HV & LV issues. I tried my 3rd and final pair, all voltages are pretty much "spot on", other than +Reg A and the 4P1L heaters. The 4P1L filament regulator measured:
I = 7.1V
0 = 2.8V
The rest of the measurements at the boards are:
IA 180-220V = 204V, 204V
OA 150V ± 1% = 150V, 149.4V
+reg (A side) 2.5V = 1.1V, 1.3V
IB 150V ± 1% = 150V, 149.4V
OB 45-75V = 53V, 57V
Kreg (B side) 3-5V = 4.7V, 4.9V
Breg (B side) 150V ± 1% =150V, 149.4V
+reg (B side) 150V ± 1% =150V, 149.4V
Cheers,
Geary
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It's possible that feeding the regulator board with mostly AC (from the disconnected capacitor) damaged the regulator. It might be a good next step to replace the L200 chip.
-PB
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Thanks Paul! That did it! All readings in spec, (getting 4.1V out on the filament reg board ;D), except +reg (A side) 2.5V = 1.1V, 1.3V, still low. You haven't commented on the +reg (A side) being low, so I am assuming it is OK?
I am still getting about 3-5mV of hum at the outputs. I will work on that in the next day or so!
Thanks for your help and patience.
Cheers,
Geary
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If you aren't getting 2.5V out of the 431 chip on one side, you can try replacing it.
-PB
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If you aren't getting 2.5V out of the 431 chip on one side, you can try replacing it.
-PB
Actually not getting 2.5V out on either board, (+reg (A side) 2.5V = 1.1V and 1.3V). Should I replace both?
Thanks,
Geary
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What are you getting from OB on each board?
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Paul,
OB is 47V & 50V.
Cheers,
Geary
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Did you cut out the HLMP diodes when installing your Smash-up?
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Yep, they are gone!
Geary
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If you aren't getting 2.5V out of the 431 chip on one side, you can try replacing it.
-PB
Replaced one of the the LM431's. Before voltage output was 1.3VDC, now the same, 1.3VDC. Didn't do the other.
Cheers,
Geary
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Replaced one of the the LM431's. Before voltage output was 1.3VDC, now the same, 1.3VDC. Didn't do the other.
They are in parallel, so you'd need to do them both.
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Thanks Paul! Problem solved! Although my LM431 stock took a big hit! I am getting 2.5VDC out of both boards at +reg A. Also solved my ripple on the outputs, as well. Sounds damn fine!!
Cheers,
Geary