Working on Kaiju all testing previously was fine after wiring driver tubes and installing cs4 boards all readings off, both sides A side LEDS not lighting, B light fine, voltages about 233-235 at IA and OA respectively. Initial reading at 36 and 46 fine at 175. Any help suggestions appreciated
Issues with driverboard testing [resolved]
- Thread starter ericoto
- Start date
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You will need to slip one wire out of one IA pad, then fire the amp up to see if the other IA pops up. If it doesn't, then trade which IA wire is connected and which isn't, then recheck. When you find which board is pulling down the high voltage rails, remove it and post more photos of the top and bottom. Also post photos of the string of zener diodes mounted to the 5 lug terminal strip on that side of the amp.
-PB
-PB
The red wire from one of your plate chokes is not attached and soldered where it's supposed to be. It's probably trying to short out the high voltage power supply to the chassis. I would correct that mistake, then with the amp off, unplugged, and discharged, be sure that the DC resistance between the blue and red wires on each plate choke is still roughly the same. If the plate choke on the offending side has dropped substantially in resistance, you will need to remove it and purchase a replacement.
Thank you for getting back to me so quickly. I did recheck the choke connections, they appear to be in the right place 35L and 43L, I desoldered both and then resoldered. I still have the same issues, the voltages are low around 240 in both IA as well as OA. The resistance is to both chokes is also the same approximately 485 ohms Should anything else be attached at these points? Also I have 4 60 ohm resistors remaining I dont see where these ayyach. Thank you again for your help
Paul Joppa
Moderator
Yes, that could explain the problem. The two diodes make up a voltage doubler, so if one of them is disconnected ... :^)
Yes, those are good resistances. The remaining resistors will go on the amp as you wire in the remaining connections on the output transformers.
I have listened for over one week and then went ahead with DC filament supplies. Tried soem 10UF Clarity caps which did improve sound slightly but too big with DC filament, with 300b tubes, my reading at B1 B4 And C1 C4 runs higher than expected at around 5.4 to 5.5 VDC. IS this OK? Our line current is often high over 124V, I am testing on bench will be used with a power conditioner when connected to system. Thanks
What are the voltages between +Reg and -Reg on each side of the DC board?
It could be that Psvane tubes draw a little less filament current, though that would be unexpected. Depending on your meter, if you have on that has something like a 200V and 500V scale for DC, then 5.5V may actually be an OK reading (some meters just won't resolve low voltages all that well).
It could be that Psvane tubes draw a little less filament current, though that would be unexpected. Depending on your meter, if you have on that has something like a 200V and 500V scale for DC, then 5.5V may actually be an OK reading (some meters just won't resolve low voltages all that well).
Paul Joppa
Moderator
Yes it's an issue. That's why PB asked for the voltages at the DC board, which should be 6.3v +/- a percent or two. You'll get a better measurement on a 20v scale compared with measuring voltage to ground on each tube pin (on a 200v scale) and subtracting.
If those voltages are correct, then the series resistors at the tube socket may need to be adjusted for non-standard heater current. If they are greater than 6.3v, there may be an error on the DC board.
The point of the Kaiju DC board is to make the filament voltage both correct and independent of the power line voltage.
If those voltages are correct, then the series resistors at the tube socket may need to be adjusted for non-standard heater current. If they are greater than 6.3v, there may be an error on the DC board.
The point of the Kaiju DC board is to make the filament voltage both correct and independent of the power line voltage.
I honestly didn't see that part, I was looking on my phone and it was cutoff. I will recheck tomorrow, I have it working now, sounds great, the DC supply an improvement. No audible hum. Thank you for pointing that out. I noted that the 300b on the BeePre are cooler than the Kaiju, and with an infrared non contact thermometer by about 100F, is that normal? The 300b are from different manufacturers
It is possible to connect the filaments of the 300Bs to the unregulated output of the DC filament supply, which are the pads on the side of the board facing the front of the amp, and that will provide more filament voltage than is desired to the 300B.
Yes, the Kaiju runs the 300Bs at about 27W of plate dissipation and the BeePre runs the 300Bs at about 5-6W, so the temperature difference is certainly expected.
Yes, the Kaiju runs the 300Bs at about 27W of plate dissipation and the BeePre runs the 300Bs at about 5-6W, so the temperature difference is certainly expected.
4.53 also isn't desirable, but what I am remembering is that the 300B will draw a fair amount of startup current which tapers off over time, so you may see 4.5V after a few seconds of operation, then it slowly should come up closer to 5V as the amp is allowed to run for a few minutes.
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