Building an RH84 revision 2 with 5r4gy rectifier and Sony Tamradio power & Output transformers. The case is an old suite case \ portable record player - re vamped with many hours of sanding & spraying etc.
Problems so far, i noticed I have wired my 200uf cap as the first cap rather than the 47uf one. I will change this next its an easy fix.
The two 100uf 100v Kemet peg124 Caps that i bought are way off in value, one measures 98uf the other 128uf. Iam not going to use them. Probably order some rubycons.
I sure am running out of space too.
Problems so far, i noticed I have wired my 200uf cap as the first cap rather than the 47uf one. I will change this next its an easy fix.
The two 100uf 100v Kemet peg124 Caps that i bought are way off in value, one measures 98uf the other 128uf. Iam not going to use them. Probably order some rubycons.
I sure am running out of space too.
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Thanks both yep used the kemets after your advice. Just have to wire B+ now then inputs and outputs. I finished the other channel today and realise when doing this that I had grounded the wrong pin on the LM317 so i sorted that on both channels too.
I think that I will buy a variac, i keep going through the circuit but am not 100% confident that i havent made a mistake. I have found a few silly ones along the way. Are there any voltages / test points published any where for the circuit? My 1st P2P build 🙂 Thanks Matt
I think that I will buy a variac, i keep going through the circuit but am not 100% confident that i havent made a mistake. I have found a few silly ones along the way. Are there any voltages / test points published any where for the circuit? My 1st P2P build 🙂 Thanks Matt
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Trying to check out my wiring for those sony output trans. I downloaded the tc500 schematic. It looks like red (p) goes to the plate and brown (b) goes to B+ . Not sure about the black and white wires though can any one confirm which should go to red and which black please? If not I will wire black to black and check for screeching or howling.
Hi thanks for rhe reply. Yes the schematic confirmed that my wiring was correct for B+ and plate, but I couldnt underdstand the speaker post wiring for the 8 ohm tap. Does the white wire go to the red speaker post and black one to the black speaker post. If i get this wrong the amp oscilate.
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This hasnt gone well today. Voltage from transformer is 325v x 2 (650v). I have an unloaded b+ of 397v at the 200uf cspacitor + terminal.
I thought this would decrease when I connected the amplifier circuits (load). But it didn't. I have conected the speakers and a source so that they are not un loaded.
I am using a current dim bulb device and variac. If i crank the variac up slowly at about 200v of b+ i get crackles on the speakers. But the bulb starts to glow a bit this gets brighter as I increase voltage on the variac.
Something else that i have noticed the 12at7 heaters are not coming on. This is odd as I get 6v on the socket pins when the tube isnt in. I also disconnected the b+ from the amp and put ane el84 in the same socket as they use the same heater pins. The heaters on the el84 work fine. The rectifier is working but b+ is high is it not at 400v. But the 12at 7 works fine in my other amp. I dont know where to start to be honest. The wiring on the rectifier and power supply circuit look fine to me. And irs a pretty simple circuit. Please can someone help if possible.
I thought this would decrease when I connected the amplifier circuits (load). But it didn't. I have conected the speakers and a source so that they are not un loaded.
I am using a current dim bulb device and variac. If i crank the variac up slowly at about 200v of b+ i get crackles on the speakers. But the bulb starts to glow a bit this gets brighter as I increase voltage on the variac.
Something else that i have noticed the 12at7 heaters are not coming on. This is odd as I get 6v on the socket pins when the tube isnt in. I also disconnected the b+ from the amp and put ane el84 in the same socket as they use the same heater pins. The heaters on the el84 work fine. The rectifier is working but b+ is high is it not at 400v. But the 12at 7 works fine in my other amp. I dont know where to start to be honest. The wiring on the rectifier and power supply circuit look fine to me. And irs a pretty simple circuit. Please can someone help if possible.
If you are trying to run a 12at7 with 6.3 volts on pins 4&5 It is running with a VERY starved filament. (12.6 @ 6.3 volts)
To use a 12at7n on 6.3 volts wire filament to pins 9 and 4 with a jumper wire from pin 4 and 5
To use a 12at7n on 6.3 volts wire filament to pins 9 and 4 with a jumper wire from pin 4 and 5
Mike that is superb thanks. That explains a lot. That is one issue solved then hopefully.
Anyone have any idea about my b+ issue. Thanks.
Thats interesting I was wondering about that myself, infact i already have another few on order just in case. Would this affect b+ though? Do i just take a reading of the output of the 317's and make sure it is 37v?
the lm317'swill affect the loading on the tube . 37 volts seems high for an el84. the tube is running near cutoff. (tube turned off). voltage should be about 22 volts. Can you post an as built schematic? I can't make out the wiring on the el84's
No. The EL84 has two heater pins. The 12AT7 has three heater pins. I can't see what you are doing, so check yourself.
Please attach a complete and accurate schematic of your amplifier.
No schematic, an incomplete schematic, or an in-accurate schematic is the same as:
Blindfolding an archer, and asking him to hit the bullseye in the target.
Just my opinions.
No schematic, an incomplete schematic, or an in-accurate schematic is the same as:
Blindfolding an archer, and asking him to hit the bullseye in the target.
Just my opinions.
Hi yes all. I know that I am definately using just pins 4 and 5 for the heaters. I know I have done this no question, and also I know that I should not have done this. Thanks for pointing it out Mike. I should have known better to be honest. Didn't set about correcting it tonight as I had already sunk my 1st beer, one for tomorrow morning.
Hi thanks for the further suggestions.
I have tripple checked lm317 as I did find this confusing, and I am sure I have it right. Pin 1 to ground and the the side of r7 (27r) that needs to be grounded. pin 2 other side of r7 (27r), pin 3 goes to pin 3 of el84 (cathode).
I have rewired 12at7 one side is not crackling now but quiet music and slightly destorted.
Please excuse my crude drawings I have gone through my circuit and sketched it out . One side of amp and the power circuit.
I have tripple checked lm317 as I did find this confusing, and I am sure I have it right. Pin 1 to ground and the the side of r7 (27r) that needs to be grounded. pin 2 other side of r7 (27r), pin 3 goes to pin 3 of el84 (cathode).
I have rewired 12at7 one side is not crackling now but quiet music and slightly destorted.
Please excuse my crude drawings I have gone through my circuit and sketched it out . One side of amp and the power circuit.
