Traynor YBA-1 to 1987 Conversion

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marshallnoise
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Re: Traynor YBA-1 to 1987 Conversion

Post by marshallnoise » Mon Jul 06, 2015 9:57 am

neikeel wrote:
marshallnoise wrote:Most definitely, the mixer resistor area is where the source of all the amp's noise comes from. When I ground the amp from any part AFTER the resistors approaching the grids of V2, I stop the noise.

Would that mean that the grounding problem is from that point forward? When I pull V2, the noise stops.

Also, when the guitar cord is NOT plugged in, the noise stops. When it is plugged in, that is when the noise starts. :what:
Is one of your switchingjacks partly open circuit/high impedemce on the inputs, do you have the 1M resistors securely to ground?
They are brand new authentic Cliff Jacks. And I wired them up the same as this:

Image

I will take pictures tonight and show the grounding as you've requested. I appreciate your re-engagement into the thread.

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Re: Traynor YBA-1 to 1987 Conversion

Post by marshallnoise » Mon Jul 06, 2015 10:03 am

marshallnoise wrote:
neikeel wrote:
marshallnoise wrote:Most definitely, the mixer resistor area is where the source of all the amp's noise comes from. When I ground the amp from any part AFTER the resistors approaching the grids of V2, I stop the noise.

Would that mean that the grounding problem is from that point forward? When I pull V2, the noise stops.

Also, when the guitar cord is NOT plugged in, the noise stops. When it is plugged in, that is when the noise starts. :what:
Is one of your switchingjacks partly open circuit/high impedemce on the inputs, do you have the 1M resistors securely to ground?
They are brand new authentic Cliff Jacks. And I wired them up the same as the drawing on the left:

Image

I will take pictures tonight and show the grounding as you've requested. I appreciate your re-engagement into the thread.

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Re: Traynor YBA-1 to 1987 Conversion

Post by marshallnoise » Mon Jul 06, 2015 11:25 pm

Ok, here is a big puke of all the pictures I just took.

Remember, click pictures to make them larger.
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And I implemented the star grounding that was approved from Larry per this thread. http://forum.metroamp.com/viewtopic.php ... +grounding

Image

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Re: Traynor YBA-1 to 1987 Conversion

Post by neikeel » Tue Jul 07, 2015 3:27 am

Hmmm

You can go OT with grounding too :lol:

Amps are not like cars/bikes where you use as star earth and if too many come together with different parts of the signal then you may cause ground loops. I cannot tell but I presume you implemented the Larry grounding exactly with no personalised extras?

I have never wired my input jacks that way I use the stock Marshall method with half the ground lugs excluded.

Wonder if you will also lose some highs with so much shielded cable? What value are those grid resistors on the input jacks?

They are upside down for a Marshall (maybe the Traynor panel has them like a Hiwatt bottom input is Hi?)
Neil

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Re: Traynor YBA-1 to 1987 Conversion

Post by marshallnoise » Tue Jul 07, 2015 11:20 am

neikeel wrote:Hmmm

You can go OT with grounding too :lol:

Amps are not like cars/bikes where you use as star earth and if too many come together with different parts of the signal then you may cause ground loops. I cannot tell but I presume you implemented the Larry grounding exactly with no personalised extras?

I have never wired my input jacks that way I use the stock Marshall method with half the ground lugs excluded.

Wonder if you will also lose some highs with so much shielded cable? What value are those grid resistors on the input jacks?

They are upside down for a Marshall (maybe the Traynor panel has them like a Hiwatt bottom input is Hi?)
I thought it was nuts to do the Larry grounding, but I can say it is pretty darned quiet with the exception of the buzz. Nothing but faint hiss when the volume is cranked. And no extras at all. Completely stock 1968 Plexi 50 Watt circuit with the exception of the power transformer not having a center tap, thus the use of the full wave bridge diode rectifier.

Regarding the shielded cable, I would imagine I have lost some highs. But this amp is pretty bright so I am not all that disappointed. Much more noticeable on channel 1 versus channel 2.

The input jack resistors are 1M like they should be. The 68k resistors are on the board like normal too. And I have wired the input jack like the one on the left where the high input is up on top and the low input is on the bottom.

Tomorrow my Classic Tone output transformer arrives and I'll wire that one in along with a impedance switch. I am interested to see if the new transformer hums/buzzes like the old one. I will also install the hum balance control because I can. If it is ineffective, I will delete it. I got some new 12AX7s as well. Two EH and one JJ. Went for quiet tubes.

I may disconnect each ground and fire the amp up and see what gives. So many damn ground points with the Larry setup.

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Re: Traynor YBA-1 to 1987 Conversion

Post by marshallnoise » Tue Jul 07, 2015 11:51 pm

I think my hum originates at the presence pot. I remember changing my NFB resistor to 10K from 47K, This reduced hum significantly.

Well, I tried to by pass the 10k resistor with a jumper wire...and fire came out of my presence pot!

EDIT: I reconnected the presence pot and we are back to normal..or so. I need to recheck power section voltages. When I crank the bias voltage, the hum gets louder.

I also replaced the preamp tubes with the new ones and that has drastically lowered the noise floor. Glad for that. I still have the low level hum.

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Re: Traynor YBA-1 to 1987 Conversion

Post by marshallnoise » Wed Jul 08, 2015 3:26 pm

Ok, more hunting around. I isolated all of the grounds and really endured some loud noises to see if my buzz is related to grounding. I really don't think so at this juncture.

I have identified the hum/buzz as 120hz which tells me it is in the b+. I agree the hum balance pot is pointless at this juncture. I may install the 100 ohm resistors on the bias lines and tape off the CT just to eliminate it as a factor.

That being said, my amp is not using a typical 50 watt power supply. It is much more like the 100 watt JCM800 2203 (not the JMP 2203). It doesn't use a center tap. What is different is the center tap of the HT isn't used. Well, my Hammond that came with the Traynor doesn't have a CT. See this thread: http://el34world.com/Forum/index.php?topic=12330.0

Here is the JMP on the left and the JCM800 on the right.
Image

What I wonder is if I have the wiring of the filter capacitors done incorrectly.

Here is what I have currently.
Image

And here is the stock Traynor YBA-1 power section using the same transformer I have now.
Image

Another thought is if I should be adding filtering the dedicated bias tap line to smooth out the -DC going to the control grids of the EL34s. Ahh!

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Re: Traynor YBA-1 to 1987 Conversion

Post by marshallnoise » Wed Jul 08, 2015 6:21 pm

Going off of my theory that the filtering is incorrect for the B+, this is what I am thinking.

This is what it is based on the layout and what I currently have. Two 50uf cans wired in series which equals 25uf.
Image

This is what it should be according to the JCM800 2203. B+ hitting one 50uf can, then into another 50uf can then out to the HT fuse. This equals 100uf of capacitance.
Image

Is there a difference? (BTW, came up with those combined values with this: http://www.electronics2000.co.uk/calc/s ... ulator.php.)

This is what I am trying to achieve since the 2203 in the JCM800 uses the same rectifier as my Hammond.
Image

:hide:

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Re: Traynor YBA-1 to 1987 Conversion

Post by ivan H » Wed Jul 08, 2015 11:43 pm

Hi, if I'm understanding u right u currently have wot is shown in the top (or 1st) diagram in the last post. That is two 50uf caps wired in parallel to give 100uf, exactly the same as the next diagram & wot is shown in the schematic. It is impossible to wire a dual cap can in series. Series wiring means one caps positive to the other caps negative, leaving a positive free at one end & a negative free at the other. Cheers

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Re: Traynor YBA-1 to 1987 Conversion

Post by marshallnoise » Thu Jul 09, 2015 1:21 am

ivan H wrote:Hi, if I'm understanding u right u currently have wot is shown in the top (or 1st) diagram in the last post. That is two 50uf caps wired in parallel to give 100uf, exactly the same as the next diagram & wot is shown in the schematic. It is impossible to wire a dual cap can in series. Series wiring means one caps positive to the other caps negative, leaving a positive free at one end & a negative free at the other. Cheers
I kind of wondered if I was being retarded thinking about it in that manner. So the JMP 2203 just has two 50/50uf cans wired in series. So I could potentially do that. I wonder if I have a bad cap can. It is brand freaking new. Bahh.

If I am getting 120hz buzz/hum through the amp that goes away when I touch the chassis, then what do I have?

Does this mean I have DC introduced where signal is? Does that also mean I have a grounding issue?

I have tried every which way to redo all of the grounds in the amp and I am kind of at a loss.

In other news, I installed the Classic Tone OT and the impedance tap. I love the character of the Classic OT. It further reduced some of the hum. I think that the OT was dying. I also installed a false center tap setup on the heater wiring to see if I could reduce hum further. It made no difference. So i am removing it. Neikeel called that one.

I have two other interesting things going on. First, channel 2 allows signal to come through when the pot is at 0. Channel 1 doesn't. Also, it is by far the noisiest. Which I think is expected.

Second, the hum gets worse the more I turn up the presence pot. I really think that is where I am getting the main source of hum. My NFB resistor is 10K because at 47K the hum was unbearable.

Getting closer though. Much closer.

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Re: Traynor YBA-1 to 1987 Conversion

Post by neikeel » Thu Jul 09, 2015 11:50 am

Diodes can cause switching noise (UF5408 diodes are brilliant and quiet :wink: ).

Did you ground the heater centre tap to teh inputs as per Larry grounding and have you tried separating the presence pot from the ground bus and taking the ground back to the lug that the PI can cap is grounded too.

Your mains has a dedicated ground?
Neil

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Re: Traynor YBA-1 to 1987 Conversion

Post by marshallnoise » Thu Jul 09, 2015 12:33 pm

neikeel wrote:Diodes can cause switching noise (UF5408 diodes are brilliant and quiet :wink: ).

Did you ground the heater centre tap to teh inputs as per Larry grounding and have you tried separating the presence pot from the ground bus and taking the ground back to the lug that the PI can cap is grounded too.

Your mains has a dedicated ground?
I wouldn't mind swapping out the diodes. I will price them out.

Yes, the heater center tap is grounded at position 1 (inputs).

The Phase Inverter cap can is grounded at point 2 with the Volume pots.

The Presence pot is grounded with the Middle pot, Speaker output ground and the first can cap ground.

And the mains has a separate ground with plenty of lead incase I chuck it off the Empire State Building. :bang:

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Re: Traynor YBA-1 to 1987 Conversion

Post by marshallnoise » Thu Jul 09, 2015 6:02 pm

I uploaded my first youtube video to get the buzz sound on tape for you guys. Below is a description of what happens.

https://youtu.be/B6Nb67EvbCs

I first turn the amp on with a guitar cable plugged in the Channel 1 Hi input then turn up and down the volume several times. Then I disconnect the cable and put it in Channel 2 and do the same thing. Then I put it on standby and then off.

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Re: Traynor YBA-1 to 1987 Conversion

Post by ivan H » Thu Jul 09, 2015 6:09 pm

U should have the PI filter cap, Presence control & the Speaker Output all grounded at Position 3. The volume pots should be grounded at position 2, along with the pre amp dual cap can etc. Cheers

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Re: Traynor YBA-1 to 1987 Conversion

Post by marshallnoise » Thu Jul 09, 2015 6:38 pm

ivan H wrote:U should have the PI filter cap, Presence control & the Speaker Output all grounded at Position 3. The volume pots should be grounded at position 2, along with the pre amp dual cap can etc. Cheers
Ok, so i have it wired like this:

Position 1: Inputs, 1st gain stage, heater center tap.
Position 2: 2nd gain stage, 33/33uf cap on the board (is this the PI filter cap?), volume pots
Position 3: Middle pot, Presence pot, output jack, 32/32uf can cap (connected to 2 watt resistors)
Position 4: Bias supply ground, negative of full wave bridge diode rectifier
Position 5: 1 ohm power tube pin 7 & 8 grounds, 50/50uf can cap for HT filtering
Position 6: 120AC ground

This matches this circuit here except for the lack of a HT center tap because I don't have one.
Image

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