[BUILD] fripholm's TG1 Zener Limiter boards - support thread

[Voodoobeat]

anybody acutally build a unit from ChrioN PCB copies?

 

[Potato Cakes]

anybody acutally build a unit from ChrioN PCB copies?

This would be answered in a new thread.

 

[ron_swanson]

Hello everyone!

Tried to power up my TG1 tranny and power supply today as a first verification step resulting unfortunately in a potential meltdown.

I have the tranny connected to a grounded, fused, switched IEC power input module in a chassis enclosure.

Tested the enclosure for ground continuity and first powered up just the tranny ( no +-28 PS connected to secondaries) checking that the expected 30VAC secondary output was correct.  120VAC in, ~33VAC across both secondaries.

Then connected my fripholm's PCB power supply build and slowly brought up the AC from 0 to 120V using a Variac checking visually and measuring AC while keeping an eye on total current.  Nothing seemed out of line.  I've got a 1A fuse in place in the IEC module.  The Variac was showing something like .04A.  I had the PS center output lug connected to chassis ground (is that correct?) in case that makes any difference here.  Checked one side of the PS DC output... saw something like ~22VDC (U2 side of output connector).  The other side measured ~46VDC (U3 side of output connector).  Uh, oh...

I then noticed that C2 and C3 where starting to bulge on the top.  A quick check of the caps indicated they were both extremely hot, so I pulled the plug.  All of this occurred over a period 1 - maybe 2 minutes.

I couldn't tell if the +WW- bridge was abnormally hot or not, so that's unclear, but none of the other components seemed to be hot or even marginally warm including both regulators.

I desoldered by C2 and C3 and tested.  They both seem to be within spec, so didn't blow, but...

So, where to go now? I'll replace C2 and C3 just to be safe.  Does any of this description point to something obvious that I should first start looking at to troubleshoot?

Disclaimer... While I've successfully built a number of both tube and SS audio projects, I still consider myself a rank beginner.  Always appreciative of any help offered even if it's just a pointer.  Thanks in advance...

Cheers,
Greg

 

[Potato Cakes]

Make sure your secondaries that you tie into the PSU are connecting to the rectifier AC connections as shown on the PCB overlay in the manual. Make sure that measuring voltages on the secondaries while they are connected to the PCB are about 30VAC. If that is the case, then you get to do what we all get to do when a freshly built board doesn't work correctly..... check all the solder points and component placement and orientation. The PCB is indeed correctly laid out and does work when built as per the BOM and instructions.

Let us know what you find.

Thanks!

Paul

 

[ron_swanson]

Make sure your secondaries that you tie into the PSU are connecting to the rectifier AC connections as shown on the PCB overlay in the manual. Make sure that measuring voltages on the secondaries while they are connected to the PCB are about 30VAC. If that is the case, then you get to do what we all get to do when a freshly built board doesn't work correctly..... check all the solder points and component placement and orientation. The PCB is indeed correctly laid out and does work when built as per the BOM and instructions.

Let us know what you find.

Thanks!

Paul

Hey Paul,

Bingo!

Yep, I inadvertently mis-connected the secondary to the PSU as you suggested.  After soldering in a new pair of caps, I was able to adjust the output to a rock solid +28/-28DCV.

I'm not happy that my mistake was a knucklehead move, but all is good now.  Appreciate the assist here!

I'm loosely following  fripholm's enclosure / interface as shown in the manual as I wanted to tackle a build that included switches with lights.  Now, to figure out how that's all that powered and implemented... 

Cheers,
Greg

 

[dogvoid]

Hi friends!

I am building a second stereo unit, in "luxury" mode:
Resistors 0.1% and mundorf capacitors in some parts, I think it can be interesting (C3, C1, C29), Sifam AL20-6-7 Retro VU-Meter Set, U3 custom rack, control hold and everything by rotary steps, custom SC frequencies …

The rotary shorting or non sorting?

The resistance of SC "curve" are R48, R49? to calculate capacitors, I read by the thread that they are those.

Any proposal to "improve" the sound quality with components in specific parts will be welcome

Thanks.

Abel

 

[warpie]

Any proposal to "improve" the sound quality with components in specific parts will be welcome

transformers?

 

[Rob Flinn]

Any proposal to "improve" the sound quality with components in specific parts will be welcome

Did the first unit you built sound sub standard ?

 

[TwentyTrees]

Did the first unit you built sound sub standard ?

Agreed - “improve” is a hugely subjective word, to different folks it could mean make it as clean as possible, as authentic as possible,  make it truly funky, or almost anything else. 

I’ve not built mine yet, so this is an open question and I’m genuinely interested in your thinking - what are you looking for that’s different from your first build?

 

[dogvoid]

transformers?

Yes, Transformers use the carnhills the same as Chandler:
CA-18-VTB9046 input
CA-18-VTB2281 output
The upper next option would be sowter ... that I know.

 

[dogvoid]

Did the first unit you built sound sub standard ?

I am delighted with my first unit, it sounds great!The new one is for the study of a friend and we have decided to improve as much as possible, but above all it is my desire to experiment.Evidently the retro vu and the Emi buttons are a "presence" theme, but the price hurts.

 

[dogvoid]

Agreed - “improve” is a hugely subjective word, to different folks it could mean make it as clean as possible, as authentic as possible,  make it truly funky, or almost anything else. 

I’ve not built mine yet, so this is an open question and I’m genuinely interested in your thinking - what are you looking for that’s different from your first build?

Yeah, I agree on everything!
Basically, 0.1% resistances to further adjust the pairing (psychomatched)
The Mundorf in my 1176 gave me surprising results, the change, when possible, film foil capacitors instead of electrolytic improves the definition and makes a clearer sound.
Tg1 is a compressor with character, I do not pretend transparency, the idea is the same sound but more quality, like going from 1080 to 4K with the same movie ... I do not know if I explain …
In any case, when I repeat a unit I like to experiment.

Truly Funky forever!!!

 

[warpie]

Yes, Transformers use the carnhills the same as Chandler:
CA-18-VTB9046 input
CA-18-VTB2281 output
The upper next option would be sowter ... that I know.

What I meant is that the transformers might be the first thing you should be looking at if you want to experiment.

 

[dogvoid]

What I meant is that the transformers might be the first thing you should be looking at if you want to experiment.

Yes, I understand that the transformers are probably the most important part of the "character" of the sound, my idea is to test different configurations with the carnhill, the input basically.
Experimenting with different brands (sowter, carnhill, lundahl, etc.) leaves the budget.
But I understand what you say, thank you very much for the observation.

 

[warpie]

anybody acutally build a unit from ChrioN PCB copies?

I also got a pair from Chrion. Are those boards any different? I remember reading that these boards were rip-offs?
Haven't even started working on them but I will sometime in the future.

But I understand what you say, thank you very much for the observation.

No problem  Let us know of any progress!

 

[ron_swanson]

Hello,

I'm trying to gain some clarity over the bypass instructions in fripholm's build manual.  Hoping someone can shed some further clarity so I understand what exactly is expected and to confirm my initial reading of the requirements.

On page 2 of the manual there's diagrams showing both a DPDT switch and a relay?  Is this indicating that either a switch or relay can used (either / or) or both must be used to perform the bypassing function?  My read is the instructions/diagrams indicate an 'or' configuration.

For my build, I'm using the same British style LED DPDT square switches I assume fripholm used in his example (Don-Audio sourced) and planning on using this switch in addition with a relay to cover both the LED power switching on the switch and the actual audio passing / bypassing duties.

In previous builds I have built where a bypass circuit was in play, the bypass circuit completely bypassed the entire circuit.  Meaning the audio was bypassed before and after the the I/O transformers - two relays per channel.  From studying fripholm's schematic, in this build it appears that while fulfilling a bypass function, the actual bypassing is being made from within the circuit using either a physical DPDT switch or a 24VDC DPDT relay. 

Lastly, assuming using a relay, does anyone have a recommendation for a MBB 24VDC relay?    I was first thinking of using Omron G5V-2-DC24's (or like offering and because I have a supply of these on hand) relay on a bespoke PCB, but don't see on the datasheet for any of these signal relays where they offer MBB options.

Thanks in advance,
Greg

 

[Ilya]

I don't think you can get MBB relays. I'm not sure if they exist.
For this application any relay should be fine. G5V is a good choice. If you want a clickless solution, you'd better look into FET switching.

 

[fripholm]

On page 2 of the manual there's diagrams showing both a DPDT switch and a relay?  Is this indicating that either a switch or relay can used (either / or) or both must be used to perform the bypassing function?  My read is the instructions/diagrams indicate an 'or' configuration.

Either way.

A DPDT switch can perform the bypass function alone and a relay can do that as well. As soon as you want to indicate with an LED you'll need both, as in your case (or in my, for that matter). You'll be using the switch to toggle the LED and the relay - which in turn does the BYPASS. This is what I did with the british style square switches.

The guide does not cover this case - only the bypass function by itself, done by either a switch OR a relay.

In previous builds I have built where a bypass circuit was in play, the bypass circuit completely bypassed the entire circuit.  Meaning the audio was bypassed before and after the the I/O transformers - two relays per channel.  From studying fripholm's schematic, in this build it appears that while fulfilling a bypass function, the actual bypassing is being made from within the circuit using either a physical DPDT switch or a 24VDC DPDT relay.

In this case, BYPASS only bypasses the compressor stage. The signal still goes through the input transformer, the output stage and the output transformer. I still wanted some coloration instead of a full bypass - but there's other ways, although not covered in the guide.

Hope, that clears things up.

 

[ron_swanson]

Either way.

A DPDT switch can perform the bypass function alone and a relay can do that as well. As soon as you want to indicate with an LED you'll need both, as in your case (or in my, for that matter). You'll be using the switch to toggle the LED and the relay - which in turn does the BYPASS. This is what I did with the british style square switches.

The guide does not cover this case - only the bypass function by itself, done by either a switch OR a relay.

In this case, BYPASS only bypasses the compressor stage. The signal still goes through the input transformer, the output stage and the output transformer. I still wanted some coloration instead of a full bypass - but there's other ways, although not covered in the guide.

Hope, that clears things up.

Thanks Ilya and fripholm!  Appreciate the input and, 'yes' clears things up.

Greg

 

[ron_swanson]

Hello All!

Fired up my build last night with issues right off the bat - no audio bypassed or engaged.    After some poking around (byp1 wired backwards from DPDT - ugh!) , I can now get audio to pass both in bypass and engaged modes and I have meter activity when engaged, but too early to say what may also be in play as I haven't gotten to any of the tuning procedures.  Upon initial listening,  not hearing any obvious ground or buzzing noises that point me to larger concerns...  but, this...

For some reason that I so far cannot find a reason for...  the output gain controls on both channels are working backwards - meaning, when I turn the output gain control CW, the output volume reduces from full volume to nothing (fully CW) instead of increasing the volume as I would expect.  I'm a bit flummoxed about this at the moment as all seems to be wired per the schematic.  Be that as it may be, I tried swapping the wiring in the output gain header connection, that either rendered the signal dead or the gain control still working backwards.  Pots are wired hot= 1, cold / wiper = 2, drain = 3.

Two questions....

1. Just in case, both the input and output gain controls should work normally  - meaning, full CCW is 0% (no volume) and full CW is  full (100%) volume.

2. While there is a good amount of wiring instructions contained within fripholm's documentation, I didn't see (or, couldn't find) a visual diagram for wiring the off board controls anywhere within this thread.  Because of the backwards output control issue stated above, I'm not 100% sure about the proper wiring of the gain controls so was looking for a deeper wiring digram to confirm what I have gleaned from the schematic / following board traces.  Is there something more obvious I could be using to verify the wiring that my inexperience is preventing here?

In case it matters, using Sowter I/O's (2:1 in, 1:1 out), dual channel build, fripholm's +-28V PSU.

Thanks in advance!
Greg