[BUILD] 1176 Rev F/G - new board, new transformer!

[Echo North]

Oh the penny just dropped .... in case I didn't mention earlier I'm building a rotary version not push button so I'm using the old school gyraf style ratio and meter pcbs.

Ya 4 same as the schematic then.  It goes over to the meter PCB because that's where your bypass is.  just keep following it to pad 22 to see where the AC dies.

 

[Finlaywatt]

Looking at the overlay CR9 & CR10 were the wrong way round. Power pads read -9.5V and about +24V. It's calibrated and seems to work perfectly well apart from its pretty noisy. It could well be cables that're causing that though so I'll be in the studio on Monday and i'll patch it into the rack and give it a bash. Thanks for all your help!

 

[Echo North]

Looking at the overlay CR9 & CR10 were the wrong way round. Power pads read -9.5V and about +24V. It's calibrated and seems to work perfectly well apart from its pretty noisy. It could well be cables that're causing that though so I'll be in the studio on Monday and i'll patch it into the rack and give it a bash. Thanks for all your help!

No your noise is most likely caused by your low +30VDC power rail.  24V is WAYYYY too low.  Get that up to 30 and your noise will go away.

Not sure what it could be.  If it were me, I'd replace the diodes, caps and maybe the regulator in the power section.

Mike

 

[Finlaywatt]

Okay. Which way round should the voltage regulator be? Could it be caused by it being round the wrong way?

 

[Echo North]

Okay. Which way round should the voltage regulator be? Could it be caused by it being round the wrong way?

I can't imagine it would work installed incorrectly. Orientation is on the PCB.

 

[Finlaywatt]

The pcb shows a rectangle with a line along it. Does that line represent the metal lug at the top where the heat sink is screwed to?

 

[Echo North]

The pcb shows a rectangle with a line along it. Does that line represent the metal lug at the top where the heat sink is screwed to?

Exactly.

 

[Echo North]

More than likely something was damaged with the reversed diodes.  I really could be anything but the PS is a good place to start.  That's why MNATS and I have tried to stress again and again to build and test your power supply first.  Not sure what to tell you at this point.  Replacing the PS components would be cheap and a good place to start.  If you have 25V AC between your CT and each of the sides you'll know your power transformer is ok. Have your tech friend have a look and see if you can sort why the rail is so low.

Mike

 

[Finlaywatt]

Okay. The voltage regulator is the wrong way round then. Don't know how I'm getting the -9 :/ between the ct pad and ac pads each side? Thats reading just over 30V for each.

 

[frazzman]

Oh the penny just dropped .... in case I didn't mention earlier I'm building a rotary version not push button so I'm using the old school gyraf style ratio and meter pcbs.

Ya 4 same as the schematic then.  It goes over to the meter PCB because that's where your bypass is.  just keep following it to pad 22 to see where the AC dies.

Thanks Mike - will keep at it. What am I expecting to see at pad 22 so I know if i'm on the right track?

 

[Echo North]

Oh the penny just dropped .... in case I didn't mention earlier I'm building a rotary version not push button so I'm using the old school gyraf style ratio and meter pcbs.

Ya 4 same as the schematic then.  It goes over to the meter PCB because that's where your bypass is.  just keep following it to pad 22 to see where the AC dies.

Thanks Mike - will keep at it. What am I expecting to see at pad 22 so I know if i'm on the right track?

Audio signal (AC voltage)

 

[Echo North]

Okay. The voltage regulator is the wrong way round then. Don't know how I'm getting the -9 :/ between the ct pad and ac pads each side? Thats reading just over 30V for each.

Your -10 rail does not use the regulator.  You transformer seems fine.

 

[Finlaywatt]

Phew. Will take It to the tech I know tomorrow and get him to flip the voltage regulator as the solder pads will pop off if I try any more.

 

[frazzman]

Oh the penny just dropped .... in case I didn't mention earlier I'm building a rotary version not push button so I'm using the old school gyraf style ratio and meter pcbs.

Ya 4 same as the schematic then.  It goes over to the meter PCB because that's where your bypass is.  just keep following it to pad 22 to see where the AC dies.

Thanks Mike - will keep at it. What am I expecting to see at pad 22 so I know if i'm on the right track?

Audio signal (AC voltage)

Hrmmm... I am seeing some AC there but its pretty low . Mega confused. Me thinks might order the push button boards and try my luck there

 

[Echo North]

Oh the penny just dropped .... in case I didn't mention earlier I'm building a rotary version not push button so I'm using the old school gyraf style ratio and meter pcbs.

Ya 4 same as the schematic then.  It goes over to the meter PCB because that's where your bypass is.  just keep following it to pad 22 to see where the AC dies.

Thanks Mike - will keep at it. What am I expecting to see at pad 22 so I know if i'm on the right track?

Audio signal (AC voltage)

Hrmmm... I am seeing some AC there but its pretty low . Mega confused. Me thinks might order the push button boards and try my luck there

How low compared to your PAD 15 and at what ratio?  Do you have continuity between pad 4 on your ratio and pad 22 on your PCB with GR on?

 

[frazzman]

Oh the penny just dropped .... in case I didn't mention earlier I'm building a rotary version not push button so I'm using the old school gyraf style ratio and meter pcbs.

Ya 4 same as the schematic then.  It goes over to the meter PCB because that's where your bypass is.  just keep following it to pad 22 to see where the AC dies.

Thanks Mike - will keep at it. What am I expecting to see at pad 22 so I know if i'm on the right track?

Audio signal (AC voltage)

Hrmmm... I am seeing some AC there but its pretty low . Mega confused. Me thinks might order the push button boards and try my luck there

How low compared to your PAD 15 and at what ratio?  Do you have continuity between pad 4 on your ratio and pad 22 on your PCB with GR on?

Hi Mike... checked measurements today with 1khz sine wave feeding in, GR on.

I have no AC at all on the 5 terminals in the GR control amp section (20, 18, 22, 21, 19)

I have DC readings on Pad 21 which increase as ratio changes, no DC on pad 22
I do have AC reading on pad 15 on the mainboard - its the same when measured directly on the output pot too, so its getting through ok via the ratio board

I DO have continuity between pad 4 on ratio and pad 22 with GR on, when I switch to bypass or VU the connection breaks so I know that the switching here is working.

Also today I checked every single resistor on all 3 boards to check for incorrect component but they are all ok.

What do you think I should check next? I've yet to have a build as evasive as this one yet but I am persistant! Thanks again

 

[Echo North]

You have an issue with PAD 22, it should only have audio (AC) and you have none.  Pad 21 has -DC no AC but don't worry about it for now.

Don't worry about anything right now except getting your AC audio signal from your output pot to your pad 22.  look at the schematic again, it takes a very direct linear route.  output pot->ratio board ladder->meter board for GR off switch->pad 22

Where does it die?

 

[Finlaywatt]

So i took it to my tech friend. He put in a new voltage regulator the right way round. Getting about +29.8V and about -9.7V!

Works like a dream. A/B'd it with an original Urei Rev H in the studio and they're remarkably similar. All buttons in on this thing is crazy! Love it!

Cheers for all your help

Finlay

 

[Echo North]

So i took it to my tech friend. He put in a new voltage regulator the right way round. Getting about +29.8V and about -9.7V!

Works like a dream. A/B'd it with an original Urei Rev H in the studio and they're remarkably similar. All buttons in on this thing is crazy! Love it!

Cheers for all your help

Finlay

Cool beans.  Glad to hear it!

 

[rob61]

I have an original F that I thought I'd recap... never done that before. The original used all axial style caps. Many of the "audio" grade caps are radial. Is it better to stay with the axials (mostly Vishays) or should I mount radials in their place?

When these were originally made, did they even grade caps as "audio" or were they simply radial caps?