All things G1176 - the new "repost" thread.

[gswan]

Both resistors are getting very hot as are Q8 and Q9 - within seconds of powerup.
I think I am just noticing the smoke off the 1R0 first but its all getting hot.

Pull these transistors and check them. They maybe dead now. Are you sure you have them in the correct way around and in the correct set of hols (there are two sets).

I also rechecked CR1 and 2 because the ones I got dont have a marker band to indicate cathode.

Get some ordinary 1N4004 diodes for these, which always have a stripe.

 

[mac]

It was the diodes...my fault. My aussie electronics supplier RocXXy kindly provides the parts with labeled baggies. But they sent me P6KE6V8CA Voltage Protection 600W 6.8V Bidirect diodes labeled as IN4003's.

I picked up on the other two wrongly provided parts in that order, both were caps and easy to spot, but I missed this one...

now to figure out what else i have fried

mac.

 

[goldenGeek]

Could by a number of things. Check for electro's reversed in signal amplifiers.

Forget the meter on the unit itself, it could be messed up. Use an external, calibrated audio millivoltmeter or equivalent to be sure of what you are reading. Then start probing to see where the signal starts to disappear.

that`s a pretty quick reply Thanks
I`ve checked the electros and they are all the right way. I`ve also had my scope hooked up to the output and it acts just the same way as the VU, so I guess there`s time to start probing for the evil component

I`m trying to learn the basics of troubleshooting, but it`s really hard I guess I have measured the voltages as mentioned in the first post of this thread, and they all seem pretty okay I think. They`re all a bit off (a bit lower), but nothing really off. So now I`m trying to trace the signal, but it`s hard to figure where the good places to probe is. At the input pot I have the same level as the signal I`m feeding. I leave the input pot fully open and I read the output pot. This one reads about half the signal. I leave the output pot fully on. And on the output terminal after the OEP I have a slightly higher signal again. I would guess about between the input pot level and output pot level levelwise. Are these levels drops/rising the way it should be? And what signal strength should I feed my 1176 with?

Edit: after leaving the unit on a bit longer the output-pot level seems to have dropped even more. Maybe this is a sign of the signal pre-amp being faulty? If so, what are good places to check and do I measure voltges or waveforms?

Edit #2: just after power up the output-pot reads about twice as strong signal than the input-pot. But after a while the signal drops to under half of the input. Any clues??

 

[ChrioN]

Shorting point 22 to ground doesn't bypass the gain reduction. I'm routing the point 22 from the main pcb through the meter pcb and then to the bypass toggle switch.

 

[Chrome Heart]

Im sure this has been covered but I coudlnt seem to find it with "search". Is there a way to add "all button" mode to the Lorlin rotary switch on ratio? A wiring diagram would be really helpful.
thanks all

 

[mac]

Hey Chromeheart,
we were just discussing this on the last page of this thread (go back one page).

ChrioN,
Can you please clarify - (I am easily confused)  ???

Shorting point 22 to ground doesn't bypass the gain reduction. I'm routing the point 22 from the main pcb through the meter pcb and then to the bypass toggle switch.

Because this is exactly what I am planning to do once I get my boards into my case. But Geoff provided this info one page back, which seems to conflict with your statement...

When in 'disable' mode, the input to the GR amp (22) must be connected to GND.
When not in 'disable' mode, the input to the GR amp (22) must be connected to the output from the ratio switch.

cheers,
Mac

 

[Chrome Heart]

Hey Chromeheart,
we were just discussing this on the last page of this thread (go back one page).

ChrioN,
Can you please clarify - (I am easily confused)  ???

Shorting point 22 to ground doesn't bypass the gain reduction. I'm routing the point 22 from the main pcb through the meter pcb and then to the bypass toggle switch.

Because this is exactly what I am planning to do once I get my boards into my case. But Geoff provided this info one page back, which seems to conflict with your statement...

When in 'disable' mode, the input to the GR amp (22) must be connected to GND.
When not in 'disable' mode, the input to the GR amp (22) must be connected to the output from the ratio switch.

cheers,
Mac

Ah yes, thank you Mac. It was right under my nose. There appears to be some debate regarding the effects of all button vs. 4 and 20 bridge. I guess thats to be expected. It also looks like an additional switch is required.
One other thing. does anyone have an .fpd file they would like to share for the 1176?
cheers

 

[gswan]

Ah yes, thank you Mac. It was right under my nose. There appears to be some debate regarding the effects of all button vs. 4 and 20 bridge. I guess thats to be expected. It also looks like an additional switch is required.
One other thing. does anyone have an .fpd file they would like to share for the 1176?
cheers

No debate, examine the circuits and it's very plain.

I have a couple of fpd files for my 1176 front panels if they are of any use to you. There's one that can be downloaded here, with the wider Flashstar meters.
http://www.axtsystems.com/index.php?option=com_content&view=article&id=53:1176lnenclosure&catid=34:1176ln&Itemid=62

 

[Chrome Heart]

Ah yes, thank you Mac. It was right under my nose. There appears to be some debate regarding the effects of all button vs. 4 and 20 bridge. I guess thats to be expected. It also looks like an additional switch is required.
One other thing. does anyone have an .fpd file they would like to share for the 1176?
cheers

No debate, examine the circuits and it's very plain.

I have a couple of fpd files for my 1176 front panels if they are of any use to you. There's one that can be downloaded here, with the wider Flashstar meters.
http://www.axtsystems.com/index.php?option=com_content&view=article&id=53:1176lnenclosure&catid=34:1176ln&Itemid=62

Thanks gswan. Yes I did read your post with respect to the circuit and its certainly clear regarding 8 and 12 being out of the circuit. casrec stated hearing a difference. Im always intrigued at the subjective nature of "hearing" audio

 

[goldenGeek]

I`m expering a raher drastic signal drop in the pre-amp section of my 1176 (in all three modes, so it`s not like it is compression going on). Which components in the ore-amp are likely to be broken, and how can one measure the components to find that messed up punk? Do I have to remove the condensers to check those, or can it somehow be checked in the circuit (with DMM or scope)? The transistors seems to be okay (at least the voltages check out fine).

 

[danjpiscina]

Im always intrigued at the subjective nature of "hearing" audio

Yes! That's why I believe people REALLY REALLY need to post listening examples for comparison. At the end of the day, most of us are making this gear and using it to make music! I'm dying to hear mnats blue stripe compared to an original. I will soon post a comparison of this guy http://www.groupdiy.com/index.php?topic=33834.0 and an original and I hope more people do the same. Especially if you're living in LA. It's so easy to rent one (like $30-40 a day, and if you ask me it's worth it. We spend all this time, money, and effort making these things and we're satisfied when they work. It would be even more satisfying to know that they're as good as originals costing 4-6k!

Dan P.

 

[casrec]

Ah yes, thank you Mac. It was right under my nose. There appears to be some debate regarding the effects of all button vs. 4 and 20 bridge. I guess thats to be expected. It also looks like an additional switch is required.
One other thing. does anyone have an .fpd file they would like to share for the 1176?
cheers

No debate, examine the circuits and it's very plain.

I have a couple of fpd files for my 1176 front panels if they are of any use to you. There's one that can be downloaded here, with the wider Flashstar meters.
http://www.axtsystems.com/index.php?option=com_content&view=article&id=53:1176lnenclosure&catid=34:1176ln&Itemid=62

Thanks gswan. Yes I did read your post with respect to the circuit and its certainly clear regarding 8 and 12 being out of the circuit. casrec stated hearing a difference. Im always intrigued at the subjective nature of "hearing" audio

Build one with push buttons and tell me if the compression, meter and sound doesn't react differently to pushing in all the buttons or just 4 and 20. 

 

[Chrome Heart]

Im always intrigued at the subjective nature of "hearing" audio

Yes! That's why I believe people REALLY REALLY need to post listening examples for comparison. At the end of the day, most of us are making this gear and using it to make music! I'm dying to hear mnats blue stripe compared to an original. I will soon post a comparison of this guy http://www.groupdiy.com/index.php?topic=33834.0 and an original and I hope more people do the same. Especially if you're living in LA. It's so easy to rent one (like $30-40 a day, and if you ask me it's worth it. We spend all this time, money, and effort making these things and we're satisfied when they work. It would be even more satisfying to know that they're as good as originals costing 4-6k!

Dan P.

I own the 1176 Rev D reissue from UA and a Urei Silverface Rev H. At the moment Im building 2 of the Mnats Rev J Units with the op amp input and Lundahl output tranny, and Ill be glad to post audio samples of all three versions when Im done. If for no other reason, than to stir the soup a little.

 

[casrec]

I think that is a great Idea. I will upload some wave files to my dropbox when I get my next two built.

 

[Chrome Heart]

BTW gswan, very nice work on those units. And thank you for the link.

 

[danjpiscina]

I own the 1176 Rev D reissue from UA and a Urei Silverface Rev H. At the moment Im building 2 of the Mnats Rev J Units with the op amp input and Lundahl output tranny, and Ill be glad to post audio samples of all three versions when Im done. If for no other reason, than to stir the soup a little.

I think that is a great Idea. I will upload some wave files to my dropbox when I get my next two built.

Cool. Thanks guys. I actually started a new topic intended for comparisons. I also included a link to my iDisk public folder for easy upload/sharing. Check it out:

http://www.groupdiy.com/index.php?topic=35303.msg432808#msg432808

All the best,

Dan P.

 

[mac]

Whilst it is always very subjective, I am keen to post samples when I am finished too. Will have to be to the group DIY gmail account though - I dont have my own server.

ChrioN and Geoff - can you please provide clarification of this outstanding point from up the page a bit....

ChrioN,
Can you please clarify - (I am easily confused) 

Quote ChrioN
Shorting point 22 to ground doesn't bypass the gain reduction. I'm routing the point 22 from the main pcb through the meter pcb and then to the bypass toggle switch.

Quote - Gswan
When in 'disable' mode, the input to the GR amp (22) must be connected to GND.
When not in 'disable' mode, the input to the GR amp (22) must be connected to the output from the ratio switch.

cheers,
Mac

 

[gswan]

What I said was correct. Look at the circuit.
The input of the GR amp/rectifier is shorted to GND when in bypass mode. It is connected to the ratio switch when GR is activated.

 

[mac]

Thanks Geoff,
Yes the schematic makes perfect sense. However, between interpreting the pcbs, meter board and the conversation here I guess I was just losing confidence that I understood correctly.

When you're a noob - patience and knowledge are vital - but the confidence to implement new knowledge is the key to acheiving anything!!!

So my original intentions of a SPDT (on - on) wired to point 4 / 22 / G (28) will be fine.



Mac

 

[gswan]

It sounds like your release pot is upsetting the Qbias.
This could be due to a faulty pot (cracked element or join) or dry joins in the soldering/wiring between the board and the pot. The Qbias voltage goes through the 5M release pot to the release timing capcitor (C27). It will affect both metering FET and compression FET operation, and it won't matter what the GR disable setting is.