Rehabbing serial number 1 and 2 Universal Audio 1176

[mypantsrblue]

Hey all,

I purchased a while back two 1176LNs that were given to former universal audio employee. they are silverfaced, and they carry serials 1176-001 and 1176-002. They are the protoype units that were created when they decided to reissue them. They are dated Dec of 1998. I was able to get UA to verify them, but they would not give me any info but that.

They're in slight disrepair. I have never plugged them in.

I took them somewhere and was quoted a very high price to fix them mostly for labor because the parts weren't that bad..... however I honestly think I can get them going with a little help. I am not as good as some of you, but I have built old and new Hairball 1176s and GSSL.

I have attached photos of the units in their current condition. I have an idea of what I want to do to start off with, but can anyone tell me what THEY would do first if they had these infront of them?

My plan was to check the wiring of and replace the caps in the power supply section, and then turn it on and see if I am getting +30 and -10 at the points listed on the schematic I'm looking at. I am using UREI schematic rev E, as I was told this is the closest I am going to get to the actual schematic. the PCB is also labeled so I will reference that for all component values. I think this +30 / -10 is the same across all anyway.

From there, I obviously need to replace the missing FETs, and I think I will recap the entire unit. I also see one power transformer has a wire thats come unsoldered etc.

What else would you guys do to these? I'm pretty confident that with new FETs and caps these will probably just start working.....

I also do know I'm missing a transformer for one, but luckily I'm in LA so I plan on getting it from Studio Electronics.

Thoughts?

 

[Bo Deadly]

Those look pretty rough. If I had them in front of me I would probably eyeball one into a working condition using parts from the other, plug it into a variac, santity check power, get it to pass signal replacing specific parts as necessary and then study it with a scope and an analyzer using pluses as a stimulus. If it passes a clean signal and the circuit isn't weird, I would then disassemble the whole thing to clean it up and make one good working unit. Then I would decide what to do with the other.

 

[JohnRoberts]

The odds are that they gave them away to employees because they weren't comfortable selling them.

These may have some historical value due to low SN.

I wouldn't expect any extra mojo from being prototypes... To make the most money flipping them you want to make both of them work. A good start would be to source production schematics and try to bring them up to spec..

JR

 

[mypantsrblue]

Thanks for the

Those look pretty rough. If I had them in front of me I would probably eyeball one into a working condition using parts from the other, plug it into a variac, santity check power, get it to pass signal replacing specific parts as necessary and then study it with a scope and an analyzer using pluses as a stimulus. If it passes a clean signal and the circuit isn't weird, I would then disassemble the whole thing to clean it up and make one good working unit. Then I would decide what to do with the other.

thank you for this advice

 

[mypantsrblue]

The odds are that they gave them away to employees because they weren't comfortable selling them.

These may have some historical value due to low SN.

I wouldn't expect any extra mojo from being prototypes... To make the most money flipping them you want to make both of them work. A good start would be to source production schematics and try to bring them up to spec..

JR

Hey

thanks for the reply. I definitely don’t think these were ever intended for sale that’s for sure. They apparently were sat on a shelf for years and this employee helped move some of UAs stuff during his tenure and came upon them and was told he could take them.

I actually don’t expect these to sound any different than a current production 1176LN, and I also don’t plan on reselling them at all. Maybe in 10-20 years. I agree that they have historical value and they’re a cool story so I just want to see them work again.

if you know where I can find the schematic for the current production UA1176s I’d love to hear because all I can get is what I have which is the UREI. Although many people have told me that it’s nearly identical anyway.

 

[Whoops]

I would concentrate in just one of them first like Bo Deadly suggested.
Choose the one that looks better or has more parts.

Then you need to get the closest schematic possible, as far as I know the Reissue was Revision D and not E.
So check both those schematics.

Before Re-capping I would just turn it on and measure PSU voltage rails, start from there.
If the voltage rails are fine just follow the schematic and check if there's missing parts.
When you know what revision is that you should also look in the DIY 1176 threads around here for that specific revision.

I guess it shouldn't be too hard to make them work, plenty of info around here

 

[mypantsrblue]

I would concentrate in just one of them first like Bo Deadly suggested.
Choose the one that looks better or has more parts.

Then you need to get the closest schematic possible, as far as I know the Reissue was Revision D and not E.
So check both those schematics.

Before Re-capping I would just turn it on and measure PSU voltage rails, start from there.
If the voltage rails are fine just follow the schematic and check if there's missing parts.
When you know what revision is that you should also look in the DIY 1176 threads around here for that specific revision.

I guess it shouldn't be too hard to make them work, plenty of info around here

Thanks! Rev D/E are nearly identical sans the switch for 110-240. I believe these have that switch, that’s why I went with E.
Thank you for your input.
Do you know if I can power it on with the FETs removed, just to test the rails?
I think that should be fine right?

 

[Whoops]

yes you can

 

[mypantsrblue]

Reviving this thread to say that these units are back in my hands.

I have successfully tested the power supply of the one that’s got both transformers and appears to be in slightly better shape (#2). I am getting +30 and -10 respectively. It took me a while to figure out exactly where to test by looking at the schematic but once I understood I was glad to see the right voltages where I expected. Can anyone confirm where they would look for these voltages? I found them at cathode of CR8 and 9.

no smoke, no fireworks. I ordered all the missing FETs. I also picked up 2 pair of the pre matched FETs for Q1 and 11 from studioelectronics here in LA. (That’s where they were for repair)

I was able to order another 5002 transformer directly from cinemag who made them for UREI and currently make them for UA, which is awesome.
Will update the group with my success or failure when I get the FETs. i will also edit this post to add the test results of unit 1 when I resolder the jumpers on the power transformer later today.

 

[Michael O]

I have what I assume is one of the first production UA Classics 1176LN units (serial 12x, and built in 2000 judging by the components), and maybe this interior photo of it can be of assistance somehow.

It differs from other production units I’ve encountered (specifically: older UA serial number sticker, captive power cord rather than an IEC inlet, non-CE-compliant power supply, old Philips electrolytic caps, transformer stamps I haven’t seen in other UA 1176LN units, etc.), and may be a good reference for the restoration of your prototype units. The PCB layout of this unit is seemingly identical to a Urei Rev. E (i.e., board assembly C11223), though, so it differs from your units in that regard.

You have a cool and unique project on your hands, and I wish you luck!

 

[mypantsrblue]

I have what I assume is one of the first production UA Classics 1176LN units (serial 12x, and built in 2000 judging by the components), and maybe this interior photo of it can be of assistance somehow.

It differs from other production units I’ve encountered (specifically: older UA serial number sticker, captive power cord rather than an IEC inlet, non-CE-compliant power supply, old Philips electrolytic caps, transformer stamps I haven’t seen in other UA 1176LN units, etc.), and may be a good reference for the restoration of your prototype units. The PCB layout of this unit is seemingly identical to a Urei Rev. E (i.e., board assembly C11223), though, so it differs from your units in that regard.

You have a cool and unique project on your hands, and I wish you luck!

thank you so much for this, it has proved pretty useful to me

 

[mypantsrblue]

Happy to report that serial number 2 is working, calibrated, and in my studio rack. The only issue with it, is that after some time of being on, when in GR, the meter starts drafting down towards -20. A quick power off and on rectifies it immediately.

I am going to have my usual tech take it from here, and recap and reflow the whole thing, and fix whatever is causing that (if its not just a leaky cap)

Serial number 1 is proving a bit more challenging. I was able to source a new UA-5002 from cinemag(nice people over there!) however, It does nothing upon power on, but the power supply rails are operating properly. I have noticed that there is 30V coming off the chassis. IE if you put the DMM in a cover bolt hole, and then anywhere else on the case you will read that the case is essentially energized to 30V.

I am assuming the issue is 30V leaking to ground, but I'd love some advice on where and the best ways to start tracing that out before I send it off to my tech. Ideally I want them mostly working before I get it to them.


Thanks so much!

 

[Whoops]

I have noticed that there is 30V coming off the chassis. IE if you put the DMM in a cover bolt hole, and then anywhere else on the case you will read that the case is essentially energized to 30V.

Auchhh, that's not good.
And the mains circuit breaker doesn't trip? and the fuse doesn't blow?

That's really strange I would expect the fuse to blown or the circuit breaker to trip.
You seem to have some short to ground,
any loose wire?
any pcb trace touching the chassis?
any pcb screw touching a trace?

Are there any tantalum capacitors in the power supply?
Tantalum capacitors normally fail short circuit, so they can cause that.

Do a complete re-Cap of the unit even before testing ot powering up, shotgun style.
Replace All Tantalum capacitors and replace All Electrolytic capacitors.
Check for shorts, see my questions above

 

[mypantsrblue]

Auchhh, that's not good.
And the mains circuit breaker doesn't trip? and the fuse doesn't blow?

That's really strange I would expect the fuse to blown or the circuit breaker to trip.
You seem to have some short to ground,
any loose wire?
any pcb trace touching the chassis?
any pcb screw touching a trace?

Are there any tantalum capacitors in the power supply?
Tantalum capacitors normally fail short circuit, so they can cause that.

Do a complete re-Cap of the unit even before testing ot powering up, shotgun style.
Replace All Tantalum capacitors and replace All Electrolytic capacitors.
Check for shorts, see my questions above

Thanks for this. Yeah, sort of scary…

No fuse blow or mains trip, probably because it’s such low amperage?

I only noticed this was a thing when I happened to be touching the chassis, and then I touched a bolt on the meter and it pinned the meter.

So, since I’m not dead and that means it flowed through me, it’s low amperage. I did check the amps, don’t remember but it wasn’t much.

Will investigate the caps, that’s kinda what I thought too.

 

[JohnRoberts]

Modern DVM are often very high impedance so stray voltage readings may be innocuous. Sticking one probe through a bolt hole does not adequately describe what you are measuring.

Perhaps add a 1k resistor across the DVM probes and you can then impute a current using ohm's law.

It may be harmless or dangerous.

JR

 

[mypantsrblue]

Modern DVM are often very high impedance so stray voltage readings may be innocuous. Sticking one probe through a bolt hole does not adequately describe what you are measuring.

Perhaps add a 1k resistor across the DVM probes and you can then impute a current using ohm's law.

It may be harmless or dangerous.

JR

Yeah, maybe I’m not explaining right. but i didnt just stick one probe in a bolt hole and think that i measured current.

i measured current using the port on my DMM for doing so, and i used both probes and had current between ground (chassis bolt hole) and anywhere else i touch inside the case.. thats why i think the case itself is energized. i also read 30Vdc when touching the case and anywhere else such as the meter post.

but I’m also not proceeding as if it’s safe. thank you

 

[JohnRoberts]

Did you measure the voltage with a 1k ohm termination?

JR

 

[mypantsrblue]

I'd like to come back to this. I have two questions

1, where the heck can I find caps for these? 2000uf 50v axial for the power section is shockingly hard to find, unless i'm crazy?

2, im kind of not understanding why that 30V i was reading on 1176 #2 was inaccurate. I'd like to explain my thought process, and maybe you can correct me where I'm wrong in my understanding.

When I am testing a circuit, I set my DMM to DC and I put my black probe in a chassis bolt cover for ground, and then I use my red probe to test various points in a circuit and get a voltage reading. On any other device that I do this on, if i touched the side of the case with the red, I would not read any voltage. With 1176 number 2, I am reading voltage, power supply voltage to be exact. I am aware this is not good, but we sort of went off on a tangent that I did not understand about how the way I'm measuring matters, which I am sure it does. But why does it not matter when I am reading voltages, like the power supply rail (that show up as expected from schematic) but reading it at the case itself does not?

I noticed the issue because one of the leads of the meter touched the case while the other was on the meter, and it pegged the meter. Leading me to realize that the case had DC.

What am i not understanding correctly so that I can learn more?

Unit 1 worked for a while after I posted that, but now the meter pins whenever its in GR and there is capacitor leak all over the board. I'm thinking I will recap both units, and start over but that lead me to question 1 and re replying here



Thanks

 

[Script]

I'd recap with radials first to get the second (and first) unit going. cos cheaper.

Eventually though, in this case -- cos the units are 'historic'-- I'd go for axial once the units are confirmed over a bit of time to work properly. Could get those axials any time later...

 

[Whoops]

1, where the heck can I find caps for these? 2000uf 50v axial for the power section is shockingly hard to find, unless i'm crazy?

I just always use Radial capacitors instead of Axial, there's much more options and they're cheaper.
But if you want to use Axial you have quite a lot of options in Mouser, Farnell and Banzai.
2200uf is the standard present day value, so search for that. As for the voltage always search 50V and and also 63V

3 entries in Farnell:

https://pt.farnell.com/w/c/passive-...ded&range=inc-in-stock|exc-delivery-surcharge

10 Entries in Mouser:

https://pt.mouser.com/c/passive-com...trolytic-capacitors-axial-leaded|~Capacitance

Banzai:

https://www.banzaimusic.com/illinois-tta-2200uf-50v.html