Agilent 1670G - I Killed it - Opinions

[BradC]

Lost my bid for a sweet new-ish clean Superior Electric Variac on eBay tonight...sad panda.  Most of them seem pretty old and crusty.  Based on the variac thread trying to avoid the "One Hung Low" brand units.  Don't need a house fire right now.

Despite what others may have said earlier in your thread, a Variac is *not* a current limiting device. It will limit current to an extent due to its own internal resistances and in theory lower voltages result in lower current, but if you short the output you'll draw sufficient current to blow the fuse / smoke the Varaic (depending on whether it has a fuse). You can certainly blow up old reforming electrolytic capacitors, faulty mains filters and let the smoke out of power semiconductors sitting behind a Variac. The old "dim bulb tester" *is* a current limiting device and is good practice even if you are using a Variac. It's also a lot cheaper to start with.

[Specmaster]

We used to use variacs at college years ago as a soft start up device. A lower voltage does indeed limit current to an extent, basic ohms law will tell that much but they do have the failing that they can be turned up to much or even accidentally turned to a higher setting than you really wanted. But a bulb on the other hand, has a fixed maximum current let through and with a selection of bulbs that can be swapped in and out of the lampholder, you can adjust the amount of current flowing though to your device under test. As BradC rightly said, a lot cheaper too.

[alm]

I would also be hesitant to use a variac on a switch-mode power supply unless I was sure the under-voltage condition would not saturate their magnetics or defeat the inrush protection. And if the power supply has a proper under-voltage lockout, then it will just do nothing until you wind the variac up to 90 VAC or so.

[CoalCreekPlastics]

Okay I'm going to do some Googling and see if I can't find how the light bulb method is done.  I want to fire this thing up and test per the service manual as safely as possible.  Given my inexperience I think it is very possible to make a mistake and short something.  Thanks again all.

[rsjsouza]

Lost my bid for a sweet new-ish clean Superior Electric Variac on eBay tonight...sad panda.  Most of them seem pretty old and crusty.  Based on the variac thread trying to avoid the "One Hung Low" brand units.  Don't need a house fire right now.

Years ago I have purchased a 2kVA Mastech variac and I am pretty pleased with its quality. I provided some pictures at:
https://www.eevblog.com/forum/buysellwanted/mastechvolteq-variac-comments-on-quality/msg161815/#msg161815

[Strada916]

You just place a 100W light bulb in series to the active or neutral. Or even a 60W depends on the power rating of the unit.

[Specmaster]

You just place a 100W light bulb in series to the active or neutral. Or even a 60W depends on the power rating of the unit.

It needs a normal GLS lamp, not an energy saving one though. Please note that it is normal when using this type of current limiter that on switching on, for the bulb to glow fairly brightly for a split second as the smoothing caps charge up. Then, if everything is OK, the bulb should go and the device your testing should, if everything else is OK, switch on. If so then you can remove the bulb tester and power up normally.

If the bulb remains lit then you still have a problem somewhere that is causing more current to flow then normal to be resolved, the good thing is that because of the bulb in series you should not have done any harm to your equipment.

[TerraHertz]

Someone was expecting a more dramatic fuse blow.  I pulled out the second fuse I found after it didn't buzz out.
 Here it is.

Yep, that's vigorously blown! The only stage above that is where there isn't any glass left either.
So, was that fuse contained in opaque shrink-tube? If not, then there's the flash you saw.
Also those RIFA caps are the death-caps others & I have mentioned. The hairline fractures let in moisture, which kills them. ALL those type caps should be replaced when found.

However, it's quite unusual for them to show no visible sign (or smell, did you sniff them?) of the kind of failure than can blow a fuse like that. Btw, try them with a multimeter. You might find one short circuit. But even if all are 'open', it doesn't prove they are blameless. They can short out, then do much the same as the fuse - burn back to open circuit.

However we still don't know for sure it was one of those caps that shorted. After replacing all these and the fuses, it would still be a good idea to power up with a bulb as current limiter.

[CoalCreekPlastics]

Yep, that's vigorously blown! The only stage above that is where there isn't any glass left either.
So, was that fuse contained in opaque shrink-tube? If not, then there's the flash you saw.
Also those RIFA caps are the death-caps others & I have mentioned. The hairline fractures let in moisture, which kills them. ALL those type caps should be replaced when found.

However, it's quite unusual for them to show no visible sign (or smell, did you sniff them?) of the kind of failure than can blow a fuse like that. Btw, try them with a multimeter. You might find one short circuit. But even if all are 'open', it doesn't prove they are blameless. They can short out, then do much the same as the fuse - burn back to open circuit.

However we still don't know for sure it was one of those caps that shorted. After replacing all these and the fuses, it would still be a good idea to power up with a bulb as current limiter.

Fuses were indeed enclosed in black heat-shrink tubing.  I also inspected the fa and can find no scoring or burn marks whatsoever where I thought I saw the spark.  The caps did have the hairline cracking of course and when it blew there was a smell of burnt something with smoke.    I am unconvinced the fan shorted, I don't know for sure.

Definitely going to replace the death-caps, fuses of course and power up with an incandescent bulb in series to probe and do the service manual diagnostics once I replace everything.  I have already pulled them out with the fuses, I haven't checked the EM filter caps for a short with a "moldymetah," I will try that, sounds like if there is continuity between the leads it's shorted?

[CoalCreekPlastics]

Okay I think I have found replacements, on Mouser for everything, can someone check my work?

Fuses: 10A 250V (Marked F 10A l 250V)

Eaton replacement at Mouser (fast blow): http://www.mouser.com/Search/ProductDetail.aspx?R=AGC-V-10-Rvirtualkey50400000virtualkey504-AGC-V-10-R

RIFA 4n7 Y2 Filter Capacitors:

Original (Have these improved?): http://www.mouser.com/Search/ProductDetail.aspx?R=PME271Y447MR30virtualkey64620000virtualkey80-PME271Y447MR30

Panasonic ECQUL replacement (because all the best stuff is made in Japan) with "close" lead spacing and Class X2, Class Y2/X2 :  http://www.mouser.com/Search/ProductDetail.aspx?R=ECQ-U2A472KLvirtualkey66720000virtualkey667-ECQ-U2A472KL

RIFA 15n Y2 Filter Capacitors:

Original: http://www.mouser.com/Search/ProductDetail.aspx?R=PME271Y515MR30virtualkey64620000virtualkey80-PME271Y515MR30

Panasonic ECQUL replacement: http://www.mouser.com/Search/ProductDetail.aspx?R=ECQ-U2A153KLvirtualkey66720000virtualkey667-ECQ-U2A153KL

OR

This Panasonic one is in stock but I can't tell the difference from above (Description says 275V but in the stats on Mouser it says 250V and it has an "A" at the end of the part no.  ):
http://www.mouser.com/Search/ProductDetail.aspx?R=ECQ-U2A153KLAvirtualkey66720000virtualkey667-ECQ-U2A153KLA

And dammit both the RIFA and Panasonic ECQ-U2A153KL 15000pf caps are out of stock with unknown lead times.  I can get  a lot of 50 of the RIFA 15n's on eBay for $14 shipped but that's like bulk buying turds if they haven't improved.  I wanted to order from Mouser so I could get my Plato SMD well tips for my Hakko 888D at the same time so I can be cool like Dave and solder SMD components I can't even see.

Also what are the transparent plastic sleeves/sheathing that serve as insulation on leads called?  Google was worthless, it can't just be called insulation?

Any suggestions as far as brands to consider for replacements and advice is of course welcome. You guys have been incredible.  I know you'll tell me if anything is "a bit how d'ya do there." It's been fun researching and looking at datasheets.

[rsjsouza]

This Panasonic one is in stock but I can't tell the difference from above (Description says 275V but in the stats on Mouser it says 250V and it has an "A" at the end of the part no.  ):

The manufacturer says 275V.

And dammit both the RIFA and Panasonic ECQ-U2A153KL 15000pf caps are out of stock with unknown lead times. 

This one is in stock...

[CoalCreekPlastics]

This one is in stock...

Okay so I have a similar problem here, this says 275VAC in the description, and 250V in the "Voltage Rating AC:" in the mouser data below.  I can't find this part number on Panasonic's site or data sheets. What do you guys do in that situation?  I don't like to ask this stuff for fear of the "here let me google that for you" thing, I'm pretty self reliant but this is unclear.

[rsjsouza]

This one is in stock...

Okay so I have a similar problem here, this says 275VAC in the description, and 250V in the "Voltage Rating AC:" in the mouser data below.  I can't find this part number on Panasonic's site or data sheets. What do you guys do in that situation?  I don't like to ask this stuff for fear of the "here let me google that for you" thing, I'm pretty self reliant but this is unclear.

Oh, I see what you menat by the part number not found. There is an "A" letter suffix. According to page 74 of their Product catalog, the "A" suffix means it is cut lead instead of "straight".

[Specmaster]

This one is in stock...

Okay so I have a similar problem here, this says 275VAC in the description, and 250V in the "Voltage Rating AC:" in the mouser data below.  I can't find this part number on Panasonic's site or data sheets. What do you guys do in that situation?  I don't like to ask this stuff for fear of the "here let me google that for you" thing, I'm pretty self reliant but this is unclear.

I found a picture of that part number on on Ebay, it is a Panasonic and the photo clearly shows 250VAC on the side of it. If you have the schematic, check the declared voltage on the rail, if its 250V or less then that one will be fine.

[JFJ]

Okay so I have a similar problem here, this says 275VAC in the description, and 250V in the "Voltage Rating AC:" in the mouser data below.

A Panasonic ECQUL capacitor datasheet specifies the 'Voltage Rating' as:  275 V.AC (250 V.AC on CSA C22.2 No.8 spec.).

The CSA C22.2 No.8 specification is the Canadian standard for potted RFI filters, and is equivalent to UL1283 in the United States.

[CoalCreekPlastics]

This one is in stock...

Okay so I have a similar problem here, this says 275VAC in the description, and 250V in the "Voltage Rating AC:" in the mouser data below.  I can't find this part number on Panasonic's site or data sheets. What do you guys do in that situation?  I don't like to ask this stuff for fear of the "here let me google that for you" thing, I'm pretty self reliant but this is unclear.

I found a picture of that part number on on Ebay, it is a Panasonic and the photo clearly shows 250VAC on the side of it. If you have the schematic, check the declared voltage on the rail, if its 250V or less then that one will be fine.

No schematics, I am basing my replacement selections off the old parts.  I hope this one is right and that cut leads aren't more difficult to solder!

[Specmaster]

Hmm, I'm not too sure just what cut leads means but I'm assuming that it means the long leads are cut down a bit. If this is not correct I'm sure that someone will advise us just what it does it mean.

Assuming I'm correct, then as long as the lead goes through the hole on the PCB then will be able to solder just the same with no problems.

[CoalCreekPlastics]

Hmm, I'm not too sure just what cut leads means but I'm assuming that it means the long leads are cut down a bit. If this is not correct I'm sure that someone will advise us just what it does it mean.

Assuming I'm correct, then as long as the lead goes through the hole on the PCB then will be able to solder just the same with no problems.

Specmaster, you were right on, cut just means shorter leads which must be usable for pick and place etc.  They are still solderable.  I have discovered a bad habit in working on this, since I bend the leads at a 45 deg angle to get them to stay on the board, my cut off's leave them at 45 degrees possibly making things difficult for a de-soldering tool!  Fascinating journey this has been. 

I did solder in the replacements, and no joy on powering it from mains with a 100 watt incandescent bulb attached in series, the lights dimmed and then came back up so something is shorted and/or I didn't have the bulb wired in properly.  I need to suck the fuses back out and continue troubleshooting it.

In the meantime I was able to source a replacement power supply, so repair of the original supply will shift to the back burner.  Thank you all for your help, I need to get moved to a new house and I will yank this supply back out!

[Specmaster]

Hmm, I'm not too sure just what cut leads means but I'm assuming that it means the long leads are cut down a bit. If this is not correct I'm sure that someone will advise us just what it does it mean.

Assuming I'm correct, then as long as the lead goes through the hole on the PCB then will be able to solder just the same with no problems.

Specmaster, you were right on, cut just means shorter leads which must be usable for pick and place etc.  They are still solderable.  I have discovered a bad habit in working on this, since I bend the leads at a 45 deg angle to get them to stay on the board, my cut off's leave them at 45 degrees possibly making things difficult for a de-soldering tool!  Fascinating journey this has been. 

I did solder in the replacements, and no joy on powering it from mains with a 100 watt incandescent bulb attached in series, the lights dimmed and then came back up so something is shorted and/or I didn't have the bulb wired in properly.  I need to suck the fuses back out and continue troubleshooting it.

In the meantime I was able to source a replacement power supply, so repair of the original supply will shift to the back burner.  Thank you all for your help, I need to get moved to a new house and I will yank this supply back out!

Good to hear that you have sourced a new power supply, SMPS units can be difficult to work on, give me a linear one any day. I have power problems with a scope, tried just about everything and it still doesn't work. Even purchased a refurbished one from a service agent, still doesn't work. I have put it on the back burner for a while so I can get on with other things and I'll come back to it later.

You made a good point there about bending the leads at 45 degree angle, it does indeed make using a desoldering tool a bit more difficult. It can still be used if you can angle the tool to get the tool over the lead and then as you heat the solder up, you can straighten the lead in the process of wiggling the lead and sucking the solder, using the tool to do the straightening.

[CoalCreekPlastics]

Boom.  Running self-tests.  Further testament that these are simply not designed to be repaired at the component level.  I will however use that old power supply as a learning platform.  Glad the acquisition board wasn't fried!

[Specmaster]

Yes, those switch mode supplies are tricky to work on, nice to see it working again. Glad that the replacement psu worked out for you, unfortunately it didn't for me, the fault that knocked mine out in the first place is still there. Circuit resistance readings all seem fine, so for me its back to the drawing board. 

[CoalCreekPlastics]

Yes, those switch mode supplies are tricky to work on, nice to see it working again. Glad that the replacement psu worked out for you, unfortunately it didn't for me, the fault that knocked mine out in the first place is still there. Circuit resistance readings all seem fine, so for me its back to the drawing board.

Good luck to you Specmaster I wish I had more experience to lend a hand.  Thank you again for your help and participation.  And that goes for all of the board that jumped in to help!

[Nemesis1207]

Bumping this thread because it's the best source of hardware info on this system from google. I recently got myself a 1670G as well, and wanted to pre-emptively deal with the RIFA caps and generally get the unit future proofed. One thing I discovered - there are actually 5 RIFA caps in the power supply, not 4. We have these four near the back of the unit which were shown previously:


There's also a 250V 1nf Y2 cap towards the back of the main board:


I had ordered new Y2 caps to replace the four previously mentioned, but I didn't have one on-hand to replace this fifth one, so I removed it and left it out. I've ordered a replacement which I'll fit when it arrives. I didn't put RIFA caps back in, I went with TDK ones with the blue plastic outer housing. Here are the caps I used to replace the originals:
2x https://au.mouser.com/ProductDetail/871-B32021A3472M
2x https://au.mouser.com/ProductDetail/871-B32022A3153M
1x https://au.mouser.com/ProductDetail/871-B32021A3102M
These have the same important characteristics (with slightly better voltage rating), while having compatible sizes and lead spacings to be easy drop-in replacements.

If you're doing this work, it's also worth noting there's a CR1225 button cell lithium battery for the main board which is worth replacing while you're in there.