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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
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15th Jan 2020, 2:33 pm | #1 |
Diode
Join Date: Jan 2020
Location: Muscat, Oman
Posts: 2
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Farnell L30-5
Hey all,
Just found you from a quick internet search, nice find I have a Farnell L30/5 PSU, that I have had for over 30 years (eek) and this morning it decided to stop working I opened it up to take a look and saw the two fuse holders on the bottom that I never even knew existed checked them and all was sadly OK. Symptoms are that the main LED lights up, but no O/P. Before I dig back into my memory to remember my electronics theory and investigate this in earnest, can anyone point me to any likely culprits? I did a quick check on the O/P transistors and they looked ok, although I've not unsoldered any yet to be absolutely sure. Thanks |
15th Jan 2020, 2:50 pm | #2 |
Dekatron
Join Date: Jun 2016
Location: London, UK.
Posts: 3,687
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Re: Farnell L30-5
Worth checking the output switch. I've seen one where that was duff.
Also were you charging batteries with it? That seems to kill Farnell stuff. |
15th Jan 2020, 5:37 pm | #3 |
Octode
Join Date: May 2010
Location: Grantham, Lincolnshire, UK.
Posts: 1,175
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Re: Farnell L30-5
My one just stopped working, when checked all the components on the PCB seemed to have corroded so none were in fact soldered.
Not fixed, attempts to clean the legs of the Rs and Cs achieved nothing. I had been using my one to charge sealed LA batteries, though not certain why that should have caused the problem, no reverse current. |
15th Jan 2020, 6:23 pm | #4 |
Dekatron
Join Date: Jun 2016
Location: London, UK.
Posts: 3,687
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Re: Farnell L30-5
If you are charging batteries there’s no reverse protection diode so when the DC source collapses during a mains transient or power failure it’ll blow the pass transistor and driver up. Very common problem with Farnell supplies. The two I’ve had go through had diodes added.
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15th Jan 2020, 7:11 pm | #5 | |
Nonode
Join Date: Jan 2016
Location: Stafford, Staffs. UK.
Posts: 2,532
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Re: Farnell L30-5
Quote:
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16th Jan 2020, 7:23 am | #6 |
Dekatron
Join Date: Jul 2009
Location: Sleaford, Lincs. UK.
Posts: 7,662
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Re: Farnell L30-5
Mine came with no OP. Easy things to check - after checking series pass Q's check sense resistor and swap opamp for any sort you have in your stash as long as it's pin compatable.
Andy.
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16th Jan 2020, 11:36 am | #7 | |
Dekatron
Join Date: Jul 2007
Location: Evesham, Worcestershire, UK.
Posts: 4,244
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Re: Farnell L30-5
Quote:
When faulty, the E series give high output because the driver leaks heavily or goes short (never had an issue with pass transistors). However, this one is giving no output. To the OP: what voltage checks have you done? The manual gives plenty of readings, so that's a good start. There are no "stock faults" as such - you're going to have to dive in. If you don't already have it, the manual is here: https://www.vintage-radio.net/forum/...08&postcount=2 Mark |
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16th Jan 2020, 1:38 pm | #8 |
Nonode
Join Date: Oct 2008
Location: Warsaw, Poland and Cambridge, UK
Posts: 2,677
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Re: Farnell L30-5
I have an L30/5 which gets used from time to time, and it has a recurring problem with the contacts in the white Molex connectors on to the PCB. The usual symptom on mine is that the ammeter swings over hard right and the current limit LED comes on even though there's nothing connected. Removing and reseating the connectors usually fixes it until the next time I take it off the shelf!
Chris
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16th Jan 2020, 2:27 pm | #9 |
Pentode
Join Date: Mar 2013
Location: Leeds, West Yorkshire, UK.
Posts: 246
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Re: Farnell L30-5
info here (and circuit with voltages) the "l series" had 3 different control pcbs over its production run
https://www.vintage-radio.net/forum/...d.php?t=142722 regards S-W |
17th Jan 2020, 8:26 am | #10 | ||
Diode
Join Date: Jan 2020
Location: Muscat, Oman
Posts: 2
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Re: Farnell L30-5
Quote:
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