HP power supply question - Page 1
Forum section: electronics / beginners

author: djf123
author_rank: Newbie
timestamp: March 31, 2019, 12:33:50 am
content: I recently purchased a cheap used Hewlett Packard 6201B DC power supply off ebay after having been advised not to purchase a new cheap chinese power supply off ebay, presumably due to these being bad. But I am rather disappointed as I have encountered some problems, and I need some advice. Primarily I want to know if I bought a lemon. My first problem is that when I turn it on I immediately begin smelling a strong metallic and burnt electronics smell. Its intense but I don't see any visible smoke. I suspect that it is coming from the transformer as one can see the wiring pushing out from it on the side. Is this whats causing the smell and how can I stop the smell? Is it worth trying to fix this thing and if so can you buy new transformers for this, assuming this is the problem, and if so where? Overall its pretty dirty inside, but it does appear to work and provide steady voltage. The second problem is that the plastic covering over one of the dials is broken off. Can you buy replacements for this and if so where? Lastly, the plastic red indicator light is broken off on the back. Can you buy new ones of these online? So did I buy a lemon and is this worth restoring? If so, how would you go about it?

author: Andy Watson
author_rank: Super Contributor
timestamp: March 31, 2019, 01:08:00 am
content: Quote from: djf123 on March 31, 2019, 12:33:50 amHard to say. Was it in that condition when you bought it?It looks like it has received some severe impact damge - possibly in transit. The top view of the unit shows that the meter has become partially displaced from its mountings. The neon-indicator has been totally snapped-off. However, the most obvious damge is to the transformer mountings - it has obviously been displaced towards the bottom right corner of the frame. I would want to sort all those issues and inspect for further damage before powering it up again. Was it a lemon? May be not, but it is now!QuoteThat's not good. However, as I said, I would throughly examine it for further damage before attempting to power it up again.Is it worth fixing? That depends - do you want a project or a power supply? "Fixing" is not going to be a trivial task, and since you are asking, I assume it will be an extremely steep learning curve for you. I would fix it, but then, I like the idea of restoring old devices and I don'tneed(antoher) power supply.

author: bitseeker
author_rank: Super Contributor
timestamp: March 31, 2019, 04:07:51 am
content: Welcome to the forum, djf123. Buying quality used gear is a good way to go, especially here in the US where there's much to choose from. However, it does require some care so that you get one with low risk of problems.Model-specific parts (identical knobs, transformers, meters, enclosure pieces) for these are not available new. That's usually solved by buying a parts/not working one to transplant parts from (a.k.a., a parts mule) or getting lucky and catching someone who is parting theirs out, though prices can be rather high on individual pieces.Generic parts such as resistors, capacitors, diodes, some transistors, and the like are usually available new, so old power supplies are still relatively repairable.What was the condition of this power supply in the listing? Was it listed as "Used" or "For parts/not working"? As Andy asked, was it damaged in transit? Reply with more details so we can better help.

author: Cubdriver
author_rank: Unknown
timestamp: March 31, 2019, 05:54:14 am
content: Ouch! Based on that displaced transformer, it certainly appears that it took a high-impact shock. How much actual damage it suffered will not be clear until it's been further dismantled and examined. If you can repair it, it will serve you very well - HP gear is pretty bulletproof for the most part.If you can get some better pictures of it, and perhaps remove the sides so we can view the area near the power transformer, it will let us better assess things and offer guidance. I dont think I have a 6201B here, but will take a look tomorrow and see; if I do I'll be able to offer more suggestions.It sucks that you may have been burned on this purchase, but don't give up hope just yet.-Pat

author: edpalmer42
author_rank: Super Contributor
timestamp: March 31, 2019, 07:02:47 am
content: As the other posters indicated, disassembly and more pictures are required.At this point, I'm not even sure if the transformer has been displaced or not. Yes, I see those white things on the right side of the transformer, but look at the L-brackets on the left side of the transformer. They don't show any hint of a violent displacement. I expect to see that the transformer is mounted withfourL-brackets, so what are those white things? Also, look at the gaps in the four corners of the case. They're all the same - no hint of any shifting.Djf123, what do you mean by "the wiring pushing out from [the transformer] on the side"? All I see is a perfectly normal looking transformer.Have you downloaded the service manual?Do you know how to read a schematic? What test equipment do you have access to? We need to know this so we can give appropriate advice.Ed

author: rdl
author_rank: Super Contributor
timestamp: March 31, 2019, 12:20:32 pm
content: Those "white things" to the side of the transformer look like they could be hex standoffs. If they are, I think they should be a lot straighter than they are.

author: bd139
author_rank: Super Contributor
timestamp: March 31, 2019, 12:55:11 pm
content: That's had one hell of a beating. The transformer in those weighs a lot. Any impact will cause all sorts of problems.I bought a pretty knackered one a while ago and it was in a right state. This shows roughly what you should expect for transformer mounting. There are two hex standoffs which the transformer is bolted to on the outside and inside.If it smells funny, power it up, leave it a few minutes then turn it off, unplugs it (IMPORTANT!) and have a feel around. Might be unrelated. Also take the bottom off and check the board for cracks. However the thing has live mains on the bottom so be careful.They're really nice power supplies though!As for the knobs, they're quite difficult to find. Keep an eye on ebay.

author: bitseeker
author_rank: Super Contributor
timestamp: March 31, 2019, 04:10:51 pm
content: Since this was a recent purchase, the most important first step is to resolve if this qualifies as a damaged/not-as-described merchandise case or not. It's not clear from the original description.

author: bitseeker
author_rank: Super Contributor
timestamp: March 31, 2019, 04:36:19 pm
content: Is it this one?https://www.ebay.com/itm/153380567821If so, it's been over 30 days. Might be stuck with it. I don't remember what the not as described limit is. However, they say that they only checked that it powered on.From what I've seen over the years, this vendor/recycler sells a lot of banged up stuff.

author: edpalmer42
author_rank: Super Contributor
timestamp: March 31, 2019, 06:03:58 pm
content: I was looking at the neon bulb. How was it mounted? There are no threads or hooks that I can see. I've seen similar bulbs that are mounted with a metal speednut pushed on from the back. Is it bouncing around somewhere in the unit?Ed

author: bitseeker
author_rank: Super Contributor
timestamp: March 31, 2019, 08:02:26 pm
content: Normally, there's a plastic holder/diffuser that the bulb goes into. The holder is then affixed with a spring clip. The plastic gets brittle with age and breaks loose. My 6200B recently suffered this. A little hot glue or silicone caulk suffices, but it looks like the holder was completely missing from the OP's unit.I'm very curious where the smell is coming from.

author: bitseeker
author_rank: Super Contributor
timestamp: April 01, 2019, 03:37:53 am
content: A quick-n-dirty way to deal with the neon bulb might be to tape a piece of milk jug plastic over the rear of the hole in the front panel as a diffuser. Then affix the bulb. The viewing angle will be reduced, but it'll glow.

author: Cubdriver
author_rank: Unknown
timestamp: April 01, 2019, 03:42:12 am
content: That neon power indicator appears to be the lamp only, so that means that the series dropping resistor is on the circuit board. Assuming that's the case, make sure that the leads to the neon aren't twisted in such a way that they're shorted, overloading the resistor.-Pat

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: April 01, 2019, 04:13:00 am
content: DJF123, since you got steady voltage out, and I take it at a voltage level that you expected, then that means the regulator circuit, transformer (and meter?) were working. So I would suspect the caps of generating the smell that you detected.That horizontal cap near the transformer looks like it got hot, and probably more than once. It's probably a good idea to replace all 5 of those big electrolytics, anyway.

author: bitseeker
author_rank: Super Contributor
timestamp: April 01, 2019, 05:36:31 am
content: Taking a closeup look at the first photo, it seems like the power supply was dropped onto the lower-right corner, bending the fin on the heatsink and causing the transformer to bend the two long posts. The transformer's dislocation rotated the PCB clockwise, which broke loose the mount for the analog meter. I'm not sure if the bulb holder sheared as a result of the impact or if that might've been a separate incident (or just age-related, like my supply).

author: Jwillis
author_rank: Super Contributor
timestamp: April 01, 2019, 06:23:29 am
content: I've worked on a few very old things such as radios ,Televisions,oscilloscopes,frequency counters ect. and every one gave off a funny electrical smell upon start up.This is probably do to being in storage unused for long periods of time .Probably just dust making momentary shorts and burning off .If it works don't fix it.Give it a good cleaning. There are a few restoration sites that can point you in a direction of used parts .Or one may show up on Ebay thats only good for parts.