Hameg HM8142 PSU - request for comments - Page 1
Forum section: electronics / testgear

author: olewales
author_rank: Regular Contributor
timestamp: March 27, 2014, 04:42:41 am
content: Note: there is a link to an auction in this post, but I am looking for comments on the hardware itself. Nevertheless if this breaks the rules please moderate the post or move it to more appropriate section.As as result of theterrible disease this forum seems to be spreadingI decided on buying new PSU for playing at home (I would not dare to call what I have "a lab"). I know that the proper way of obtaining such gear is looking for used unit made by good brand. However, there is not a lot of decent used gear in Poland and the prices on it seem to be noticeably higher than in more developed countries. I was therefore set on buying a new Korad KA3005P. There are problems with it, but a lot of people seem to use it so I should be Ok.Recently, however I found (I may regret posting link to this auction on popular forum)this(automatic english translationhere).The seller seems to not know a lot about the device he is selling. Item description basically describes the photos. Roughly translated: It powers up, displays are working,right side outputs voltage, left one is used as a load. I am curious if left channel really does not work or the seller just did not test it at all. I was trying to call the seller and I send him an email but no response so far.My question is: Is it worth it for a hobbyist to invest in such gear? (over lets say new Korad psu) Specs I found in themanualare really quite impressive (despite only 1A output per channel). Electronic load function seems quite attractive. On the other hand this unit may or may not work and I may not be able to fix it. I found SOME schematics in the french version of the manual on Hameg website, but not a lot more. Hameg is also not a brand I am very familiar with. I heard the name before but I couldn't position it on the market in the terms of quality of their products. (They are part of R&S now, but I don't know if it says anything about their products from 20 years ago).Finally there is a question what is it really worth in terms of money. Right now the price sits at about 300PLN which is about $100, so pretty much KA3005P price, but I expect the price to rise before the auction ends. How much would you be willing to pay for an item in this condition? I am interested in using it, not buying to resell, but I don't want to be ripped off.I am open to any comments about this from you. I hope this will help me to make a decision.

author: Bored@Work
author_rank: Super Contributor
timestamp: March 27, 2014, 06:06:21 am
content: The PSU itself is certainly miles ahead of that Korad stuff. A working HM8142 for $100 would be steal. $100 for a broken one that needs repair would be ok, but it shouldn't be much more expensive. Buying a broken instrument is a gamble. You can be lucky and it is an easy fix, or it might be not fixable and a waste of money. No one can tell this in advance.As for all potentially broken gear, first thing before buying is to check if the service manual is available. Hameg has a policy to release the service manual latest when they discontinue a product. So it should be possible to get one for that PSU. Ask them. But without a service manual I don't buy a potentially broken instrument. I also don't buy a broken instrument if someone already tried to repair it.Hameg itself is a small, 50 year old company. They always produced good quality gear and have good service. Compared to Chinese stuff they aren't cheap.

author: anotherlin
author_rank: Frequent Contributor
timestamp: March 27, 2014, 09:52:02 am
content: Hameg is a german company with a long history (50 years as already stated), especially in oscilloscope. Part of the design and manufacture was done in France, but not anymore. The stuff they make now (as part of R&S) and then, is solid. I owned quite a lot of their 8000 series modules for the 8001 rack. Most of them were more than 20 years and they all worked perfectly.I even owned a 8142 at one point, it is a very solid and reliable PSU that can easily compare with Agilent ones. I think the guy who's selling it has absolutely no idea how it works. Both left and right outputs can work as output or load. There's also a 5V fixed output, handful for digital. From the picture of the auction, it seems the unit even has the GPIB option. I don't think the current 8143 model is more than the 8142, just 2A outputs instead of 1A.The full schematics are available in the french manual as you mentioned, and uses only "standard" easy to find through hole components. So it should be very easy to fix even if I don't see why it would be broken. I'd rather think the guy doesn't know how to test it.They usually go around 300 euros on ebay.de, if you can snatch this one for less, go for it !

author: nowlan
author_rank: Frequent Contributor
timestamp: March 27, 2014, 02:12:21 pm
content: The one toploser sold the other day was the current version, which has arb waveform for output.As said, they psu can output or sink current. Most likely left channel is in wrong mode.

author: anotherlin
author_rank: Frequent Contributor
timestamp: March 27, 2014, 03:41:45 pm
content: Quote from: nowlan on March 27, 2014, 02:12:21 pmThe older version also had arbitrary waveform through GPIB or RS-232. There is even a connector for a keypad to enter values.I've never had a change to look at the inside of a 8143 but I strongly suspect it is basically same design as the 8142, except for the outputs which have been beefed up for 2A instead 1A.