peter@julian.UUCP (09/26/87)
We recently received one of these modems for testing. They are supposed to sell for about $CDN350 retail. We might see another copy, if so I'll send an adendum. My review follows. Capetronic 2400 bps modem (non-error correcting model) A Review by Peter Marshall, 1987-09-25 First Impressions Taking the modem out of its box, it looks like a pretty normal 2400 bps model. It is a little shorter than the USR courier (my normal modem) and a few more LEDs on the front panel. The box is a simple, standard enclosure, not the specially designed courier box. The manual looks rather skimpy. It is just typed, not type-set. The back panel is rather open to the elements and the power switch is a very cheap looking metal toggle. Standard parts make up this modem. The external power supply/adapter is very similar to the USRobotics one, made in Korea by Ault Inc. Unlike the USR adapter it is not labeled with the Capetronic name. It is three prong and carries both CSA and UL stamps. The modem does not carry a Communications Canada approval sticker. It does have an FCC test declaration and registration number though. Set up My first problem came when (as I followed the quick installation directions given in the manual) it came time to connect the power cable to the back of the modem. There is a CAUTION saying that you must install the connector the right way up and advises you to consult the illustration. The illustration is a pathetic drawing made with ascii characters like "____|---". This would not be so bad if the plug were polarized, but it seems to attach easily either way. I have some experience with this type of connection. I put a non-polarized power connector on the first micro-computer I built. After frying an expensive CPU chip or two, I purchased a power connector that could not be inserted backwards. We will return to power later... My second problem came when I tried to hook up my terminal. I have a null modem in my line from my terminal (for complex reasons). That reversal is easy to accommodate with the USR courier modem. It has a switch that switches the meanings of pins 2 and 3. Not many people will need this, but it does come in useful on occasion. The modem has 4 dip switches that for most applications can be left in the down position. On-Line My usual command for connecting to CCS on my USR modem is "atx6td6613512". When I tried this all I got was an error message from the Capetronic modem. Upon further investigation I found that despite the manual, only response codes X0 through X4 are recognized as valid. Not really too bad. I think that all I miss is the RING message if the modem at the other end does not answer very quickly and recognition of a voice at the other end (usually meaning that I have mistyped the number). The manual should not lie about such things. The display produced by the HELP command "at$" is very poorly written. It is all in uppercase and seems to have been written (like this review) in the wee small hours of the morning. It is very disorganized and really does not say very much. When the "at$" command is illustrated in the manual the part after it gives the speed and parity setting of the communications port is shown as a series of "xxxx"s. The real thing was not much more use. The USR modem's help is a very useful summary of commands in a tabular format. It also has other help screens to describe dialing characters and register setting. The bottom of the modem (Silly place. Right?) consists of a concise summary of the commands on the USR. The Capetronic modem does have some non-volitile memory for storing one number. This is a very nice feature that the USR modem lacks. This allows your most common host to have its number stored away and you can dial it by giving the simple "atds" command. The manual never mentions that you can get tone dialing by preceeding this stored number with a "td". It also neglects to mention that when setting this number with the "at&z" command <back-space> characters appear to be erasing errors, but in fact are just ignored when you try to play the number back. The numbers that I entered successfully survived a power off. When I listened to a number being tone dialed, it was significantly slower than the USR modem. A small point. The speaker on the test modem seemed to be broken. When I should have been hearing a dial tone and then the actual dialing, ringing and answer all I could hear was a whine. I tried to adjust the volume of the speaker with the "atl2" command, but it did not seem to change anything. The whine disappears when a connection is made. I noticed as I worked that a plasticy smell was coming from over in the modem's direction shortly after I powered it up. I attributed this to the modem being very new. The power adapter seemed to be rather hot though. The manual told me not to worry about heat since high powered LSI components were in use! I had the modem on for perhaps 30 minutes, trying out the various things mentioned above. I was starting to work on the VMS system to see how well the modem handled phone line noise when there was a buzz, the lights flickered and the modem went dead with a pop. The power adapter was too hot to hold in my hand. The DIP switches at the back seemed to have half moved from the down position to the up position. The modem was dead and stayed dead. I am composing this review using my USR Courier. -- Peter Marshall, Data Comm. Manager CCS, U. of Western Ontario, London, Canada N6A 5B7 (519)661-2151x6032 pm@uwovax.BITNET; pm@uwovax.uwo.cdn; peter@julian.uucp; ...!watmath!julian!peter
blgardne@esunix.UUCP (09/30/87)
in article <975@julian.UWO.CDN>, peter@julian.UWO.CDN (Peter Marshall) says: > I noticed as I worked that a plasticy smell was coming from over in > the modem's direction shortly after I powered it up. I attributed > this to the modem being very new. The power adapter seemed to be > rather hot though. The manual told me not to worry about heat since > high powered LSI components were in use! This sounds much like the manual that came with the Desktalk II 2400 baud modem. I opened the case, and their "high power VLSI" turned out to be a 5 volt tab regulator and it's heatsink. They were using the Rockwell 2400 baud chipset though. -- Blaine Gardner @ Evans & Sutherland 540 Arapeen Drive, SLC, Utah 84108 UUCP Address: {ihnp4,ucbvax,decvax,allegra}!decwrl!esunix!blgardne {ihnp4,seismo}!utah-cs!utah-gr!uplherc!esunix!blgardne "I don't see no points on your ears boy, but you sound like a Vulcan!"
hull@hao.UCAR.EDU (Howard Hull) (10/03/87)
In article <502@esunix.UUCP>, blgardne@esunix.UUCP (Blaine Gardner) writes: > in article <975@julian.UWO.CDN>, peter@julian.UWO.CDN (Peter Marshall) says: > > ... > > this to the modem being very new. The power adapter seemed to be > > rather hot though. The manual told me not to worry about heat since > > high powered LSI components were in use! > > This sounds much like the manual that came with the Desktalk II 2400 > baud modem. I opened the case, and their "high power VLSI" turned out to > be a 5 volt tab regulator and it's heatsink. They were using the > Rockwell 2400 baud chipset though. Yeah. I got a mitac 2400BD (ril cheap). It didn't seem to generate large amounts of heat, though it was tolerably warm on top. But naturally, I wanted to see what technology they used, so I opened it up. Like you, I found a Rockwell 2400 baud chipset. Also like you, I found a 7805 tab regulator, but with an ~4-inch on a side sheet aluminum heat sink projecting to the right, up, and then over about 1/3 of the other IC's. Wanting to see who they were torturing under the shadow of this heatsink, I pulled up slightly on it - and discovered that there was nothing to prevent it from rotating (with far less force). I also discovered that the speaker was held in place with a piece of _masking tape_. I removed that and substituted a butyl rubber o-ring I happened to have handy (you know what masking tape does after a long time in a hot place...). When I put it back together, none of the lights would come on. Ok, I sez, musta dinged it. Back apart, I removed the heat sink mounting nut and discovered a small square of paper cemented over a 10-mil land under the sink, and another land with a via that was not protected at all. The usual via solder bump was squashed flat and wiped a little. I had expected (perhaps) to find a mica spacer. Not so. Anyway, I followed the spirit of things and stuck another piece of paper over the munged land and via, put it all back together, and was back in business. Thank God for overcurrent protect that's in the 7805. As for the mitac, well, talk about cheap... any other nominations anybody? Howard Hull [If yet unproven concepts are outlawed in the range of discussion... ...Then only the deranged will discuss yet unproven concepts] {ucbvax!hplabs | decvax!noao | mcvax!seismo | ihnp4!seismo} !hao!hull for domain mailers: hull@hao.ucar.edu