HP 115BR Clock Available Again - Page 1
Forum section: electronics / general

author: George_Race
author_rank: Regular Contributor
timestamp: October 07, 2012, 03:57:19 pm
content: Hi all, you may remember a while back that I put a lot of vintage test equipment on the EEVBlog.Here is the address of that post:https://www.eevblog.com/forum/buysellwanted/vintage-50%27s-60%27s-test-equipment-available/msg149549/#msg149549Among the pieces was the HP-115BR. Several of you indicated an interest.The first offer I got was for $250 and I accepted the offer and emailed back most of you who also had expressed interest. Before packing it up I plugged it in, applied a 100KHZ signal to the input, and nothing happened. The voltage monitor meter showed nothing in any position. I opened the unit up and found that the 24 volt power supply transformer was burnt up. I notified the original buyer that there was a problem and I would let him know if I could get it repaired and we would go from there.Doing some trouble shooting it appeared that the 24 Volt DC line was a dead short to ground. Rather than start lifting leads from terminal strips, I ordered and downloaded the User/Service Manual for the unit. It did not take long to find that there were 4 Power Transistors that were dead shorted. They were the Regulator pair and the Power Amplifier pair.Replacements were ordered, installed, and the unit is back in top working condition again. It has been on the bench running now for about a day and a half. Everything looks really, all the outputs have clean on frequency signals, the tick pulse is there and the meter shows the correct indications for all positions, as indicated in the service manual.I am using a Thunderbolt-Trimble GPSDO to drive my frequency counter. The counter has a 100KHz output that is driving the 115BR. I tuned in WWB on 5MHz and started setting the 115 to match the time as close as I could.Cranking the Milliseconds dial around, I was finally able to get a setting where the tick output pulse was occurring in coincidence with the WWV time tick. In the past 24 or so hours, it has not changed a bit, still right together. An absolutely amazing piece of equipment for being built back 50 or so years ago.Anyway, I still want to sell it to someone who will give it a good home and put it to use. You can see by the pictures that there is some paint missing on the front panel where there was an ID tab removed. The insides look just like brand new! Has a built in 24 VDC power supply so all you need do is plug it in to a 110 VAC outlet, put a 100KHZ signal into it, flip the internal switch back and forth to start the unit running and then spin the internal knurled knob to start the clock. And if you spin it the wrong way, it will actually run backwards as well! Full instructions for starting and setting the clock are in the manual.I have about $50 in parts and a lot of fun time troubleshooting invested in getting it restored to operation. I am asking $250, plus FedEx shipping costs, and will include a set of 4 extra transistors, I bought two sets just in case, and the User/Service Manual on a CD.And oh yes, the original buyer used his funds for another purchase and told me to go ahead and offer it up again.Drop me an email if you are interested with your offer. My email address is:george@mrrace.comIf I get multiple offers, I will consider them in the order they arrive.George RaceAlbion MI