Wavetek LT8600 tester will not power on - Page 1
Forum section: electronics / repair

author: 1audio
author_rank: Frequent Contributor
timestamp: August 04, 2023, 03:58:49 am
content: I have an LT8600 cable tester that will not power on. The battery has a charge. I have it connected to a charger as well. Simply nothing when I press the power button. I opened it and replaced the internal backup battery which was dead. But I cannot get it to start. Does anyone have more insight into these? I can find no info on line beyond the user manual.

author: picburner
author_rank: Frequent Contributor
timestamp: August 04, 2023, 06:08:28 am
content: I just bought an LT8600 which I think is in the same condition. As soon as it arrives (I think at the end of this month) I'll see if it's possible to make it work. I think it is impossible to find a service manual for this instrument unfortunately. Do you have the internal backup battery data? So I can get it in advance.

author: 1audio
author_rank: Frequent Contributor
timestamp: August 04, 2023, 09:48:50 pm
content: The battery is a CR2032 PC mount- soldered in. I got 10 from Amazon- minimum order it seems. The battery was completely dead when I got to it. The unit worked when I last tried it about 4 years ago. I'll open it to see if the battery discharged again. I hope you can get yours working. These were really expensive new. They should be maintainable.

author: 1audio
author_rank: Frequent Contributor
timestamp: August 05, 2023, 01:53:14 am
content: I checked and the little battery is OK. However the unit is completely dead.

author: picburner
author_rank: Frequent Contributor
timestamp: August 05, 2023, 05:22:40 am
content: That type of battery should theoretically not leak electrolyte and therefore should not have caused damage to the instrument.Unless the memory powered by that battery requires some sort of external initialization once all previously contained data is lost.Did you happen to take any pics of the pcb?

author: picburner
author_rank: Frequent Contributor
timestamp: August 06, 2023, 07:19:18 am
content: In the meantime I have found, in addition to the user manual, these two programs that could come in handy after repairing the devices.PC management programandfirmware updating.Browsing through the various files that make up the firmware you can find error messages that could be of some little help in troubleshooting.

author: 1audio
author_rank: Frequent Contributor
timestamp: August 10, 2023, 04:44:34 pm
content: I have not been able to get this one to start at all. The charger ckt is working. There is supply inside the unit. However I cannot see a way to fully uncase it and confirm the power button is working. Maybe I'm overlooking something but it seems the case holds the boards together. I'll try again.When it was working its an impressive instrument. 300 MHZ VNA with switching etc. The external software is good as well.I hope you are having some success.

author: picburner
author_rank: Frequent Contributor
timestamp: August 10, 2023, 06:07:53 pm
content: Which unit won't turn on? The master one with the display or the other one? Or both? If you still have the units open could you take some pics of the pcb?I'll let you know when mine arrives if there's anything I can do to make it work.Let's hope we don't both end up owning a set of expensive paperweights.Meanwhile, my shipment seems to take longer than expected.

author: 1audio
author_rank: Frequent Contributor
timestamp: August 13, 2023, 11:33:12 pm
content: Its the master that doesn't start. The slave starts fine. I'll send some pics tomorrow. I hope yours will be healthier.

author: picburner
author_rank: Frequent Contributor
timestamp: August 24, 2023, 06:47:04 pm
content: My LT8600 arrived today. As described by the seller, the main unit would not turn on. I completely disassembled the unit and replaced the CR2032 lithium battery which was dead. I put everything back together but the unit wouldn't turn on like in your case. I disassembled everything for the second time and checked the whole CPU board. I found a tiny tin jumper between some pins of the CPU, probably ended up there during the extraction of the old battery.I removed the jumper and reassembled everything and the unit turned on without problems. Make sure something like this hasn't happened to you too.

author: picburner
author_rank: Frequent Contributor
timestamp: August 24, 2023, 06:48:58 pm
content: While I was at it I took some pcb photos of the main unit.

author: 1audio
author_rank: Frequent Contributor
timestamp: September 10, 2023, 03:56:49 am
content: Wow! Thanks for your efforts. I will do a similar evaluation. Mine was working, sat for a few years and then was dead. This is worth exploring.

author: picburner
author_rank: Frequent Contributor
timestamp: September 10, 2023, 05:56:25 am
content: I can confirm that the small CR2032 battery, if completely discharged, prevents the main unit from turning on.Not having the schematic I cannot give an explanation for this anomaly.Wouldn't an error message have been better?However, replacing the battery restores regular operation of the instrument without further intervention, all that is needed is a RAM clear via software.Of course you have to be careful not to create new faults like what happened to me

author: 1audio
author_rank: Frequent Contributor
timestamp: September 16, 2023, 12:37:02 am
content: I have not been so lucky so far. I'll check a few other possibilities but no luck yet.

author: picburner
author_rank: Frequent Contributor
timestamp: September 16, 2023, 11:50:14 am
content: I don't know if it helps in any way but, to make sure the crystal quartz Y1 worked, I powered the CPU board (without the top pcb) via the J1 header.There are two pins, one connected to +5V and one to GND (You can find them by referring to a nearby TTL).I did this as a first test, I don't know if this could have affected the operation in any way.