Wavetek 178 need repair - Page 1
Forum section: electronics / repair

author: Daxxin
author_rank: Regular Contributor
timestamp: March 04, 2018, 03:33:00 pm
content: who experiencd this before? really no idea where to start , power supply rails is fine checked alredy.how to check the optocouplers?

author: Stray Electron
author_rank: Super Contributor
timestamp: March 04, 2018, 04:37:46 pm
content: It sounds like the CPU isn't starting properly. Is it in a socket? If so I would check the connections VERY carefully. I've found that the IC sockets are a big problem in older equipment. The socket and the IC pins are usually made of different material and over time, the different materials cause corrosion. Exposure to humidity will make it worse. Check your clock and power signals ON THE CPU PINS and not on the socket or anywhere else. If the power and clock are ok then look for a stuck data or address bit or a bad connection to one of those pins.A Fluke 9010 Troubleshooter with the proper CPU pod is GREAT for troubleshooting microprocessor based systems like this. But they're become collector's items.

author: Daxxin
author_rank: Regular Contributor
timestamp: March 04, 2018, 05:59:32 pm
content: Thanks Stray Electron your info very useful , comparing schematic to board something look wrong the U45 must be an static ram but i found an intel eprom B2716and U44 must be an 27128 but i found an national eprom NM2716Q tried to read both but they are empty , so maybe owner befor replaced with no sense.I guess will be hard to find the binary to load in the eprom.

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 04, 2018, 06:34:59 pm
content: I think they just wore out and blew. The UV widows are covered meaning they probably had data at some point.

author: PA0PBZ
author_rank: Super Contributor
timestamp: March 04, 2018, 07:43:38 pm
content: Quote from: Daxxin on March 04, 2018, 05:59:32 pmI have a working one so I could read the contents and post it. Any idea if there is more firmware that should match in version or is this the only eprom?

author: Daxxin
author_rank: Regular Contributor
timestamp: March 04, 2018, 08:20:27 pm
content: thanks very much PA0PBZ , there is another cpu (6803) front panel board with its eprom but there no stickers no idea what version , and there no others roms aroundboard label its a rev. P here attached rom file from fp board

author: PA0PBZ
author_rank: Super Contributor
timestamp: March 05, 2018, 01:01:16 pm
content: Well, that got interesting. Here's my 178:Both eproms are 2716, and I checked the documentation I have but that also shows a RAM chip. If I pull both chips it does what you see: 15 times 'selftest' and then the 'prw-on-err restart'. While reading U45 was no problem, U44 gave me mostly 00's until I increased VPP to 5.5V. Now I get consistent results so I hope the file is correct.I thought of checking the bin file by burning it into another 2716 but all I could find are 25V VPP ones and my minipro only goes up to 21V.Anyway, see attachments and let us know.

author: Daxxin
author_rank: Regular Contributor
timestamp: March 07, 2018, 10:59:29 am
content: I have also tl866cs programmer but to reflash i have bring back my old chipmax from eetools that supports this romsWell now sometime restarting i get same message and sometime i get reference unlocked , small progress since before i get only power_on_err ..still some logic problem . By the way you have never connected it to gpib card? I have try but cannot get any activity. I need to investigating more ...will updating.

author: Daxxin
author_rank: Regular Contributor
timestamp: March 07, 2018, 07:51:55 pm
content: Problem was U45 pin12 no more contact to ground join , soldered again and maybe lost data eprom, thanks PA0PBZ

author: PA0PBZ
author_rank: Super Contributor
timestamp: March 07, 2018, 08:06:22 pm
content: Quote from: Daxxin on March 07, 2018, 07:51:55 pmGood to see! I will test GPIB this week and let you know if I can get any response.

author: lmester
author_rank: Regular Contributor
timestamp: March 11, 2018, 02:30:38 am
content: Daxxin,Do you have an external timebase connected? That is the only time that you should see the "Reference unlocked" or "Reference locked" message. Getting this message without an external timebase means that you have a problem that needs repaired.Also, my wavetek works good on GPIB. It's the only way I can easily use it. The front panel pushbuttons are in very poor condition. Bouncy and some barely work. It's unfortunate that they put cheap click-dome type switches on an expensive instrument.If you're interested I can upload a copy of my control program. First you should know that I use a Prologix USB to GPIB adapter. If you don't have a Prologix or Prologix compatible adapter the software won't work.

author: PA0PBZ
author_rank: Super Contributor
timestamp: March 14, 2018, 06:47:52 pm
content: By the looks of it my U44 gave up, so I had to wait for some 12.5V programmable 2716's (AM2716B) to make a new one.Now my Wavetek is working again, but I can't find a GPIB cable anywhereIs this still relevant after the reply from lmester?

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 14, 2018, 07:12:01 pm
content: Quote from: PA0PBZ on March 14, 2018, 06:47:52 pmSolder wires to the board. That's what I do.