tl866 zif socket problem  - Page 1
Forum section: electronics / repair

author: fadyeid
author_rank: Contributor
timestamp: March 23, 2017, 09:06:27 pm
content: hello i have got a tl866 a from a month ago but the zif socket is broken so after i changed it some tracks are moved away from the motherboard , now when i try to do system self check it gives error VCC testing number 4,5,6 error need help to fix this

author: Bushougoma
author_rank: Regular Contributor
timestamp: March 23, 2017, 11:59:23 pm
content: You'll need to repair the lifted traces with wire jumpers.Provide some pictures of the ZIF socket daughter board and the damaged traces.

author: fadyeid
author_rank: Contributor
timestamp: March 24, 2017, 08:17:03 am
content: so can you tell me which pins are for vcc ? , I cant determine which pins are moved away

author: Armadillo
author_rank: Super Contributor
timestamp: March 24, 2017, 09:27:14 am
content: All the pins should be programmable to suit the vast majority of devices to program or read. For example each of them can be either VCC, GND, Data pin, input pin, output pin, Program Voltage pin, etc...As shown on the self-test screen, from #4, #5 and #6 has a problem. Assume # means number or Pin number, trace all those where the traces are lifted or shorted, also check the VIA traces etc...Can you take a photo of the traces you mentioned in your post "moved away from the motherboard"? What exactly do you mean?

author: fadyeid
author_rank: Contributor
timestamp: March 24, 2017, 06:53:52 pm
content: first I want to thank u for helping me , I mean by moved away tracks ( the tracks are cuted so need to be jumbered ) , I have checked all the pins and found these 3 pins need you help where to connect them

author: Armadillo
author_rank: Super Contributor
timestamp: March 24, 2017, 09:00:00 pm
content: You can download the schematic easily on the web. Please refer to it.Pin 7 is connected to IC L7  Pin 15 [thru the discrete switch]Pin 8 is connected to IC L7  Pin 12 [thru the discrete switch]You marked another 7, I supposed is Pin 34 of the ZIL you referring, it is connected to IC L6  Pin 16 [thru the discrete switch].Please spend time to compose your question and locates the parts and ICs. I hope this provides some guide for you as I will not be able to lead you to every steps of the way.Regards;Armadillo;

author: fadyeid
author_rank: Contributor
timestamp: March 24, 2017, 10:07:28 pm
content: yes I am just a beginner , I am studying electrical engineering , now I just downloaded the schematic but even I cant determine which ic you mentioned I have many ics by this number and the lapel is written under ic , so I am happy to learn from you and thank u so much for helping me

author: Bushougoma
author_rank: Regular Contributor
timestamp: March 25, 2017, 12:32:48 am
content: Nice catch I didn't realize that there was a reverse engineered schematic available there is also a theory of operation document too.For future reference both can be found at this link:http://minipro.txt.si/index.php?title=Main_PageI see you've already been told where to solder your jumpers but it's a good idea to get comfortable reading schematics so spend some time looking at it and tracing the VDD lines out yourself.

author: Armadillo
author_rank: Super Contributor
timestamp: March 25, 2017, 04:48:54 am
content: As a beginning, I know it can be overwhelming at times, with the vast amount of new symbols, legends and information. I attached example of Pin 7 connection for your understanding of where Pin 7 is connected to so many places and pages. The switches [transistors, diodes and resistors] are at the underside of the boards.To locate the related switch and IC, you can use a good uncut pin to trace it with a continuity buzzer tester. Example instead of Pin 7 is ZIF 7 and is connected thru the transistor switch to GND 7 of IC L7. Instead of using Pin 7 which has been cut, you can use Pin 6 to trace to the related transistor switch and then to the IC 7 to identify the IC location, so the next one should be your cut connection to the switch or to the IC. I don't know whether your cut severed how many connections. So it is best to check all the connections to all the related switches and pins to make sure they are connected.To learn, you need to trace. There is no easy formula here. But after you did it, you conquered the TL866 boards. Apply above methods to all the other pins.I suspect the cut/damage must be quite bad, hence no photo for us to see until now.Anyway, enjoy the experience.Regards;Armadillo;

author: Bushougoma
author_rank: Regular Contributor
timestamp: March 25, 2017, 05:32:39 am
content: Essentially what's happening when you initialize the self test is the programmer is verifying each individual transistor drivers ability to connect a ZIF pin to either VCC, VPP, or GND.How does it know if the connection was successful and the driver is working?Each ZIF pin that's connected to a driver (all 40 pins are not) is also connected to an input pin on the main processor (PIC 18F) if you connect a pin to VCC or VPP the input will be read by the micro as a logic 1 if you connect a pin to GND it will be read as a logic 0.If the micro doesn't like what it sees (anything but a logic 1 for VCC or VPP and anything but a logic 0 for GND) the test for that pin will fail.

author: fadyeid
author_rank: Contributor
timestamp: March 25, 2017, 02:01:08 pm
content: so now I checked all the connections like the schematic ! but it seem like no connections at all just the Gnd line only ! I have attached the photos !