UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

NikPrice · 4th Feb 2020, 2:27 pm

I managed to get the TMS1000NLC from ebay, the seller was in Germany.

I'm going to remove the zener and test it. I'm not sure that I understand the way it is supposed to work in this circuit. I thought that it should create a 6.2V difference from one side to the other. It's not doing this, and nor does D26, which is a 7.5V zener.

If REF H is supposed to be 8.2V then I think I need to find the source of REF H and follow this through to D24. Changing the op-amp chip IC5 made no difference so I'm guessing that REF H is out of spec before that.

4th Feb 2020, 2:27 pm	#4
NikPrice Triode Join Date: Feb 2020 Location: Portsmouth, Hampshire, UK. Posts: 35	Re: Another Quad FM4 problem I managed to get the TMS1000NLC from ebay, the seller was in Germany. I'm going to remove the zener and test it. I'm not sure that I understand the way it is supposed to work in this circuit. I thought that it should create a 6.2V difference from one side to the other. It's not doing this, and nor does D26, which is a 7.5V zener. If REF H is supposed to be 8.2V then I think I need to find the source of REF H and follow this through to D24. Changing the op-amp chip IC5 made no difference so I'm guessing that REF H is out of spec before that.