[spassmaker]

Hi dear Members

I’m in a little trouble with an BG 4000.

Did already a refurb including Caps and cleaning/ alingning all Switches. The turntable is starting, platter spins but even with a record on the tonarm won’t stop or Set down. Had already changed 3IC0 wich made the tonearm travelling again, Q0 (not) signal was missing.

Now I’m looking for IC’s FCH131 and FCH 111.

Maybe someone has a old Keypad in his workshop and could desolder 2 of each IC’s for me. Or some n.o.s.

Please help, thank you very much.

If you got one of these IC’s let me know and PM me with suggested price incl. shipping to north Germany zip Code 23701

Kind regards

Christian

[auric]

Christian:

They are available here:

https://www.electronicparts-outlet.com/en/integrated-circuits/4688-mullard-fch131-dual-4-input-nand-gate-with-rc-dip14.html

https://www.electronicparts-outlet.com/en/module/iqitsearch/searchiqit?s=FCH+111

FCH131 is a 4 input Nand Gate. Can you use a 7420?

FCH111 is a 8 input Nand Gate. Can you use a 4068?

Those are much cheaper if they work. I didn’t check the pinouts and operating parameters.

 

Derek

 

 

 

[spassmaker]

Hi Derek

Thanks fore information.

I already saw these offers in the www.

In between I desoldered all IC’s from the PCB and tested them on a breakoutboard.

Found one mor defective FCH 131 wich had an steady High level on one output.

I decided to solder all back in and only leave 3 IC 5 open because the there are only two and three inputs of the NAND’s used.

I will try to rewire an CD 4012 an look what will happen….fingers crossed.

Still waiting for deliver the CD4012, when they arrive I will report.

The failing of the IC’s was, in my opinion, caused by the Z Diode 2D4 6,8 Volt.

This diode was loose in the solderjoints by some strange human activity. If it’s loose or not connected anymore, from my knowlege, the voltage on Emitter 2TR6 is raising near to the input voltage Collector 2TR6 (haven’t measured what comes out from the bridge rectifier) and fries the IC’s.

 

Kind regards

Christian

[Author]

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