06-01-2017, 05:14 PM
(06-01-2017, 10:05 AM)Terry Wrote: I'm wondering if the TC8H was fitted to overcome a low gain fault in the amplifier in the past? It might be worth more investigation.
You could be right Terry. The original volume pot in the record player was marked as 1M B but it measured 275k ohms.
In my limited experience I have never known a pot to go significantly low, they always seem to go high.
This would probably have an effect on the working of the cartridge as it is wired directly across the 2 ends of the track of the pot.
Apart from loss of volume I think it may also result in a significant loss in bass response from the cartridge, must have sounded horrible.
Anyway I have now fitted a new 1M pot.
I have assembled it all back together and the volume issue is not so bad now the twin speakers are fitted in the cabinet. It is louder and now more comfortable listening at close quarters with the volume down by about a 1/4 from full, but it still does not go into distortion.
There is a problem with the GP91-1sc cartridge, it is distorting in phases, on some records, as the record rotates. It gets worse if you increase the stylus pressure, but the pressure is more or less on the minimum to keep the stylus following the grooves.
I have ordered a new stylus, but I may end up having to order a new cartridge altogether. (I wondered why the GP91-1 was in my spares box, probably came out of a KB at some time)
Mike
