Thread: PLZ pre-preamp
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Old 24th February 2019, 10:15 AM
Black Stuart Black Stuart is offline
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Join Date: Dec 2005
Location: France
Posts: 1,159
Default Re: PLZ pre-preamp

Bob,
you have different caps to me - the 2 Anodia caps are 100uF/10V and the 4 Samar caps are 470uF/16V which is totally at variance with your values.

There is no mystery about the trim pot, that is what it is a Spanish Piher - no one seems able to state what the info relates to - 100 321. looking at trimpot definitions, these figures mean nothing.

I contacted Vickers Hifi who deal with the residue of Pickering UK products and whose address was the same as that company in it's heyday that QED made the PLZ. The PCB clearly shows the QED logo and other info but QED deny that they made it. I simply don't accept that any company would allow another to use their trade name.

The contact at QED did admit that they made a PLZ type product. As I understand it they were virtually the same. If the original info was available it would make life so much easier.

Re. voltages of the regs/transistors/ whatever - the highest V I measured was 0.626V.

Nowhere do I measure anything like 3V even though that is the battery supply

Bob - does your PCB clearly show, in the middle of the board the logo QED? - bottom left in vertical format MCA1?

Andy the caps are most definitely not bi-polar, they are electrolytics.

Why did the designer choose values that you say are not needed, it's not as if lower values were not available then.

I'll see if I can get some pics loaded.
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