SPEC 4 variants (AWM-146-0 / AWH 066-B)

[david winter]

Hi,

I recently scored a nice Pioneer bundle: SPEC3 + SPEC4 along with a PL1000 and CT-F1250.

I started going through the SPEC4 and noticed some differences in the board revisions, which brings a first question: is there a place where all revisions can be found to compare ? I downloaded two different SM but none refer the meter board as AWM-146. They say AWM-113 instead.

My meter board has the following differences (I didn't check the transistors, resistors etc):
C11 and C12 should both be 47µF/80V as per SM, but one was a 100µF/80V.
C1 should be a 220µF/10V as per SM but I found a 100µF/25V instead.
There was absolutely no visible difference between the solders of those different parts and the rest.

Also, the board has a 33µF/25V between R23 and R25, which is not shown in the SM. Did they forget to include it on the pcb sketch (pages 24-25 of the SM) ?

Thanks.

 

[Shikaka]

I’ve only repaired and/or restored around a half dozen or so of Pioneer’s higher end units from the late 1970’s, but I’ve seen such discrepancies several times. The actual boards in these units often differ slightly from what’s shown in Pioneer’s service manuals.

As far as I know there isn’t any documentation currently available detailing Pioneer’s design revisions from during their production runs. Having worked in engineering for decades myself, I can’t imagine that Pioneer didn’t have internal standards for engineering design and document control. But 40+ years later I think those details and documents are lost to posterity.

Unless one has the depth of technical knowledge to do otherwise, I believe the safest approach is to replace components with what was actually found in the unit, rather than change, add, or remove components to match the service manual. I’m assuming Pioneer’s service manuals were written very early during a models production run and weren’t revised afterward for design improvements (or flaws) found after units were being sold. Their engineering departments were probably already too busy working on designs for the next model to bring to market.

If any of the more experienced restorers in this forum have additional insight into this topic I know many of us would be interested.

 

[ivandezande]

Keep whatever's in there. Don't change values.

 

[IMF_Pioneer]

Keep whatever's in there. Don't change values.

What he said !

 

[IMF_Pioneer]

The other thing to consider which variant of unit do you have ? The USA / Canadian, the Euro or the Oceania / Australian variant as I know there are differences with the main amp boards in the Aussie versions. I have one of these units here in Australia and most of the info is more biased towards the US model.

I will dig out my genuine hard copy Pioneer SM and have a look as I think I have a supplement to that model within it's pages.