Hello everybody.
I haven't published any posts for a while.
What better way to get back into the game?
I have a ZAPCO reference 1000.4 30th ANNIVERSARY amp that was devastated.
I proceeded to restore the power supply and 2 channels completely destroyed by a previous repair attempt made by someone else.
The amplifier turns on and works completely, but 2 channels sound less than the other 2 remaining.
The least sounding channels are the Left of both FRONT and REAR, but all channels react perfectly to all the frequency and gain adjustments I touch.
I have already contacted ZAPCO, particularly John Borges to find out if he could get a copy of the electrical schematic, but I have not received any response.
Can someone help me?
thanks a lot to everyone.
I haven't published any posts for a while.
What better way to get back into the game?
I have a ZAPCO reference 1000.4 30th ANNIVERSARY amp that was devastated.
I proceeded to restore the power supply and 2 channels completely destroyed by a previous repair attempt made by someone else.
The amplifier turns on and works completely, but 2 channels sound less than the other 2 remaining.
The least sounding channels are the Left of both FRONT and REAR, but all channels react perfectly to all the frequency and gain adjustments I touch.
I have already contacted ZAPCO, particularly John Borges to find out if he could get a copy of the electrical schematic, but I have not received any response.
Can someone help me?
thanks a lot to everyone.
Please write in english...
Yes the amp Play good music on all 4 channel
But left channels for both Front and Rear produce less power
if the bias is ok of the final transistors it is probably a problem with the preamp stage or some faulty trimmer in my opinion!
Find the point where the preamp goes into the power amp section and compare the levels there. That will tell you if the loss is in the preamp or in the power amp.
This amp is becoming a real nightmare.
Unfortunately I didn't find any point in the preamp section that showed a lower signal than the others .... they are all perfect ...
For safety I have changed all the op amps (TL074 - TL072 and NE5532) but the situation does not change.
In the first message I made a mistake, it is not the left channels that deliver less power, but the right ones.
Also I did some tests, this amplifier can be set to double bridge, where each bridge carries the signal of a single RCA, then the FRONT channel bridge will amplify the LEFT RCA and the REAR channel bridge will amplify RCA RIGHT, and even that case, the REAR channel bridge sounds less than the FRONT channel bridge. In short, the problem seems to be related only and only to the RIGHT channels in whatever mode you configure the amplifier.
I would like to take the board out of the chassis and split it into 2 parts.
With a signal driven into the amp, what's the voltage at the input to the power amplifier section and then at the output of that same channel. Use an output level (no load) that will drive the amp to near clipping. Post the two voltages for each channel. Use the non-bridging speaker terminal for the channel you're measuring for both input and output voltages.
I understand what kind of test you recommended.
You want to understand if each channel is receiving the proper signal and based on the output signal of each channel, understand if they all have the same gain factor.
But Perry, this is very strange, because when the amplifier is configured in four-channel mode, the channels that sound less are the right (one for the FRONT section and one for the REAR section), while when I configure the amplifier in DOUBLE BRIDGE mode, the channels that sound less are only the REARs (because in this configuration the two REAR channels added together will amplify the right RCA signal) so the problem moves to a channel that previously had no problems.
For this reason I firmly believe that the 4 amplification stages are perfectly functional and that the problem depends on the preamp section, but unfortunately I could not understand where it is located.
The electrical schematic, or a very similar one, would help.
But now ZAPCO does not provide anything and John Borges strangely did not answer me at all (2 weeks have passed since I wrote him an email).
The various manufacturers change policies. Zapco used to provide diagrams.
Is this layout anything like any of the clarion amplifiers?
Can you map out the path for each channel in all configurations to find the point where you're losing signal?
Is this layout anything like any of the clarion amplifiers?
Can you map out the path for each channel in all configurations to find the point where you're losing signal?