I dont know how to approach this problem...

[Soundork]

I just saved a Criterion Mark VII Stereo Receiver from a trip to the landfield. After initial listening test, I decided to keep it.

Now the plan is to refurbish it (its 37 years old...) and I have the following two questions:

1. I cant find the Service Manual anywhere. Can someone help me locate one?

2. If I were unable to find a service manual, how would you suggest I approach this problem? My intention is to initially recap and possible replace the low power transistors of the input stages if necessary. Without the service manual I can easily do that, but how do I adjust it at the end to factory specs?

I have done such work in the past and it could be a pretty complicated procedure...Any advice would be appreciated.

Thanks in advance.

Best

 

[DF96]

Replace faulty capacitors, one or two at a time, retesting after each attempt.

By "input stages" do you mean RF or audio? If the former then you need to have the necessary equipment and knowledge to realign afterwards. Why do you think they need replacing?

 

[Soundork]

Replace faulty capacitors, one or two at a time, retesting after each attempt.

By "input stages" do you mean RF or audio? If the former then you need to have the necessary equipment and knowledge to realign afterwards. Why do you think they need replacing?

Thank you for your reply. I was thinking capacitors only in the RF section and capacitors and a possible upgrade of the transistors in the audio section. I have the equipment to do that.

My question was exactly this: How does one go about aligning without a service manual? For example one aligns the power amplifier section of Pioneer SX1250 by:
1. Turn VR2 fully counter-clockwise before turning on the power
2. Remove jumper plugs connecting POWER IN and PRE OUT jacks.
3. Connect 5.1KOhm resistor to POWER IN jacks
4. Set the power amplifier for no load.
5. Set POWER switch to ON
6. Adjust VR1 for 0V between terminal 9 and ground
7. Adjust VR2 for 100mV between terminals 7 and 19
8. Allow set to warm up for at least 10 minutes, then readjust

I am pretty sure that the adjustments for the Criterion are similarly complicated. How would a tech at a repair shop properly do this without a Service Manual?

Thanks in advance.

Best

 

[AndrewT]

I would target ONLY the electrolytic capacitors in the Power Supply section.
Replace a few (two) at a time and power on via a Mains Bulb Tester and then direct power to test the modified assembly.

 

[DF96]

I was thinking capacitors only in the RF section

Don't touch anything in the RF section, especially capacitors, unless you have the knowledge and equipment to do a realignment. This is not a matter of twiddling a pot until you get a particular meter reading. An expert may be able to do it without the manual; anyone else hasn't a hope, and newbies will probably fail even with the manual. An expert would only replace faulty caps, and those known to be unreliable.

What you call 'alignment' in the audio section is quite different, and trivially simple by comparison.

'Re-capping' is hugely popular, yet at best mostly a waste of time and money and at worst a quick way to render old equipment worthless and useless. Fix faults, then stop.