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See ECO's 74, 75 and 348, AFTER FINDING FAULT.

I downloaded the manual and rotated drawings to make it easier to read. See aattachment

Those resistors are in parallel with the regulators. There is a downstream fault. My guess is either a chip or electrolytic cap(s) in backwards. There is potential danger if it's a cap as it could become a projectile if allowed to fail. To troubleshoot use the nose and index finger to find...

Got a schematic? I don’t think the resistors are the issue. There’s a fault someplace. Power resistors often run very warm. But they shouldn’t be hot enough to blister your finger.

Excuse my ignorance. I don’t get out much. Who is Amir?

Lee, I’m still laughing. My wife even laughed.

Sunbobb, I like the plug-in voltmeter for the test set. Where did that come from? I had that desoldering tool for a week or so, and ended up returning it, although I don’t recall why. Then I went off the deep end and bought the Hako desoldering tool, and I’ve been very pleased with it. Looks...

See attached.

see attached. If there is a P/L manual I most likely have it. The later stuff is bare minimum, but has specs and drawings. No B.O.M. People who download agree not to throw it up on EBAY. That's lame. Don't slam it on the first time. Use the light bulb test set with the smallest...

If it's a stock board, one of the front end differential transistors is failing. On every PL14 board I've seen in the last couple years, Q3 or Q4 has failed. I'm pretty sure it's Q4. Replace both with MPSA93. Make sure to read the service bulletins for pin outs in the service manual.

I learned the hard way of the value of cat 5 cable. When I did my home network in the late 90's I mistakenly used one wire from one pair and one wire from a different pair. The network cards' LED lit up ok. The network crashed and crashed. My friend stopped by and looked at the install and...

What part of Alaska? I've been to Anchorage and Prudhoe Bay a few times and hope to get to Valdez later this year.

There is a replacement switch available, but I think it requires a new mounting bracket that is also available. I'll try to look it up. I've got a small pcb with a triac (solidstate switch) that is controlled by the main power switch. The existing power switch controls the triac which...

Check the value of the resistors you're measuring across. If possible, run the amp into a resistive load until the heatsinks are very warm. Recheck the bias. The bias should drop as with increase in temperature and return to original value when the amp is idling.

Attached is the service manual. see the bulletins. It wouldn't hurt to add a small electrolytic cap, say 100uf/25 volt and a 0.1uf film cap in parallel with the zeners.

The service manual has a procedure for checking outputs in circuit. Adapt the procedure to use a Digital meter. The pprcedure was written before DVM's existed.

The web site is somewhat outdated. If you have questions let me know.

I take exception to the comments on the relay board. I use 20 amp relays. Thus far no report of relay failures in 400 or 700.

I hate to be a buzz kill, but the 4000 is a (small) time bomb waiting to happen. If you pull the bottom cover you'll likely see hundreds of cracked solder joints on the mother board. Reflow the solder around the pins. The phono jacks also like to breaK. I bought a few hundred last year on a...

The relay board install procedure attempts to eliminate ground loops for the stock driver board. The stock version has the signal ground and output ground shared. That saves at least two or three cents worth of wire. It is assumed that upgrading to the W/O control board uses the W/O procedures.