Tuesday, September 29, 2009

Whack for My Daddy-o

For your listening pleasure here are several versions of Whiskey in the Jar. First up is the original rock-ified version by Thin Lizzy. Do not mistake Eric Bell's antics for a bona fide attempt at music simulation... We want to see fingers actually playing notes!

The studio version by Metallica is absolutely great, but what I believe is the official video misses the mark. The song is titled 'Whiskey in the Jar' not 'Puking in the Toilet', but maybe I am just getting old. Here is an excellent live version from Dublin.

And here is a stellar live version with two of Thin Lizzy' s guitarists: Gary Moore and Eric Bell.

I particularly enjoy Bell's performance in this video, enough to forgive his goofing in the video 35 years earlier.

Sunday, September 27, 2009

Li'l Mar: Where Something Gets Snipped

Li'l Mar is the Marantz 4220 Quadradial receiver that has become my life's work. When we last visited her we were making progress, of a sort. The distortion in the left channel was healed, but we had worn out sliders. The front was totally kaput and the fader and the rear were less than perfect, so the executive decision was made to remove them from the circuit.

Here is the before, courtesy of Jay's telephone. Evidently modern telephones even come with very respectable macro capability:

Jay's photo is a bit overexposed. Not much of a telephone, eh? The strip attached to the face plate at the bottom via the sliders (note the 3 visible squarish posts) is a very simple circuit board that needs to be disconnected from the dangling preamp board. The wires from the sliders to the preamp (eg. the brown one at the right) needed to be removed, and the wires coming in to the sliders needed to take their place. Above is before, below is after.

The wires above were formerly connected to the sliders and now were connected directly to the preamp: front left and right, rear left and right . Hmm, Jay, much better photo. This might actually be useful at some point in the future.

So we fired her up and it sounded... awful. Arrggh! Now what?? Well, the power switch was humming like that guy from Crash Test Dummies on about every third click.

Note the blue wire above. This power switch is essentially a two parter: the front with all the wires attached (at the right, lower corner) is a muting switch to make your ons and offs nice and quiet. The taller back portion with the two rivets is the actual power switch and it was worn out. We jumpered the connection with the blue wire so it is on all the time. If I had the stomach to be (even more of) a hero I could have Dremeled the rivets and taken apart the switch, but even I have my limits. Mike and Robert claim they actually do this. Really.

So we gave Li'l Mar another listen... and it is getting late. There is more, much more.

Saturday, September 26, 2009

The Pioneer SX 1250 Receiver

The Pioneer SX 1250 is one serious, high quality electronic monster. Sold from '77 to '79, it was Pioneer's top of the line receiver and boasted 160 watts per channel in a sixty pound chassis. The build quality is very high and properly restored they sound great. Not all of the late '70s monster amps and receivers sound great, but the SX 1250 truly does. I restored one about 6 months ago and neglected to write it up at the time, but it recently wandered back into my life due to a problem.

This unit's original problem was two blown main filter caps. My original thought was it was just time for the caps to go, now 30 years old, but the restoration revealed problems on the regulator card. Someone had previously done a completely inadequate repair and that card required replacement of pretty much every component, active and passive. Poor voltage control could have been a contributing factor in the death of the main filters. A 1250 deserves quality parts and someone didn't give this receiver the respect it deserved.

I replaced all 4 main filters with lovely Hitachis and recapped all 4 vertically mounted cards, the AC relay board underneath, the phono section, and the preamp cards behind the face. The two relays were burnished and all the pots and switches were squirted. The post restoration listening was a total pleasure.

Time passed and the unit ended up back at Mike's for resale. Mike set it up for a listen and proceeded to punch all its buttons. I confess I never use most of the tone controls on my receivers and I must have missed testing the two high cut filter switches towards the left side of the front panel, just above the bass and treble pots. When Mike clicked them there was a significant pop in the left channel, so it was time to peel the face again and make it right.

These two filter switches sit on their own board above the tone control board which needs to be removed for access. It had been pulled to spritz the switches with blue foam and deoxit, but no components had been replaced in the original restoration since it only had two small transistors, 4 tantalum caps and a few film and ceramic caps. These components are not typically points of failure, but 'typically' is not exactly 'ever'. Mike's estimated order of likely offenders was transistors, then tantalums and then the ceramics. Mike checked them all out in circuit and all seemed normal.

Mike swapped the transistors and the offending pop was still there.

Next up were the 4 relatively low voltage blue egg tantalums, at 4.7mfd and 10mfd, and that solved the problem.

Here is the modified board with two new transistors and 4 electrolytics replacing the tantalums:

The SX 1250 was reassembled and Patricia Barber spun on the highly tweaked Samsung DVD player with very impressive results. The SX 1250 is a head turner, one of those amps that sound good enough in the next room to drag you in for a listen. It even sounds great on Mike's beloved Infinity Quantum 2's that can get very agressive with many amplifiers. It takes an amp with considerable low end control and weight to balance out the 3 emit tweeters on the front.

It's a great looking piece of gear for those with a strong back, a very heavy duty shelf and a taste for the top of the line. It's a great representative of the very best Japanese solid state engineering in the '70s.

Props to Fed Ex and a Few Packing Suggestions

I recently had one of those all too common eBay shipping catastrophes. The shipping originator was some sort of local drop off, but I assume the inadequate packing was the fault of the seller. The actual shipper was Fed Ex.

Through a communication snafu the Fed Ex driver arrived weeks before I expected him, so the package was in a closet. He returned the next day and was very patient and courteous despite the return trip, and he did a good job at explaining the claims process. I was concerned about the outcome of the claim due to the obviously inadequate packing. The claim was handled very quickly and professionally, and I was able to confirm the positive outcome very quickly. Fed Ex essentially salvaged a difficult situation this buyer, so they will get my business in the future.

I now have a much greater appreciation of what shippers have to deal with on a daily basis.

Which brings up the subject of poor packing of electronics by eBay sellers. This happens way too often. They show up at Austin Stereo and there is often little Mike can do to salvage the situation. I have even seen a pancaked Marantz 10B. I still shudder at the thought...

I would love to know how much we all pay per transaction to subsidize people who do not care enough to properly pack fragile items. Damage claims are not 'free', we subsidize them.

Amplifiers might seem ruggedly built, but ugly things happen to them when they rattle around in a box protected only by a few peanuts. This packing subject deserves a detailed post at some point in the future, but for now here are a few suggestions:

The item absolutely cannot move around in the package. Too big a box will lead to damage.

Heavy, expensive electronics deserve double boxing. I buy my boxes at Uhaul. Their 'electronics box' is big enough to hold a Pioneer Spec 4 (as in inner box) and durable enough to survive several uses. And it costs under 6 bucks. Mike at Austin Stereo is getting business from around the country restoring these and he hates it when he has to repair shipping damage as part of his service.

Forget packing peanuts. They are useless for heavy items. There oughta be a law.

Bubble wrap can be effective, but do not skimp. One layer is a joke. Air packs can be effective if used in sufficient quantity, but the light gauge ones can pop.

And here is a secret ingredient to quality shipping: swim noodles. They are cheap, flexible, and you can carve them to fit with a steak knife. Dollar tree has them for a buck in season, and they are typically 2 bucks at your pool supply retailer. They come in several sizes and they have just the right crush quality to protect your heavy equipment. Use enough of them to immobilize the item in a grid, and take care with corners. If the outer box is too large you can use swim noodles to occupy the space and immobilize the item or the inner box. They will survive the trip, and can be used for the return.

Use your noodle and Mike will thank you, and I will give you fabulous feed back.

Thursday, September 10, 2009

Close, So Close.... But.... : Mar Episode #5

In a prior life L'il Mar must have been loved, because she was most certainly used.

Sometimes I forget that the components that I work on are electro-mechanical devices, and often their most challenging problems are caused by old fashioned physical wear and tear. Caps dry out, contacts tarnish and transistors die in lightning strikes, but switches and pots succumb to the human touch. And sometimes just moving a component can be the difference between working and not.

In our last episode we had made some progress: the rear channel of the Marantz 4220 Quadradial receiver had come to life after replacing 8 transistors in the tone control ciruitry. But the front channels remained distorted and the balance control sliders seemed... wrong.

The next trip to the bench started with pulling the tone control card to expose the slender strip of a card that holds the 3 sliders: front, fader and rear balance control. Here is the front slider:

In my brief experience refurbishing vintage gear I have grown to dislike slide controls. While satisfying ergonomically they are harder to clean and much more fragile that the typical pot. A quick check with the meter indicated the front was completely gone. I removed it from the board and took it apart and discovered the tiny contact was missing. Evidently it broke off and eventually fell out the slit. The fader in the middle was functioning, but the rear was marginal and the sonic mid point was skewed left. I put the front slider back and left the question of 'to slide or not to slide' until another day.

Look, Ma! No tines!

While useful to discover, unfortunately the sliders were not the source of distortion in the front left channel. Something else was afoot. At this point the A Team (eg. Mike) decided I had suffered enough and pulled out the 'scope. He walked through the very dense tone control circuitry and isolated the distortion to a section of the card between the bass and treble controls. He then flexed the card and the distortion healed. Eureka! Sort of.

Above, at the lower right is the tone control circuit board, dangling. Just above it you can see the front fader attached to the face plate.

The tone control/preamp circuit board is very dense and two sided, and there was most likely a faulty solder joint between the sides causing our distortion. Less than perfect soldering is probably the second most common cause of failure in vintage gear (behind faulty caps). But it is by far the most common cause of failure in modern gear. If your home theater receiver quits working, try picking it up and shaking it. It's liable to work for a few more weeks after 'treatment'. (Try at your own risk. We are all adults here, right?) The constant thermal ebb and flow along with occasionally moving a component will eventually cause weak solder work to fail. And sometimes just another move will fix the problem, albeit temporarily. A few years ago I fixed the kids' modern Sherwood receiver by merely shipping it in for warranty work. Sherwood said it worked fine, and it did for about a month on return.

Mike spent a solid 10 minutes hitting every solder in the tone control of area and especially the rivets and the very complex pots, and finally the front left channel lost its distortion.

At this point I celebrated a bit, but as we all know that is a very dangerous thing to do. Yes, the saga of L'il Mar is not over by a long shot...