Analog board & power supply compatibility...

[phreakout]

Okay, this totally sucks. The analog board on my SE converted to an SE/30 has possibly bitten the dust. It must be the vertical sweep IC (U2) that failed or something else. It suddenly began showing a black screen with a bright single horizontal line and now is just a blank screen. Looking up what to do, it was suggested to try resoldering the P1 connector or that the chip is bad and replace it. If I don't fix this, I would be going totally blind when I do SE/30 logic board recapping.

I was looking on eBay and found this. My question: Can anyone verify if whether that analog board is fully compatible with the power supply and CRT I have? The power supply is a Sony CR-44 Apple P/N: 699-5047 and the CRT is:

Clinton Taiwan Corp.

CE792M9H118GHZYB

CEULL76 1/4 A1TE

Apple P/N?: 630-5144

If not, I will try replacing the vertical sweep IC on the original analog board and see what happens. Luckily, I can get the part individually for $11.63 from Mouser.com.

Thank you for your help.

73s de Phreakout. :rambo:

 

[Scott Baret]

This should work. Power supplies are universal for all SE, SE SuperDrive/FDHD, and SE/30 analog boards, as are CRT connectors. The two brands of power supply for SEs (Astec and Sony) are interchangeable as well. Sonys are consistently more reliable.

You have to worry about CRT connector types when you're dealing with Classics, which use two types of CRT connector. However, all Macs in the SE line shared the same display.

The only possible significant difference between logic boards is the fan assembly. Early SE boards used the "rat cage" or "squirrel cage" fan, which was noisy and could cause screen interference. Most SE series machines have the blade fan, and since Apple offered a free replacement for those with the earlier fan, it's rare to find the old-style boards with the less desirable fans out there. In general, the only SEs with these old fans are the ones made in 1987 (unless an old analog board was used as a replacement in a 1988-1991 SE series computer).

 

[phreakout]

One thing I forgot to mention is that it originally started out as a Mac SE dual 800K floppy, but swapped out the faulty logic board for one from an SE/30. So everything but the drives and logic board are the original parts. I doubt this has any relevance to the problem, but just wanted to add it anyway.

Scott, thanks for the info. I will make a quick decision and update on what happens.

73s de Phreakout. :rambo:

 

[techknight]

time to break out the old oscilloscope and DMM... have at her. there are schematics available for that analog board, including voltage charts as i remember seeing it somewhere. so narrowing down the problem with those 2 peices of equipment should be relatively easy.

Another thing to check is the yoke, that blasted yoke connector likes to break loose solder on the board. and at the yoke as well..... check this.....

 

[tomlee59]

From the sequence of symptoms, I doubt that the vert IC has died. It is much more probable that the yoke connector (P1) simply needs resoldering (use fresh solder; do not simply reheat what's there). Before spending the money on ordering a replacement IC, try the easy thing first.

Be sure also to inspect the mating surfaces of the connector halves. Look for signs of oxidation, pitting, burning, etc.

 

[phreakout]

tomlee59,

I already resoldered P1 with no luck. It just shows up blank screen now. #6 listed here is what I used as a reference. I may also assume #5 on that page.

73s de Phreakout. :rambo:

 

[tomlee59]

When you turn it on, does it seem to come to life (makes the bong sound, disk activity happens, etc.)?

If not, you have bigger problems than a (possibly) bad vertical drive chip. Check supply voltages (if you haven't already done so). Check the CRT connector to make sure it hasn't worked loose, and to verify that no solder connections need refreshing there.

Did you check the yoke connector (by unmating the two halves and inspecting)?

Answers to these questions will go a long way toward narrowing down the list of suspects.

 

[phreakout]

Q: When you turn it on, does it seem to come to life (makes the bong sound, disk activity happens, etc.)?

A: Yes. I get startup tone, hard drive is booting into System 7.0.1, but right now it is just a blank black screen. The P1 connector is securely connected.

73s de Phreakout. :rambo:

 

[techknight]

What kind of testing tools do you have in your arsenal?

 

[phreakout]

I just have a DMM. But that is limited to about 400V. I don't have any oscilloscopes to test with. And I'm using the Repair Mac website for reference, since it's very detailed in diagnosing problems with Mac SE/30s.

73s de Phreakout. :rambo:

 

[techknight]

crap. DMM might be ok, but it isnt really going to get you too far without a good scope.

Well, if you had a voltage reference sheet of a known working unit, then a DMM would help you find the problem as there will be a voltage or a number of voltages wrong somewhere, caused by a circuit malfunction.

 

[phreakout]

Well, I think what I'll do is purchase that analog board and also purchase the vertical sweep IC, as well. When they come in, I'll work on them both and give you my results. If I find that replacing the vertical sweep IC didn't fix the problem, then we'll know that more was in store for failure. If the new analog board does work, I'll let you all know, so it can be documented.

73s de Phreakout. :rambo:

 

[techknight]

im sure a new analog board will fix the problem. but i dont see a failed vertical IC causing the loss of horiz scan/HV, which results in a blank screen. Then again, never know.

the HV/video circuits are seperate from the vertical circuit, so a failure in the vertical circuit alone would NOT cause blank raster in that analog board. the horizontal line you had the beginning, yes, it would cause that. but that would be the extent of it.

however..... if the vertical IC shorted, its possible that it took out the 12v supply to the analog board, and THAT would cause the blank raster.... that voltage comes from the power supply, labled as the "sweep" voltage. on the red wire. probe this to verify the presence of 12V. if 12v is missing, you will have a blank screen with no sweep.

but without a scope, you cant probe the video, horiz and vert drive signals to make sure they are present.

 

[tomlee59]

Since it's going through its usual boot process correctly, a great deal is working. Since the hard drive needs both +5 and +12, all the supplies are basically ok.

In the absence of other data, loss of raster subsequent to loss of vertical deflection still screams "connector trouble" to me. Yes, it is possible for multiple failures to produce the effect you're seeing, but the probability is low enough that I'd still spend a fair amount of time investigating carefully the "usual suspects" first. Verify that the +30V video power line is within, say, 5-10% of nominal. If it's only +12 or zero, that would explain loss of raster.

With power disconnected, carefully verify continuity between the yoke connections at the crt end of things and their points of origin (i.e., flyback terminals in the case of the horizontal drive, and the TDA1170+ associated components in the case of vertical drive). That test will exercise all interfaces along the way, just to make sure you haven't missed something.

Disconnect and reconnect all cables on the analog board. Inspect all mating surfaces for any telltale signs of corrosion, burning, etc.

Perform a careful visual inspection of both sides of the analog board.

 

[phreakout]

Well, the chip should be on its way as of today. Strange enough, I powered up the chassis and a recapped logic board that I was testing, and everything was actually working right this time. This could be only temporary and completely out of luck. I am still going to pursue a replacement analog board or keep my eyes out for a used good SE/30 to buy.

73s de Phreakout. :rambo:

 

[techknight]

further proves defective solder joints.