Gould 1602 repair help

[noodlebear]

Hi,

I've just acquired a Gould 1602 scope which has a problem. On power on, the power light comes on but there is no other activity. After leaving the scope running for a while and then turning off and on I occasionally see all the channel 1 LED's flashing and once saw the CRT flash.

The service manual is available at http://dl.dropbox.com/u/8513299/Gould%201602_1604_Service%20Manual.pdf
and schematics at http://dl.dropbox.com/u/8513299/Gould%201602%201604%20schematics.pdf

I have had a look at the power supply voltages and all seem within spec. VAC on multimeter shows minimal ripple however I don't have another scope to test this properly.

Going through the troubleshooting guide in the service manual the first thing to check is the 1MHz E clock on U1 (the main processor, MC68B09P). Since I don't have a scope to check this with I used the frequency counter on my multimeter. This shows a frequency of almost exactly 2MHz (not 1MHz).

I wonder whether this could be a discrepancy in the service manual since it seems exactly double? Does anyone have any ideas as to how I could check this more thoroughly?

Thanks

[scirturbo]

Hi,

I've repaired my 1604 several years ago and from what I can remember is that one logic circuit had a short and also several tantalium caps were low on resistance. It had also a out of focus image which was caused by dry caps in the powersupply. A couple of inputs had short/open components.  A good start will be replacing all the tant. caps.  Look for brown and hot caps.

Hope this helps........

Simon 

[Skeluroth]

Hello,
yeah, i know this is a old thread but i have the exact same problems as you're describing it and i could not find anyone else with this problem.
So i am wondering if you (or any other member) found a solution?