But they have to be OK because they are brand new.

Are you sure you replaced everything with the appropriate part? If you didn't use the exact replacement part, the pinouts on the transistors may be different. Wholesale replacement of parts that are not known to be bad is not a good idea.

 

Are you sure you replaced everything with the appropriate part? If you didn't use the exact replacement part, the pinouts on the transistors may be different. Wholesale replacement of parts that are not known to be bad is not a good idea.

Not the exact part but parts with the same technical similarities ... Exact parts don't exist anymore and even in this particular model which had original parts until now, were not exactly identical to the parts list.

And to answer your question: I checked the pinout from every new transistor (datasheet) and referenced it with the circuit diagram to ensure the correct placement of the replacement transistor.

Replacement guide

 

Can you measure the collector voltage of each of the transistors in the +15V supply and report the voltages here.

 

Sure!
Will test them tomorrow in the afternoon

 

Wait a sec.

Input Voltage AC on "high" plug: 96V -> should be: min 108V AC max 132V AC

That's a problem. Check the AC power in the house. Check at the end of the power cord.
Check at the transformer tap.

The fuse or any contact or switch can drop voltage. With the unit on, you can measure across things like the fuse and switch.

The absolute wierdest thing I ever trouble shot was an intermittant fuse. Two of them. Ohmmeter tested fine, but it opened under load.

Get the AC input voltage right.

 

Wait a sec.



That's a problem. Check the AC power in the house. Check at the end of the power cord.
Check at the transformer tap.

The fuse or any contact or switch can drop voltage. With the unit on, you can measure across things like the fuse and switch.

The absolute wierdest thing I ever trouble shot was an intermittant fuse. Two of them. Ohmmeter tested fine, but it opened under load.

Get the AC input voltage right.

thanks for your concern about my house voltage but thet is fine at 230V ...
I use a variac for the testing in case something (like now) went wrong and a transistor heats up quickly.

 

Can you measure the collector voltage of each of the transistors in the +15V supply and report the voltages here.

Uhhh new unexpected problem turned up.
The Q880 overheats very quickly -> at 30V AC input and -2V (dropping) output
I haven't changed anything except checking Q880

 

So lots of current is flowing through Q880.
If you have nothing connected to the -15V output then the only places that current can go are C880, CR880 or something not shown on the schematic - trapped wire, stray blob of solder, etc.

 

So lots of current is flowing through Q880.
If you have nothing connected to the -15V output then the only places that current can go are C880, CR880 or something not shown on the schematic - trapped wire, stray blob of solder, etc.

Yeah thought so as well i am currently searching where the problem is.
So the measurements from the Collectors will come later today

 

Yeah thought so as well i am currently searching where the problem is.
So the measurements from the Collectors will come later today

Checked for shorts on the pcb and some transistors/ diodes and some capacitors.
All od the checked work fine.
No clue ... Will check everything tomorrow.

 

Why is your AC power in only measuring 96V? What do you have the variac set at?

 

Why is your AC power in only measuring 96V? What do you have the variac set at?

AC into the variac 230V
AC out of the variac 96V

 

AC into the variac 230V
AC out of the variac 96V

Why don't you set it at 115v, like it should be?

 

Why don't you set it at 115v, like it should be?

Like i probably said in the posts above, the voltage of the +/- 30V DC rail is way above the intended specs.
So i turned it down to match the specs on the 30V rail to troubleshoot better

 

Then you really need to get the +/- 30 volt regulators operating properly first. The -30 volt regulator is primary here, and the +30 volt regulator is a mirror of the -30 volt. What voltages are you reading on the +/- 38 volt lines to ground? i.e. the voltages across C930 & 932?

 

So, you set the line voltage select for your region but only got to 96V before something bad happens?

Usually the fuse rating has to change too.

Be aware that some power supplies need a minimum load to work. I haven;t looked at this one.

 

Most of the regulator circuits (all except the +30 volt and the + 5 volt) have a resistor across the series pass element and therefore would require a minimum load to operate properly.