Hi.
Today a friend brought me his Fostex DMT-8VL (Digital Multitrack Recorder), 'cause it wouldn't turn on.
After taking a look at the PSU, I found that the primary winding on the transformer went open.
What are the odds for this to happen?
Does anyone know where to get a new PSU-trafo for the DMT-8VL?
Or how to repair the old one?
And: does anyone have the schematics for the PSU?
Thanks in advance,
Phantombox
Today a friend brought me his Fostex DMT-8VL (Digital Multitrack Recorder), 'cause it wouldn't turn on.
After taking a look at the PSU, I found that the primary winding on the transformer went open.
What are the odds for this to happen?
Does anyone know where to get a new PSU-trafo for the DMT-8VL?
Or how to repair the old one?
And: does anyone have the schematics for the PSU?
Thanks in advance,
Phantombox
Check if there is a thermal breaker in the trafo. Sometimes deep in the winding itself...
Follow the secondary and You'll find a bridge / smoothing capacitors and after that a voltage regulator. The regulator and the capacitor voltage can give You a hint of the voltage needed. If it is an SMPS PSU, it's better to replace it.
Follow the secondary and You'll find a bridge / smoothing capacitors and after that a voltage regulator. The regulator and the capacitor voltage can give You a hint of the voltage needed. If it is an SMPS PSU, it's better to replace it.
Hello MAAC0.
Thanks for your reply.
It is not an SMPS PSU. all diodes on the bridges as well as caps and regulators have been checked and are OK.
The problem is definitively on the trafos primary winding.
And you saying that sometimes a thermal breaker is on the winding makes sense to me (kind of), but that it could be deep inside the winding itself is not really encouraging...
Do you know - by any chance - how many windings should be there on the primary for 110V? And if its separate from the secondaries (there are 4 of them)?
Also, I would have to separate the metal core from the coil(s) and this core is made of laminated metal sheets in "E" form and then covered with varnish...
I attached some images of this transformer so you can take a look.
Thanks for your reply.
It is not an SMPS PSU. all diodes on the bridges as well as caps and regulators have been checked and are OK.
The problem is definitively on the trafos primary winding.
And you saying that sometimes a thermal breaker is on the winding makes sense to me (kind of), but that it could be deep inside the winding itself is not really encouraging...
Do you know - by any chance - how many windings should be there on the primary for 110V? And if its separate from the secondaries (there are 4 of them)?
Also, I would have to separate the metal core from the coil(s) and this core is made of laminated metal sheets in "E" form and then covered with varnish...
I attached some images of this transformer so you can take a look.
Attachments
Number of primary turns for 110V depends on the details of the transformer design. It will be a separate winding from the secondaries.
Thermal breakers in windings are intended as a last ditch safety feature and are not resettable.
You need to find a replacement transformer, or find someone to rewind it for you.
Thermal breakers in windings are intended as a last ditch safety feature and are not resettable.
You need to find a replacement transformer, or find someone to rewind it for you.
If you fix or replace the transformer check the power supply capacitors, bridge etc for faults or you might blow the new transformer too !
As the transformer is Kaputt… You could attempt to carefully disassemble / break the plastic covers. Sometimes there is a small piece of wire near the connectors You can fix. If it is deep inside the winding, only rewinding is the cure. I believe the problem is on the second image on the right solder. Brown and White seems to be the primary. Follow the connector on the board, or measure with a DVM from the mains plug to this connector if there is continuity (Disconnected from mains and On / Off switch in On position !!). Anyway, in order for rewind it must be disassembled... but don't break or unwind the windings as the rewinder needs to count them. Don't use a knife in order not to damage more windings. Use a small plier and break the plastic carefully. With patience perhaps You can save it.
- Status
- Not open for further replies.