HRO 697 Doghouse PSU

[pwdrive]

Anyone ever managed to extract a duff mains transformer from one of these PSU's.
The mains transformer and filter choke are sealed in a potted metal box, sealed with bitumen type substance.
I need to know if the transformer is fixed within the potting box or was it just loosely placed in there prior to filling up with bitumen?

Lawrence.

[Skywave]

I know not, but the usual practice at that time implies that the latter is the most likely method.

Al.

[pwdrive]

I know not, but the usual practice at that time implies that the latter is the most likely method.

Al.

Thanks for the reply Al, the one I have at the moment has shorted turns syndrome, the bitumen cooks.
I wan't to try out an idea to remove which consists of the following (don't try this at home folks)

Short all secondaries out, connect mains lead direct to primary via 13A plug with 13A fuse fitted, take outside and prop up upsidedown on bricks, plug into 13A extension lead, plug extension lead in inside house, stay inside house and hopefully watch the transformer plop out. Failing that it will be a blowtorch job. When I was an apprentice we did this with an oil filled transformer just to see what would happen, the results were spectacular to say the least. (don't try this at home either)

I would really like to restore this PSU.

Lawrence.

[tiv48]

best to remove transformer from the set .put it in the oven with somethig to catch the crud transformer will fall out.
the save up £xxx for a new cooker before shmbo finds out
rob t

[pwdrive]

best to remove transformer from the set .put it in the oven with somethig to catch the crud transformer will fall out.
the save up £xxx for a new cooker before shmbo finds out
rob t

Hi Rob t, we only have a small table top oven, I have wired up for a full size oven but not got so far as buying one yet, I am under constant pressure from my other half to get the new oven purchased and installed also a new fridge. What you suggest is a valid thought though.
The said transformer is in a seperate PSU unit, the top of the enclosure is open and filled with the original bitumen/tar like substance so the receiver it supplies (The HRO) won't have to undergo any stress, just the 697 power unit which needs a full rebuild anyway, fortunately it only consists of a switch, 80 type rectifier, choke and an 8+8+8 uf, the caps being in one can which I can restuff no problem. The choke is potted in the same box as the transformer.

Lawrence.

[pwdrive]

Talk about can't see the wood for the trees, I have just had a reply on another forum from someone who has managed to extract the old transformer from his 697 PSU...A camping stove..

Lawrence.

[Skywave]

All of which goes to prove, yet again, that there is not one problem in the repair and restoration of popular classic vintage receivers that someone, somewhere, hasn't met before. The problem then is finding that person: which is where the 'Net proves to be so useful!

Al.

[pwdrive]

It does indeed..

Lawrence.