Ampeg V4 shorted diodes- primary OT

[Normybaby]

have a 70’s Ampeg V4 with no history. It was plowing the fuses; I narrowed it down to the two pairs of diodes D7 – D10 tested as a short. When I disconnected the diodes the fuses held and the amp powered up with all of the correct voltages (no power tubes) One of the power tubes (7027) was missing (might have been the culprit). I’m waiting to receive a new tube to try everything under power.
Does the amp really need these diodes; are they there to prevent a catastrophic failure if the power tubes shorts?????
If so, I’m have trouble finding the exact value replacements
Thanks
http://v4bpream

[Bruce / Mission Amps]

have a 70’s Ampeg V4 with no history. It was plowing the fuses; I narrowed it down to the two pairs of diodes D7 – D10 tested as a short. When I disconnected the diodes the fuses held and the amp powered up with all of the correct voltages (no power tubes) One of the power tubes (7027) was missing (might have been the culprit). I’m waiting to receive a new tube to try everything under power.
Does the amp really need these diodes; are they there to prevent a catastrophic failure if the power tubes shorts?????
If so, I’m have trouble finding the exact value replacements
Thanks
http://v4bpreamI'll have to look at the schematic but if they from the plates to ground with the cathodes connected to the plates, they are suppression-snubber diodes used to short out flyback voltages from the OT if there is no load on the OT.
In that case a string of three 1N4007s on each plate side of the OT is good enough.

If it is the main rectifier block you are talking about... then the 1N4007s are still OK too but use eight total with two in each leg of the FWB.

[J Martin]

You have an amp blowing diodes and you are only replacing one power tube? How do you know it will match the other tubes? I have fixed a whole lot of V4's and in my experiance people tend to leave the tubes in them until they are ready to vaporize. Of course, I stock output transformers for them so they can always fixed. Check for carbon tracking where the missing tube was also. The early 70's models are happier with 1K screen resistors. Later models had a different screen supply.

[Normybaby]

Sorry, I thought I attached a schematic with the diodes circled. Yes these diodes are connected directly to the ends of the OT prim. (the other side of the plate resisters). The reason I'm buying just one tube (these tubes are expensive) is to see if everything works; I'm doing it for a friend who wants to sell this beast on ebay.
Thanks guys